Copper-pyridine-2,4,6-tricarboxylate metal organic framework nanoparticles based opto-electrochemical sensor for sensitive detection of matrix metalloproteinase‑2

We designed a multiple signal sensing probe based on highly luminescent nanosized Cu-PTC metal-organic framework (MOF). The as synthesized nano-MOF was characterized by various techniques to confirm its morphology, crystallinity and elemental composition. A positively charged matrix metalloproteinase-2 (MMP-2) substrate (a polypeptide) was designed and prepared to interact electrostatically with the negatively charged Cu-PTC MOF probe, resulting in decrease in fluorescence response of the probe. Subsequently, MMP-2 was specifically recognized by the MMP-2 substrate and cleavage of the MMP-2 substrate resulted in “turn-on” fluorescence response from 1 to 175 ng/mL of MMP-2 concentrations with a limit of detection (LOD) of 0.8 ng/mL. In addition, the developed Cu-PTC MOF also exhibited peroxidase-like activity, which was exploited in the electrochemical detection of MMP-2 subjected to the catalysis of 3,3,5,5-tetramethylbenzidine (TMB) in the presence of H₂O₂. The large surface area of the probe and unique catalytic activity toward TMB facilitated fabrication of an excellent sensing platform to detect MMP-2 with a linear range of 0.5–200 ng/mL with a LOD of 0.25 ng/mL. Various potential interfering biomolecules were evaluated and the stability of the constructed biosensor was assessed in optical and electrochemical modes. The reliability of the electrochemical detection mode was further executed by monitoring MMP-2 in biological samples (human serum and cell samples) and good recoveries were recorded.