A novel proteinaceous photolinker for simultaneous binding to an inert surface and a biomolecule

A simple and versatile method is developed for covalently binding a protein ligand onto a matrix irrespective of functional groups either on the ligand or the matrix. Prerequisite of the method is a novel proteinaceous photolinker having multiple light-activable functional groups. We have made photoreactive-BSA – a proteinaceous photolinker by the reaction of bovine serum albumin (BSA) with excess of 1-fluoro-2-nitro-4-azidobenzene (FNAB). When an enzyme is placed on an inert polystyrene matrix in presence of photoreactive-BSA and exposed to light the later forms highly reactive nitrenes some of which bind to the matrix and the rest to the ligand resulting simultaneous formation of covalent bonds with the matrix and the enzyme. The method is further exemplified by performing ELISA by covalent binding of antigen or antibody on a polystyrene microtiter plate in just 30 min using photoreactive-BSA. ELISA carried out in less than 3 h using photoreactive-BSA showed comparable results with that of conventional ELISA carried out in 18 h. Thus the method is potentially useful for rapid ELISA or covalent immobilization of ligands onto an inert surface without prior activation.