Development of an Effective and Economic Biosensor for Diabetic Blood Monitoring Based on MWCNTs, Artificial Redox Mediator Ferrocene, Nafion Polymer and a Local Extracted and Purified Glucose Oxidase Enzyme from Penicillium Notatum F-158 Fungus

Abstract

Enhancement of the properties of glucose oxidase (GOx) enzyme is still receiving attention due to its extensive applications. Eight different fungal strains were isolated from soil and orange fruit samples for inexpensive GOx production. Penicillium notatum F-158 (P. notatum) strain produced a remarkable amount of GOx. Its culture condition was optimized for optimum GOx production. GOx was purified and its activity, stability and kinetic parameters were studied. An effective biosensor {GCE/[MWCNTs–Fc–GOx(FAD)–NF]} based on layer by layer immobilization of MWCNTs, aritificial ferrocene (Fc) redox mediator, extracted P. notatum GOx enzyme and nafion polymer (NF) on glassy carbon electrode (GCE) surface was developed for glucose determination. Fc acts as an electron relay between enzyme and MWCNTs/GCE. The synergy of MWCNTs and Fc enhances the electrocatalytic action of Fc to the enzymatic oxidation of glucose. Low potential (+0.3 V) of Fc applied in amperometric measurements avoids interference of the main electroactive substances present in the real plasma samples. This biosensor showed broad linear ranges {2.80 × 10–4 to 14.99 × 10–3 M} and low detection limit (8.68 × 10–6 M) for glucose determination. The achieved glucose concentrations in six plasma samples are consistent with normal values in human blood indicating that such biosensor could be used clinically.