Polymeric Bionanocomposite Cast Thin Films with In Situ Laccase-Catalyzed Polymerization of Dopamine for Biosensing and Biofuel Cell Applications

Abstract

We report here on the facile preparation of polymer−enzyme−multiwalled carbon nanotubes (MWCNTs) cast films accompanying in situ laccase (Lac)-catalyzed polymerization for electrochemical biosensing and biofuel cell applications. Lac-catalyzed polymerization of dopamine (DA) as a new substrate was examined in detail by UV−vis spectroscopy, cyclic voltammetry, quartz crystal microbalance, and scanning electron microscopy. Casting the aqueous mixture of DA, Lac and MWCNTs on a glassy carbon electrode (GCE) yielded a robust polydopamine (PDA)−Lac−MWCNTs/GCE that can sense hydroquinone with 643 μA mM−1 cm−2 sensitivity and 20-nM detection limit (S/N = 3). The DA substrate yielded the best biosensing performance, as compared with aniline, o-phenylenediamine, or o-aminophenol as the substrate for similar Lac-catalyzed polymerization. Casting the aqueous mixture of DA, glucose oxidase (GOx), Lac, and MWCNTs on a Pt electrode yielded a robust PDA−GOx−Lac−MWCNTs/Pt electrode that exhibits glucose-detection sensitivity of 68.6 μA mM−1 cm−2. In addition, 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonate) diammonium salt (ABTS) was also coimmobilized to yield a PDA−Lac−MWCNTs−ABTS/GCE that can effectively catalyze the reduction of O2, and it was successfully used as the biocathode of a membraneless glucose/O2 biofuel cell (BFC) in pH 5.0 Britton−Robinson buffer. The proposed biomacromolecule-immobilization platform based on enzyme-catalyzed polymerization may be useful for preparing many other multifunctional polymeric bionanocomposites for wide applications