Nanoarchitectonics of a new rGO/poly(p-aminobenzoic acid) (pPABA)-based molecularly imprinted polymer electrode for detecting ascorbic acid, uric acid and glucose

Developing electrochemical sensors for ascorbic acid, uric acid and glucose detection provides advantages of rapid, precise and economical monitoring of disease condition, and they have the potential to transform healthcare by enabling point-of-care diagnostic and personalised treatment. Facile and cost-effective potentiometric sensors have been developed in this work for selective and sensitive detection of ascorbic acid, uric acid and glucose, based on molecularly imprinted polymer (MIP). The imprinted polymeric matrix of para-aminobenzoic (pPABA) was developed on the surface of electrochemically reduced graphene oxide modified paraffin impregnated graphite rod electrode (rGO/PIGE). The monomeric para-aminobenzoic acid (PABA) was electropolymerised with template, viz., ascorbic acid, uric acid and glucose individually. The molecularly imprinted electrode surface was created by removing the trapped template molecule. The surface analysis of the modified electrodes was carried out by cyclic voltammetry (CV), scanning electron microscopy (SEM), attenuated total reflection spectroscopy (ATR), Raman spectroscopy and contact angle measurements. Parameters controlling the performance of the MIP (p-PABA), viz., pH of the supporting electrolyte and number of polymerisation cycle, were optimised. Under optimised conditions, the potentiometric responses of MIPs were linearly related to concentrations of ascorbic acid, uric acid and glucose in the range of 3.4 x 10-7 M-2.5 x 10-5 M, 3.3 x 10-7 M-1.3 x 10-5 M, and 3.5 x 10-7 M-2.9 x 10-5 M with a correlation coefficient, R2 of 0.99, 0.99 and 0.98 respectively. All three sensors showed high selectivity even in the presence of high concentration of similar interfering compounds. A limit of detection (LOD) for ascorbic acid, uric acid and glucose was found to be 1.1 x 10-8 M, 2.8 x 10-8 M and 1.3 x 10-8 M respectively. In addition, the developed sensors exhibited long-term stability and good reproducibility.