Cuvette and apparatus for performing biological assays

Apparatus for performing a biological assay on the contents of a cuvette which contains a plurality of spheres having a specific binding agent on the surface thereof and to which a sample reagent is to be added which may or may not contain a specific binding partner for the agent on the spheres, the presence of a specific binding partner being detected by an increase in diameter of the spheres which results in a different light scatter pattern from the spheres in the presence of appropriate illumination, and which includes detector means for determining the light scatter pattern before and after a sample reagent has been added, including

• means for automatically illuminating the cuvette,
• means for moving the cuvette in a predictable manner to effect at least a preliminary movement of said cuvette,
• a light sensitive detector for checking for the presence of light at a point along a path which light will be diverted from a particular optical element located at a wall of the cuvette, and
• circuit means responsive to electrical signals from the light sensitive detector which normally inhibits the operation of the apparatus to perform the said assay but which generates an enabling signal to permit the apparatus to perform the assay if an appropriate signal pulse is generated by the detector during the said preliminary movement of the cuvette.

An analyser for use with a cuvette which includes an optical element as at least part of one of its walls to divert light incident thereon off axis in a particular direction, and by which a biological assay can be performed by investigating the change in light scatter from coated spheres within the cuvette due to chemical bonding with the cuvette, including

• (a) a source of light for projecting light onto a wall of the cuvette having the optical element formed therein,
• (b) first light detector means from which electrical signals can be obtained for determining changes in the pattern of the light scattered by particles contained within the cuvette, due to the addition of a sample reagent thereto,
• (c) second light detector means radially displaced from the axis for receiving light diverted by an optical element in the cuvette, and
• (d) circuit means responsive to the second detection means for inhibiting performance of the biological assay if said second detector means does not receive diverted light.

A method of performing a biological assay comprising the steps of:

• (a) inserting a cuvette into an analyser;
• (b) shining light through the cuvette so as to at least in part divert the light by an optical element in the cuvette;
• (c) rotating the cuvette relative to a light detector situated on a circular path which the said diverted light will describe as the cuvette is rotated to generate an electrical signal output when light falls on the detector during the said rotation;
• (d) determining if a single electrical pulse appears in the output of the detector during the rotation of the cuvette about its axis and generating an enabling signal for the analyser if a single electrical pulse appears;
• (e) causing a mixing of the sample reagent and the coated spheres in the cuvette, and
• (f) performing the assay by comparing light scatter before and after mixing, only if the enabling signal is generated.