Abstract: Methods and kits are disclosed for detecting betalactam-containing compounds in a sample, and typically liquid products intended for human consumption such as milk. Betalactam-containing compounds include the class of betalactam antibiotics which may be present as undesired contaminates of milk. The methods involves contacting the sample with a D,D-carboxypeptidase and a substrate having a carboxyterminal D-alanine-D-alanine to form a reaction mixture, wherein the D,D-carboxypeptidase is capable of cleaving the terminal D-alanine from the substrate to yield a cleaved substrate. In an optional step, the reaction mixture is further contacted with a ligand specific to the cleaved substrate or substrate. The cleaved substrate or substrate of the reaction mixture, or the ligand specific to the cleaved substrate or substrate, is then captured by a surface-bound binding partner, with the amount of captured material being indicative to the amount of betalactam-containing compound in the sample.

Abstract: A method of determining affinity and kinetic properties for the solution interaction between an analyte and a binding partner therefor, which method comprises: (a) mixing a solution of said analyte with a solution of said binding partner, contacting the resulting reaction solution with (i) immobilised binding partner, or analogue, for said analyte, and/or (ii) immobilised analyte, or analogue, and monitoring the binding of said analyte and/or binding partner in said reaction solution to the respective immobilised species to determine the variation with time of the concentration of free analyte and/or binding partner in said solution; and/or (b) contacting a solution of the reaction complex of said analyte and a binding partner therefor with (i) immobilised binding partner, or analogue, and/or (ii) immobilised analyte, or analogue, and monitoring the binding of said analyte and/or binding partner in said reaction complex solution to the respective immobilised species to determine the variation with time of the

Abstract: Methods are disclosed for producing a substrate surface supporting a continuous planar bilayer lipid membrane by covalently binding a plurality of micellar of vesicle liposomes, optionally comprising a membrane protein or other biologically active membrane-bound component, to a substrate surface supporting a self-assembled monolayer (SAM) of essentially straight long chain molecules. In one embodiment, the micellar or vesicle liposomes covantly bind to hydrophilic spacer molecules attached to the functional groups of the self-assembled monolayer.

Abstract: An assay method comprising the step of binding a second substance to a first substance immobilized to a solid phase surface, the first substance being either a ligand or a species bound directly or indirectly thereto. The method is characterized in that the solid phase surface having the first substance immobilized thereto exhibits and electric charge, and that the reaction for binding the second substance to the first substance is performed at an ionic strength below 100 mM, and at such pH conditions that the electric charge of the second substance is opposite to that of the solid phase surface so that the second substance is electrostatically attracted by the solid phase surface to be concentrated thereto.