Polyaniline/gold nanoparticle multilayer films: Assembly, properties, and biological applications

Polyaniline (PANI) and mercaptosuccinic-acid-capped gold nanoparticles (MSAG(NP)) can form stable multilayer films prepared by the layer-by-layer method. The MSAG(NP) inside the multilayer films can effectively dope PANI and shift its electroactivity to neutral pH, which makes it feasible to use these layers in bioassays. The films can electrocatalyze the oxidation of NADH and can be utilized to detect DNA hybridization either by an electrochemical method or by surface plasmon enhanced fluorescence spectroscopy (SPFS). Both methods can effectively discriminate complementary from noncomplementary DNA, even at the single-base mismatch level.