Microneedle array sensor for monitoring glucose in single cell using glucose oxidase-bonded polyterthiophene coated on AuZn oxide layer

Abstract

A monomer precursor of conducting polymer, 2,2´:5´,5″-terthiophene-3´-carboxylic acid, (TCA) was electropolymerized on the raspberry-like AuZn oxide (AuZnOx) layer coated on microneedle array electrode (μ-NAE) at single and multi-cell analysis. The AuZnOx was used to elevate the catalytic effect of H2O2 oxidation and to prevent the passivation of the Au surface by chloride ion in biological samples. After optimizing the experimental variables affecting the analytical signal, in terms of monomer and GOx concentrations, electropolymerization cycles, pH, applied potential, and temperature. The sensor was responded with in 1 s, and showed the two dynamic ranges of 0.01–5.0 and 5.0–50.0 mM with detection limit of 1.2 (± 0.026) μM. The sensor performance and reliability were examined by measuring glucose in cells of different cancer types (PC-12, MG-62, HeLa, A549, and Saos-2), comparing with normal (Vero) cells. In addition, the effect of K+ ion on the glucose level was also investigated for a single cell. The sensor confirmed the higher concentration of glucose in cancer cells than the normal cells, where the intracellular glucose level was 2.2 folds higher as compared to the extracellular levels in PC-12 cells.