Alkaline-promoted regulation of the peroxidase-like activity of Ni/Co LDHs and development bioassays.

Abstract Nanozymes' activities could be regulated by a simple and effective pH change in an in situ manner. In this work, for the first time, the peroxidase-like activity of Ni/Co layered double hydroxides (LDHs) was regulated via the alkaline-promoted reaction of fluorogenic substrate homovanillic acid and H 2 O 2 , and a promising tool for pH sensing was developed over the pH range of 8.3–9.6. As peroxidase nanozyme model, Ni/Co LDHs showed ease of preparation, low-cost, and water-solubility, which played an important role in this luminescence system. Based on the pH-dependent regulation of the Ni/Co LDHs activity, we constructed the bioassay platform for the determination urea, urease, penicillin G, and penicillinase with a wide linear range of 17–1000 µM, 3.3–270 mU mL−1, 3.3–1300 µM and 3.3–100 mU mL−1, respectively. This study not only demonstrated the alkaline-promoted modulation the nanozymes' activities, but also established a facile approach to develop novel bioassays. Graphical abstract fx1 Highlights • The alkaline-promoted regulating Ni/Co LDHs' peroxidase-like activity has been explored. • A pH sensor was developed based on the system of Ni/Co LDHs-HVA-H 2 O 2. • A platform for the detection urea, urease, penicillin G, and penicillinase was established. [ABSTRACT FROM AUTHOR]