Development of a Single-Particle Collision Electrochemistry Strategy for the Sensing of Matrix Metalloproteinase-9 with High Sensitivity and Selectivity

As a potential biomarker associated with various diseases, high sensitivity and selective quantitative detection of matrix metalloproteinase-9 (MMP-9) are of great significance. Single-particle collision electrochemistry (SPCE) has attracted great attention in the biosensing field due to its advantages of simplicity, speed, and homogeneous detection. Herein, we developed a sensing strategy for highly sensitive and specific detection of MMP-9 using the SPCE technique. Ag nanoparticles (AgNPs) can collide on gold ultramicroelectrodes (Au UME) and produce peak collision signals due to the oxidation of AgNPs. When MMP-9 aptamers adsorb on the AgNPs surface to form AgNPs-Aptamer conjugates, the oxidation of AgNPs on Au UME is inhibited, and the collision signals are weakened. However, when target MMP-9 is present, the strong binding affinity between MMP-9 and aptamers reduces the DNA content of the AgNPs surface, thereby promoting the recovery of collision current and frequency, which can be used to detect MMP-9 with high sensitivity and selectivity. This SPCE-based strategy does not require complex biomarkers and washing procedures and can sensitively and homogeneously detect target MMP-9 molecules.