Covalent linking peptide to hydrothermally reduced graphene oxide for ultrasensitive detection of matrix metalloproteinase 9

Abstract

Exact assay of matrix metalloproteinase 9 (MMP9) has attracted considerable attentions for the clinical diagnosis of disease in early stage. In this report, we covalently engineer a fluorescein isothiocyanate-labeled peptide (Pep-FITC) linker containing the specific cleavage substrate of MMP9 onto the surface of hydrothermally reduced nano-graphene oxide (nrGO) to develop a FRET-based nrGO-Pep-FITC nanoprobe for ultrasensitive detection of MMP9. Upon cleavage of the Pep-FITC at the amide bond between Ser and Leu by MMP9, FITC was separated from nrGO, and fluorescence recovery of FITC was proportional to the MMP9 concentration within 0.01–0.06 nM and 0.06–0.15 nM ranges, respectively, in an aqueous solution, exhibiting 0.83 pM of detection limit. This nanoprobe is stable under borate buffer (pH = 7.4) with bovine serum albumin or 0.1% surfactant Triton 100 or Tween 20, and has good specificity for MMP9 detection, which is meaningful for MMP9-related clinical and bio-analytical applications.