Ultrasensitive nonenzymatic electrochemical glucose sensor based on gold nanoparticles and molecularly imprinted polymers

Abstract

A non-enzymatic electrochemical glucose sensor with high sensitivity and selectivity was developed using gold nanoparticles-decorated molecularly imprinted polymers (AuNP-MIPs). The AuNP-MIPs were synthesized on a gold surface by multistep amperometry using the optimized conditions and in-house synthesized gold nanoparticles in the presence of glucose as the template. The AuNP-MIPs were investigated by employing atomic force microscopy (AFM), scanning electron microscopy (SEM) and electrochemical techniques to confirm successful fabrication of the sensor. The electrochemical measurements for glucose binding on the AuNP-MIP sensor revealed a high affinity toward glucose with a dissociation constant (K_d) of 3 × 10^-8 M whereas the MIPs without AuNPs could not detect even the highest concentration of the investigation range (1.25 nM-2.56 μM). The comparative rebinding studies with AuNP-MIP and non-imprinted polymer (AuNP-NIP) exhibited an excellent selectivity toward glucose. The specificity of AuNP-MIP sensor was further investigated by studying with interfering compounds (sucrose, dopamine, starch, and bovine serum albumin), resulting in negligible cross-reactivity except for sucrose. The behavior of imprinted polymers in fluid solvents was also investigated by employing the AFM for the first time. The sensor could detect glucose in human serum with a detection limit of 1.25 nM and preserved its stability up to around 95% during a storage time of 40 days. Hence, such a sensor demonstrates a promising future for the detection of clinically relevant small molecules with its facile, cheap, and highly sensitive nature.

Keywords: AuNP decorated Molecularly imprinted polymers; Glucose sensing; Nanomaterials; Non-enzymatic electrochemical glucose sensor.