Fabrication and characteristics of microcantilever-based biosensor for detection of the protein-ligand binding

This paper describes a proposal for a microcantilever-based biosensor that can be used in investigating the adsorption characteristics of protein-ligand binding on a silicon nitride/gold coated surface. We have detected streptavidin-ligand binding using this microcantilever detection system. The microcantilevers can be mass-produced by a conventional surface micromachining technique. This technique has advantages of cost efficiency, simplicity, and the ability to be fabricated in an array. A transparent fluid cell system, where a gold coated microcantilever was mounted for the injection of bio-molecular solution, was fabricated using polydimethylsiloxane (PDMS) and fused silica glass. The microcantilever was deflected as a result of the difference of surface stress caused by the formation of the self-assembly monolayers (SAMs) of biomolecules on the gold coated side of the microcantilever. The sequential specific interactions of cystamine dihydrochloride/ glutaraldehyde/streptavidin were detected by both optical and electrical methods. We confirmed that the deflections were induced by biomolecular adsorption on the gold coated microcantilever. This study proved to be applicable to real-time monitoring of biological interactions such as specific DNA sequences, proteins, and so on.