A dual-channel sensing platform for ATP and copper ions via the target-induced peroxidase mimics activity and fluorescence variations of iron oxide nanoparticles-modified metal-organic frameworks

The simultaneous or continuous detection of multiple targets in complex samples is for various applications, notably in medical diagnostics and environmental monitoring. A novel dual-channel colorimetric and fluorescent method has been developed for the continuous detection of adenosine triphosphate (ATP) and copper ions based on PCN-224@Fe₂O₃, which exhibits both fluorescent and enhanced peroxidase-like (POD-like) properties. The synthesis of PCN-224@Fe₂O₃ involved the in-situ growth of ferric oxide on Zr-based metal-organic frameworks (PCN-224). Through catalyzing the colorless compound 3,3′,5,5′-tetramethylbenzidine (TMB) to produce a blue product (oxTMB) in the presence of H₂O₂, PCN-224@Fe₂O₃ allows for the detection of ATP and copper ions. The unique mechanism involves ATP weakening the POD-like activity of PCN-224@Fe₂O₃ by forming Zr-O-P bonds with Zr in PCN-224, which also leads to fluorescence recovery. Copper ions, through chelating with ATP, counteract the effect of ATP on PCN-224@Fe₂O₃, resulting in increased POD-like activity and the amount of oxTMB alongside the quenching of the fluorescence of the system. This facilitates colorimetric “on-off-on” and fluorescence “off-on-off” switch sensing for ATP and Cu²⁺. The application of PCN-224@Fe₂O₃ in the detection of ATP and Cu²⁺ in human serum yielded satisfactory results. This innovative approach not only provides a means to regulate the mimic activity of oxides but also presents a convenient, sensitive, and accurate detection method for ATP and Cu²⁺, significantly broadening the potential application of MOFs and nanozymes in bioanalysis.