Iodide-enhanced Co/Fe-MOFs nanozyme for sensitively colorimetric detection of H₂S

In this paper, a simple, rapid, and low-cost colorimetric method was designed based on Co/Fe-MOFs-iodide composite for the quantitative detection of H₂S. It is know that iodide can improve the catalytic activity of bimetallic porous material Co/Fe-MOFs via adsorption into the framework of MOFs. Herein, we demonstrate a novel strategy to enhance the peroxidase-like activity of MOFs. Compared to horseradish peroxidase (HRP), the kinetic measurement results show that Co/Fe-MOFs-iodide exhibits excellent affinity to substrates, promoting electron transfer. Due to the synergetic effect of Co/Fe-MOFs and iodide, and rapid electron transfer process, Co/Fe-MOFs-iodide demonstrates improved peroxidase-like activity. As a proof-of-concept application, a novel, highly sensitive H₂S colorimetric method is established with a detection limit (LOD) of 0.33 nM. In the absence of iodide, LOD is approx. 200-fold higher than that of the amplified colorimetric assay. The proposed method can also accurately detect traces of H₂S in serum samples.