Sensitivity enhancement of SPR biosensor with silver mirror reaction on the Ag/Au film.

Based on well-known silver mirror reaction the Ag film was formed on Au film modified by self-assembled monolayer (SAM) of 1,6-hexanedithiol (HDT). The sensitivity of the biosensor based on this Ag/Au film is enhanced compared to that based on Au film. When the surface plasmon resonance (SPR) biosensor based on this Ag/Au film was used to determine human IgG, the range of concentrations of human IgG that could be determined is 0.30-40.00 microg mL(-1). The lowest concentration (0.30 microg mL(-1)) that could be detected was about 8 times lower than that obtained by the biosensor without modification by Ag film (2.50 microg mL(-1)), which demonstrated that the biosensor based on Ag/Au film could make the resonant wavelength move to longer wavelength following with the sensitivity enhancement of the SPR biosensor.