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

Abstract

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 μA 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-)6GOx 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 μA/mmol L–1 cm−2, a detection limit (DL) of 27.4 μmol L-1 and a quantification limit (QL) of 91.4 μmol 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 app m) 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.