FIELD OF THE INVENTION

[001] The present invention relates to the field of marking at least one object or a subject of interest in situ during an ongoing event, for tracking and/or future detection purposes. Specifically, the present invention is directed to a method for marking at least one object or a subject of interest using at least one non-toxic composition comprising at least one photoluminescent compound, and detecting and/or tracking the at least one marked object or subject of interest using at least one specialized detection device.

BACKGROUND OF THE INVENTION

[002] It may be sometimes desirable to mark and detect (or track) the movement of objects or subjects of interest. For example, it can be desirable to mark a subject of interest or a body portion thereof during a civil or other disorder or disobedience, such as a riot or a demonstration, at a certain location within a city or non-urban terrain. Then, it is possible to covertly track the subject of interest movements for later identification and possible detention. Successful detection and/or tracking, which can lead to the identification of the subject of interest can be performed by providing a marking compound which is difficult to detect by the naked human eye.

[003] For this purpose, a marking material can be employed, which contains for example an infrared (IR) fluorescent agent. Some molecules and minerals (among them mineral pigments) exhibit infrared (IR) fluorescence. This phenomenon is similar to visible light fluorescence, where a beam of ultraviolet light produces visible light emission. In the case of infrared fluorescence, a beam of visible light generates an emission of infrared radiation, which can be detected by special infrared detectors (e.g., IR cameras).

[004] Compositions including infrared fluorescent agents for various medical and practical uses have been previously reported. For example, US Pat. No. 10,927,267 discloses a composition comprising a pigment, wherein the composition is suitable for roofing applications, including coating a surface that is exposed to the sun, wherein the pigment comprises particles that fluoresce in sunlight, thereby remaining cooler in the sun than coatings pigmented with non-fluorescent particles. The particles comprise solids that fluoresce or glow in the visible or near infrared (NIR) spectra, or that fluoresce when doped.

[005] The use of infrared fluorescent agents and/or IR cameras for tracking the movements of objects have been previously reported. For example, US Pat. No. 7,304,300 discloses a method of tagging an object for later tracking including providing a material capable of being applied to the object and comprising deuterium, and detecting the material from a distance using an infrared camera that is not a microscope.

[006] US Pat. No. 7,483,049 discloses a system for automatically videoing the movements of one or more participants or objects as they move about within the entire performance area of a sporting, theatre or concert event, throughout the entire time duration of the event, comprising providing fluorescent markers in advance to the event, wherein the markers are adhered onto one or more locations on each participant or object to be tracked, where said markers are detectable by said first or said second set of stationary cameras.

[007] However, in order to successfully mark and detect subjects or persons of interest without causing them any harm, the marking material being employed is preferably required to be non-toxic and visibly inconspicuous by the naked human eye. These requirements are not met with the existing known materials and/or methods, and therefore they are not suitable for these purposes.

[008] Thus, there is an ongoing need to provide compositions and methods for marking and detecting the movements of objects or subjects of interest, without causing them any harm, using non-toxic and visibly inconspicuous compounds.

SUMMARY OF THE INVENTION

[009] The present disclosure is directed towards compositions and methods for marking, detecting and/or tracking the movement of objects or subjects of interest, without causing them any harm, using non-toxic compositions comprising photoluminescent compounds (such as for example, infrared fluorescent or phosphorescent compounds) wherein said compositions can be adjusted to be visibly inconspicuous to the naked eye under visible light. Thus, the functions of marking and/or detecting can be performed in a covert manner.

[010] Thus, according to a first aspect, there is provided a composition for use in marking in situ during an event an object or a subject of interest for tracking and/or future detection, the composition being non-toxic and comprising at least one photoluminescent compound, wherein the at least one photoluminescent compound absorbs radiation in the ultraviolet (UV) spectrum, visible light spectrum, or both, wherein the photoluminescent compound emits radiation in the infrared (IR) spectrum, visible light spectrum, or both, and wherein the photoluminescent compound is a fluorescent or phosphorescent compound. According to some embodiments, there is provided a composition for use in marking in situ during an event an object or a subject of interest for tracking and/or future detection, the composition comprising at least one photoluminescent compound, wherein the at least one photoluminescent compound absorbs radiation in the ultraviolet (UV) spectrum, visible light spectrum, or both, wherein the photoluminescent compound emits radiation in the infrared (IR) spectrum, visible light spectrum, or both, and wherein the photoluminescent compound is a fluorescent or phosphorescent compound.

[Oil] According to some embodiments, the photoluminescent compound comprises an IR fluorescent compound selected from the group consisting of plant color reagents, food coloring dyes, fluorescent nanoparticles, phosphorescent pigments, non-toxic reagents, and combinations thereof.

[012] According to some embodiments, the plant color reagents are selected from Chlorophyll, Spirulina platensis, natural fruit extracts, and combinations thereof. According to further embodiments, the plant color reagent comprises at least one type of Chlorophyll.

[013] According to some embodiments, the food coloring dyes are selected from the group consisting of Allura Red; Sunset Yellow, Brilliant Blue, Fast Green, lemon yellow Tartrazine,

Erythrosin, Ponceau 4R, Amaranth, or a combination thereof.

[014] According to some embodiments, the fluorescent nanoparticles comprise carbon dots (CDs). [015] According to some embodiments, the photoluminescent compound comprises a phosphorescent compound selected from the group consisting of strontium aluminate, crystals of zinc sulfide doped with copper, or a combination thereof.

[016] According to some embodiments, the at least one photoluminescent compound is present in an amount selected from the range of 0.0001-10% w/w of the composition, including each value and sub-range within the specified range. According to further embodiments, the at least one photoluminescent compound is present in the composition in an amount selected from the range of 0.0001-0.001, 0.001-0.01, 0.01-0.1, 0.1-1, or 1-10 w/w of the composition. Each possibility represents a different embodiment. [017] According to some embodiments, the composition comprises a mixture of compounds, wherein at least one of the compounds is the photoluminescent compound, and wherein said mixture of compounds is adjusted whereby the composition appears as white, another color (human or animal body color), or non-visibly colored to the naked human eye under visible light. Each color represents a separate embodiment of the invention. According to some embodiments, the mixture comprises at least three pigments (or more), wherein at least one of the at least three pigments comprise the at least three photoluminescent compound. According to some embodiments, the mixture comprises a plurality of pigments, optionally selected from the group consisting of: lycopene as a red color pigment; blue butterfly pea powder as a blue color pigment, Chlorophyll as a green color pigment and as an IR fluorescent compound, and combinations thereof.

[018] According to some embodiments, the composition further comprises one of more of: thickening or gelling agents, adhesive agents, stabilizers, surfactants, wetting agents, antioxidants, and combinations thereof.

[019] According to some embodiments, the composition further comprises at least one agent selected from the group consisting of malodorous ingredients, pepper powders, lachrymatory agents, and combinations thereof.

[020] According to some embodiments, the composition is in the form of a powder, a suspension, a liquid, a solution, a colloid dispersion, or an emulsion. [021] According to some embodiments, the composition is adjusted to be covertly sprayed into the object, subject of interest, or portions thereof. According to some embodiments, the composition is provided in a concealable container or concealable liquid distribution device configured to administer the composition to object or a subject of interest in a covert manner. According to some embodiments, composition is provided in one spraying device selected from the group consisting of: a sprinkler, an irrigation tube, a jet liquid distribution device, a water cannon, a paintball marker and a spray container. According to some embodiments, there is provided a spraying device comprising a container, which contains the composition of the present invention. According to some embodiments, the spraying device is selected from the group consisting of: a sprinkler, an irrigation tube, a jet liquid distribution device, a water cannon, a paintball marker and a spray container. According to some embodiments, the spraying device is concealable.

[022] According to another aspect of the present invention, there is provided a method of marking in situ during an event at least one object or at least one subject of interest for tracking and future detection, the method comprising: (a) providing at least one non-toxic composition comprising at least one photoluminescent compound as disclosed herein above, specifically wherein the at least one photoluminescent compound absorbs radiation in the ultraviolet (UV) spectrum, visible light spectrum, or both, wherein the photoluminescent compound emits radiation in the infrared (IR) spectrum, visible light spectrum, or both, and wherein the photoluminescent compound is a fluorescent or phosphorescent compound. According to some embodiments, there is provided a method of marking in situ during an event at least one object or at least one subject of interest for tracking and future detection, the method comprising: (a) providing at least one composition comprising at least one photoluminescent compound as disclosed herein above, specifically wherein the at least one photoluminescent compound absorbs radiation in the ultraviolet (UV) spectrum, visible light spectrum, or both, wherein the photoluminescent compound emits radiation in the infrared (IR) spectrum, visible light spectrum, or both, and wherein the photoluminescent compound is a fluorescent or phosphorescent compound.

[023] The method further comprises step (b) of marking the at least one object or the subject of interest with the at least one non-toxic composition in situ during an ongoing event. [024] The method further comprises step (c) of detecting and/or tracking and/or identifying the at least one marked object or subject, within the site of the event of step (b) or after movement to another site, using at least one detection device configured to detect the at least one photoluminescent compound of the at least one non-toxic composition.

[025] According to some embodiments, the at least one object is selected from the group consisting of: one or more body parts of said at least one subject of interest; an item belonging to the at least one subject of interest which is present at the event; a clothing article; an ornament; a vehicle, and a combination thereof. According to some embodiments, the method is used for enforcement uses, wherein the event is a riot, and wherein the at least one object is selected from a vehicle, a clothing article, and combinations thereof.

[026] According to some embodiments, the compound is not detectable to the naked eye in the range of ordinary human vision. It is to be understood that the range of ordinary human vision is about 380 nm to about 720 nm.

[027] According to some embodiments, the photoluminescent compound comprises an IR fluorescent compound selected from the group consisting of plant color reagents, food coloring dyes, fluorescent nanoparticles, phosphorescent pigments, non-toxic reagents, and combinations thereof. According to some embodiments, the plant color reagents are selected from Chlorophyll, Spirulina platensis, natural fruit extracts, and combinations thereof. According to further embodiments, the plant color reagent comprises at least one type of Chlorophyll. According to some embodiments, the food coloring dyes are selected from the group consisting of Allura Red; Sunset Yellow, Brilliant Blue, Fast Green, lemon yellow Tartrazine, Erythrosin, Ponceau 4R, Amaranth, or a combination thereof. According to some embodiments, the fluorescent nanoparticles comprise carbon dots (CDs).

[028] According to some embodiments, the photoluminescent compound comprises a phosphorescent compound selected from the group consisting of strontium aluminate, crystals of zinc sulfide doped with copper, or a combination thereof.

[029] According to some embodiments, the at least one photoluminescent compound is present in an amount selected from the range of 0.0001-10% w/w of the composition, including each value and sub-range within the specified range. [030] According to some embodiments, the composition comprises a mixture of compounds, wherein at least one of the compounds is the at least one photoluminescent compound, and wherein said compounds mixture is adjusted whereby the composition appears as white, another color (body color), or non-visibly colored to the naked eye under visible light. According to some embodiments, the mixture comprises at least three or more pigments, wherein at least one of the at least three pigments comprise the at least one photoluminescent compound. According to some embodiments, the mixture comprises a plurality of pigments selected from the group consisting of: lycopene as a red color pigment; blue butterfly pea powder as a blue color pigment, Chlorophyll as a green color pigment and as an IR fluorescent compound, and combinations thereof.

[031] According to some embodiments, the composition further comprises one of more of: thickening or gelling agents, adhesive agents, stabilizers, surfactants, wetting agents, antioxidants, and combinations thereof. According to some embodiments, the composition further comprises at least one agent selected from the group consisting of malodorous ingredients, pepper powders, lachrymatory agents, and combinations thereof.

[032] According to some embodiments, the composition is in the form of a powder, a suspension, a liquid, a solution, a colloid dispersion, or an emulsion.

[033] According to some embodiments, step (b) comprises applying the composition to the object or the subject of interest by spraying it thereon, optionally by utilizing at least one spraying device selected from the group consisting of: sprinkler, an irrigation tube, a jet liquid distribution device, a water cannon, a paintball marker, and a spray container. According to some embodiments, the spraying is performed using at least one of a vehicle, an aircraft, an unmanned aircraft, a watercraft, and combinations thereof. According to some embodiments, the aircraft or the unmanned aircraft is selected from the group consisting of: a drone, an airplane, a helicopter, and combinations thereof.

[034] According to some embodiments, following spraying the at least one composition onto the at least one obj ect or subj ect of interest during step (b), the composition forms a thin coating layer thereon. According to further embodiments, step (b) further comprises forming a thin coating layer onto the at least one object or subject of interest, following the spraying thereof. According to some embodiments, the thin coating layer comprises at least three or more types of pigments, wherein at least one of the at least three pigments comprise the at least one photoluminescent compound, and wherein the thin coating layer exhibits a white color, another (body) color, or a non-visible color, to the naked eye under visible light radiation.

[035] According to some embodiments, step (b) comprises applying the composition to the object or the subject of interest in a manner in which in the appearance thereof is not changed to the naked eye.

[036] According to some embodiments, the at least one detection device comprises at least one of a camera, a sensor, specialized glasses, and combinations thereof.

[037] According to some embodiments, step (b) of marking the object or the subject of interest with the at least one composition is performed covertly or non-covertly using at least one article selected from the group consisting of: a vehicle, an aircraft, an unmanned aircraft, a watercraft, and combinations thereof, and wherein the composition is sprayed manually by a user or automatically via the at least one article.

[038] According to some embodiments, step (c) of detecting and/or tracking the marked object or subject is performed covertly or non-covertly using at least one article selected from the group consisting of: a vehicle, an aircraft, an unmanned aircraft, a watercraft, a satellite, and combinations thereof, and wherein the detection device is carried manually by a user or is attached to the at least one article.

[039] According to some embodiments, step (b) comprises marking a plurality of objects or subjects of interest, optionally simultaneously, with at least one or a plurality of compositions, and wherein step (c) comprises tracking and/or identifying said plurality of objects or subjects of interest.

[040] According to some embodiments, the photoluminescent compound is a fluorescent compound comprising at least one of chlorophyll a, chlorophyll b, and combinations thereof, and wherein step (c) comprises detecting and/or tracking the at least one object or subject of interest using a laser-induced fluorescence (LIF) technique for the remote detection thereof.

[041] According to some embodiments, there is provided a method of marking in situ during an ongoing civil disorder event at least one object or subject of interest for enforcement uses, the method comprising: (a) providing at least one composition comprising at least one photoluminescent compound as disclosed herein above; (b) spraying the at least one composition onto at least one object or subject of interest in situ during an ongoing civil disorder event; and (c) detecting and/or tracking and/or identifying the at least one marked object or subject of interest, within the site of the event of step (b) or after movement to another site, using at least one detection device configured to detect the at least one photoluminescent compound. Enforcement purposes typically involve the public sector, for example, the police for law enforcement. Civil disorder may include riots, civil unrest etc. According to some embodiments, the composition is non-toxic.

[042] According to some embodiments, there is provided a method of marking in situ during an event at least one object or subject of interest for tracking and future detection, the method comprising: (a) providing at least one non-toxic composition comprising at least one fluorescent compound as disclosed herein above; (b) spraying the at least one non-toxic composition onto at least one object or subject of interest in situ during an ongoing event; and (c) detecting and/or tracking and/or identifying the at least one marked object or subject of interest, within the site of the event of step (b) or after movement to another site, using a laser- induced fluorescence (LIF) technique configured to detect the at least one fluorescent compound. According to some embodiments, the at least one fluorescent compound comprises at least one type of Chlorophyll selected from chlorophyll a, chlorophyll b, and combinations thereof.

[043] According to some embodiments, step (b) of any one of the methods of the invention is performed in the light, wherein the at least one photoluminescent compound in not visible in visible light, and wherein step (c) is performed in the dark. According to some embodiments, step (b) is performed at daylight and step (c) is performed at night-time. The terms “light” and “daylight”, as used herein, refer to outdoor illuminance from 1 lux to 120,000 lux. The terms “dark” and “night-time”, as used herein, refer to outdoor illuminance of less than 1 lux, or from 0.0001 lux to 1 lux.

[044] Certain embodiments of the present invention may include some, all, or none of the above advantages. Further advantages may be readily apparent to those skilled in the art from the figures, descriptions, and claims included herein. Aspects and embodiments of the invention are further described in the specification herein below and in the appended claims. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In case of conflict, the patent specification, including definitions, governs. As used herein, the indefinite articles "a" and "an" mean "at least one" or "one or more" unless the context clearly dictates otherwise.

[045] The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, but not limiting in scope. In various embodiments, one or more of the above-described problems have been reduced or eliminated, while other embodiments are directed to other advantages or improvements.

BRIEF DESCRIPTION OF THE FIGURES

[046] Some embodiments of the invention are described herein with reference to the accompanying figures. The description, together with the figures, makes apparent to a person having ordinary skill in the art how some embodiments may be practiced. The figures are for the purpose of illustrative description and no attempt is made to show structural details of an embodiment in more detail than is necessary for a fundamental understanding of the invention. For the sake of clarity, some objects depicted in the figures are not to scale. [047] In the Figures:

[048] Figures 1 shows a flowchart for a method 100 for marking an object or a subject of interest for tracking purposes, in some embodiments.

[049] Figures 2A-2B illustrate step 120 of method 100, in some embodiments.

[050] Figures 3A-3B illustrate step 130 of method 100, in some embodiments. DETAILED DESCRIPTION OF SOME EMBODIMENTS

[051] The present disclosure is directed toward compositions and methods for marking, highlighting, detecting, probing and/or tracking the movement of objects or subjects of interest, without causing them harm, using non-toxic compositions comprising photoluminescent compounds.

[052] In the following description, various aspects of the disclosure will be described. For the purpose of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the different aspects of the disclosure. However, it will also be apparent to one skilled in the art that the disclosure may be practiced without specific details being presented herein. Furthermore, well-known features may be omitted or simplified in order not to obscure the disclosure.

[053] Reference is now made to Figures 1-3B. Figure 1 shows a flowchart for a method 100 for marking an object or a subject of interest for tracking purposes, according to some embodiments. Figures 2A-2B illustrate step 120 of method 100, in some embodiments. Figures 3A-3B illustrate step 130 of method 100, in some embodiments.

[054] According to an aspect of the present invention, there is provided a method 100 of marking in situ during an event at least one object or subject of interest for tracking and/or future detection purposes. According to some embodiments, the method of the present invention comprises step 110 of providing at least one non-toxic composition comprising at least one photoluminescent compound. According to some embodiments, the at least one photoluminescent compound is selected from the group consisting of a fluorescent compound, a phosphorescent compound, or a combination thereof.

[055] According to some embodiments, the composition comprises a plurality of photoluminescent compounds. According to some embodiments, the composition comprises a plurality of fluorescent compounds, phosphorescent compounds, and combinations thereof.

[056] According to some embodiments, method 100 further comprises step 120 of marking or contacting or highlighting the at least one object or subject of interest with the composition in situ during an ongoing event. In some embodiments, the marking or contacting is performed covertly, wherein the subject of interest does not notice that he or she has been marked during the ongoing event. In some other embodiments, the marking is not performed covertly, wherein the subject of interest can notice that he or she has been marked during the ongoing event. In some embodiments, step 120 comprises marking or highlighting a plurality of objects or subjects of interest with at least one composition or a plurality of different compositions, in situ during an ongoing event.

[057] According to some embodiments, method 100 further comprises step 130 of detecting and/or subsequent tracking the at least one marked object or subject, within the site of the event of step 120 and/or after movement to another site, optionally using at least one detection device configured to detect the at least one photoluminescent compound. According to some embodiments, step 130 comprises illuminating or radiating the at least one marked object or subject using at least one illumination beam (generated by a radiation source), thus causing the at least one photoluminescent compound to undergo fluoresce or phosphorescence, and to emits radiation which can be detected by the detection device. The radiation source can be coupled to the detection device or separate therefrom.

[058] In some embodiments, the detecting and/or tracking can be performed covertly from a distance, using the detection device. In other embodiments, the detecting and/or tracking are not performed in a covert manner. In some embodiments, the detecting and/or tracking can be performed during real time. According to some embodiments, step 130 comprises detecting and/or tracking a plurality of marked objects or subjects, wherein each the marked objects or subjects can be marked with the same composition or with different compositions.

[059] According to some embodiments, the object is selected from one or more body parts of the subject of interest; an item or a portion thereof belonging to the subject of interest which is present at the event, and a combination thereof. According to some embodiments, the body part of the subject of interest can include hair, a hand, a leg, a shoulder, and the like. An item belonging to the subject of interest which is present at the event can include a clothing article (shirt, pants, shoes, headgear, etc.), an ornament, a vehicle (car, bike, truck, etc.), and the like. The ongoing event can be selected from a riot, a demonstration, a protest, any event involving (or that may involve) violence, any event requiring surveillance, combinations thereof, and the like. [060] According to some embodiments, the composition of the present invention is used to mark, for future detection and/or tracking purposes, a variety of objects or subjects under a number of operational scenarios. For example, a subject of interest can be marked during a riot (i.e., the ongoing event) at a certain location within a city or non-urban terrain (i.e., the site of the ongoing event), and then covertly tracked using method 100 and the present composition to the subject’s residence or hiding place (i.e., another site), for later identification and possible subsequent capture (e.g., arrest or detention). Therefore, according to some embodiments, the present method 100 is adapted to assist a user (i.e., law enforcement, public sector, and the like) in marking and preferably covertly detecting/tracking subjects of interest during and/or following various events.

[061] Furthermore, the acts of marking and detecting/tracking do not have to necessarily be performed in a continuous manner. For example, a subject of interest (e.g., a person) can be marked using the present method (i.e., method 100) and the present composition during a riot at a certain location within a city. Next, said subject can return to a residence or hiding place undetected, and later may be identified during a routine inspection using a detection device adapted to detect the present composition. For example, such device may include a detector configured to detect the radiation emitted from the photoluminescent compound. Therefore, according to some embodiments, the present method is adapted to assist the user (e.g., an enforcer) in marking subjects of interest for later detection, wherein the detection is not performed in situ during the ongoing event.

[062] As used herein, the term “photoluminescence” refers to a light emission by a material after the absorption of photons (i.e., electromagnetic radiation), which is one of the several forms of luminescence. Fluorescence and phosphorescence are forms of photoluminescence.

[063] As used herein, the term “visible light photoluminescent” refers to a material which absorbs and emits radiation in the visible light spectrum (i.e., typically in the range of about 380 nm to about 700 nm), wherein the photoluminescent material is typically either fluorescent or phosphorescent.

[064] According to some embodiments, sources which can provide light radiation in the visible light spectrum and/or UV spectrum can include the sun, night sky, a torch, a lamp, a laser, a flashlight, other suitable sources, and combinations thereof. [065] According to some embodiments, the at least one photoluminescent compound absorbs radiation in the ultraviolet (UV) spectrum, visible light spectrum, or both. According to some embodiments, the at least one photoluminescent compound emits radiation in the infrared (IR) spectrum, visible light spectrum, or both. According to some embodiments, the at least one photoluminescent compound is a fluorescent or phosphorescent compound configured to emit radiation in the IR spectrum, visible light spectrum, or both.

[066] According to some embodiments, the at least one photoluminescent compound is an infrared (IR) fluorescent or phosphorescent compound configured to absorb radiation in the visible light spectrum and emit radiation in the IR spectrum. Some IR fluorescent or phosphorescent compounds may also emit radiation in the visible light spectrum.

[067] According to some embodiments, the at least one photoluminescent compound is a UV fluorescent or phosphorescent compound configured to absorb radiation in the UV spectrum and emit radiation in the visible light spectrum.

[068] According to some embodiments, the at least one photoluminescent compound is a visible light fluorescent or phosphorescent compound configured to absorb and emit radiation in the visible light spectrum. Some visible light fluorescent or phosphorescent compounds may also emit radiation in the IR spectrum.

[069] According to further embodiments, the at least one photoluminescent compound is selected from the group consisting of: an IR fluorescent compound, an IR phosphorescent compound, UV fluorescent compound, UV phosphorescent compound, visible light fluorescent compound, visible light phosphorescent compound, and combinations thereof. Each possibility represents a different embodiment.

[070] As used herein, the terms “Infrared” and “IR” are interchangeable, and refers to electromagnetic radiation having wavelengths longer than those of visible light, i.e. in the spectrum range of about 700 nm to about 1 mm. Infrared radiation can be divided into the following three wavelength regions (or spectrums): (1) Near-IR (NIR) in the range of 780 nm to 3 pm; (2) Mid-IR (MIR) in the range of 3 pm to 50 pm; and (3) Far-IR (FIR) in the range of 50 pm to 1 mm (according to International Standards Organization (ISO) Standard No. 20473). As used herein, IR radiation incorporates therein the NIR region, MIR region, and the FIR region.

[071] According to some embodiments, the present method (i.e., method 100) is adapted to detect compounds emitting IR radiation within the NIR region, MIR region, FIR region, and combinations thereof. In some embodiments, the IR region includes electromagnetic radiation in the NIR region, MIR region, the FIR region, and combinations thereof.

[072] As used herein, the term “IR fluorescent compound” refers to a material which can absorb radiation in the visible light spectrum and as a result undergo fluoresce and emits radiation the IR region. The IR fluorescent compound may fluoresce in the NIR region, MIR region, FIR region, or a combination thereof. Typically, a fluorescent pigment or compound cease to glow nearly immediately when the radiation source stops, unlike a phosphorescent pigment or compound which continue to emit light for some time after.

[073] An IR phosphorescent compound can undergo fluoresce and also emit radiation the IR region similar to that of the fluorescent compound, except that the phosphorescent compound does not immediately reemit the radiation it absorbs. Instead, the phosphorescent compound typically absorbs some of the radiation energy and reemits it for a much longer time after the radiation source is removed. According to some embodiments, the phosphorescent compounds of the present invention can emit radiation the IR spectrum, visible light spectrum, or both.

[074] As used herein, the term “UV fluorescent or phosphorescent compound” refers to a material which can absorb radiation in the ultraviolet (UV) spectrum (i.e., typically in a spectrum range of about 10 nm to 400 nm), and as a result undergo fluoresce or phosphorescence, accordingly, and emits radiation the visible light region.

[075] According to some embodiments, the composition of the present invention is configured to absorb radiation in the visible light and/or UV spectrum and emit radiation in the IR spectrum and/or visible light spectrum. Each possibility represents a separate embodiment of the invention.

[076] According to some embodiments, the at least one photoluminescent compound is non toxic and biocompatible for human and/or animal contact. According to further embodiments, the at least one photoluminescent compound is derived from natural materials from plants like chlorophyll. Each possibility represents a separate embodiment of the invention.

[077] According to some embodiments, the IR fluorescent compound is selected from plant color reagents, food coloring dyes, fluorescent nanoparticles, other non-toxic reagents, and combinations thereof. Each possibility represents a separate embodiment of the invention.

[078] According to some embodiments, the plant color reagents are selected from Chlorophyll, Spirulina platensis, natural fruit extracts, and combinations thereof. Each possibility represents a separate embodiment of the invention.

[079] According to some embodiments, the plant color reagent comprises at least one type of Chlorophyll. Chlorophyll is the name of several green pigments found in algae and/or in plants.

Chlorophyll is considered as a non-toxic reagent and is known for its ability to undergo fluoresce in the IR region (Neil R. Baker, et al., “Applications of chlorophyll fluorescence can improve crop production strategies: an examination of future possibilities”, Journal of Experimental Botany , Volume 55, Issue 403, August 2004, Pages 1607-1621). [080] According to some embodiments, the at least one type of Chlorophyll is selected from chlorophyll a, chlorophyll b, and combinations thereof (NI, Zhuoya, et al. "Estimation of chlorophyll fluorescence at different scales: A review", Sensors , 2019, 19.13: 3000). Each possibility represents a different embodiment.

[081] According to some embodiments, the plant color reagent comprises Spirulina. Spirulina is a biomass of cyanobacteria (i.e., blue-green algae) that is non-toxic and can be typically used as a dietary supplement and/or whole food. Spirulina is also known for its ability to undergo fluoresce in the NIR region (Roberto SP King, et al., "Seeing into the infrared: A novel IR fluorescent fingerprint powder. " Forensic science international , volume 249, April 2015, Pages e21-e26). According to some embodiments, the plant color reagent comprises Spirulina platensis.

[082] According to some embodiments, the plant color reagent comprises at least one type of natural fruit extract. Natural fruit extracts, including but not limited to, natural fruit extracts from the genera Rhamnus, Ribes, Sambucus, Viburnum, Sorbus and Beta are known as non toxic, safe, and ecological alternatives to chemical fluorescent dye for various uses (Vujanovic, S., et at., Natural fruit extracts as non-toxic fluorescent dyes for staining fungal chlamydospores. World J Microbiol Biotechnol 28, 387-390 (2012)).

[083] According to some embodiments, the food coloring dyes are selected from the group consisting of Allura Red, Sunset Yellow, Brilliant Blue, Fast Green, lemon yellow Tartrazine, Erythrosine, Ponceau 4R, Amaranth, or a combination thereof. These food coloring dyes are non-toxic and are known for their ability to undergo fluoresce in the IR region.

[084] According to some embodiments, the fluorescent nanoparticles comprise carbon dots (CDs). Carbon dots have outstanding physiochemical properties such as high luminescence, low-toxicity, good biocompatibility, and excellent water solubility (Khan, W.U., et al. “High Quantum Yield Green-Emitting Carbon Dots for Fe(III) Detection, Biocompatible Fluorescent Ink and Cellular Imaging”. Sci Rep 7, 14866, 2017).

[085] According to some embodiments, the non-toxic reagents comprise fluorescein. Fluorescein is a non-toxic organic compound and an IR fluorescent dye.

[086] According to some embodiments, the phosphorescent compound comprises fine crystals of zinc sulfide doped with copper (Zns:Cu0). Copper is added to the Zinc Sulfide as an activator, thus allowing the crystals to absorb visible light and slowly emit it over time by phosphorescence. Said crystals are known as nontoxic and typically emit a light-yellow color. According to some embodiments, said zinc sulfide crystals comprise 6SSU phosphorescent zinc sulfide crystals (distributed by UMC). Advantageously, in some embodiments, the phosphorescent compound can absorb radiation energy and then reemits it for a long time after the radiation source is removed, thus enabling enhanced detection capabilities without the need to continuously illuminate the composition to enable the detection and/or tracking thereof. For example, the phosphorescent compound can absorb light and then reemits it for four to ten hours after the removal of the light source.

[087] According to some embodiments, the at least one phosphorescent compound comprises Strontium Aluminate, with or without doping with Europium.

[088] With the intention to avoid any possible health hazards to the subjects of interest that are marked and detected using the present method (i.e., method 100), the composition and its inner ingredients as disclosed herein are non-toxic and safe for human exposure or skin contact (i.e., biocompatible). In order to comply with this requirement, it is proposed herein to use a safe, non-toxic, biocompatible compounds, including non-limiting examples such as food coloring dyes or non-toxic plant-based (or algae-based) pigments like chlorophyll.

[089] The term "non-toxic" as used herein refers to a biocompatible material or materials capable of being in contact with living tissues (e.g., human skin) without causing them long term harm.

[090] The term “biocompatible” as used herein means that the composition of the present invention is capable of being in contact with living tissues or organisms without causing them any harm. Biocompatible materials and compositions are substantially non-toxic when contacting a subject (human or animal) or a body portion thereof, and are not substantially rejected by the subject's physiological system (i.e., is non-antigenic). This can be gauged by the ability of a material to pass the biocompatibility tests set forth in International Standards Organization (ISO) Standard No. 10993 and/or the U.S. Pharmacopeia (USP) 23 and/or the U.S. Food and Drug Administration (FDA) blue book memorandum No. G95-1, entitled “Use of International Standard ISO-10993, Biological Evaluation of Medical Devices Part-1: Evaluation and Testing”. Typically, these tests measure a material's toxicity, infectivity, pyrogenicity, irritation potential, reactivity, hemolytic activity, carcinogenicity and/or immunogenicity.

[091] Certain fluorescent compounds, such as certain dyes, can be toxic and/or cause negative side effects when contacting human skin (e.g., cause skin irritation, rash, inflammation, etc.). The occurrence of such negative side effects following marking of a subject may alert the subject to being monitored or marked, thus harming the preferably covert marking and/or detection process. Advantageously, the present compositions as disclosed herein contain non toxic and biocompatible photoluminescent compounds, suitable for contacting living tissues (human or animal) in an inconspicuous manner. Therefore, in some embodiments, the composition of the present invention can be administered/applied to the subject during step 120 without harming the subject of interest, or without drawing attention to the administration thereof due to any negative side effect.

[092] According to some embodiments, the at least one photoluminescent compound is present within the composition in an amount selected from the range of 0.0001-10% w/w of the composition including each value and sub-range within the specified range. According to further embodiments, the at least one photoluminescent compound is present in the composition in an amount selected from the range of 0.0001-0.001%, 0.001-0.01%, 0.01-0.1%, 0.1-1%, or 1-10% w/w of the composition. Each possibility represents a different embodiment of the present invention.

[093] According to some embodiments, the composition comprises a substantially low weight percentage of the at least one photoluminescent compound therein, preferably below about 1% w/w of the composition. In further embodiments, the composition comprises the at least one photoluminescent compound in a weight percentage of below about 0.1%, or optionally below about 0.01%, of the composition. Advantageously, in some embodiments, the composition is not visually noticeable to the naked eye, since the substantially low weight percentage of the photoluminescent compound is below the visibility range of the human eye abilities, thus allowing to covertly mark and/or detect the present compound by an adequate optical instrument (e.g., detection device). In some embodiments, the low concentration of the at least one photoluminescent compound can be detected using a detection device configured to amplify the emitted radiation thereof. According to some embodiments, the detection device comprises a detector configured to detect the radiation emitted from the photoluminescent compound.

[094] Furthermore, according to some embodiments, the at least one photoluminescent compound is present within the composition at a substantially low weight percentage in order to assure the low-toxicity qualities thereof.

[095] According to some embodiments, the composition of step 110 comprises a mixture of compounds, wherein at least one of the compounds is the photoluminescent compound. In further such embodiment, said mixture is configured/adjusted to affect the final resulting color of composition, whereby the composition appears as white, another color (e.g., human body color), or non-visibly colored by the naked human eye, under visible light radiation. In some embodiments, the mixture is configured/adjusted to affect the final resulting color of composition, whereby the composition appears as white. In some embodiments, the mixture is configured/adjusted to affect the final resulting color of composition, whereby the composition appears as non-visibly colored. [096] As used herein, the term “non-visibly colored” refers to a material that under visible light radiation appears as substantially transparent (i.e., having the physical property of allowing visible light to pass through the material without appreciable scattering of the visible light).

[097] According to some embodiments, the mixture is non-toxic. In some embodiments, the mixture comprises IR fluorescent or phosphorescent compounds such as the plant color reagents (e.g., Chlorophyll) and/or the food coloring dyes (e.g., Allura Red; Sunset Yellow; Brilliant Blue, etc.). According to some embodiments, the mixture may comprise non- fluorescent colorants (e.g., pigments, dyes, tints, and the like) in order to adjust the final color and properties thereof. In some embodiments, the colorant may be organic or inorganic, and can be agglomerated or non-agglomerated. In some embodiments, the colorant can be in the form of a dispersion including, but not limited to, a nanoparticle dispersion. In some embodiments, the colorant can be in the form of fine crystals.

[098] With the intention to make it difficult for marked subjects of interest to know whether they have been marked and/or are still marked, it is suggested to use the mixture as disclosed herein, which will preferably appear as white, body color, or non-visibly colored by the naked human eye, under visible light radiation, but will still include the photoluminescent compound (i.e., fluorescent or phosphorescent compound) for detection/tracking purposes. According to some embodiments, the mixture as disclosed herein may comprise a mixture of non-fluorescent colorant(s) with IR fluorescent or phosphorescent compound(s), in order to adjust the final color of the mixture/composition, to assure enhanced covert detection/tracking capabilities thereof.

[099] According to some embodiments, the final color of the mixture preferably appears as white, another color (e.g., body colored), or non-visibly colored, wherein the types of pigments present within the mixture and their concentrations are selected according to the principles of the color wheel (i.e., trichromatic model of color) to achieve the final desired color. In some preferred embodiments, the mixture is not detectable to the naked eye in the range of ordinary human vision, preferably due to its color or lack thereof. [0100] The term "ordinary human vision" as used herein, refers to the vision of the visible light spectrum, that is visible to the human eye. The term "naked eye" as used herein, refers to the ordinary human eye vision without the use of any filters or detection devices.

[0101] As used herein, the term “trichromacy” refers to the possessing of three independent channels for conveying color information, derived from the three different types of color receptors present within the human eye, primarily adapted to detect red, green and blue. As used herein, the term “color wheel” refers to the arrangement of color hues in a circle form, which illustrates the relationships between primary colors, secondary colors, tertiary colors, etc. Most visible colors can be created by combinations and different levels of the three primary colors: red, green and blue. Therefore, most color wheels are based on the three primary colors (i.e., the trichromatic model of color), as well as additional colors such as secondary colors and tertiary colors (intermediate colors formed by mixing a primary with a secondary color).

[0102] Thus, according to some embodiments, the mixture of the present invention comprises at least three types of pigments (e.g., green, blue and red) or more, wherein the mixture appears as white, another color, or non-visibly colored to the naked eye under visible light, and wherein at least one of the at least three pigments comprise the at least one photoluminescent compound. In further embodiments, all three or more pigments are photoluminescent compounds. According to some embodiments, at least one of the pigments comprise the IR fluorescent or phosphorescent compound, thus enabling the mixture to undergo fluorescence in the IR spectrum, and appear as white, another color, or non-visibly colored to the naked eye under visible light. Advantageously, the concentration of each color pigment present within the mixture/composition can be adjusted in order achieve the final desired color of the mixture (or lack thereof), thus providing a composition adapted for enhanced covert detecting purposes and optionally covert marking.

[0103] For example, in some embodiments, the mixture comprises lycopene as a red color pigment (derived from tomatoes); blue butterfly pea powder as a blue color pigment (derived from Clitoria ternatea ), and chlorophyll as a green color pigment and as the IR fluorescent compound (derived from plants or algae), wherein the mixture of these pigments results in a white or non-visibly colored mixture. [0104] According to some embodiments, the mixture of the present invention comprises three or more types of pigments, wherein at least one of the pigments comprise the IR fluorescent or phosphorescent compound. In further such embodiments, the mixture comprises a plurality of pigments selected from the group consisting of lycopene, blue butterfly pea powder, chlorophyll, Allura Red, Sunset Yellow, Brilliant Blue, Fast Green, lemon yellow Tartrazine, spirulina platensis, fluorescein, Erythrosin, Ponceau 4R, Amaranth, other suitable pigments, and combinations thereof. Each possibility represents a different embodiment.

[0105] According to some embodiments, the composition further comprises one or more additives selected from: thickening or gelling agents, adhesive agents, stabilizers, surfactants, wetting agents, antioxidants, and combinations thereof. These additives can be used to enhance the composition’s stability, enhance the binding thereof to the object or subject, and to increase the shelf life thereof.

[0106] According to some embodiments, the thickening or gelling agents may serve multiple purposes such as thickening, gelling, emulsifying and/or stabilizing the composition, and may for example be selected from: (1) cellulosic thickeners and their derivatives, including but not limited to carboxymethyl hydroxyethylcellulose, cellulose, hydroxybutyl methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropyl methyl cellulose, methylcellulose, microcrystalline cellulose, and sodium cellulose sulfate; (2) natural gums, including but not limited to the gums of acacia, calcium carrageenan, guar, gelatin, hydroxypropyl guar, karaya, kelp, locust bean, pectin, sodium carrageenan, tragacanth, and xanthan; (3) acrylates, including but not limited to polyacrylic acid copolymer, potassium aluminum polyacrylate, sodium acrylate/vinyl alcohol copolymer, and sodium polymethacrylate; (4) starches, including but not limited to oat flour, potato starch, wheat flour, and wheat starch; (5) stearates, including but not limited to methoxy polyethylene glycol (PEG)-22/dodecyl glycol copolymer, PEG-2M, and PEG-5M; and (6) fatty acid alcohols, including but not limited to caprylic alcohol, cetearyl alcohol, lauryl alcohol, stearyl alcohol, oleyl alcohol, cetyl alcohol, palm kernel alcohol, salts, derivatives and/or combinations thereof, or any other suitable agent.

[0107] According to some embodiments, the thickening or gelling agents may comprise cetyl alcohol, palmitic acid, salts, derivatives and/or combinations thereof, or any other suitable agent. In further embodiments, the palmitic acid comprises the aluminum salt thereof. In further embodiments, the palmitic acid is in the form of the ester derived therefrom, i.e., cetyl palmitate.

[0108] According to some embodiments, the adhesive agents are configured to enable the attachment/adhesion of the composition to the object or subject of interest, preferably for a long duration of time. For example, if the composition is applied on the hair and/or skin portions of a subject of interest, the adhesive agents present within the composition can enable the sustained attachment thereof to said subject, preferably after several cycles of thorough washings or the use of cleaning utilities/reagents, thus enabling to effectively detect/track the subject of interest for prolonged durations of time.

[0109] According to some embodiments, the adhesive agents are configured to enable the attachment/adhesion of the composition to the object or subject of interest, for a time duration of at least 1 day. In further embodiments, the adhesive agents enable the attachment/adhesion of the composition to the object or subject of interest, for at least 1 week, 2 weeks, 3 weeks, 1 month, 2 months, 3 months, or more. Each possibility represents a different embodiment.

[0110] It is suggested, in some embodiments, that the effectiveness of the adhesive agents can be dependent upon the location along the object or body part of the subject of interest where the composition was applied, and the use of cleaning reagents and washing. For example, in some embodiments, the attachment of the composition to an unwashed shoe portion may be more effective and prolonged than the attachment of the composition to the hair or skin of a person, which is regularly washed with water and soap.

[0111] Suitable adhesive agents may include ammonia and an oxidizing agent, similar to those used to produce permanent hair color materials, in some embodiments. According to some embodiments, the adhesive agents comprise ammonia and at least one suitable oxidizing agent.

[0112] According to some embodiments, the adhesive agents comprise biocompatible bioadhesive agents derived from natural organic sources, including but not limited to plant resins (e.g., starch, dextrin, etc.), animal resins (e.g. types of casein, animal glues, etc.), and combinations thereof. According to some embodiments, the bioadhesive agents comprise animal glues derives from animal hides, hoofs, skin, bones, combinations thereof, and the like. According to some embodiments, the bioadhesive agents are derived from natural sources and are selected from casein, starch, dextrin, gelatin, cetyl alcohol, palmitic acid and salts thereof, derivatives and/or combinations thereof, or any other suitable natural agent.

[0113] According to some embodiments, the composition further comprises at least one riot control agent, selected from but not limited to: malodorous ingredients (e.g., skunk odor), pepper powders (e.g., black pepper powder), lachrymatory agents (i.e., tear gas), and combinations thereof, preferably for use as a riot control measure. Riot control measures can be used by a user (i.e., law enforcement, public sector and the like) to control, disperse, and detain subjects of interest who are involved in the ongoing event (e.g., riot, demonstration, protest, and the like).

[0114] According to some embodiments, the composition is in the form of a liquid, a solution, a suspension, a colloid dispersion, an emulsion, and combinations thereof. According to some embodiments, the solution can be aqueous or organic solvent (e.g. alcohol) based.

[0115] According to some embodiments, step 120 comprises contacting or applying the composition to the object by spraying it onto the object, subject of interest, or portions thereof.

[0116] According to some embodiments, following spraying the composition onto the object, subject of interest, or portions thereof, the composition forms a thin coating layer thereon. In some embodiments, under visible light and/or UV radiation, said thin coating layer undergoes fluoresce or phosphorescence and emits radiation in the IR spectrum and/or in the visible light spectrum.

[0117] According to some embodiments, the thin coating layer is preferably not visually noticeable. In further embodiments, the thin coating layer can be dried in the surrounding air to form a solid coating layer, wherein the drying can be expedited by sun and/or wind exposure. In some embodiments, the adhesive agents present within the composition enable the improved and/or prolonged attachment of the thin coating layer onto the object, subject of interest, or portions thereof.

[0118] According to some embodiments, the thin coating layer comprises at least three types of pigments (or more), wherein at least one of the at least three pigments comprise the at least one photoluminescent compound (e.g., fluorescent or phosphorescent compound), and wherein the thin coating layer exhibits a white color, another color (e.g., body color), or a non-visible color to the naked eye under visible light radiation.

[0119] According to some embodiments, step 120 comprises applying the composition to the object or the subject of interest in situ during the ongoing event, wherein the composition is not applied onto the object or the subject of interest beforehand or in advance. The act of marking the object or the subject of interest with the composition of the present invention can solely occur in situ during the ongoing event (e.g., a riot, a demonstration, a protest, etc.), thus enabling users (e.g., law enforcement) to mark unknown and/or known persons of interest for future detecting/tracking purposes.

[0120] According to some embodiments, the composition is stored within a spraying device (e.g., a spray container). According to some embodiments, the composition is disposed within a spraying device. According to some embodiments, the spraying device is selected from the group consisting of: sprinkler, an irrigation tube, a jet liquid distribution device, a water cannon, a paintball marker, and a spray container Each possibility represents a separate embodiment of the invention.

[0121] According to some embodiments, the composition can be sprayed during step 120, preferably covertly, onto the object, subject of interest, or portions thereof, using an unmanned aircraft (e.g., a drone). According to some other embodiments, the composition can be directly sprayed, preferably covertly, onto the object, subject of interest, or portions thereof, by a user. The user can be optionally positioned on a high platform (e.g., a tall building, a bridge, etc.) or at a relatively similar or identical height as the subject. According to some embodiments, the composition is sprayed onto the object or subject by the user or unmanned aircraft, wherein the composition is sprayed onto the object or subject from: above; below; or from at least one side thereof (e.g., front side, back side, etc.).

[0122] According to some embodiments, step 120 of marking the object or the subject of interest with the composition is performed covertly or non-covertly, using at least one article selected from the group consisting of: a vehicle (e.g., a car, a bike, a truck, etc.), an aircraft (e.g., a plane, a helicopter, etc.), an unmanned aircraft (drone), a watercraft (e.g., a boat), and combinations thereof. In some embodiments, the composition is sprayed manually by a user. In other embodiments, the composition is stored within a spraying device and is sprayed automatically, wherein the spraying device is attached or coupled to the at least one article (e.g., a car, a drone, etc.).

[0123] Figure 2A illustrates an example of step 120 of method 100 of the present invention, comprising marking at least one object or subject of interest 123A (a person) or a plurality thereof with a composition 125 (i.e., the composition of the present invention), which comprises spraying the composition thereon in situ during an ongoing event (e.g., a demonstration), wherein the composition can be sprayed manually by a user 121 utilizing a spraying device 122, or alternatively by an unmanned aircraft 124 (drone) operated by the user.

[0124] Figure 2B illustrates another example of step 120 of method 100 of the present invention, comprising marking at least one object or the subject of interest 123B (a vehicle) with the composition 125, which comprises spraying the composition thereon in situ during an ongoing event, wherein the composition can be sprayed by an unmanned aircraft 124 (drone) operated by the user onto a portion of a car driven by the subject (or subjects) of interest.

[0125] According to some embodiments, step 120 comprises applying the composition to the object in a manner in which in the appearance of the object is not changed to the naked eye. For example, the composition can be non-visibly colored (i.e., transparent), and therefore make it difficult for marked subjects of interest to know whether they have been marked and/or are still marked, thus enabling covert detecting/tracking abilities.

[0126] According to some embodiments, the detection device of step 130 comprises at least one of a camera, a sensor, specialized glasses, other optical instruments, and combinations thereof. In some embodiments, the camera and/or sensor is configured to detect visible light radiation, IR radiation, or both. In some embodiments, the camera is an infrared camera and/or sensor, configured to detect the IR radiant energy emitted by the at least one IR fluorescent or phosphorescent compound. In some embodiments, the specialized glasses comprise an IR filter. In some embodiments, the camera and/or sensor is configured to amplify emitted radiation, in order to enable the detection of low concentrations of photoluminescent compounds.

[0127] According to some embodiments, the acts of detecting and/or tracking of step 130 are performed continuously/immediately following the marking of step 120. For example, an object or a subject of interest can be marked during a riot and then immediately tracked (preferably covertly) to a residence place, a hiding place or to another location, using the detection device which is constantly monitoring the location of the at least one luminescent compound present within the present composition. The marked object or subject of interest can be viewed and detected/tracked in real time, or photographed and recorded via the detection device for future uses.

[0128] According to other embodiments, the acts of detecting and/or tracking of step 130 are performed separately (in a non-continuous manner) from the marking of step 120. For example, an object or a subject of interest can be marked during a riot and then move to another location, undetected. Later, said subject of interest may be identified during a routine inspection using a detection device adapted to detect the at least one luminescent compound present within the present composition. Advantageously, the marking as disclosed herein above may eliminate the need for continuous tracking during step 130 of the objects or subjects of interest, which may require complex image processing and/or expensive specialized equipment, wherein the marking itself can be used for later detection and/or identification in a simple and economic manner.

[0129] According to some embodiments, the acts of detecting and/or tracking of step 130 are performed using at least one article comprising the detection device selected from the group consisting of: a vehicle (e.g., a car, a bike, a truck, etc.), an aircraft (e.g., a plane, a helicopter, etc.), an unmanned aircraft (a drone such as a quadcopter), a watercraft (e.g., a boat), a satellite, and the like, or combinations thereof. The marked object can be observed by a user (i.e., a person which is a member of law enforcement, public sector and the like) utilizing the detection device, from overhead platforms such as aircraft, helicopters, bridge overpasses, or tall buildings, in some embodiments. The detection device may illuminate or radiated the marked object or subject using at least one illumination beam (generated by a radiation source) at a certain wavelength, and/or detect emitted radiation therefrom at various wavelengths.

[0130] According to some embodiments, the detection device (e.g., camera, sensor, etc.) can be connected or coupled to the article (e.g., a car, a drone, etc.) and operated by the user (e.g., a cop) during step 130, thus enabling to track the movement of the marked subject of interest from Figure 2A (optionally during real time) to his residence or to another location. Figure 3 A illustrates an example of step 130 of method 100 of the present invention, comprising detecting and/or tracking a marked object or subject 123 A (a person), using a detection device 133 which may be coupled to a vehicle 132, or alternatively to an unmanned aircraft 124. The detection device 133 may illuminate the marked object or subject 123A using at least one illumination beam 131, and/or may detect emitted radiation therefrom at various wavelengths.

[0131] According to some embodiments, the detection device (e.g., camera, sensor, etc.) can be connected to a drone operated by the user (e.g., a cop) during step 130, thus enabling to track the movement of a subject (or subjects) of interest driving within the marked car from Figure 2B (optionally during real time), wherein the car has been marked during step 120. Figure 3B illustrates another example of step 130 of method 100 of the present invention, comprising detecting and/or tracking a marked object or subject 123B (a vehicle), using a detection device 133 which may be coupled to an unmanned aircraft 124. The detection device 133 may illuminate or radiate the marked object or subject 123B using at least one illumination beam 131, and/or may detect emitted radiation therefrom at various wavelengths.

[0132] In some embodiments, if the photoluminescent compound within the composition is a phosphorescent compound, the marked vehicle (e.g., car) can be illuminated/radiated once by the detection device coupled to the drone (e.g., radiation source), wherein the phosphorescent compound absorbs radiation energy therefrom and then reemits it for a long time after the radiation source is removed, thus enabling to covertly detect/track the marked car without the need to continuously provide the illumination thereof.

[0133] According to some embodiments, method 100 can be used to mark in situ objects or subj ects of interest for enforcement purposes during violent events or potentially violent events. According to some embodiments, the violent event includes a riot, a demonstration, a protest, or any event that requires violent response from the public sector. The objects can include one or more vehicles. The marking of step 120 can be performed for the purpose of detecting and/or locating and/or identifying certain targets (i.e., the objects or subjects of interest) in violent events during step 130, wherein the violent events may optionally take place during night time. The identification during step 130 of various sorts of targets can be performed by marking them at step 120 with different compositions, according to various predetermined criteria. [0134] The marking of step 120 can be performed during the day time (under day light) that precedes the violent night event or during the same night. The marking of step 120 can be performed by spraying the objects or subjects of interest with the compositions of the present invention from the air by various aircrafts (such as drones (e.g., quadcopters), airplanes, helicopters, etc.), from the ground, or from watercrafts (marine devices) such as ships, boats, and the like. The spraying can be performed using at least one spraying device such as asprinkler, an irrigation tube, a jet liquid distribution device, a water cannon, a paintball marker, a spray container, or any other spraying instruments known in the art.

[0135] According to some embodiments, the composition of step 110 comprises at least one photoluminescent compound which comprises at least one fluorescent compound. According to further embodiments, the at least one fluorescent compound comprises chlorophyll a, chlorophyll b, and combinations thereof. Step 120 may comprise marking or highlighting the at least one object or subject of interest with the at least one fluorescent compound in situ during an ongoing event. Step 130 may comprise detecting and/or subsequent tracking the at least one marked object or subject using a laser-induced fluorescence (LIF) technique for the remote detection thereof.

[0136] The laser-induced fluorescence (LIF) of green plants is known as a means of remotely detecting plant stress (Chappelle, E. W. at. ak, "Laser-induced fluorescence of green plants. 1: A technique for the remote detection of plant stress and species differentiation", Applied Optics (1984), 23(1), 134-138; and Krause, G. H. at. ak, "Chlorophyll fluorescence as a tool in plant physiology", Photosynthesis research (1984), 5(2), 139-157.). The optional utilization of the LIF technique during step 130 can comprise the use of a nitrogen laser (emitting radiation at a wavelength of about 337 nm) for illuminating the at least one marked object or subject, wherein step 130 may further comprise detecting and/or tracking the at least one marked object or subject, which undergoes fluorescence and emits radiation at a wavelength of at least one of about 440, 690, 740 nm, and combinations thereof. The fluorescence thereof can be detected from the ground, sea, air, a satellite, and combinations thereof. Advantageously, the use of the LIF technique can enable accurate and reliable tracking and/or detection capabilities of the at least one marked object or subject. [0137] According to another aspect of the present invention, there is provided a composition as disclosed herein above, for use in marking and/or detecting an object or a subject of interest during an ongoing event (optionally during real time), the composition being non-toxic and comprising at least one photoluminescent compound, wherein the photoluminescent compound is a fluorescent or phosphorescent compound as disclosed herein above, wherein the at least one photoluminescent compound absorbs radiation in the ultraviolet (UV) spectrum and/or visible light spectrum, and wherein the photoluminescent compound emits radiation in the infrared (IR) spectrum and/or visible light spectrum.

[0138] According to some embodiments, the composition is configured to be sprayed onto the object, subject of interest, or portions thereof, and to form a thin coating layer thereon as disclosed herein above, wherein said thin coating layer absorbs visible light and/or UV radiation and emits radiation the IR region, visible light region, or a combination thereof. In some embodiments, the thin coating layer is preferably not visually noticeable by the human eye. In some embodiments, the thin coating layer comprises three or more types of pigments, wherein at least one of the pigments comprise the photoluminescent compound, and wherein the thin coating layer exhibits a white color, another (body) color, or a non-visible color to the naked eye under visible light radiation. In the context of the present invention, the phrase “the composition is configured to be sprayed” is intended to refer to a spraying device containing the present composition, wherein the composition is present therein in a sprayable physical form.

[0139] According to another aspect of the present invention, there is provided a spray container comprising a composition disposed or stored therein, wherein the composition comprises at least one photoluminescent compound as disclosed herein above, and optionally wherein the composition is non-toxic. According to further embodiments, the at least one photoluminescent compound is selected from the group consisting of a fluorescent compound, a phosphorescent compound, or a combination thereof, wherein the at least one photoluminescent compound absorbs radiation in the ultraviolet (UV) spectrum and/or visible light spectrum, and wherein the photoluminescent compound emits radiation in the infrared (IR) spectrum and/or visible light spectrum. According to still further embodiments, the at least one photoluminescent compound is selected from the group consisting of: an IR fluorescent compound, an IR phosphorescent compound, UV fluorescent compound, UV phosphorescent compound, visible light fluorescent compound, visible light phosphorescent compound, and combinations thereof. Each possibility represents a different embodiment.

[0140] As used herein, the term “plurality” refers to more than one.

[0141] As used herein, the term “about”, when referring to a measurable value such as an amount, a temporal duration, and the like, is meant to encompass variations of +/-10%, more preferably +/- 5%, even more preferably +/- 1%, and still more preferably +/-0.1% from the specified value, as such variations are appropriate to perform the disclosed devices and/or methods.

[0142] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub combination or as suitable in any other described embodiment of the invention. No feature described in the context of an embodiment is to be considered an essential feature of that embodiment, unless explicitly specified as such.

[0143] Although the invention is described in conjunction with specific embodiments thereof, it is evident that numerous alternatives, modifications and variations that are apparent to those skilled in the art may exist. It is to be understood that the invention is not necessarily limited in its application to the details of construction and the arrangement of the components and/or methods set forth herein. Other embodiments may be practiced, and an embodiment may be carried out in various ways. Accordingly, the invention embraces all such alternatives, modifications and variations that fall within the scope of the appended claims.