Study Of Piezoelectric Biosensor Based On Enzymatic Amplification

Use of biosensor to detect the bio-markers for the accurate,rapid and diagnosis of clinical diseases has been an attractive and hot topic in the current medical studies. The quartz crystal microbalance (QCM) is a simple, high specificity, cost effective, free from tracer labeling, real-time digital output sensing technique, which is sensitive to multiple signals such as the surface mass, and the density, viscosity, conductivity, and dielectric effect of the test solution. The technique possesses a wide detection range. In this paper, incorporating high sensitivity of piezoelectric response and being easy to several piezoelectric biosensor, we developed immunosensor and DNA sensor for the diagnosis of some clinical diseases including Schistosomiasis, L. pneumophila etc. The detailed matericals are shown as follows:(1) A gas piezoelectric quart sensor for simultaneously detection of the antibody of Schistosoma-Japonicum (SjAb) was developed. This work is based on enzymatic deposition of silver leading to amplify frequentcy shift which is localized where the enzymatic lable goat anti-rabbit IgG is attached. The sensor is simple,sensitive and rapid. In addition, we also provide a novel assay to readuce the background by using complexing agent as washing solution. The detection limit is obtained as low as 1 ng/mL.(2) A hairpin probe modified with a thiol at its 5ˊend and a biotin at its 3ˊend was combined with a sandwich-type hybridization assay, using streptavidin-alkaline phosphatase as reporter molecule. The sensor is simple and frequent. The detection limit is obtained as low as 0.45 nmol/L. The presented DNA biosensor has good selectivity, being able to discriminate L. pneumophila and its interference which is double-base mismatches.(3) Using Fe@Au as carrier, the immobilization of MB was more effective because of good biological compatibility of Au nanoparticle. Moreover, we also developed a easily reproducible DNA sensor. The detection limit is obtained as low as 0.09 nmol/L. The sensor has good sensitivity and selectivity.