The Role of a Layer-by-Layer Film Containing Pt Nanoparticle on the Performance of a Glucose Enzymatic Biosensor

A novel glucose biosensor based on immobilization of glucose oxidase in LbL films containing platinum nanoparticles (PtNPs) nanohybrid incorporated in 3-n-propylpyridinium silsesquioxane chloride (SiPy+Cl-) was developed. These films were assembled with the poly(2,5-methoxypropyloxy sulphonatephenylenevinylene) (PPV-SO3) as polyanion alternated with the (Pt-SiPy+Cl-) nanohybrid polycation to obtain the (PPV/Pt-SiPy+Cl-)(n) and (Pt-SiPy+Cl-/PPV)(n) LbL films. The formation of these LbL films was monitored by linear increase observed in the absorbance in the UV-Vis spectra and the number of Pt-SiPy+Cl-/PPV (R =0.994) or PPV/Pt-SiPy+Cl- (R = 0.997) bilayers. FTIR and Raman spectra confirmed the presence of the polyelectrolytes in the LbL films. The films were electrochemically studied using phosphate buffer saline (PBS) solution 0.1 mol L-1 (pH 7.0), and it was observed that the (PPV/Pt-SiPy+Cl-)(6) LbL films containing 6 bilayers showed better performance in H2O2 detection with Ipa = 6.16 mu A and Epa = 1.06 V. Thus, glucose oxidase (GOx) was immobilized onto (PPV/Pt-SiPy+Cl-)(6) LbL film surface to obtain the (PPV/Pt-SiPy+Cl-)(6)GOx biosensor. The properties of the resulting glucose biosensor were studied by amperometric measurements. The biosensor displayed good repeatability and reproducibility with a sensitivity of 1.17 mu A/mmol L-1 cm(-2), a detection limit (DL) of 27.4 mu mol L-1 and a quantification limit (QL) of 91.4 mu mol L-1. In addition, the resulting glucose biosensor exhibited a constant electrochemical answer to glucose for a period of approximately 30 days, thus indicating a stable adsorption of GOx. The apparent Michaelis-Menten constant (k(m)(app)) obtained was of 2.64 mmol L-1, this is an excellent value compared to those obtained with hybrid materials due to PtNPs available in the structure of the SiPy+Cl- which increase the surface area.