Boosting the Peroxidase‐like Activity of Cobalt Ions by Amino Acid‐based Biological Species and Its Applications

Recent Progress on Peroxidase Modification and Application

Peroxdiase is one of the member of oxireductase super family, which has a broad substrate range and a variety of reaction types, including hydroxylation, epoxidation or halogenation of unactivated C-H bonds, and aromatic group or biophenol compounds. Here, we summarized the recently discovered enzymes with peroxidation activity, and focused on the special structures, sites, and corresponding strategies that can change the peroxidase catalytic activity, stability, and substrate range. The comparison of the structural differences between these natural enzymes and the mimic enzymes of binding nanomaterials and polymer materials is helpful to expand the application of peroxidase in industry. In addition, we also reviewed the catalytic application of peroxidase in the synthesis of important organic molecules and the degradation of pollutants.

Amplified Peroxidase-like Activity of Co2+ Using 8-Hydroxyquinoline and Its Application for Ultrasensitive Colorimetric Detection of Clioquinol

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 (k_cat ) tens to hundreds of times higher than that of Co₃ O₄ 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.

Accelerating the peroxidase-like activity of Co2+ by quinaldic acid: Mechanism and its analytical applications

Although enzyme mimics have been widely developed, limited catalytic efficiency is still a bottleneck, especially under neutral condition. Herein, we reported the bioactive quinaldic acid (QA) significantly boosted the peroxidase-like activity of Co²⁺ in the presence of bicarbonate (HCO₃^-). With 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonate) (ABTS) as the substrate, the catalytic activity of Co²⁺ (1 μM) was increased by over 300 times upon adding 100 μM QA. The formed Co²⁺ complex had much higher turnover number (5.52 min^-1) than that of cobalt-based nanozymes (0.011-0.51 min^-1) in decomposing H₂O₂. Based on this system, ultrasensitive colorimetric methods for the detection of Co²⁺, bicarbonate and urease activity were achieved with limits of detection of 4.6 nM, 40 μM and 0.00125 U/mL, respectively. For the first time, this work established an ultrasensitive method for the detection of urease activity by activating a peroxidase-like mimic with the produced HCO₃^-.