A novel electrochemical sensor for determination of hydroxyl radicals in living cells by coupling nanoporous gold layer with self-assembled 6-(Ferrocenyl) hexanethiol

Abstract

The detection of hydroxyl radicals (•OH) in live cells is significant to study its physiological and pathological roles, while it is full of challenge due to the extremely low concentration and short lifetime of •OH. Herein, we have developed a novel electrochemical sensor based on 6-(Ferrocenyl) hexanethiol (6-FcHT) self-assembled nanoporous gold layer (NPGL) modified GE (6-FcHT/NPGL/GE), which can detect the release of •OH from living cells with high sensitivity and selectivity. The superior sensitivity can stem from the unique porous architecture of NPGL, which enlarged electrode surface area and expedited electron transportation during electrochemical reactions. Additionally, NPGL provides more active binding sites for the assembly of capture agent (6-FcHT) of •OH, thus ensuring high selectivity. For comparison, 6-FcHT/GE was applied to detect •OH, and the obtained sensitivity was 0.0305 mA nM−1 and detection limit was 0.133 nM in the linear range of 0.4 nM–70 nM. After modification of NPGL, the sensitivity of 6-FcHT/NPGL/GE to the •OH response was increased to 0.1364 mA nM−1, detection limit was reduced to 0.316 pM and the linear range was extended from 1 pM to 100 nM. It is worth mentioning that a plenty of extra merits has also been validated like reproducibility, repeatability and stability, enabling to direct electrochemical detection of •OH in HepG2 cells.