Direct Electron Transfer and Electro-Catalytic Activity of Non-Enzymatic Glucose Biosensor Based on Silver Nanoparticle (AgNPs) Stabilized with Sodium Tripolyphosphate (NaTPP) Cross-Linked Chitosan

Abstract

The development of non-enzymatic glucose biosensor has been the concern of many researchers mainly because enzymes based sensor despite having excellent sensitivity and selectivity, has the limitations such as poor stability, complicated enzyme immobilization, critical operating conditions such as optimum temperature and reproducibility. This study developed a cheap biocompatible non-enzymatic glucose biosensor based on silver nanoparticle (AgNPs) stabilized with sodium tripolyphosphate (NaTPP) cross-linked chitosan. Direct electron transfer and electro-catalytic activity of the AgNPs modified glassy carbon electrode (AgNPGCE) was investigated using potentiometric and amperometric techniques. AgNPs was prepared and characterized by Fourier transform Infra-red spectroscopy (FTIR), X-ray diffractometry (XRD) and Scanning electron microscopy (SEM). The crystalline size of the AgNPs was revealed with XRD. However, the SEM micrograph of AgNPs revealed the spherical shape with a non-uniform granular shape attributed to bio-mediated ionic gelation process. The FTIR spectra of AgNPs shown peaks at 1054 – 1645 cm -1 suggesting the presence of phosphonate linkages between ammonium, -NH 3 + of chitosan and -PO 3 2- moieties of NaTPP during cross linking process. Electro-catalytic oxidation of glucose at the AgNPGCE surface and the mechanism involved in glucose oxidation was revealed via cyclic voltammetry. The AgNPGCE showed a better electrochemical response towards glucose. This glucose sensor showed high sensitivity at +0.54 V. A low detection limit of 1.22 µM (the confident level κ = 3), and wide linear range of 2 to 24 µM with a correlation coefficient of 0.9987 were obtained. The calculated parameters revealed that AgNPGCE had shown better overall electrochemical performance and response than enzymatic biosensor.