Dual Mechanism Enhanced Peroxidase-like Activity of Iron–Nickel Bimetal–Organic Framework Nanozyme and Its Application for Biosensing

The study of the mechanism of peroxidase-like activity of nanozymes, to obtain high-performance, is of great significance in biosensing and biocatalysis. Herein, the developed bimetal–organic frameworks (Fe x Ni y -MOF) all showed enhanced peroxidase-like activity, and the research was carried out on behalf of Fe 3 Ni-MOF with the best catalytic activity. The dual mechanism (electron transfer mechanism and generation of hydroxyl radicals ( • OH) mechanism) of the enhanced peroxidase-like activity of Fe 3 Ni-MOF was deduced through the cyclic voltammetry and electron spin resonance. The enhanced peroxidase-like activity mainly depends on the introduction of Ni, which improved the redox capacity of Fe 3 Ni-MOF and accelerated the electron transfer between TMB and H 2 O 2 . In addition, the introduction of Ni also improved the conversion efficiency between Fe 3+ and Fe 2+, to promote the generation of • OH, and then enhanced the peroxidase-like activity. The Fe 3 Ni-MOF we obtained can achieve ultrasensitive detection of H 2 O 2 with a linear range of 0.02–15 μM and a detection limit as low as 11 nM. This makes the enhancement of peroxidase-like activity of practical significance. Then, a glucose detection system was successfully established with using H 2 O 2 as an intermediate product, which has great potential in the development of biosensor applications.