Bioelectrochemical Sensing Using Benchtop Fabricated Nanoroughened Microstructured Electrodes

Cost-effective miniaturized electrodes that maintain a high electroactive surface area (ESA) are needed for the widespread deployment of point-of-care sensors. Cost-effective methods are recently developed to fabricate nanoroughened microstructured gold electrodes (NR-MSEs) with ultrahigh ESA. In this work, the effectiveness of NR-MSEs for bioelectrochemical enzymatic sensors is evaluated. A glucose sensor is constructed by first casting onto NR-MSEs a solution containing reduced graphene oxide decorated with gold nanoparticles, glucose oxidase, and glutaraldehyde, followed by a solution containing ferrocene, and a layer of chitosan to prevent the leakage of sensor components. A urea biosensor is also fabricated using Nafion as a cationic exchanger for the electropolymerization of polyaniline, followed by the deposition of a composite containing urease, bovine serum albumin, and glutaraldehyde. The limit of quantification for both biosensors is below clinically relevant concentrations of the analytes in biofluids, 0.67 mm for glucose and 1.70 mm for urea. The sensors exhibit excellent performance in complex matrixes (human blood serum and wine for glucose and human blood serum and urine for urea), with recovery for spiked analytes in the range of 92–108%. It is anticipated that NR-MSEs will expedite the development of highly sensitive bioelectrochemical sensors for use in resource-limited settings.