Antifouling and sensitive biosensor based on multifunctional peptide and urease@ZIFs for metal matrix protease-7

For the early diagnosis and treatment of diseases, it is of great significance to develop biosensors that can detect low concentrations of biomarkers in complex biological environments. However, biofouling in biological samples is a great challenge for electrochemical biosensors. In this work, a precise, low-fouling sensing platform was developed to accurately capture targets in complex biological fluids based on a strategy of combining a multifunctional peptide with urease@zeolite imidazole frameworks (urease@ZIFs). The multifunctional peptide and sodium alginate-graphene oxide-Pb2+ (SA-GO-Pb2+) gel were used to construct an antifouling electrode interface. The modified electrode interface was coupled with a novel carboxyl-rich pyrrole doped ZIF (ZIF-Py) loaded with urease. In the presence of urease@ZIF-Py, CO2 produced by urea decomposition reacted with Pb2+ in the gel to form PbCO3 precipitation, resulting in a significant decrease in the conductivity of the sensing interface. Matrix metalloproteinase-7 was considered to be the model of this biosensor because the multifunctional peptide contained its specific hydrolytic sites. Based on the versatility of the designed peptide and the ability of urease@ZIF-Py to trigger the cascade amplify reaction, the biosensor exhibited obvious antifouling performance and sensitivity, demonstrating a wide linear range (0.1 pg mL−1-100 ng mL−1) and a low detection limit (24.34 fg mL−1). Meanwhile, the detection of clinical serum samples has excellent accuracy. This strategy provided potential prospects for the development of sensitive and low-fouling biosensors for complex environments.