A novel amperometric immunosensor based on three-dimensional sol-gel network and nanoparticle self-assemble technique

A novel hepatitis B surface antigen (HBsAg) immunosensor has been developed by self-assembling gold nanoparticles to a thiol-containing sol-gel network. A cleaned gold electrode was first immersed in a hydrolyzed mercaptopropyltrimethoxysilane (MPS) sol-gel solution to assemble three-dimensional silica gel, and then gold nanoparticles were chemisorbed onto the thiol groups of the sol-gel network. Finally, hepatitis B surface antibody (HBsAb) was adsorbed onto the surface of the gold nanoparticles. Thus, an interfacial design of bare gold electrode (BGE)/MPS/Au/HBsAb was prepared to detect HBsAg in human serum based on the specific reaction of HBsAb and HBsAg. The electrochemistry of ferricyanide redox reaction was used as a marker to probe the interface and as a redox probe to determinate HBsAg. The main conditions of the assembly of MPS sol-gel, gold nanoparticles, the immobilization of HBsAb, and incubation time were investigated in detail. Compared with the glutaraldehyde binding approach, the antibodies immobilized by this method present larger amount and higher immunoactivity. The linearity of HBsAg in the range of 2-360 ng/mL with the correlation coefficient of 0.998 was obtained. This immunosensor system was evaluated on several clinical sample, the analytical results obtained by this method were in agreement with those detected by the enzyme-linked immunosorbent assay (ELISA) method, indicating a promising alternative tool for clinical diagnosis. Moreover, the studied immunosensor exhibited good reproducibility, long-term stability, high sensitivity and specificity.