Background Art Presently, sample plates or titre plates are designed to receive samples in an array of wells in the plate. The content of these wells may then be investigated optically and/or by a sample being drawn from the wells and a test performed on those samples. The applications for these sample plates are many and varied in the sciences and particularly biotechnology applications.

In certain applications it is desired to provide a sample plate containing an array of wells, with a reagent already provided within the well. One example of such an arrangement would be the provision of an oligonucleotide probe, such as that described in International Patent Application PCT/AU01/01246 (WO 02/29085).

It is vital that the integrity of such probes be protected as far as possible during handling of the plate, including its storage and handling. Any interference with such probes will impact upon the reproducibility of any tests.

It is one object of the sample plate of the present invention to overcome substantially the abovementioned problems of the prior art, or to at least provide a useful alternative thereto.

The preceding discussion of the background art is intended to facilitate an understanding of the present invention only. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge in Australia as at the priority date of the application.

Throughout the specification, unless the context requires otherwise, the word "comprise"or variations such as"comprises"or"comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Disclosure of the Invention In accordance with the present invention there is provided a sample plate characterised by having provided therein an array of wells open to an upper surface of the plate, the upper surface of the plate having provided thereacross a film or sheet sealing the wells from contamination and/or contact.

Preferably, a base of at least a portion of the wells are at least in part transparent, such that a lower surface of the sample plate may be placed on or in close proximity to an optical measuring device whereby an optical measurement of activity within the wells may be undertaken from beneath the sample plate.

Still preferably, an inner surface of the film or sheet is reflective such that light incident upon the inner surface is reflected downwardly into the well below it.

The film or sheet is preferably sealed to the upper surface of the sample plate. A plurality of contact points upstanding from the upper surface of the sample plate are preferably provided for sealing with the film or sheet.

The sides of the wells are preferably at least opaque to prevent light transmission between adjacent wells.

Still preferably, the sheet or film is formed of a material that may be pierced without substantially interfering with the integrity of the sheet or film, such that a sample or reagent may be introduced into one or more of the wells without destroying the integrity of the sheet or film.

In accordance with the present invention there is further provided a method for the optical measurement of an array of samples, the method characterised by a

sample plate containing an array of discreet wells, at least a portion of the wells containing a sample to be measured, the sample plate being positioned above a charged coupled device whereby an optical image of the samples within the wells can be obtained from beneath so as to determine an activity or similar measurement within the well, the charged coupled device being such that all wells of the sample plate are measured simultaneously.

Preferably, the charge coupled device utilised is capable of imaging a plate containing 324 wells in an 18 x 18 array.

Brief Description of the Drawings The sample plate of the present invention will now be described, by way of example only, with reference to one embodiment thereof and the accompanying drawing, in which:- Figure 1 is a cross-sectional side or end view of a sample plate in accordance with the present invention, showing the sheet or film in position thereon; and Figure 2 is a plan view of the sample plate of Figure 1, showing the sheet or film having been removed to expose the wells.

Best Mode (s) for Carrying Out the Invention In Figures 1 and 2 there is shown a sample plate 10 of generally square configuration, the sample plate 10 having a plate body 12 defining edges 14, an upper surface 16 and a lower surface 18. The plate body 12 in turn comprises upper and lower portions, 11 and 13 respectively.

The upper portion 11 of the plate body 12 has provided therein an 18 x 18 array of wells 20 extending through the full thickness thereof. The wells 20 extend from their opening at the upper surface 16 to end at the lower portion 13, forming a base 22 therein. Each well 20 is further provided with walls 24 that diverge

from the base 22 towards the upper surface 16. Such that each well 20 is of generally inverted frusto-conical form.

The upper portion 11 is formed of an opaque material whilst the lower portion 13 is formed of a transparent or at least translucent material.

The upper surface 16 has provided at its edges 14 an upstanding contact point or rim 26 extending thereabout. In addition to the rim 26 there are also provided a series of additional upstanding contact points 28 spread across the upper surface 16 in between various of the wells 20. A film or sheet 30 is attached to the rim 26 and contact points 28, for example by way of ultrasonic welding, such that the upper surface 16 and wells 20 of the sample plate 10 are hermetically sealed.

The film or sheet 30 is provided with a reflective inner surface, being the surface adjacent the upper surface 16 of the plate body 12. It is envisaged that the film or sheet 30 may be formed of silicon rubber.

The walls 24 of the wells 20 are at least substantially opaque such that light from one well 20 does not penetrate into an adjacent well 20. The base 22 of each well 20 is at least in part transparent. Further, at least the portion of the lower surface 18 of the plate body 12 adjacent each base 22 is transparent such that the sample plate 10 may be placed on an optical measuring device, for example a charge coupled device (CCD), and an optical measurement of activity within the well 20 may be undertaken.

If the sample plate 10 of the present invention were, for example, to be utilised in the method described in International Patent Application PCT/AU01/01246 (WO 02/29085), the content of which is incorporated herein by reference, this would allow oligonucleotide probes for three single nucleotide polymorphisms to be applied to the wells 20 across each row thereof such that diallelic polymorphisms are investigated three times across that row. Once the probes are applied to the well 20 as desired the film or sheet 30 is ultrasonically welded to the rim 26 and

contact points 28 to hermetically seal and protect the upper surface 16 and the wells 20 of the plate body 12.

One or more reagents 32 may be injected into the wells 20 by the punching of a small hole through the film or sheet 30 adjacent each well 20, without substantially interfering with the reflective nature of the inner surface, nor with the integrity of the film or sheet 30. In the method of PCT/AU01/01246 the relevant investigation is the detection of the cleavage of a 3'base from the oligonucleotide probe and the subsequent primer extension by way of a DNA polymerase. Such a method may include the use of ATP sulfurylase and firefly luciferase (Nyren, 1987, Anal. Biochem. 167: 235). These comprise a means of converting pyrophosphate to ATP, the ATP being hydrolyse by the luciferase to produce light.

As described in the above referenced specification, the cleavage event is typically detected by optical means, including the use of a charge coupled device (CCD) or digital camera. The image that is generated by the optical means is typically then processed by a computer equipped with suitable software to convert that image into desired and meaningful information.

Any light generated in a well 20 may be detected through the base 22 of the well 20 and the lower surface 18 by the CCD on which the plate 10 sits, largely due to the substantially transparent nature thereof. However, as noted above, light generated within one well 20 is not passed into adjacent wells 20. The reflective nature of the inner surface of the film or sheet 30 adds to the sensitivity of any such method using the sample plate 10 of the present invention, as light generated is reflected downwardly back into the well 20 for potential detection by the CCD.

It is envisaged by the inventor that the CCD utilised will be able to simultaneously detect activity or otherwise within each of the wells 20 of the sample plate 10, thereby facilitating rapid processing of large numbers of sample plates 10.

In the sample plate 10 described above the walls 24 of the wells 20 diverge at an angle of 6° to the vertical, each well is 0.8 mm in diameter, each well 20 is about 2 mm deep, the plate body 12 is 4 mm thick, each well base 22 is 0.7 mm in diameter, and the sample plate is 25 x 25 mm. However, it is envisaged that the wall 24 of the wells 20 need not diverge and may be substantially parallel.

Modifications and variations such as would be apparent to the skilled addressee are considered to fall within the scope of the present invention.