CN- as a cofactor enhancing the laccase-like activity of copper porphyrin metal-organic frameworks facilitates the sensitive cyanide detection

Excessive presence of cyanide in various environmental and biofluids poses a significant threat due to its highly toxic nature and potential threat to living organisms. Nevertheless, a multitude of current techniques encounter difficulties in sensitivity and selectivity issues. Inspired by the Cu-N active sites in natural laccase, we propose novel copper-based porphyrin metal-organic frameworks (Cu-TCPP) nanosheets that act as potent laccase mimics, which has been firstly used for the ultra-sensitive cyanide detection. The electron-rich nature, strong reductivity, and Cu-ion coordination ability of cyanide ions (CN^-) specifically enhances the mimic activity of Cu-TCPP. The incorporation of CN^- also increases the Cu⁺/Cu²⁺ ratio and oxygen vacancies, accelerates the interaction between Cu-TCPP and its substrates, enhancing the electron transfer and improving oxygen activation efficiency and catalytic cycling. Notably, the regulatory effect of CN^- is concentration-dependent, enabling sensitive CN^- detection. To address potential interferences from the inherent color and UV absorption of the nanomaterials, a post-reaction centrifugation technique has been introduced, allowing for accurate measurement with improved resolution and sensitivity. The innovative strategy of utilizing a cofactor to regulate the laccase mimics activity provides fresh insights into the design of advanced nanozymes and offers an alternative method for detecting cofactors, facilitating broader applications in various fields.