CROSS REFERENCE TO RELATED APPLIC ATION

This application claims priority from U.S. Provisional Application Serial No, 61 /885,57 1 filed October 2, 2013, which is incorporated herein by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

This work received support from NIH Grant AG T3328 and NIH Grant AG03049S. The government may have certain rights in the invention, introduction

Approximately 4 million Americans suffer from Alzheimer's disease (AD), a progressive neurodegenerative disorder with an estimated annual healthcare cost of $100 billion. AD can involve the appearance of distinct abnormal proieinaceous deposits:

extracel lular amyloid plaques that are characteristic of AD. and intracellular neurofibrillary tangles, which can also be found in other neurodegenerative disorders. Accumulation of amyloid beta (Αβ) can be an initiating event in the pathogenic cascade of AD. An

overexpression of amyloid precursor protein (APR) is characteristic of Down Syndrome (DS), and early onset AD has been shown to be present in these patients (Teller, J.„ Nature Med. 2, 93-95 (1996); Leraere, C, et ai. Neurob Disease 3, 16-32, .19%). europathologicai criteria for AD currently reiy on densities of senile plaques (SPs) and neurofibrillary tangles (NFTs) to differentiate AD and aging. The presence of SPs and NFTs in non-demented older adults can represent AD at a stage prior to clinical expression (Price, J,L„ et ai. Neurobiology of Aging 30, 1026-1036, 2009). Amyloid formation can commence prior to the start of a nenrodegenerarion phase. -

68: 1205-1212,. 2007); ^!S F-FDD (2-(W _. 6- (2-[l 8FjfluoroethylXmethyl)aramoj-2- naphi y1}eihyli<.iene)inaloi) nitrile _; (Shoghi-Jadiii ., et al.. Am 3 { C]4-M-methyIamino-

' -hydroxy sti ( ^" Verhoeff, N.P., et al.. Am.

-595, 2004) and ^!ii F-AV-45

(Hsiao, I.T., et a!.,

Eur. J. Much Med. Mol Imaging 39, 613-620, 2012) have been investigated in humans as probes for PET imaging of Ap. in addition, [ ^{'f 2} I/ ^s -¾|- ^' i7.DM ([ ^{ί Ι5} ϊ/ ^ι ¾]2«(4'-

Zhuang, Z.P., et a!, J. Med. Chera. 44: 1905-1914, 2001 ) and ^i2S i-I PY <{ ^U H) Wodo-2-(4'-dtmethy}amino-)phenyl-imtd82o l _> 2-a]pyridme,

2002) have also been investigated for SPECT applications. While ^{,: i} C-P.!B has been most intensely studied, »«F-AV-45 ((Ε)-4-(2- 6-(2-(2- 2-({; I SP]- fl«o.o ethoxy}ethoxy)ethoxy) _. pyridia-3-yl)vtnyI)-N-methyl benzenamine,

approved by FDA for Ap Imaging, Other examples of !igancSs for Αβ aggregates include

(BAY94-



ucl. Med, 50: 1887- 1894, 2009; Cui, M., et a!., J. Med, Chem. 55, 9283-9296, 2012),

However, each of (he established ligands. for Ap aggregates has its drawbacks. For example, ^H C-P1B, S8-1.3, and ' F-AV-45 each exhibit low biological half-lite in serum. While metabolites of PiB have been posiulaied not to penetrate the brain (Nordberg, A, Lancet Neurol. 3, 51 -527, 2004; Mathis, C„ et al J. Med. Chem. 46, 2740-2754 2003), two metabolites of ^!:S F-AV-45, i.e.,

been shown io permeate the brain (4.5% injected dose/gram (I /g) and 3.3% i.D g

respectively, at 2 mm in normal mice) thus complicating analysis (Choi, S.R., et al, J, Nucl Med. 50, 1887- 1 894, 2009). Systematic investigations of PIB binding (at the tracer

cooce.ntratio.ns achieved during in vivo imaging scans) to human neuropathologies ^' ! brain specimens indicated PiB binding to classical plaques, neurofibrillary tangles, and cerebrovascular amyloid angiopathy (CAA) that was not disp!aceable, indicating limited utility of PiB to diagnose and monitor progression of the disease, (Lockhart, A.., et ai.. Brain 130, 2607-2615, 2007), FDDNP has been shown to bind to neurofibrillary tangles and prion plaques in addition to fibrillar Αβ, demonstrating a lack of specificity towards probing AD (Nordberg, A., Lancet Neurol. 3, 519-527, 2004; Agdeppa,, E., et ai. J. Neuroses. 21 , RC 189, 2001 ; Agdeppa, E., et af, Neuroscience I I?, 723-730, 2003). FDDNP has been shown to bind both BS i and BS3 sites with low affinity (Ye, L„ et al. J. Biol. Chem. 280, 23599-23604 2005). US Patent 8, 163,928 to Gravenfors, assigned to AstraZeneea, discloses structure

wherein: l can be, inter alia, CVC¾ ftuoroalkoxy; R2 can be H; Q is an aromatic sing; X I can be C; X.2 can be , X3 can be C and X4 can be C; and R3 can be (0-3 aifc.ylte. This

patent includes

structure disclosed iti US Patent 8, ^' l 63,928 has only a bond linking the benzothiazole moiet and the pyridine moiety. i ^S F-agents such as flutemeiarnoi i ^ss F-PlB), lorbetaben (BAYER.94-91.72} and ilorbeta.pir (AV-45 (Choi, S/R., ei aL J. ach Med, 50, 1887- 1894, 2009; Zhang, W., NucL Med. Biol. 34, 89-97, 200?) show high levels of nonspecific white matter retention that can be attributed to high lipophiiieity. This high level of nonspecific retention can. limit the sensitivity of PET imaging in a prodromal phase of disease when plaque levels are low. Combined with the possibility that these agents couid be targeting the same binding site on Αβ, the diagnostic potential of existing imaging agents to segregate patients at earlier stages of the disease to benefit front available therapeutics is debatable, P1B, AV-45, and other agents have beers known to bind weakly to amorphous cortical plaques (Ikonomovtc, M.D., et a.L. Brain 13 ! , 1630- 1645, 2008; Baeskai, B J,, et ai„ A ch. Neurol. 64, 43.1 -434, 2007). These agents target fibrillar plaques and interact weakly with diffuse plaques that occur in. earl stages of the disease prior to clinical manifestation of symptoms.

Previous agents have shown white matter binding, which provide a challenge for analysis in early stages of AD, For example, ^{! f} C-PlB binding of cerebral Αβ was reported below the level required for detection in a patient. (Cairns, N.J,, et al,. Arch, Neurol. 66, 1557- ! 562, 2009) thus raising concerns for P1B and other agents in their sensitivit to detect AD variants characterized predominantly by diffuse Αβ plaques. Agents such as FIB and AV-45 have been postulated to bind a high affinity and low dense site on fibrils (Loekhart, A.. et aL J, Biol, Cheni. 280. 7677-7684,2005) thus raising further concerns regarding their diagnostic potential to map early stages of AD. Because the presence of senile plaques in iwn-demented older adults can represent an early manifestation of AD prior to its clinical expression (Price, J.L., et at, Neurobiology of Aging 30, Ϊ 026-1036, 2009; Morris, J.C., et al, Neurology 46, 707-719, 1996; Price, J.L. & Morris, j.C, Annals of ^" Neurology 45, 358-368, 1 99; Schmitt, F.A., et a.!.. Neurology 55, 370-376, 2000) the orientation of Αβ binding sites can also be different at earlier stages. Thus, additional iigaruls for amyloid beta are iieeded.

Summary

The present inventors have developed iracers for detecting amyloid beta (Αβ), In various embodiments, the tracers can include radionuclides for imaging using known imaging modalities such as PET scanning or SPECT scanning, in various embodiments, the tracers can have fluorescence properties, and can be used for optical imaging, in various embodiments, iracers of the present teachings can possess enhanced specificity (minimal white matter binding) and/or enhanced sensitivity compared to C-PIB or F-AV-45. In some

embodiments, a disclosed tracer can be capable of targeting binding sites different from those

U I S

targeted by C-PiB or F-AV-45, In some embodiments, a disclosed tracer can provide diagnostic PET agents for Αβ imaging at earlier stages of Alzheimer's disease compared to tracers such as C-ΡΪΒ or F-AV-45. In some embodiments, a disclosed tracer can be used to monitor efficacy of therapeutics, in some embodiments, a disclosed tracer such as, without limitation, F-AH 87, can be used for imagin and/or diagnosis of a tumor such as, without limitation, a prolactinoma, a ehrotd plexus papilloma, a low grade lyrnphbma, or a. pituitary tumor.

In various embodiments, the present teachings include, without limitation, a

com ound or a pharmaceutically acceptabl e salt thereof of structure

wherein: J can be selected from the group consisting of a halogen, hydroxy, cyano, COOR', ea ^' rboxy, amide, smmieo, niiro, NR¾ ^J and OR ⁴ ;

can be an integer from 0-4 or an integer from i-4;

can be selected from the group consisting of Cih _f O, R ⁵ , S and Se;

e ch of At, A?, and As can be independently selected from the group consisting ofH, F, CI,

0 ₂ , NHR ⁶ , 'RlO ⁹ , SR ⁵⁰ , COOR ⁿ , COR ¹² , sulfonic acid. wherein is a bond , 2-ethylideneroa!ononitrile, (li}-2-(bui-2-en-l- iidene)malon:OnitriSe, 2-((2E, E)-he a-2,4-dien- 1 -yBdene}maiononiirile, acetyl, -{OCH2- CH¾)«4- and R- ³ ; 11s can be an integer from.0-4; n can be an integer from 0-4; Xi can. be selected from the group consisting of C and N; Xj cat) be selected from the group consisting ofCHa,CH, O, NR ^W , S, Se and N:

Xi can be selected from ibe group consisting of CMi, CH, O, R ^L \ S, S and N;

X-i isC or Ci-i; Xs is C, CM. or N; wherein * is CM, X? and X4 are linked by a single bond and X? and Xi are linked by a single bond, or X is C, X2 and X4 are linked by a single bond and Xs and X are linked by a double bond, or X.4 is C, Xz and * are linked by a double bond and X? and X ^' are linked by a single bond; wherein when Xi can be C then Xi and Xs are linked by a double bond; wherein when X t can be N, then Xi and Xs are linked by a single bond; wherein when X2 can be R ^,4 ,S, O or Se, then X2 and are linked by a single bond; wherein when Xi can. be N, then X2 and Xn are linked by a double bond; wherein when X.5 can. be R ^{! 5} ,S, O or Se, then X; and X.¾ are linked b a single bond; wherein when X? can be , then X3 and X* are linked by a double bond; wherein when both the X2 and Xs are N, then X) and X2 are linked by a double bond, X2 and X are linked by a single bond, Xs and X.4 are linked by a double bond, and Xs and X _> are linked b a single bond; wherein when both the t and X2 arc N, then X≥ and X.< are linked by a double bond, X? and X-¾ are linked b a single bond, X> and Xs are linked b a double bond, and Xt and Xs are linked fay a single bond; L can be selected from the group consisting of (Ci-C4) alky I, (C C¾) cycioaikyi, (C2-

Cs) alkene (straight or branched), (Cs-Cs) aik.yne. and «2 can be aa integer from 0-4 or aa integer from 1 -4; each o Qs, Q2, Qs, Q* and Q5 caa be independently selected from the group consisting of C and , with provisos that at least two of Qi, Q2, QJ, Qit and Q? are C and at least one of Qi, Q2, Q?., Q4 and Qs is N; and

each of VR can be independeatly selected from the group consisting of H, C : liaear alk S Cz.it linear alkene, linear alkyne, C n branched chain alkyl, d-n branched chain alkene, C3 2 branched chain alkyne and C3.7 eycioaikyl aryl and a combination thereof.

In. various aspects of these embodiments _* the halogen can be selected from the group consisting of CI, F, Br and Ϊ. n various aspects, the halogen can be selected from the group consisting of F-.18, Br-75, Br-76, Br-77, 1-123, 1-124, 1- 1 25 and 1-131 , In various aspects, R ⁴ can be or comprise a .radionuclide such as a C-1 1 . in various aspects, R ^{, s} can be or comprise a radionuclide such as a C- i 1 .

In various embodiments, the present teachings include, without limitation, a compound or a pharmaceutically acceptable salt thereof, of structure

J can be selected from the group consisting of a halogen (CI, F, Br, !) or a radionuclide (such as F- i,8, Br-75, Br-76. Br-77, 1- 123, 1-124, 1- 525, 1- 131 ), hydro&y, cyano, COOR ^! , carboxy, amide, iraniino, nitro, NR ² R- ^? and OR ⁴ (with a radionuclide, such as C-1 .1 or an unlabeled counterpart); m can be an integer from 0-4 or an integer from 1 -4; Z can be selected from the group consisting of C¾, O, MR ⁵ , S and Se; As can be selected from the group consisting of

CM, OH, NO , N.H.R*, NR ⁷ R ^s ,OR ⁹ , SR ^Ki , COOR ^a , COR", sulfonic acid, wherein is a bond , 2-ethylidenemalononitrile, (£) ^« 2 ^« (but~2-en-l- acetyl, -(OCH2- CH2)R ₄ -(CH2)2-J and R ^i;? (including radionuclide); 113 can be an integer from 0-4; can be an integer from 0-4;

X( can be selected from the group consisting of C and N; Xi> can be selected from the group consisting of CM?, Of, O, NR ^!4 , S, Se and N; Xs can be selected from the group consisting of Cifc.CH, O, N '-\ S, Se and N; wherein when Kz is MR ^w , S, O or Se, then Xj and X* are linked by a single bond; wherein when Xs is N, then X∑ and are linked by a double bond; wherein when 3 is R ^S -\ S, O or Se, then Xs and X>J are linked by a single bond; wherein when X? is , then X? and J are linked by a double bond; wherein when both the X? and X-s are N, then Xt and X; are linked by a double bond, X. and X are linked by a single bond, Xs and X-i are linked by a double bond, and Xj and Xs are linked by a single bond; wherein when both the Xi and 2 are N, then Xj and X* are linked by a double bond, Xs and XA are linked by a single bond, X?. and Xs are linked by a double bond, and J and Xs are linked by a single bond; L can be selected from the group consisting of ar L (O-Cs) aikyl, (tV ⁽ ¾) cyeloalkyk

(O-Cs) aikene (straight or branched). (C2-C8) alkyne. m cm be ars integer from 0-4 or an integer from 1-4; and each of R'-R ¹ * ¹ can be independently selected from the group consisting of H, Cf-12 linear aikyl. Cz (2 linear aikene. CMS linear alkyne, Cs-a branched chain aikyl, C S branched chain aikene, C3-S2 branched chain alkyne, C3.7 cyeio !kyl aryS and a combination thereof.

In various aspects, a compound or a pharmaceutically acceptable salt thereof of these embodiments, the halogen can be selected from the group consisting of CI, F, Br and I, or selected from the group consisting of P- 18, Br-75, Br-76, Br-77, 1- 123, 1-124, 1-125 and 1~ } 31. In some aspects, R ⁴ can be or can comprise a radionuclide such as, without limitation, a C-l I . in some aspects, R ^!j can be or can comprise a radionuclide such as, without limitation, a C- ! i .

in various embodiments, the present teachings include, without limitation, a compound or a pharmaceutically acceptable salt thereof, of structure

wherein.: 2 can. be selected from the group consisting of CH¾ O, MR', S, Se and wherein *'wv is a bond; each of A j , A ₂ and Aj can be independently selected from the group consisting of M, F, CI, Bi\ I. C , OH,

NQ¾ Ni l R ² , NR¾ ⁴ ,OR-\ SR* COOR ⁷ , COR ⁸ , sulfonic acid, ^ wherein > ^»

Is bond , 2-ethyiidenenialononitri1e, (fi)-2-(but-2-en- i -y1idene)raalono trile, 2-((2E,4E)- hexa-2,4-d.ien~l -ylide«e)ma1ononitri.le, and R " (including

radionuclide); can be an integer from 0-4; m can be an integer from 0-4; Xs can be selected from ihe group consisting of C and ^* ; Xi can be selected from the group consisting ofCFb, CH, O _s ^Ui . S, Se and N;

Xs can. be selected from the group consisting of C¾, CH, O, NR ^! \ S, S.e and ; wherein when Xa is NR ^]: ,S, O or Se, then X? and XA are linked by a single bond; wherein whe Xi is , then X. and * are Jinked by a double bond; wherein, when Xs .is NIC ^■ .S, O or Se, then j and are linked by a single bond; wherein when Xs is N, then Xs and * are linked by a doable bond; wherein when both the Xi and Xs are N, then X t and X2 are li nked by a double bond. X2 and X.4 re Jinked by a single bond, X;? and X4 are linked b a doubie bond, and X.j and Xs are linked by a single bond; wherein when both the Xi and X2 are N, then s and * are linked by a doubie bond, κ and X-f are linked by a single bond, and Xs are linked by a double bond, and X i and Xs are linked by a single bond; L can be selected from the group consisting of (Cs-Os) alkyl. (Cj-C¾) cyeloalkyi. (Cz-Cs) alkene (straight or branched), (C2-CV)

alkyne,

m can be an integer from 0-4 or an integer from 1 -4; each ofQs, Qj, Qj, Qi and Q? can be independently selected from the group consisting of C and , with provisos that at least two of Qn C¾ QJ, Q and Q.s are C and at least one of QK QS, QJ. Q and Qs is N;

~ O, S, Se, ^' NR ^{i 2} , amide, maleiniide, urea, haloalkane, haloaikene, haloalfcyne;

6 Halogen, Ntb; NH ( ^l3:::: methyl ethyl, propyl or any alkyl straight or branched chain); O ¹⁴ , COOR ⁵ , COR ^l OH, NHQ (Q ^Chelator Core ( O ^' fA, DOT A, DTP A, TrigSycsne for chelation of metal radionuclide, such as an Son of gallium-67, -ga!Hum-68, an unlabeled gallium, or a paramagnetic racial which includes an ion of galiiura-67, an ion of ga!h ^' um-68, an ion of an unlabeled gallium, - indium- 1 1 i , ron~52, iron-59, ~eopper-62, - copper-64, 4hallitwn>201 , -technetium-99m, echnetium«94m, -rhenium- i 88, ~fubki.ki]¾-S2, - strontium-92, -yttrium-86 or yttrium-90, -zircon ium~86 or zirconium-89, and a paramagnetic metal ion such as, & transition metal (exemplied by iron, manganese, and a cobalt), or lanthauide metal ion, such as gadolinium); each of R^R'- and R «R ^i!> can be independently selected from the group consisting of H, Ci-jj linear alkyi, Cz-n linear aSke e, C2-12 linear alkyne. CMS branched chain atky!, Cj.-j2 branched chain alkene, CMZ branched chain alkyne and C3-? eycloalkyl aryl. 3a. A compound or a pharmaceutically acceptable salt thereof in accordance with claim 3, wherein the halogen is seiecied from (he group consisting of CI, f, Br and Ϊ.

hi some aspects of these embodiments, the halogen can be selected from, the group consisting of F-i ^' S, Br-75, Br-76. Br-77, 1.-123, 1-124, 1-125 and 1-1 1. hi some aspects, R ⁴ can be or can comprise a radionuclide, such as, without limitation, a C-I l . In some aspects, R ^VI can be or can. comprise a radionuclide, such as, without limitation., a C- 1 .1.

in some aspects of these embodiments, a compound or a pharmaceutically acceptable

cted from the group consisting of NOTA

, DOTA. (1 ,4,7, iO~tetraazacyelododeeane-

1 ,4,7,10-tetraacetic acid), DTPA (Diethylenetriaminepeniaacettc acid) and triglyeine. In some aspects, a chelator core can chelate a metal radionuclide. In some aspects, metal radionuclide can be an ion selected from the grou consisting of an ion of gallium-67and an ion of gallium-68. in some aspects the ion can be selected from the group consisting of an ion of gallium-67, an ion of gail ium-6S, an ion of an unlabeled gallium, an ion of indium- 1 1 1 , an ion of iron-52, an. ion of iron-59, an ton of copper-62, an ion of copper-64, an ion of thallium* 201 , an ion of technetium-99m, an ion of tecbnetium-94m, an ion of rhenium- 1 88, an ion. of rubidmm-82, an ion of strontiuni- 2, an ion of yttriura-86, an ion of yttrium- 0, an ion. of xirconuinv-86, an ion of xireonium-S9. In sorne aspects, the ion can be a paramagnetic metal ion. In some aspects, the ion can be selected from the group consisting of an ion of iron, an ion of manganese and an ion of cobalt in some aspects, the ion can b a tantbanide metal .ton. In some aspects, the ion can be a gadolinium ion.

in. various embodiments, the present teachings include, without limitation, a compound or a pharmaceutically acceptable sail thereof, of structure

wherein:

J can be selected from the group consisting of CI, F, Br, ! or a radionuclide (such as F- 18, Br-75, Br- 76, Br-77, 1-123, 1- 124, 1- 125. i-131 ), hydroxy, cyano, COOR ¹ , carboxy, amide, immi o, sis ro, NR ² R* and OR ⁴ (with a radionuclide, such as€-11 or an unlabeled counterpart);

ni can be an integer from 0-4 or an integer from 1 -4; Z can. be selected from the group consisting of€%,( ^' :>, N.R ^S , S and Se; each of A s, As and A3 can. foe independently selected from the group consisting ofH, C , OH, NO2, NHR ^S , NR ⁷ R ⁸ ,OR ^t> , SR ^!t) ,

COOR ¹ COR' ² , sulfonic acid, wherein k a bond, 2- ethylidenemalononitrile, (£)-2-(butr2-en-l -ylidene)malonomtrile, 2~({2E,4E)-hexa-2,4-dien- .1 -ylidene)malononitrile, acetyl, -(OCli -CHf riCHs).-,! and R ^{i ;i} (including radionuclide); u? can. be an integer from 0-4; can be an integer from 0-4; Xt can be selected from the group consisting of C and N; X,;. can be selected from the group consisting of C.H; ,CR, O, NR. ¹⁴ , S, Se and N; XJ can be selected from, the group consistin of CM. _t CH, O, NR'*, S, Se and N; wherein when X2 is NR , S, O or Se, then X2 and X are linked by a single bond; wherein when ^' X. is N, then ^' X. and X* are linked by a double bond; wherein, when X$ is NR. ¹ - , S, O or Se, then. Xj and X* are linked by a single bond; wherein when Xs is N, then. X3 and are linked by a double bond; wherein when both the X2 and Xs are . then X; and XJ are linked by a double bond, X2 and ar linked by a single bond, Xs and X* are linked by a double bond,, and X:? and Xs are linked by a single bond; wherein when both i e Xi and X." are , then Χ:Ϊ and Xi are li ked by a double bond, X? and X* are linked by a single bond, Xs and Xs are linked by a double bond, and X? and Xs are linked by a single bond; L can. be selected

2-C8 a!kene (straight or

integer from. 1 -4; each of

Qi, Qa, Q:? and Q* can be independently selected from the group consisting ofC and Ή, with ^• provisos that at least two of On Q;, Q > a dp are C and at least one of QK Q2, Qs and Q is Ni; each of ^' R^-R' ⁵ can be independently selected from the group consisting of H, Cms linear alkyl, C2-12 linear alkene, C2 2 linear alkyne, Cs-n branched chain aikyl, Cj-t?. branched chain alkene, Cs- !2 branched chai alkyne and C3-1 eycloalkyi aryl, or a combination thereof. in various aspects, A compound or a pharmaceutical ty acceptable salt thereof of these embodiments can comprise a halogen that is selected from the group consisting of Ci, P, Br and I, In various aspects, the halogen can be selected front the group consisting of F-1 8, Br- 75, Br-76, Br-??, 1-123, 1-124, 1-125 and 31. In. various aspects, R* can be or can comprise a radionuclide, such as, without limitation, a C~l 1. In various aspects, R. ^f3 can be or can comprise a radionuclide, such as. without limitation, a C-l i.

in various embodiments, the present teachings include, without limitation, a

pharmaceutically acceptable salt thereof, of structure

, wherein: Z can be selected

is a bond; each of As, Az and Aj can be independently selected from the group consisting of H, F, CI, Br, I, C , OH,

N0 ₂ , MRA NR ³ R ,OR ⁵ , SR CO R\ COR*, sulfonic acid, wherein is a bond ,2-emyiidenemalononitriie, (i?)-2-< ^' btti-2--en-l--ylidene)malononitti1e, 2-((2E,4E}~ hexa-2,4-dien-l-ylidene)malononitrile, aeeiyi-(OCi ^: i?-CI-ij}H ₄ -(Cl i2);-J and (including radionuclide); m can be an integer from 0-4; m can be an integer firom 0-4: X\ can be selected from the group consisting of G and N; XJ can be selected from the group consisting of €H:3,CH, O, NR ^!0 , S, Se and N; Xs can be selected from the group consisting of 012,0-1, O, NR ^{! !} , S, Se and N; when X2 is NR ⁱ⁴ ,S. O or Se, then Xa and 4 are linked by a single bond: when t is N, then Xj and X* are linked by a double bond; wherein, when Xj is NR. ¹⁵ ,S, O or Se, then X3 and are linked by a single bond; wherein when Xs is N, then s and X4 are linked by a double bond; wherein when both the X2 and Xs are , then X- and Xj are linked by a double bond, X2 and * are linked by a single bond, s and X4 are linked, by a double bond, and Xj and Xs are linked by a single bond; wherein when both the Xt and Xi are N, then X2 and 4 are linked by a double bond, s and X4 are linked by a single bond, Xs and Xs are linked by a double bond, and X; and Xs are linked by a single bond: L can be selected from the group consisting of Cf-Gi) alkyt (Cs-Cti) cycioaikyl, (Cj-Cg) alkene (straight or

can be an integer from 0-4 or an integer from 1-4; each of Qi, Qi, Q.5 and Q can be independently selected, from the group consisting of C and N, with provisos that at least two of Qi, Qs, Qi and Q are C and at least one of Qi, Q2, Q:> and Q4 is N; can he O, S, Se, NR ^{, ;} \ amide, raaleiraide, urea, haloalkane, haioalkene, haloakyne: s can be a halogen, M2, NHR ; R. ^!3 can be methyl, ethyl, propyl, or any alky! straight or branched chain; OR' ⁴ , COOR ^!5 , GOR ^! \ OH, HQ, wherein Q is a chelator core such as NOT A, DOT A, DTP A, Trig.iycine for chelation of metal radionuclide _; which can be, without limitation, an ion of gaiSiom-67, galliuro-68, an ttnlabcie i gallium, or a paramagnetic mesa; which, includes an ion of galiium-67, an ion of ga.lHum-68, an ion of an unlabeled gallium, or an ion of indi um- 11 1 , an ion of iron-52, an Son of iron-59, an ion of copper-62, an ion of copper-64, an ion of thaliiuni-201 , an ion of technctium- m, an ion of technetium-94m, an ion of rhenium- 1 88, an ion of rubidium~82, art ion of strontiutT)~92, an ion of yttrium~86 or an ion of yttrks ~90, an ion of 2irconitm 86, an ion of zs.rconi»ni-89, and a paramagnetic metal ion such as, a transition metai {such as, without limitation, an ion of iron, an ion of manganese, or an ion of cobalt), or a lanthanide metal ion, such as an ion of gadolinium; each of RVR ^t2 and R ^f ~R ^kl can be independently selected from the group consisting of 13, Cj- i2 linear aikyi, C n linear alkene, Ci- linear alkyne, Ci-n branched chain alkyl, C i2 branched chain alkene, Cs-n branched chain aikyne and -7 cycloalkyl aryl.

In various aspects of these embodiments _* a compound or a pharmaceutically acceptable salt thereof can comprise a halogen that can be selected from the group consisting of CI, F, Br and 1, or can be selected from the group consisting of P-18, 8r-7S, Br-?6, Br-??, I- 123. Ϊ- 124, 1- 125 and 1-131. In some aspects, R ⁴ can comprise a radionuclide such as, without limitation, a C- i 1 . In some aspects. R ¹ * can comprise a radionuclide such as, without limitation, a C- 1 .1 - in various aspects, a compound or a pharmaceutically acceptable salt can comprise a chelator core that can be selected from the group consisting of NGTA, DDT A, DTPA and triglyeine. in some aspects, a chelator core of these aspects can chelate a metal radionuclide, which can be, without limitation, an io of gailium-67and an ion of ga!lsurn-6S. In some aspects, a chelator core of these embodiments can chelate a metai radionuclide, which can be, without limitation, an ion selected from the group consisting of an ion of ga!ltum-6?, an ion of gaHium-68, an ion of an unlabeled gallium, an ion of indium- 1 1 1 , an ion of iron-52, an ton of iron-59, an ion of copper-62, an ion of eopper-64, an ton of thallium- 201 , an ton of technetium-99m, an ton of tecl.netium-94m, an ion of rhenium- 188. an ion of rubidium-82, art ion ofstrontium-92, an ion of yitrium~86, an ion of yttrium-90, an son of zircon iu.m-86, an ion of zircon ium-89. fu some aspects, the ion can be a paramagnetic metal ion. In some aspects, the ton can be selected from the group consisting of an ion of iron., an ion of manganese and an ion of cobalt. In some aspects, the ion can be a lanthanide metal ion. in some aspects, the ion can be a gadolinium ion.

In some embodiments, the present, teachings include gold tianoparticies which comprise gold conjugated to a compound described herein.

in some embodiments, the present teaching include complexes, wherein a complex comprises a compound or a pharmaceutically acceptable salt thereof described herein, and a gold nanopartiele.

In some embodiments, the present teachings include a gold nanopartiele conjugated to a compound disclosed herein. In some configurations, a gold nanopartiele of the present teachings can further comprise a Sinker, such as, without limitation, an aminothiol (Abbas, A., et al, Ltmg uir 2013, 29, 56-64). in various configurations, the aminothiol can be an aminothiophenol, in some configurtions, die aminothiophenol can be a p-aminothiophenol. In various aspects, the gold of a gold nanoparticle can be Au-199 and/or Au-1 8.

in various embodiments, the present teachings include methods of imaging distribution of amyloid beta in a sample or a -subject, in various configurations, these methods can comprise: administering a compound, a pharmaceutically acceptable sa.lt thereof or a gold nanoparticle disclosed herein to the sample or subject wherein the compound

pharmaceutically acceptable salt thereof or gold nanopattkle comprises a radionuclide, and subjecting the sample or subject to PET scanning or SPEC! scanning, in various

configurations, these methods can comprise administering a. compound, a pharmaceutically acceptable salt thereof, or a goid nanoparticle disclosed herein to the sample or subject, and applying to the sample or subject electromagnetic radiation visible and/or U V Sight of aveiength( ^' s) that is/are excitatory for fluorescence of the compound, salt thereof or gold nanoparticle. The method further include detecting Sight emitted by fluorescence of the compound, salt thereof or gold nanoparticle by known methods, such as, without: limitation, fluorescence microscopy.

In some embodiments, the present teachings include methods of imaging cardiac systemic amyloidosis in a subject, hi various configurations, these methods comprise administering an i maging effective amount of a compound, a pharmaceutically acceptable salt thereof or a gold, nanoparticle of the present teachings to the subject, and subjecting the subject to PET or SPECT scanning, or fluorescence imaging,

in some embodiments,, the present teaching include methods of inhibiting amyloid beta aggregation . In various aspects, these methods can comprise administering an effective amount of a compound, a pharmaceutical ly acceptable salt thereof or a gold nanoparticle of the present teachings, wherein the compound or salt thereof comprises at least one Se atom.

In some embodiments, the present, teachings include method of inhibiting diagnosing or monitoring progression of Alzheimer's disease. In various aspects, these methods comprise administering to a subject a compound, a pharmaceutically acceptable salt thereof or a gold nanoparticle of the present teachings, and subjecting the subject to PET or SPECT scanning, or to fluorescence imaging.

In some e mbodiments, the present teachings include methods of diagnosing or monitoring progression of a neurodegenerati ve disease, in various aspects, these methods comprise administering to a subject a compound, a pharmaceutically acceptable salt thereof or a gold nanoparticle of the present teachings, and subjecting the subject to PET or SPECT scanning, or to fluorescence imaging.

In some embodiments, ihe present teachings include methods of diagnosing or monitoring progression of cardiac systemic amyloidosis. In various configurations, these methods include administering to a subject a compound, a pharmaceutically acceptable salt thereof or a gold nanoparticle of the present teachings, and subjecting the subject to PET or SPECT scan ning, or to fluorescence imaging.

In some embodiments, the present teachings include methods for detecting or ruling out. a meningioma in a subject. In. some configurations, these methods can include

administering to a subject a compound, a pharmaceutically acceptable salt thereof or a gold nanoparticle of the present teachings. In various aspects, the compound can be targeted to any type of meningioma in the patient. An image can be acquired, to detect the presence or absence of any meningioma inside the skull or elsewhere within the patient. In some aspects, the methods can include a step of acquiring the i mage, which can be performed using an imaging method selected from PET or SPECT scanning with concurrent computed tomography (CT) imaging or magnetic resonance imaging (M ^' RI), SPECT scanning with concurrent computed tomographic imaging, fluorescence imaging, or any combination thereof

In some embodiments, the present teachings include methods for differentiating the presence of meningiomas from, other tumors types via retention of greater activity of a compound, a pharmaceutically acceptable salt thereof or a gold nanoparticle of the present teachings in meningiomas compared with other intracranial tumors, such as pituitary macroadenomas, schwannomas or ependymomas, and metastases.

acceptable salt thereof.

IS in some embodiments, the present teachings include a compound of structure

or a pharmaceutically acceptable salt thereof.

in some embodiments, the present teachings include a compound of structure

_i - _a pharmaceutically acceptable salt thereof.

hings include a compound of structure

or a. pharmaceutically acceptable salt thereof, in sorne embodiments, the present teachings include a compound of structure

r a pharmaceuticaily acceptable sail thereof.

^' In some embodiments, the present teachings include a compound of structure

or a pharmaceutically acceptable salt thereof. in some embodiments, the present teachings Include a compound of structure or a pharmaceuticaily acceptable sail thereof.

in some embodiments, the present teachings include a compound of structure

pharmaceutically acceptable salt thereof,

in some embodiments, the present teachings include a compound of structure (AM 82) or a pharmaceutically acceptable salt thereof.

in some embodiments, the present teachings include a compound of structure

harmaceutically acceptable salt thereof. in some embodiments, the present, teachings include a compound of structure

or a pharmaceutically acceptable of structure

or a pharmaceuticall acceptable sail: thereof.

.in some embodiments, the present teachings include a compound of structure or a pbarrnaceutica ^' lly iccepiable salt thereof.

in some embodiments, the present teachings include a compound of structure or a pharmaceutically acceptable salt thereof

.in some embodiments, the present teachings include a compound of structure

a pharmaceutically acceptable salt thereof.

In some embodiments, the prese nt teach ings include a compound of structure

or a pharmaceutically acceptable salt thereof. in some embodiments, the present teachings include a compound of structure or a pharmaceutically acceptable salt

{hereof.

In some embodiments, the present teachings include a compoand of structure or a pharmaceutically acceptable salt thereof. fa some embodiments, the present teachings include a compound of structure

pharmaceutically acceptable salt, thereof.

41

in some embodiments, the present teachings include a compound of structure pharmaceutically acceptable salt thereof

in some embodiments, the present teachings include a compound of structure a pharmaceutically acceptable salt thereof.

acceptable salt thereof.

In sorae embodiments, the present teachings include a compound of structure

pharmaceuiicaiiy acceptable salt thereof.

in. some embodiments, the present teachings include a compound of structure

o a pharmaceuiicaiiy acceptable salt thereof,

in. some embodiments, the resent teachings include a compound of structure

or a pharmaceutically acceptable salt thereof,

in some embodiments, the present teachings include a compound of structure

ø)· a pharmaceutically acceptable salt thereof in some embodiments, the present teachings include a compound of structure

a pharmaceutically acceptable salt thereof.

in. some embodiments, the present teachings include a compound of structure

or a pharmaceutically acceptable salt thereof.

in some embodiments, the present teachings include a compound of structure

r a pharmaceutically acceptable salt lere f.

In some embodiments, ihe present teachings include a compound of structure or a pharmaceutically acceptable saii thereof.

In some embodiments, die present teachings include a compound of structure or a pharmaceutically acceptable salt thereof.

Brief Description of the Drawings

io drawings based on multi-color originals, gray-scale versions of each color channel (red, green and/or blue) are shown, as well as a composite gray scale thai combines all 3 (RGB) color channels. FIG, I illustrates concentration dependent and saturable binding (binding constant, -i-.7nM) to preformed AjTl~42 fibrils of agent F-AI-182, of structure

FIG, 2 illustrates staining of both fibrillar and diffuse plaques ex vivo in the hippocampus and cortical region of brain sections in APPsw-i /-/PS I mice using agent F-AI- 182. Tissue sections were immunosfained with mouse monocional antibody and visualized by donkey-anti-mouse Alexa 568 (positiv control). Arrows indicate labeling of Ap plaques (arrows, diffuse; arrow head, fibrillar).

Biodistribution studies with HFLC-purifted '*P-A 82 in norma! mice revealed a transient brain uptake value of ?.28-. - 0.46% ID/g and 1 ,54 ± 0.06% ID/g, 5 min and 120 min post tail-vein injection, respectively, giving a 5 min/120 min clearance a ratio of 4,73, providing evidence for the ability of ^! *F-AI- i82 to cross the BBB and permeate into brain in vivo. ^ts F- V-45 demonstrates brain uptake values of 7,33 * 1 ,54 %lD/g and 1 .80 ± 0.07 ¾iD/g at 2 min and 120 rain post-injection respectively, thus providing a 2 rain/120 min clearance ratio of 4.07 in normal mice that lack target sites. ^' The initial data point for ¹⁸ F-Ai-I 8.2. is at 5 min compared with 2 min for ^{f 8} F-AV-45.

FIG, 4 illustrates that ^{! 8} F-AI-182 is washed out from blood (25% faster than AV-45) in absence of targeted plaques and remains non-metabolized in human serum, ^!iS F- Al- 1 82 undergoes 25% fester blood clearance from 5 min to 120 min compared with the ^!S F-A V- 45. ^S *P-AH82 sho ws facile penetration of the brain and clearance in normal mice. The initial data point for ^,$ F ^« AM 82 is at 5 min compared, with 2 win for ^S F-AV-45. FIG, 5 illustrates thai F-AI- 182 can be used to detect both, diffuse and compact Aj?> plaques in the brain cross-sections of frontal lobe of a 90-year-old female with,

nenropathologteal!y confirmed Alzheimer's disease: Left, The fluorescent probe (F-AI- 182 _» SOoM) labels both the compact fibrillar amyloid (arrow) and more diffuse beta-amyloid deposits (arrowhead); Right, Ap (10.D5, EM Lilly) iramunohistochemtsuy reveals similar beta-amyloid plaques in a section from the same tissue block as m (b); bar ~ 100 iim.

FIG. 6 illustrates real time imaging using F-AI- 182: Prior to imaging, dextran-Texas Red was injected for mapping the blood vessels. Following labeling of blood vessels, F- A.l~ 182 (2mg/kg, dissolved in D SO/PEG; 20:80) was intravenously injected. A z-stack image series was acquired from cortex surface to a depth of appro*. !OOpra using microscope LSM 510META NLO (Carl-Zeiss ine}. Multi-photon microscop in live A.P.Psw+/-/PS.l (15 months old) mice demonstrated that F-A!- 182 can label plaques in brain parenchyma and blood vessels CCAA), less than 5-mio _. post intravenous administration. The labeling of brain parenchymal plaques was visible within 10 mm, indicating facile clearance from non- targeted regions and remained labeled for at-least 30 m.in.

FIG. 7 illustrates assessment of binding sites of PIB, AV-45, and AM 82. In these studies, we used sitemap to determine binding sites on Αβ ί -42, generated a grid, then docked PIB. AV-45, and A1-1 S2 to determine rank order (AV-45 > F-Ai- 1 2> PIB) based upon th Glide score. Post docking view of PIB (left), AV-45 (Middle), and F-Al-182

(Right).

FIG. 8 illustrates staining ld)

mice using P-AI-183 of structure

Arrows indicate labeling of Αβ plaques (arrows, fibrillar plaques).

FIG. 9 illustrates detection of compact Αβ plaques in the brain, cross-sections of frontal lobe of an 88-year-old female with neuropathoiogicail confirmed A lzheimer's disease usin F-AI.- 183. The fluorescent probe (F-AI- 183) labels fibrillar amyloid (arrows).

FIG. 10 illustrates fluorescence imaging of tomor cells in vitro, labeled by uptake of fluorescent Al- i 82,

Detailed Description.

Abbreviations

Αβ Am loid beta AD AS heimers Disease

A.D E absorption, distribution, metabolism, and excretion

APP amyloid precursor protein

BBB blood-brain barrier

BS i binding site 1

BS2 binding site 2

BS3 binding site 3

^!: 'C NM.R carbon nuclear magnetic resonance

CAA cerebrovascular amyloid angiopathy

CBRA ^' D Consortium to Establish a Registry for Alzheimer's Disease

DS Down Syndrome

i ^v F NMR fluorine nuclear magnetic resonance

Ή NMR proton nuclear magnetic resonance

HP1..C high-performance liquid chromatography

f lR S high-resolution mass spectroscopy

MIRD Medical Internal Radionuclide Dose Committee

N IA-RI National institute of Aging-Reagan Institute

NFT neurofibrillary tangle

NMR nuclear .magnetic resonanc

PBS phosphate buffered saline

PET positron emission tomography

SA.R Structure-Activity Relationships

SP senile plaque

SPECT single photon emission computed tomography

WT wild type

The present teachings disclose agents that can be used for imaging cancers and neurodegenerative diseases. Reagents described herein also have therapeutic use in neurodegenerati ve diseases and cardio vascular diseases.

in various embodiments, a fiourine- 18-based PET probe can be capable of targetin high prevalence sites of Αβ and displaying faster kinetics compared to non-targeted regions, such as white matter, in various embodiments, a fiourine-18- ased PET probe can. be used for quantitative amyloid imaging for monitoring progress of Ap-trtodiiying treatments in the pre- symptomatic and symptomatic stages of Alzheimer's disease (AD), and/or premortern diagnosis of AD.

In various embodiments, the present teachings .include heterocyclic molecules (exemplified as F-Al- 182) thai can bind to Αβ aggregates in vitro with concentration

dependent and .saturable binding. For example and without limitation,, binding constants to preformed A β > . fibrils can be P-Al-182, 59±?nM; F-AI-.183, l ? oM; F-AM87, 1 ,58 n * 0,05fi , in various configurations, ihese probes cao stain both fibrillar and diffuse plaques ex. vivo in the h ippocampus and cortical region of brain sections in APPsw ^w 7PS l mice and human tissues. In some aspects, F-Al- 182 can incorporate F-1 S ( ^{! s} F; f i.¾ - I 10 min), a radionuclide for medical PET imaging (Mahmood, A. & Jones, A, Technetium

Radiopharmaceuticals. Handbook of Radiopharmaceuticals. 323-362 (2003); Eckeiman, W. The Development of 99mTc Radiopharmaceuticals for Perfusion and Biochemistry: In Technetium and Rhenium in Chemistry and Nuclear Medicine 3. M, Nicoiini, G, Bandoli and U. Mazzi (Eds.), Cortina Int., Verona, Italy, pp. 573 -580. ( 1990); Nana, R.„ et ai. A Neutral Te-99m Complex for Myocardial imaging. J. Nuci. Med. 30, 1830-1837 ( 1989); Stadalnik, R.., Kudo. M,, Eckeiman. W. & Vera, D. in. vivo functional imaging using receptor-binding radiopharmaceuticals: 99mTe-galaetosyl-neog ^' Jyeoalburam (TcNGA). investigative

Radiology 28, 64-70 (1993)). In some aspects, F-Al-182 can be used for diagnostic

assessment, of Ap burden in earlier stages of AD prior to expression of clinical symptoms. In some aspects, a radiolabeled counterpart ^ts F-Al- l 82 can demonstrate a high initial brain penetration (7.28* 0,46% %1.0 g ) of FYB mice, followed by 25 % faster clearance from the blood pool (compared with A V-45) in normal mice in the absence of targeted plaques. In some aspects, ^S *F-AW 82 can remain non-metabolized until about. 30 min (investigated highest time-point) in human serum. In some aspects, F-Al-182 can demonstrate

characteristics that enhance overall signal to background ratios and assist image analysis including lack of metabolites and high first-pass extraction, into brain of coupled with fast clearance from the blood pool.

I some embodiments, a tracer of the present, teachin gs can provide high

target/background ratios. In some aspects, multiphoton microscopy can demonstrate that an unlabeled counterpart F-Al- 1 2 of the radiolabeled PET agent can label brain parenchymal Aj ^' i plaques as well as tracked cerebrovascular amyloid angiopathy (CAA), indicating its ability to serve as a noninvasive probe for assessmen t of plaque burden in brain, i n. some aspects, these data can. illustrate a platform technology for image analysis in biomedical PET imaging, using an P- iS labeled PET agent.

In various embodiments, a functional probe of the present teachings can have hydrophobic characterfstics to cross the biood-braie barrier (BBB) and not be retained in non- targeted, regions of the brain., in various aspects, a fluorescent molecule of the present teachings can show enhanced fluorescence upon binding to fibrils, can stain both fibrillar and diffuse plaques in brain cross sections of APP/PS l transgenic mice and human AD tissues, and can show high initial penetration in the normal brain followed by clearance in the absence of targeted plaques. In various aspects, the agent can clear rapidly from other organs, such as liver and kidney, remain non-metabolized in human serum, and display modest hydrophobicity (log P 1.2) for formulation in 2% ethanol and 98% saline for intravenous injections. The scaffold of f-Al-182 can be used for interrogating AD in a prodromal phase. in some embodiments, heterocyclic small organic molecules of the present teachings can. also be used for raultimodaiity imagin of Αβ using PET Optical imaging in preclinical applications. in some embodiments, an agent can exhibit enhanced brain penetration, AfJ

interaction, and the ability to interact with highly prevalent or more-dense binding sites on Αβ. In some embodiments, an agent can be identified by either the lack of binding or reduced binding to the white matter for enhancing sensitivity of tracers for Αβ defection in human tissues. In some embodiments, an agent of the present teachings can label Ap plaques in brain parenchyma <5 rain post- intravenous administration. in some embodiments, the specificity of agents can be determined for Αβ compared to other bio arkers prevalent in neurodegenerative disorders (with overlapping symptoms) such as, tau protein, neurofibrillary tangles (NET) and Lewy body, including further -optimization of targeting properties through. SAR study. In. some embodiments, an. agent, can exceed or mimic the pharmacokinetic profiles (brain uptake and blood clearance) of ^{i S} F-AV«45, an. FDA approved agent for imaging Αβ in brain. In an embodiment, ^!ί 'Ρ-ΛΙ- 1 82 showed facile penetration of the blood-brain barrier (BBB) in in vitro targeting of Αβ in a mouse model. in some embodiments, a compound of the present teachings can be used for noninvasive assessment of Αβ in early stages of AD prior to clinical expression, and can allow therapeutic interventions for disease management. In some embodiments, a compound o f the present teachings can be used for stratification of patients in early phases of AD to allow for therapeutic interventions.

Embodiments of Αβ-Cargeted agent can include functional components including but not limited to the following examples.

An embodiment of an Αβ-targeted agent can include a benzotluaxole moiety without the methyl group on the heterocyclic nitrogen of thtoflavinT, This can allow the removal of the positive charge to increase the affinity of the probe to Αβ fibrils and enhance

ydrophobics ty to facilitate BBB penetration.

An embodiment of an Αβ-targeted agent can include modifications on the 6 ^th position of the benxothiazole ring has bee shown to impact affinity of probes for plaques.

An embodiment of an Αβ-targeted agent can include the introduction of an olefin bond between the bertzothiazole moiety and the aromatic ring to increase electron density as well as flexibility of the molecule to promote interactions with other binding sites on Ap p! amies.

An embodiment of an Αβ-targeted. agent can include substituting a basic

dimethylamino group into an aromatic ring at p-position to the olefinic carbon. In some cofvfiguraitons, this can allow an increase electron density on nitrogen.

An embodiment of an Αβ-targeted agent can include incorporation of a heteroatom, such as nitrogen in the aroraaiic ring ortho to the highly basic dimethyl-ammo group. In some configurations, this can allow better resonance stabilization of the molecule for influencing Pi-Pi interactions and can allow targeting of highly dense and moderate affinity sites on Αβ fibrils.

Methods

Methods and compositions described herein utilize laboratory techniques well-known to skilled artisans. Such technique guidance can be found in laboratory manuals and textbooks such as Specter, D. L. et al. Cells: A Laborator Manual, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, .1 98; Hedricksou et al.. Organic Chemistry 3rd edition, McGra Hill, New York, 1970; Carruthers, W. _» and Coldham, 1., Modem Methods of Organic Synthesis (4th Edition), Cambridge University Press, Cambridge, IL ., 2004; Curati, W.L., imaging in Oncology, Cambridge University Press, Cambridge, U.K., 1998; Welch, MJ,, and Redvanly, C.S., eds. Handbook of Radiopharmaceuticals: Radiochemistry and Applications, J. Wiley, New York, 2003,

In some embodiments of the present teachings, biochemical characterization of F-AJ- 182 and other molecules can by performed agents via multiple binding and competitive displacement assays using PiB. AV-45, AZD4694, and BAYER 94-9172 for evaluation of targeted sites on AjB, phosphori.raaging studies in vitro. in vivo, ex vivo binding studies of AD brain homogenates and human AD brain sections can be performed, including specificity for Afi evaluated compared with other biomarker proteins {tan, prion, TDP43,and .a-synclein) prevalent in other neurodegenerative diseases to determine target selectivity, and perform metabolite studies, in some embodiments of the present teachings, the inventors have biochemically characterized and validated agents via multiple in vitro bioassays to evaluate target sensitivity and specificity. The inventors can evaluate an Αβ-targeted agent of the present teachings to detect Afi plaques via MieroPET imaging with pharmacokinetic analysis in APP transgenic mice and their WT counterparts, investigations of the present teachings include a focused Structure-Activity Relationships (SAR) study to discover A (Marketed agents. The agents obtained from SAR can be biochemically characterized and evaluated through biodistribution and pharmacokinetic studies. The findings can be used to further characterise Afi-targeted probes such as ⁱ⁸ F-Ai- ! S2.

In some embodiments of the present teachings, heterocyclic small organic molecules can be characterized and validated through various analytical steps. In various embodiments, molecules can also be radiolabeled, HPLC purified, and undergo a chemical characterization for developing as either radiopharmaceuticals or optical probes, in some aspects, he HPLC purified organic molecules and their radiolabeled counterparts can be tested for binding affinity . The compounds can be evaluated in animal models using ei ther micro PET imaging or muldphoton imaging. The agents that can detect Αβ plaques in mice can also undergo metabolite analysis in vivo for interrogating their translational potential. The agents that remain non-metabolized in the targeted tissue (brain) can also be investigated via

pharmacokinetic studies in age-matched APP transgenic and control mice for assessing preliminary signal-to-noise ratios. in some embodiments of the present teachings, binding assays to preformed Αβ fibrils or AD brain homogenates are disclosed. in so e configurations, the present teachings .include preparation of Αβ fibrils or AD brain homogenatos. in vitro binding assays can be performed to evaluate interactions of radiolabeled peptides with fibrils of Αβ «¾> or extracts of AD brain honiogenates .{Choi, S.R., et al Preclinical properties of ^IS F~AV~45: a PET agent for Αβ plaques in the brain. J Nucl Med 50, 1887- 1 894 (2009)) in histopatbological core of the Alzheimer's Disease Research Center (ADRC), using standard procedures described in the literature (Zhuang, Z., et at Structure-activity relationships of imidaxoj _ ^' l ,2-a ^' Jpyridines as ligands for detecting amyloid plaques in the brain. J Med Chem 46, 237-243 (2003)),

In some embodiments of the present teachings, binding assays to preformed fibrils or AD brain homogenale extracts can he performed using literature procedures (Kiunk, W., et al. Uncharged thioflavin-T derivatives bind to amyloid-beta protein with high affinity and readily enter the brain. Life Sci 69, 14? I - 1484 (2001 ); Zhen, W. _» et. al. Synthesis and amyloid binding properties of rhenium complexes: preliminary progress towards a reagent tor SPEC ^' F imaging of Alzheimer's disease brain, J Med Chem 42, 2805-2815 ( 1999)). Prior to binding assays, the stock solution (2 μΜ) can be thawed. To aiiquots of this stock solution, ^{1 S} F-Ai- 182 (also exemplified for either ^! *F«Ai«l83 or ^{! S} F~A. 7) can be added at various concentrations to a final concentration of 200 nM Aj¾ fibrils or 200pL of AD brain extracts (20~2Spg), The aggregate-bound ^!¾ F-AS-182 (or other analogues) can be collected on

Whatman OF filters using Brandon M-24 ^' R cell harvester, washed, and counted in a y-eounter (Perkin Elmer), inhibition constants (Κ;) can be calculated as described previously (Han, H,, Cho, C. & Eaasbury. P.J. Technetium complexes for quantification of brain amyloid. J Am Chem Soc 1 18, 4506-4508 (1 96)). Binding assay result can assist in evaluation of target specificity.

Some embodiments of the present teachings include evaluation of binding sites, in some configurations, binding assays can be done as described above in at least Example 8 below. Fixed concentrations of Affo-tj fibrils and ¹⁸ F-A1-I 82 can be incubated in the presence of increasing concentration of cold competitors [thsoifSavin T (BS ! ), PIB (BS3 & BS! ), FDDNP (BS3 & BS I) and BSB (BS2) ^' j. Cold PIB, BSB, and FDDNP can be synthesized using published procedures. Experiments can also be performed with A V-45, BAYER 94- 9172, and AZD4694. Measurements can be performed in triplicate and processed as described in the Examples. Agents competing tor sites targeted by ^{! S} F-Ai- 1 2 can be expected to displace ^!8 P-A!-.l 82. Agents competing for different sites can he expected to have minimal effects. This analysis can identify binding site specificity on Αβ, Some embodiments of the present teachings include immunohistochemisiry and phosphorimaging of labeled probes ex vivo and in vivo,

in. various configurations, staining experiments on mice (WT and AFP transgenic) brain sections can be performed with either fluorescent Αβ-targeted F-Al-182 (exemplified for other analogues) or highly specific Αβ-targeted FII3.4 mouse monoclonal antibody conjugated to Alexa 568 (DeMattos, ft., O'deii, ., ParsadanSan, M, Holtzmao, .0, & et.al. Clusterin promotes amyloid plaque formation and is critical for neuritie toxicity in a mouse model of Alzheimer's disease. Proe Natl Acad Sci USA 99, 10843- 10848 (2002)), and phosphorimaging can also be performed using ^!fi F-A!-1 2, For in vivo experiments, '"F-AI- 182 (exemplified for other analogues) can be intravenously injected. After 2 min and up to 2h, mice (transgenic A.PP or APP PSl or WT) can be sacrificed, brains removed, dissected into two halves, processed and analyzed as described in this disclosure. Stained brain tissue sections of APPsw ^*:'* ca.n serve as positive controls and the non-stained tissue sections from brains of WT mice can. provide negative controls. Radioactive brain tissues can foe analyzed directly on a phosphori ager. ^SS F~A.1~ 1 82 (exemplified for other analogues) showing acti ity patterns consistent with the staining of unlabeled. F-Al- 182 or Α -targeted HJ3.4 mouse monoclonal antibody-Alexa 568 can be further examined. hi some embodiments, an. Αβ-targeted heterocyclic molecule can stain, or label Αβ plaques in cortical and hippocampal. brain sections of A.PPsw ^'i;'' transgenic mice compared to none or minimal interaction in WT controls. Other embodiments can include labeled heterocyclic molecules that show a correlation between inintunohistocheoristry,

phosphorimaging, and staining using Αβ-targeted HJ3.4 mouse, monoclonal antibody- Alexa 568,

Some embodiments of the present teachings include evaluation of target specificity in human brain tissues using F-A - ! 82 or other Αβ-targeted agents.

In various configurations, specificity of F-Al-182 or other agents can be interrogated. Staining using F-Al- 182 or immonohistoeliemistry can be performed using antibodies such as antibodies against Αβ (10.O5, Eli Lilly), phosphory.ialed tan (PHP- 1, Albert Einstein Medical School, Bronx, NY), ubiquitin (Dako, Glostrup, Denmark), a-synuclein (LB-3Q9, Zymed, CA), and TDP-43 (Proteintech, Inc., Chicago, II.) using established methods (e.g., Burack, .A., et at. In vivo amyloid imaging in autopsy-confirmed Parkinson disease with, dementia. Neurology 74, 77-84 (20.10)). Sections can be processed and analyzed o a Zeiss LSM 5 PASCAL confocai system coupled to a Zeiss Axiovert 200 microscope, Αβ tar e ed agents that demonstrate specificity for Αβ in brain sections of diseased subjects consistent with the expec ted regional distribution of plaques compared to their healthy controls and lack of cross reactivity with lustopathological markers (tan, TDP43; and α-synuclem) can thus be investigated.

In some embodiments of the present teachings, metabolic, stabiliiy of ^ls F~A 82 and/or other agents can be evaluated.

In various configurations, identified heterocyclic molecules can be assessed for metabolic stability for use in biomedical imaging applications both in vitro and in vivo using established procedures (e.g., Mathis, C. et at Synthesis and evaluation of ¹ 'C-iabeled.6- substituted 2~aryl ^' benzothia¾oles as amyloid imaging agents. J Med Chem 46, 2740-2754 (2003); Sharma, V . Radiopharmaceuticals for assessment of multidrug resistance P~ glycoprotem-.media.ted transport activity. Bioconjug .Chem. 15. 1464-1474 (2004)). tn some embodiments, ^ts F~Al~ 182, another agent, or a combination thereof can be incubated in either serum or human serum albumin at time points correspondin to uptake in vivo (5 min to 2 h) and filtered through filters (30kDa). Free and bound radiotracer can be calculated using previously describe methods (Bartholoma, M.D., et a!. Effect of the prosthetic group on. the pharmacologic properties of ^{l 8} F-!abeled rhodamine B, a potential myocardial perfusion agent for positron emission tomography (PET). J Med Chem 55, i 1.004-11012 (2052)), and can be analyzed by radio- TLC scanner and radio-B.PLC For in viv pharmacokinetics experiments, ^! *P-AI- ! 82 agent or other agents can be injected into mice via tail-vein, and mice can be sacrificed at the time points corresponding with, data of our biodistribution studies (5 min to 2 h). Brain tissues, liver, and kidne can be removed (liver and kidney ca be used to evaluate their metabolic stability in more stringent in vivo environments), sonicated, extracted and analyzed through radio-TLC and -BPLC. The ^iS F-Al- I 82, other agents, or combinations thereof that demonstrate stability (> 5%) at the targeted site through this analysis can be investigated further in nonhuraan primates models.

Various embodiments of the present teachings include biodisiribution and

pharmacokinetic studies of ^{! S} f-Al- lS2 or other agents in normal and transgenic APPsw ^' " /PS! mice. in various configurations- pharmacokinetic analysis of unlabeled fluorescent small organic molecules, "^-heterocyclic molecules, and/or their '^-counterparts via biodisiribution studies in age-matched APPsw ^* '' ^* transgenic mice and WT mice can be performed to determine target-specificity, and measure the detection of in vivo Αβ plaques, in APPsw ^{: i"} PS l transgenic mice versus control mice, using either raulti photon imaging or raicroPET/CT imaging system by ^iS f -heterocyclic small organic molecules. in various configurations, agents can. be evaluated in part by exploring the tissue distribution and kinetic of ^{l S} P-At- 182 or other agents in normal mice and transgenic mice. Because these heterocyclic molecules can be labeled with ^{S F using the methods described herein, biodistribution. in normal mice can be determined. In such investigations, BL/6 (control mice; ^' laconic) or A PPsw ^' ^/PS I (transgenic, Taconic) mice can be anesthetized b isoflurane inhalation and injected with ^l *F-Ai-J 82 or other agents (20 jtCi in 50-100 μ! saline) via bolus injection through a tail vein. Animals can be sacrificed by cervical

dislocation at 2, 30. 60, and 120 min post-injection (s - 2-4) and data can be quantified into %l ^' D g as described (Sivapackiam, 1, et a.l Synthesis, .molecular structure, and validation of meiailoprobes for assessment of MDR I P-g!ycoprotein-mediaied functional transport. Dalton Trans 39, 5842-5850 (201.0)). The brains can be removed and dissected into cerebellums and remaining whole brain fractions prior to weighin and counting t evaluate regional differences in the location of radiotracer in comparison with' transgenic mice. in some configurations, biodistribution. and pharmacokinetic studies can assist in pharmacokinetic analysis, in general, and in evaluation of ^!S F~Af~182 and/or oilier agents to permeate the BBB. In the absence of target, radiolabeled heterocyclic molecules can demonstrate uptake in brains of control mice, followed by washout of activity, resulting in low background signals. However, in the presence of plaques in transgenic APPsw ^" '' ^' PS i mice, enhanced accumulation and retention In brains can allow noninvasive imaging of mice.

Various embodiments of the present teachings include validation and correlation, of MicroPET imaging with ^!¾1 F-A!-182 and/or other agents, in. various configurations, validation and correlation of MicroPET imaging with ^iS P- AM82 and/or other agents can be performed in age-matched BL/6 (control) and A.PPsw ^{' "} /PS I mouse models on MicroPET/CT Focus 220 scanner. Twenty-six frames can be acquired over a 3 hour scan period with the following frame sequences; 5 1 min, 5x2 min, 5x5 min. 8x10 min, and 3x20 min. Frames of the original reconstructed PET data can be summed, and this summed image can be co-registered with C . Regions of interest can be drawn and tissue-time activity curves (TAG) can be constructed by plotting the percent injected dose per c-C- tissue (%lD/cc).

From control mice, peak activity in the brain can be detected within (he first 5 minutes post bolus injection and rapid clearance can be detected over the subsequent 2 to 3 hours. For APPsw ^':' "/PS J. mice, the early peak can be comparable in magnitude and time, but tracer clearance can be significantly slower, .reflecting binding of ^{! S} P-A1.-.1 S2 and/or ^' ther agents to j3 plaques. The differences between normal and APPs ^VPS ! mice can increase with time. This difference can be correlated with plaque load in a cohort of mice.

Various embodiments of the present teachings include SAR studies (o develop agents including but not limited to heterocyclic molecules capable of detecting Ap' plaques in early stages of AD prior to clinical expression .

In various configurations, candidate Αβ-targeied imaging agents can include but are not limited to the following characteristics: a) specific binding to Α.β plaques; b) specific binding to a prevalent binding site on AB; e) high first-pass extractio into the brain and region specific binding consistent with pathological localization of Αβ; ci) minimal binding to the white matter for sensitivity to detect plaques at earlier stages of the disease to segregate pools of patients likely to benefit from therapeutics, and e) excretion from organs of the body over a time period for I D analysis. ^i!S F-AI-! 82 as an agent demonstrates the above listed characteristics. ^iS F-A!- l82 can offer a scaffold template for further SAR exploration to develop second generation Αβ-targeted agents.

Various embodiments of the present teachings include characterization of molecules via standard analytical tools. in various configurations, these embodiments can include docking studies that can utilize Glide and A.D B calculations using QProp. Molecules can be chemically

characterized via standard analytical tools. Binding affinities with other agents, such as FIB, AV-45, and AZD46 can be compared. Molecules demonstrating different binding sites on Ap compared to these agents can be identified. Molecules demonstrating high first-pass extraction into brains of transgenic mice and low white mailer binding to nonhttman. primate or human tissues can be characterized in vivo through biochemical characterization via multiple binding and competitive displacement assays as well as through biodisiribntion and pharmacokin.eti c studies. Examples

The present teachings including descriptions provided in the Exam les, are not intended to limit the scope of any claim or aspect. Unless specifically presented in the past tense, an example can be a prophetic or an actual example. The following non-Umitiag examples are provided to further illustrate the present teachings. Those skilled in the art. in light of die present disclosure, will appreciate that many changes can be made in the specific embodiments that are disclosed and still obtain a lik or similar result without departing from the spirit and scope of the present teachings.

Example S

This example illustrates an Αβ targeted probe of the present teachings.

Utilizing the agent. F-Ai- 182, a heterocyclic molecule was synthesized vi multiple steps, purified via chromatography, crystal ized in methylene chloride and pentane mixture, and the single crystal structure was determined. F- AM 82 was further characterized via standard analytical tools, including ^l H R, proton-decoupled ^U C-NMR, ¾ NMR, high resolution mass spectroscopy iHRMS), and analyzed for uniformity using HPLC (Waters) equipped with a dual λ detector (2487) set to 280 and 364nm on a semi-preparative C- l 8 column (Vydae).

Example 2

This example illustrates ^ls F~A.M 82 synthesis and testing.

For bioassays described in following sections, '*F-A1.-182 was synthesized via standard nueleophi!ie substitution, employing 2.2,2-kryptofix ^{! si} F and Al-.l 82~tosylate analog, purified on a C- 3 8 (Vydac) column employing a gradient eluent mixture ofethanoi and water, using radio-HPLC system equipped with a radiodetector (Bioscans). The fraction at Rf" 15 min was collected, concentrated, and resusperided in PBS to 5% ethanol for all radiotracer bioassays. Furthermore, ⁵ *F-A1-1 2 was also characterized b spiking with an analytically characterized sample of an unlabeled P-Al- 182 counterpart, prior to injection on the radio-HPLC.

The agent F-Al-182 shows concentration dependent and saturable binding (binding constant, 59dc7nM; FIG. ! ) to preformed Αβϊ -42 fibrils, stains both fibrillar and diffuse plaques ex vivo in the hippocampus and cortical region of brain sections in APPsw /PS I mice (FIG. 2} and human tissues (FIG. 5), and incorporates F- l S ( F; ti£ ~-l 10 rain), a radionuclide for medical PET imaging (Mahraood, A. & Jones, A. Technetium

Radiopharmaceuticals. Handbook of Radiopharmaceuticals. 323-362 (2903); Bckeiman, W. ^" The Development of ^Wm Tc Radiopharmaceuticals fo Perfusion and Biochemistry; in Technetium and Rhenium, in Chemistry and ^' Nuclear Medicine 3, M, Nicolini, G. Bandoli and U. Mazzi (Eds.). Cortina int., Verona, Italy, pp. 571-580. (1990); Narra, R,, et al. A Neutral Tc- 9m Complex for Myocardial imaging. J. ucl. Med. 30. 1830-1837 ( 1989); Stadalmk, R., Kudo, M., Eekelman. W. & Vera. D. In vivo functional imaging using receptor-binding radiopharmaceuticals: 99mTc-galactosyl-neog!ycoalbumin (TcNOA). investigative

Radiology 28. 64-70 ( 1 93)}, The radiolabeled ^' counterpart F-Ai- 182 showed a. transient high uptake in brains (?.2&fe 0.46% %ID/g ) of FVB mice (FIG, 3), and followed by washout from blood (25% faster than AV-45; FIG. 4) in absence of targeted plaques and remains non- metabolized in human serum. The high first-pass extraction into brain coupled with faster clearance from the blood pool and. lack of metabolites offer characteristics that could potentially enhance overall signal to background ratios and assist image analysis. Multi- photon microscopy in live APPsw /PS1 ( i 5 months old) mice demonstrated that. F-Al-182 labels plaques in brain, parenchyma and blood vessels (CAA), by 5-mi.n post intravenous administration (FIG. 6). The P-AI-1.82 showed facile clearance from non-targeted regions and the plaques remain labeled for investigated time points.

Binding assays of F-Al- i 82 with preformed A^ J aggregates were performed in PBS, Following excitation a( 4l0nm _t -fluorescence spectrum of F-AI- 182 recorded In PBS containing 1% ethanol showed a broad emission peak 540-6:1 Onm with Earn at 570nm. Upon incubation with preformed of Αβ(1-42) aggregates, the peak 570 am showed remarkable enhancement in the fluorescence indicating binding t Αβ aggregates, similar to enhancement in fluorescence of thioffavin T in PBS (a positive control; data not shown). Fluorescence was not observed using Ap aggregates alone in PBS upon excitation at 410 nm (a negative control). Binding assays of the F~A.i - 182 with preformed Αβ 2 aggregates indicated a nearly saturable binding with a K<s™ 59 7nM (FIG. 1 ). Comparative analyses can be performed with other compounds such as AV-45, BAYER 94-9172, and AZD4694. An agent can be interacting with either of the two modestly hig affinity binding sites (BSI& BS2) or recognizing an entirely new site on Ap ?.. F-Ai-182 can register different complementary binding sites in relation to A|$-pathophysiology compared to current agents.

Example 3

This example illustrates ex vivo staining studies.

Ex vivo staining studies were performed on brain sections (50 urn) of an APPsw ^;';" /PS 1 mouse (24 months old) and a control WT mouse (BL/6; 24 months old) using well- established procedures. As a positive control, HJ3.4 Αβ monoclonal antibody- Afcxa 568 was used. Brain sections of APPsw ^" "" PS S ^I !CC showed abundant staining of Αβ compared with minimal levels in WT mouse (FIG, 2). Using P-AI-182 ( lOOnM, 60 min), abundant staining of fibrillar and diffuse plaques in the .hippocampus and cortical regions of brain sections in APPs ¹ ' ^" PSr ^{> ;"} mice was observed. By comparison, no staining in WT mice was seen either with F-AJ- 182 or the antibody indicating the targeting specificity ofF-Αί- ! 82. The slides were analyzed on. a Zeiss LSM 5 PASCAi.. confocal system coupled to a Zeiss Axiovert 200 microscope.

Example 4

This example illustrates biodistribution studies of ^!S F-Ai- 182.

For in vivo imaging of Ap plaques, the basic pharmacokinetic model in an unaffected normal brain involves high initial penetration of the agent, followed by rapid clearance due to lack of a binding target However, in AO brains, high initial penetration can be followed by- regional retention as the agent binds to Αβ thus leading, to differential kinetics. To accomplish this objective, biodistribotion studies of ^iS F~A.l- ! 82 were performed in normal FV mice for assessment of signal to noise ratios and clearance profiles. Brain uptake of ^{i s} F-AI-i S2 was analyzed in terms of percent injected dose per gram of the brain tissue (%!.D/g),

Biodistribution studies with FIPLC purified ^{f S} P-Al- J 82. in normal mice revealed transient brain uptake value of 7.28* 0.46% ID/g and 1.54 ± 0.06% ID g. 5 min and 120 min post tail- vei injection, respectively, giving a 5 rain/120 min clearance a ratio of 4.73, providing evidence for the ability of '*Ρ~ΑΪ- ί 82 to cros the BBB and permeate into brain in vivo (PIG. 3). This initial brain uptake value (5 min) in normal mice is approximately 15-fold high compared with our Αβ-fargeted ^¾¾f! Tc~Peptides (Harpsfrite, S.E., Prior. J., Bmz, K.., Piwtitea- Worms, D. & Sf.ran.na, V, ^!Wni Tc-Peptide conjugates for imaging β-amyloid in the brain, ACS Med Chem Lett (2013) under review). Additionally , compared to ^{! S} F-AV-45 (Liver: ! 7.0 ; 0.69 (2 min), 4.96 x 0.90 ( 120 miri); Kidney: 14.19 ± 2.34 (2 min), 2.19 ± 0.36 (120 min), ^iS E-Al- l 82 clears rapidly from, non-targeted tissues, such as liver and kidney (Liver: 16.32 ·± 1.41 (5 mm), 2.71 ± 0.2 (120 mm); Kidney: 6.76* 1 .57 (5 nun), 1.5? i- 0.08 (120 min) and these clearance profiles could translate- into better M1RD analysis, f r comparison, ^!8 F-AV- 45 demonstrates brain uptake values of 7.33 ± f, .5-4 %ID/g and 1.80 * 0,07 %lD/g at 2 rain and 120 min post-injection (Choi, S.R., et al. Preclinical properties of 18F-AV-4S: a PET agent for Abeta plaques in the brain. S Nucl Med. 50, 1887- 1.894 (2009)) respectively, thus providing a 2 min/120 rain clearance ratio of 4.0? in normal mice that lack target sites (FfG. 3). Net brain uptake of ^,t5 F-AM 82 is 1.2- fold higher than that of ^iS F- AV-45. Our data indicates a 5 rain uptake compared with a 2 min data point reported for ⁵⁸ F- AV-45 dins we do expect these 2min 120 rain ratios to be much superior, upon comparative analysis at the same time points. ^iS F-Ai- i S2 undergoes 25% foster blood clearance from 5 min to 120 min compared with the t S.F-AV-45 (FIG, 4). Compared with ^{( !} C-P!B (Mathis, C, et al. Synthesis and evaluation: of ^H C-labeled 6-subsrttuted 2-aryIbenzothiaxoles as amyloid imaging agents. J Med Ciiem 46, 2740-2754 (2003)) and ^! ¾ AV-45 (Choi, S.R., et al Preclinical propertie of ^ts F-AV-45: a PET agent for Abeta plaques in the brain. J ucl Med 50, 1 87-1.894 (2009)) that undergo facile metabolism in vivo, ^,S F-Ai-I 82 remains non-metabolized in human serum.

Example 5

This example illustrates staining experiments with an P-AH 82 agent.

Staining experiments were performed with, human brain tissues. Tissue samples wer obtained from the frontal lobe of clinically and neuropathologicaliy well -characterized cases. The neuropathologieai diagnosis of AD was based on the criteria of the Consortium to

Establish a Registry for Alzheimer's Disease (CERAD) (Mirra, S., et al. The Consortium to Establish a Registry .for Alzheimer's Disease (CERAD). Part 11. Standardization of the neuropathology assessment of Alzheimer's disease. Neurology 41 , 479-486 (1991)) or the National Institute of Aging- Reagan Institute (NIA-R ^' J) (Hyman, B. & Trojanowski, L Consensus recommendations for the postmortem diagnosis of Alzheimer disease from the National Institute on Aging and the Reagan Institute Working Group on diagnostic criteria for the neuropathologies! assessment of Alzheimer disease, J Neuropaihoi Exp Neural 56., 1095-1097. ( 1997)). For experiments, highly specific Αβ-targeted antibody (10D5, Eh. Lilly, a posi tive control, used in histopathoiogieal core of the AD.RC post-mortem eases) confirmed the presence of β plaques, Αβ-targeted F-AM 82 showed abundant staining of Αβ plaques in. the hippocampus of a 90 year-old female with AD (.FIG. 5), Additionally, P-Al-I 82 demonstrated labeling of both the fibrillar and the diffuse plaques. The ability of the P~A1~ .182 agent to detect diffuse plaques represents an. advancement to enable PET imaging of mildly demented individuals (an earlier manifestation of AD) prior io ciinicai expression (Price, J.L., et al. Neuropathology o nonderaented aging: presumptive evidence for

preclinical Alzheimer disease. Neurobiology of aging 30, 1026-1036 (2009); Morris, J.C., et at Cerebral amyloid deposition and diffuse plaques in "normal" aging: Evidence tor presymptomaiic and very mild Alzheimer's disease. Neurology 46, 707-71 (1996); Price, J.L. & Morris, J.C. Tangles and plaques in nondemented aging and "preclinical" Alzheimer's disease. Annals of neurology 45, 358-368 ( 1999); Schmitt F.A., et al- "Preclinical" AD revisited: neuropathology of cogmtively normal older adults. Neurology 55, 370-376 (2000)), thereby offering a window of opportunity for therapeutic interventions for better management of disease.

To demonstrate ability of the agent to label plaques in riva, raidtiphoion imaging was conducted in live APP/PS i 12 month old mice, post intravenous injection of F-Al- ! 82. Prior to imaging, dexiran~ ^' f exas Red was injected for mapping the blood vessels. Following labeling of blood vessels, F- AI-.182 (2mg/kg, dissolved in DMSO/PEG; 20:80) was intravenousl injected. A zstack image series was acquired ^' from cortex surface to a depth of approx. 100pm using microscope LSM 5 Ϊ0ΜΕΤΑ Nl.0 (Car!-Zeiss Inc). Multi-photon imaging in live A PP/PS i mice (15 months Old) demonstrated that F-AI- 182 labeled plaques in blood vessels (CAA) and brain parenchyma. The labeling of brain parenchymal plaques was visible within 10 min, indicatin facile clearance from non-targeted regions and remained labeled for 30 min (FIG. 6), Multi-photon imaging can be done using ^1S F-Ai- 182, other agents, or second generation agents (Bacsfcai, B,, et al Four-dimensional multiphoton imaging of brain entry, amyloid binding and clearance of an anry!oid-j) ligand in transgenic mice, Proc ati Acad Sci USA 100, 12462- 12467 (2003)).

Example 6

This example illustrates methods of assessment of binding sites.

There is an NM.R-dedueed structure in the protein data bank for A. V« (FOB .I ^' D: 2BEG). To assess binding site of PfB, AV-45, and A!-182, usin procedures described earlier in our laboratories (Sundaram, G.S.M, Marpstrite, S.E., ao, J.L., Collins, S.D. & Sharma, V, A New Nucleoside Analogue with Potent Activity against Mutant sr39 Herpes Simplex Virus- 1 (HSV-.1 ) Thymidine Kinase (TK). Organic letters (2052)), we used sitemap to determine binding sites on βί- 2, generated a grid, then docked PIB, AV-45, and AH 82 to determine rank order (AV-45 > F~At- i S2> PiB) based upon the Glide .score (PIG. 7). Ligand interaction diagram indicated that PiB 6-hydrox substitueot f the benzothazole ring forms a hydrogen bond with Lew 17 and smallest surface of hydrophobic interactions with amino acid, residues of Αβ-42. While pyridine ring of AV-45 participated in π~π interactions with Phe 19 as well as highest surface of hydrophobic interactions _* F-A.i-S.82 retained π-κ interactions but also shows intermediate hydrophobic interaction surface thus supporting the rank order of the glide score. Building on the principles that: a) jt electrons play a role in biochemical interactions (Kuropf, .A. & Dougherty, D.A, A mechanism for ion selectivity in pota ssium channels: computational studies of cation-pi interactions. Science 261 , 1708- 1710 ( 1993 )); b) Αβ recognizes planner molecules; and c) extended conjugation systems are more- likely to offer more flexibility for interaction with other sites, we can explore a focused SA.R around two sea.ffol.ds : a) slight variations in position of the heteroatoras in the six membered pyridine ring or 5-membered ring of benzothioazole in. addition to variation in number of ethy lene giyeoi moieties on the 6-position of benzothiazoie ring and b) modification of dialkyl amino grou with other functional groups.

Example 7

This example illustrates labeling of Αβ plaques in APPsw -/~ (24 months old) mice using F-AI-183,

Examples of brain tissue section staining of APPsw+Z- (24 months old) mice using F-AI-183 are shown in FIG. 8. Arrows indicate labeling of Αβ plaques (arrows, fibrillar plaques). The slides were analyzed using a Nikon Ti-E PES inverted microscope equipped with a Nikon I Ox 0.3 A Plan APO objective. Prior M l .17 ProScan flat top linear encoded stage, and Prior Lumen 200PRO illumination system, with standard DAP I and F1TC filter sets. The images were acquired using a Photometries Coo!SNAP MQ2 digital camera and MetaMorph microscopy automaton, and imaging software. Images were processed and analyzed using the Image J software package (NIH).

Example 8

This example illustrates detection of compact Ap plaques in brain cross-sections of frontal lobe by F-AI-183. F-AI-183 detected compact Αβ plaque in the brain cross-sections of frontal lobe of an 88-year-old female with neuropaihologically confirmed Alzheimer's disease as shown in FIG 9, ^' The .fluorescent probe (F-A1-J.83) labels fibrillar amyloid (arrow). The slides were analyzed on a using a Nikon Ti-E PFS inverted microscope equipped with a Nikon iOx 0.3 NA Plan APO objective, Prior il l 1.7 ProScan fiat top linear encoded stage, and Prior Lumen 200PRG illumination system with standard DAPS and FUC filter sets. The images were acquired using a Photometries CoolSNAP HQ2 digital camera, and etaMorph microscopy automaton, and imaging software, images were processed and analyzed using the Image J software package (N1F1).

Example 9

This example illustrates NMR data for some compounds of the present teachings.

25

¾ NMR (400 MHz, CDCb): 3. 1 7 is, 6H), 3.83 (s, 3Pi), 6.59 (d, /= 8.4 Hz, I H), 7,02 id, J = 9.2 Hz, ! H), 7.16 (cU -/= 16,0 Hz. I H), 7,25 (t, J 1.4,0 Hz, 2H), 7.74 (d, ./ = 8.4 Hz, i ff). 7.83 (d, J - 8.4 Hz, I H), 8.45 is, IH); '¾ NMR (100 MHz, CDCIj): 37, 14, 55.77, 104.13, 106,05, 1 15.31 , 118.33, 1 19.21 , 123.02, 134.05, 134.22, 148,93, 159.15, 1.71 ,3

26

¾ NMR (400 MHz, CDCb): 3.10 (s, 6H), 6.75 (d, J - 8.8 Hz, 1 H), 6.81 (d, J ~ 8.4 Hz, I H), 7.32 (d,. /- 16.4 Hz, iH), 7,43 (d, J - 16.4 Hz, I H), 7.81 (d, ,/- 8,0 Hz, I.H), 8, 1,8 (d, J - 8.4 Hz, I H), 8.37 (s, I H), 9.62 (s, IH): "C NMR (100 MHz, CDCb): 38.21 , 107.08, 108.21,109.62, 115,05, 116.25, 119,69, 121.37, 125.88, 126.44, 135.49, 136,1?,.136.54, 157.05, 172.69.

(F-AI-183)

Ή NMR (400 MHz, COCb): 3.15 (s, 6H), 4.28 (d, J~ 27.8 Hz, 2H), 4,77 (d, J -47.2 Hz, 2H).6.56 (ddL ,/ = 8.8, 3.2 Hz, Ill), 6.96 (d, J~ 8.4 Hz, iH), 7,14 (d, J - 16.4 Hz, IH), 7.27 (d,,/- 6.0 Hz, i ll), 7.52 (d,./- 16.8 Hz, IH), ?.72(dd, J ^■■■■ 8.6, 3.0 Hz, 2H), 8,31 is, IB); C NMR (100 MHz, CDCh): 38.12, 67,29, 67.50, 81.00, 82.70, 106.08, 107.81 , 115.05, i 19.31, 120.78, 124.98.134.41, 134,80, 136,36, 149.22, 157.85; ^iSt F NMR (282 MHz, CFCh): -224 ppm; HRMS (FAB) m/z cale. for OsHiaFNaOSe: [Μ.] ^';' 3 1.0599; found:

3 1,0602,

^! H NMR (400 MHz, CDCh): 3.24 (s, 6H), 3.87 (s, 3H), 6.93 (d,J=== 7.2 Hz, ! H), 7.16 is, 2H), 7.50 (s, IH), 7,70 (d,J- ,4 H¾ IH), 8.50 (s,2H); ⁱ³ C NMR (100 MHz, CDCh): 37.27,55,52, 107,18, 114,85, 117.07, 121.54.124.81, 128.10, 132,81, 156,54, 159.16.

161.64, 172.49

Ή NMR (400 MHz, CDCh): 3.1? (s, 6H}, 6,83 (dd,,/- 8.0, 1.6 Hz, IH), 7.30 (s, IH) 7.40 (d, J - 8.8 Hz, 211), 7.82 (d, J- 8.8 Hz, H I), 8.75 (s, 2H), 9.63 (s, 1 H); ⁿ C NMR (100 MHz, CDCb): 39-28, 109.72, 115.23, 117.66, 121.91,.125.92, 126,55, 133.49, 156.95, 157.07, 157.49, 161.59, 172.49

^! H NMR (400 MHz, C Cb): 3.24 (s, 6Ή), 4.28 (d, J = 27.6 Hz, 2H), 4.80 (d _s « ⁱ -4?,2 Hz, 2H).6.97 (d, ,/ ^::: 7.2 Hz, 1 H), 7.17 (bs, 1 H), 7.50 (s, i.H), 7.72 (d, J --- 7.2 Hz, 1 M), 8.52 (s, 211); »¾ NMR (100 MHz, CDCb): 37.28, 67.31, 67.5.1, 80.97, 82.67, 107.95, 110.00, 115.36, 117.04, 121.46, 125.01, 128.78, 133.01, 156.47, 156,57, 157.93, 158.57, 161.66, ! 72,72 ; ^,9 F NMR (282 MHz, CFCb): -224 ppm: HR.MS (FAB) m/z ca!e. for CnHisFN-tOSe: f f 392.0594; found; 392.0603.

fH NMR (400 MHz, CDCb): 0.12 (s, 6H), 0.92 (s, 9H), 3.24 (s, 6H), 4.01-4.03 (m, 2H), 4.09-4..12 (m, 211), 6.94 (dd, ^::: 8,8, 2.4 Hz, IH), 7,17 (d, J ^~ ~ 1.2 Hz, 111), 7.50 (d, J - 2.4 Hz, IH), 7.70 (d, J - 8.4 Hz, IH), 8.53 (s, 2H) ; ^! C NMR (100 MHz, CDCb): 1.04, 42.24,68.44, 76.22, ί 10.76, 1.12.22, 1.21.21, 124.34, 129,86, 140.02, 142.74, 149.96, 152.44, 162.68, 172.86.

Ή NMR (400 MHz, CDCb): 2,43 (a, 3H), 3.24 (s, 6H), 4.20 (bs, 2H), 4.4 S (bs, 2H), 6.71 (d,J=9,0 Hz, IH), 6.81 (d,J=9.0Hz ₅ IH), 7.17-7.41 (m, 4H), 7.65-7.69 (m, IH), 7.82 (d, - 7.6 Hz, 2H),8,52 (s, 1 H), 8.66 (s, 1 B) ; C NMR (100 MHz, CDCb): 2 ,64, 37.23, 5,72,68.06, .108.04, 108.25, .1.15.08, 115.50, \ 16.88, 121.41, 124.78, ^{ 24.96, 125.25, 128.00, 129.85, 131.04, 133.12, 144.95, 156.60, 157.35, 158.59, 162.68, 171.84

^! H NMR (300 MHz, CDjCN): 8.25 (s, 1 ii), S.08 (d, HI), 7.63 (d, 1H), 7.27 fdd, 11:1), 3.92 (s, 3H)

Ή NMR (300 MHz, acetone-ds): 10.00 - 9.00 (br, s, 1H), 8.51 (s, 1H), 8.09 (d, 1H), 7.63 (d, lM),7.28(dd, !H)

Ή NMR (300 MHz, acetone-*): 8.55 Cs, IE), 8.i6(d, 1 H), 7.85 id, 1 H), 7.39 (d, 1H).4,93 -4.29 im, 4H).

>H NMR (300 MHz, dmso-dft): 8.59 (%, ! 11), 8.25 <d, 2H), 8.08 (d, 2H), 8.00 (d, 1H), 7.77 (d, 1H), 7.18 (dd, I H), 3.87 (s, 3H)

Ή ^" M (300 MHz, aeetone-d*): 9.00 (br, s. Hi), S.39 (s, iH), 8.30 (d, 2H), 8. IS (d, 211), 7.94 id, ί fit.7.52 (<J, 1 !K 7.14 (dd.111). MS(LRES!) m¾ - 304.0547 (Μ-ΗΓ),

>H NMR (300 MHz, acetone-d«): 8.39 (s, IH), 8.31 (d, 211), 8.18 (cl 2H), 8.02 <d, IH), 7.73 (d, IH), 7.25 (del, IH), 4.94 - 4.36 (m, 4H). MS(LRHSI) m/z - 350.2 (M+tf),

^! H NMR (400 MHz, CDCb): 3.15 (s, 6H) _? 3.88 (s, 3H), 6.55 (d, .1 - 8.4 Hz, IH), 7.04 (d, J - 9.2 Hz, ill), 7.14 id, i == 16.0 Hz, Hi), 7.29 it, J === 14.0 Hz, 2H), .71 (d, J = 8.4 Hz, ί H), 7.83 id, J = 8.4 Hz, IH), 8.29 (s, IH); ^! ¾ NMR (100 MHz, CDCb): 38.14, 55.79, 104.13, 106.05, 115.31, 118.0, Ϊ 19.41 , 123.02, 134.08, 134.22, ί.48.93,.159.15, 165,33

Ή NMR (400 MHz, CDCb): 3.03 (s, 6H), 6.65 (d,J- 8,4 Hz, IH), 6,88 (d,J- 7.6 Hz, I H), 7.24-7.32 (m.2H), 7.66 (d, J - 8.4 Hz,.2H), 7.90 (d, 7- 7.6 Hz, I H), 8.29 (a, I H), 9.82 (s, IH); ⁿ C NMR (J 00 MHz, CDCb): 38.04, 106.51,.107.08, 116.11, 118.03, 119.58, 123.17, 134.13, 134,96, 135.60, 147.47, 149.36, 155,90, 159.25, 163.97.

.41-182

^! H NMR (400 MHz, CDCb): 3.14 (s, 6H), 4.28 ( , J --- 26.0 Hz, 2H), 6.65 (d, J - 8.4 Hz, 1 Sri), 4.7? (d, 49.6 Hz, 2H), 6,55 (d, J » 8.8 Hz, ΪΗ), 7.08 (d, J ^~ 9.2 Hz, IH), 7, 13 (<I ./ - 1 .4 Hz, IH), 7.26-7.33 (m,2H), 7.70 (d, " 8.4 Hz, ί B), 7.84 (d _s J - 9.2 Hz, IH), 8.29 (s, I M 9.82 (s, IB); C NMR (100 MHz, CDCb); 38,10, 38,13, 67,63, 67,84, 81.01, 82.70, Ϊ05.32, 106.05, 115.67, 117.86, 1.19.34, 123.12, 134,23, 134.33, 148,98, 156.36, S 59.17, 165.74; ^μ> ¥ NMR (282 MHz, CFCb): -224 ppm; FIRMS (FAB) mtz calc. for CisHtsFNsOS: {MY 343.1 55; found: 343.1.152,

Ή NMR (400 MHz, CDCb): 3,17 (s, 6H), 3.96 (s, 2H), 4.20 (s, 2H), 6.56 (d, J - 8.8 Hz, ill), 7.06 (d, .,' ··· 8.4 Hz, IB), 7.j id../ ·· 16.4 Hz, 1 H), 7.24-7.32 (in, H), 7.72 (d, J-~ S.8 Hz, 2H), 7.82 (d, - 8.8 Hz, 1H), 8.29 (s, IH).

Ή NMR (400 MHz, CDCb): 2.42 (s ₍ 3H), 3. 6 (s, 6H), 4.22 (s _: , 2H ), 4.41 (s, 2H), 6.56 (d, 8.8 Hz, 111), 7.06 (d, 8,4 Hz, IH), 7.14(d, J - 16.4 Hz, 1 H), 7.24-7.32 (m, 211), 7,72 (d,J- 8.8 i¾ 2H), 7.82 (d, J - 8.8 Hz, H i), 8.22-8.43 (m, 3H), 8.51-8.92 (in, 2H).

^! H NM (400 MHz, CPCb): 3.14 (s, 6H) ₅ 3,61-3,80 (n% 611), 3.82 (s, 2H), 4.22 (s, 2H) ₍ 4,44 (d ./ - 49.4 Hz, 2M), 6.55 (d, 8,8 Hz, 1 H), 7.08 (d, ./ - 9.2 Hz, 5 H), ?.13 (d _s i - 16,4 Hz, i F!), 7.26-7.33 (m,2H), 7.70 (d, J ^« 8.4 Hz, 1 H), 7,84 (d, J- 9.2 Hz, 1.H), 8.29 (d, J === 9,2 Hz, 2H); ⁱ⁹ F N R (282 MHz, CFCb): -224 ppra; HRMS (FAB) ro/z caic. for

CssHtsFNsOsS: [ J ^* 430.1726; found: 430, 1780.

Example i O

This example illustrates imaging of cancer ceils using Αί- 182 as a fluorescent probe.

5% C02 for 30 mm, and examined using a Nikon Ti-E PFS inverted, high resolution microscope equipped with a Nikon (Magnification: 20x) Flan. APO objective. Prior H 117 ProScan Oat top linear encoded stage, and Prior Lumen 200PRO iliu.rainat.ion s stem with standard DAP! and FITC filter sets. Results are shown in FIG. 10. Top row: Live Cell imaging of Human Glioblastoma (U ^' 8?) Cells Using Ai- 82, Middle row: Live Cell imaging of Human Pancreatic Cancer Cells (PANC.I) Using Ai- 1 82, Bottom row; Live Ceil Imaging of .Human Pancreatic Cancer Cells (Mia PaCa-2) Using AM 82. Note accumulation of the probe within cells.

All references cited herein are incorporated by reference, each m its entirely.

Applicant reserves the right to challenge any conclusions presented by any of the authors of any reference.