New polymer–enzyme–metallic nanoparticle composite films with a high‐load and a high‐activity of immobilized enzymes and obvious electrocatalysis/nano‐enhancement effects for biosensing of glucose and galactose are designed and prepared by a one‐pot chemical pre‐synthesis/electropolymerization (CPSE) protocol. Dopamine (DA) as a reductant and a monomer, glucose oxidase (GOx) or galactose oxidase (GaOx) as the enzyme, and HAuCl4 or H2PtCl6 as an oxidant to trigger DA polymerization and the source of metallic nanoparticles, are mixed to yield polymeric bionanocomposites (PBNCs), which are then anchored on the electrode by electropolymerization of the remaining DA monomer. The prepared PBNC material has good biocompatibility, a highly uniform dispersion of the nanoparticles with a narrow size distribution, and high load/activity of the immobilized enzymes, as verified by transmission/scanning electron microscopy and electrochemical quartz crystal microbalance. The thus‐prepared enzyme electrodes show a largely improved amperometric biosensing performance, e.g., a very high detection sensitivity (99 or 129 µA cm−2 mM−1 for glucose for Pt PBNCs on bare or platinized Au), a sub‐micromolar limit of detection for glucose, and an excellent durability, in comparison with those based on conventional procedures. Also, the PBNC‐based enzyme electrodes work well in the second‐generation biosensing mode. The proposed one‐pot CPSE protocol may be extended to the preparation of many other functionalized PBNCs for wide applications.

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We report on the chemical/biochemical preparation of novel polymeric bionanocomposites (PBNCs) material consisting of polydopamine (PDA), Pt nanoparticles (PtNPs), glucose oxidase (GOx), Au nanoparticles (AuNPs), and antibody for high-performance sandwich-type electrochemical immunoassay. The preparation includes chemical synthesis of PDA-PtNPs-GOx bionanocomposites with abundant GOx and PtNPs immobilized in/on the PDA matrix and biochemical synthesis of AuNPs/PDA-PtNPs-GOx bionanocomposites with highly dispersed AuNPs on the PDA-PtNPs-GOx for successive efficient adsorption of antibody and GOx, finally yielding GOx ads /antibody/AuNPs/PDA-PtNPs-GOx bionanocomposites (PBNCs 1). The thusprepared PBNCs 1 exhibit high load and activity of the enzyme label immobilized both in the interior and on the surface for ultrasensitive signal readout, as well as high load of antibody on the surface for significant immuno-recognition efficiency. Transmission electron microscopy, atomic force microscopy, UV-vis spectroscopy, and electrochemical quartz crystal microbalance are used to characterize the prepared bionanocomposites. We use PBNCs 1 to construct sandwich-type electrochemical immunosensors, which can detect the target antigen of human immunoglobulin G down to a concentration of 2 pg mL -1 . We believe that the chemical/biochemical preparation of new immuno-active PBNCs here may open a new avenue to develop other multifunctionalized PBNCs materials for wide applications in biosensing, bioseparation, and immuno-oriented drug delivery.

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