A study on the stability and sensitivity of mediator-based enzymatic glucose sensor measured by catalyst consisting of multilayer stacked via layer-by-layer

A catalyst consisting of carbon nanotube, 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO), polyacrylic acid (PAA), polyethylenimine (PEI), and glucose oxidase (GOx) (CNT/[TEMPO-PAA]/PEI/GOx) is developed to improve the stability and sensitivity of mediator based glucose sensor. In this catalyst, TEMPO is bonded with PAA to prevent the leaching out of TEMPO, which plays a crucial role in increasing the glucose sensitivity by instilling charges in it. The TEMPO-PAA composite is then linked to other components by electrostatic force. To confirm the chemical structure of the catalyst, its chemical bonds and surface charge are investigated by Fourier-transform infrared spectroscopy and zeta potential. When the stability and glucose sensitivity are measured, this catalyst preserves 80% of its initial catalytic activity for one week although other similar catalysts show far worse stability. In addition, the linear relationship of glucose concentration and reactivity of glucose oxidation shown in 1–10 mM glucose range that corresponds to actual blood glucose concentration of human being indicates that this catalyst can induce excellent glucose sensitivity. In terms of selectivity, this catalyst reacts with blood glucose highly selectively, whereas this is not reacted with other eight different saccharides.