Single-stranded DNA-based Immobilization of Ag Nanoparticles for Enzymeless H2O2 Detection

In this communication, we report a new method for effective immobilization of Ag nanoparticles (AgNPs) on thiolated single-stranded DNA (thiol-ssDNA) modified Au electrode (AuE) surface via coordination interactions between the nitrogen atoms of DNA bases and AgNPs. It suggests that the AgNP-immobilized AuE exhibits notable catalytic performance for H2O2 reduction and the loading of AgNPs on the AuE surface and therefore the effective catalytic area can be tuned by the immobilization time of thiol-ssDNA and adsorption time of AgNPs. This H2O2 sensor has a fast amperometric response time of less than 3 s and its linear range and detection limit are estimated to be from 0.1 mM to 160 mM (r = 0.995) and 0.8 mu M at a signal-to-noise ratio of 3, respectively.