Amplified Peroxidase‐like Activity of Co<sup>2+</sup> Using 8‐Hydroxyquinoline and Its Application for Ultrasensitive Colorimetric Detection of Clioquinol
Lijun Xu, Jialin Sai, Dongguo Xue, Lu Zhou, Renjun Pei, Aihua Liu
Abstract
Abstract 8‐Hydroxyquinoline (8HQ) and its derivatives display diverse bioactivities and therapeutic potentials. In this study, we unveiled that 8HQ can boost the peroxidase‐like activity of Co 2+ in the presence of bicarbonate (HCO 3 − ) in neutral pH at room temperature. With 2,2′‐azino‐bis‐(3‐ethylbenzothiazoline‐6‐sulphonate) (ABTS) as the substrate, the formed Co 2+ /8HQ/HCO 3 − complex shows robust catalytic activity with the turnover number ( k cat ) tens to hundreds of times higher than that of Co 3 O 4 and other Co 2+ complexes in terms of per cobalt ion. This system was used to design colorimetric sensors for ultrasensitive detection of 8HQ‐based drugs by activating the activity of Co 2+ . Take detecting clioquinol as an example, a detection limit of 2.4 nM clioquinol with a linear range from 0.01 to 0.2 μM was obtained. This work not only revealed a new kind of ligand that activated the activity of Co 2+ , but also provided a facile, low‐cost, ultrasensitive, easy‐to‐use, and universal strategy for sensing various 8HQ‐based drugs. Further development of this catalytic system might be beneficial to overcome drug resistance by combined medication.