Optical DNA biosensor based on molecular beacon immobilized on sol-gel membrane

Abstract

Novel biotinylated molecular beacon (MB) probe was developed to prepare DNA biosensor using sol-gel chemistry. Biotinylated bovine serum albumin was encapsulated in the sol-gel matrix to form a biotinylated silica gel. Streptavidin acted as a bridge between biotinylated MB and silica gel. The MB based DNA biosensor can detect nonlabeled DNA target in real time with high sensitivity and one-base- mismatch selectivity, which indicated the potential applications in single point mutation detection. Compared with the previous report, the sol-gel based DNA biosensor has three advantages: (1). The response time was significantly shortened to 10 minutes when the cDNA concentration was over 10 nM. (2). The silica gel prolonged the lifetime of the MB based biosensor, which could keep its activity for thee weeks if stored in a buffer. (3) The gel formed by sol-gel method has a larger surface area than the common glass cover at the same scope. The number of binding sites for biotinylated increased significantly. Hence the detection limit was down to subnanomolar/L.