Abstract: The present invention provides a viscometric method of detecting the presence or absence of an analyte in a solution. The method utilizes a dispersion of a conjugate and a receptor. The conjugate functions as an analog of the analyte, and the receptor can interact with both the analyte and the conjugate to change the viscosity of the dispersion. The test solution is introduced into an aliquot of the dispersion. Equivalent spots of the dispersion and the aliquot containing the analyte within the dispersion are then placed on a substrate such that the spots can spread upon the substrate. The presence of analyte in the test solution is detected by noting a change in the viscosity of the dispersion through a comparison of the spots. To facilitate the method, the invention provides a test kit comprising a conjugate comprising an analog of the analyte, a receptor binding the analog and the analyte, and a substrate upon which spots of liquid can spread.

Abstract: Apparatus and method for measuring properties of certain analytes are provided. The apparatus includes a sensor capsule having a processing chamber defined by a wall which in one embodiment has a semi-permeable membrane permeable to the analyte as at least a portion thereof. Receptor material is disposed within the chamber and is capable of chemically interacting with the analyte. In one embodiment, at least a portion of the sensor is translucent. A light source, which may be an optical fiber, causes light to impinge on a translucent portion of the capsule and pass therethrough. Responsive fluorescent light is generated and emitted. This light may be received by detector means and processed in a conventional manner to determine concentration of the analyte. A dye-labelled analog-analyte may be provided within the chamber. Both the receptor material and analog-analyte are of such size that they will not pass through the semi-permeable membrane although the analyte can.

Abstract: A homogenous affinity assay method, and sensor using such method, for the detection and measurement of analytes that uses an unmodified polyvalent receptor-bearing molecule and having a receptor with at least two binding sites that has an affinity for an analyte of interest, and two groups of molecules wherein one group of molecules is labeled with a molecule capable of generating a measurable response when in close proximity to a label molecule on the other group of molecules. In one embodiment, the groups of molecules also have grafted on them an analog to the analyte of interest. In the absence of the analyte of interest, members of the molecule groups are brought in close proximity to each other through affinity binding to receptor-bearing molecule. This affinity binding results in the formation of a binding complex consisting of members of the first and second groups of molecules and receptors and which results in a response between the labels on the molecules which is capable of measurement.

Abstract: A device and method for measuring properties of certain substances such as analytes are provided. The device includes a probe housing having an optical fiber associated therewith. The housing is capped on one end by a porous membrane which is permeable to the analyte being studied. The housing also includes a reflective surface member disposed between the end of the optical fiber and the membrane, thereby defining a chamber. The reflective surface member does not allow light to be transmitted into or out of the chamber. However, a dye-labeled analog-analyte can permeate the reflective surface member and thereby allow a measurement to be taken which is related to the concentration of the analyte being studied. An embodiment for use in vivo is provided. A related method is also provided.

Abstract: A system for monitoring low molecular weight compounds in blood plasma in the body by optical means includes a chamber which can be inserted into the blood stream and which contains specific receptor sites for the plasma constituent to be analyzed. The chamber interior is isolated from the blood by a dialysis membrane which permits the plasma constituents to diffuse into the chamber. A competing ligand for the receptor sites is placed within the chamber, but due to its relatively large molecular size the competing ligand cannot escape through the dialysis membrane into the bloodstream. Light emitted or absorbed by the competing ligand gives a measure of the concentration of the selected low molecular weight compounds in the blood.