Rapid and In Situ Synthesis of Gold Nanoparticles in Redox Multilayer Film for Biosensor Applications

Abstract Ferrocene‐grafted poly(ethyleneimine)/poly(acrylic acid) (PEI‐Fc/PAA) multilayer films were constructed via layer‐by‐layer assembly. When the PEI‐Fc/PAA films were immersed in HAuCl₄ solution, Fc and the Au^III were converted to Fc⁺ and Au⁰, respectively, via the redox reaction of Fc and HAuCl₄, and the PEI‐Fc/PAA@Au nanoparticles (NPs) multilayer films were rapidly fabricated. SEM and TEM results showed Au NPs were distributed homogeneously throughout the thickness of the whole film. The electron transfer behavior of PEI‐Fc/PAA@Au NPs multilayer films was investigated by cyclic voltammetry and AC impedance. The results indicated that the Au NPs greatly improve the conductivity of multilayer films and thus enhance the electrochemical properties of films. The PEI‐Fc/PAA@Au NPs films were further used for the fabrication of a hydrogen peroxide (H₂O₂) sensor, which showed good catalytic ability for the reduction of H₂O₂. This approach is expected to expand the routes towards rapid fabrication of Au NPs into multilayer films.