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 Co2+ in the presence of bicarbonate (HCO3−) in neutral pH at room temperature. With 2,2′‐azino‐bis‐(3‐ethylbenzothiazoline‐6‐sulphonate) (ABTS) as the substrate, the formed Co2+/8HQ/HCO3− complex shows robust catalytic activity with the turnover number (kcat) tens to hundreds of times higher than that of Co3O4 and other Co2+ 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 Co2+. 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 Co2+, 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.

Signal amplification techniques are highly desirable for the analysis of low-level targets that are closely related with diseases and the monitoring of important biological processes. However, it is still challenging to achieve this goal in a facile and economical way. Herein, we developed a novel dual signal amplification strategy by combining urease catalysis with the release of Ag+ from silver nanoparticles (AgNPs). This strategy was used for quantifying a DNA sequence (HIV-1) related with human immunodeficiency virus (HIV). DNA target HIV-1 hybridizes with the capture DNA probe on magnetic beads and the reporter DNA probe on AgNPs, forming a sandwich complex. The captured AgNPs are then transformed into numerous Ag+ ions that inactivate numerous ureases. Without catalytic production of ammonia from urea, the substrate solution shows a low pH 5.8 that will increase otherwise. The pH change is monitored by a pH indicator (phenol red), which allows for colorimetric detection. The proposed approach is sensitive, easy to use, economic, and universal, exhibiting a low detection limit of 9.7 fM (i.e., 1.94 attomoles) and a dynamic linear range of 4 orders for HIV-1 sequence detection.

No abstract