Amplified Peroxidase-like Activity of Co2+ Using 8-Hydroxyquinoline and Its Application for Ultrasensitive Colorimetric Detection of Clioquinol
Graphical The complex formed by Co 2 + , 8 - hydroxyquinoline and HCO 3 − could act as a robust peroxidase mimic in neutral pH at room temperature. This system provided a universal method for the ultrasensitive colorimetric detection of various 8-hydroxyquinoline-based drugs (e. g., clioquinol) by activating the catalytic activity of Co 2+ . 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.
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