A novel magnetic and fluorescent nanocomposite probe for detection of matrix metalloproteinase-2 in cells.

Detection of matrix metalloproteinase-2 (MMP-2) is of great significance for clinical diagnosis and therapy of cancer in the early stage. In this study, a novel magnetic-fluorescent nanocomposite probe for simple, fast and sensitive detection of MMP-2 was innovatively developed by self-assembly of a specifically designed MMP-2 substrate peptide and cobalt-nitrilotriacetate (Co2+-NTA) modified magnetic beads via the chelation mechanism. The specifically designed peptide consisted of green fluorescein (FITC) that acted as the fluorescence signal donor, and the MMP-2 cleavage sequence fused with the hexa-histidine (6× His) tag. In the presence of MMP-2, the His-tagged fluorescent peptides conjugated to the Co2+-NTA modified magnetic beads would be cleaved by MMP-2 due to specific substrate recognition, releasing the FITC-labeled peptide segment into the solution. After the nanocomposite probe was removed from the reaction solution by magnetic separation, high fluorescence signal intensity of the supernatant would be obtained. The proposed nanoprobe demonstrated a wide linear range and a high sensitivity for MMP-2 with a detection limit of 0.3 ng mL-1. It also exhibited satisfactory performance in cell samples. Additionally, the novel nanoprobe could be effectively separated and recycled using a magnet, which allows it to exhibit reusable characteristics. This method not only provides a novel strategy for MMP-2 assay but also offers potential application in biomedical and clinical studies.