A novel immunosensor based on self-assembled chitosan/alginate multilayers for the detection of factor B

A piezoelectric immunosensor based on a novel immobilization strategy combining cysteamine self-assembled monolayer (SAM) and chitosan/alginate adsorption procedure has been developed for the determination of factor B in human serum. Cysteamine SAM was first applied to the gold electrode surface of the crystal, and a strong positively-charged chitosan monolayer was posed on the cysteamine SAM by using glutaraldehyde cross-linking. Alginate-factor B was then electrostatically immobilized on the crystal with the aid of the negatively-charged alginate layer. The conditions of immobilizing antibodies were optimized in detail. Comparing with the conventional glutaraldehyde covalent immobilization, the immunosensor with the proposed immobilization procedure shows an improved performance in terms of the magnitude of the response and sensitivity. Moreover, the proposed immobilization procedure results in immobilized entities with relatively high biological activity and favorable immunosensing characteristics. The PQC devices are readily regenerated. Analytical results obtained from the tests of non-specific adsorption and recoveries indicated that the immunosensor prepared by use of the chitosan/alginate adsorption procedure is a useful tool for the determination of factor B in plasma in clinical diagnosis. (C) 2003 Elsevier B.V. All rights reserved.