Evaluation on covalent and noncovalent linking of peptide to graphene oxide for MMP-9 detection

ABSTRACTFITC-labeled peptide (Pep-FITC) containing the cleavage site of matrix metalloproteinase-9 (MMP9) was non-covalently or covalently linked to graphene oxide (GO) to form non-covalent or covalent nanoprobes (nGO/Pep-FITC and nGO-Pep-FITC) for MMP9 detection. nGO-Pep-FITC was prepared by formation of amide bonds between the carboxyl groups of c-nGO and the amine groups on Pep-FITC with the addition of 1-ethyl-3-(dimethylaminopropyl)-carbodiimide (EDC). Pep-FITC was physically adsorbed onto the surface of c-nGO through π-π stacking and electrostatic interactions to produce nGO/Pep-FITC. Both nGO/Pep-FITC and nGO-Pep-FITC exhibited good selectivity for MMP9 detection. nGO/Pep-FITC and nGO-Pep-FITC showed 29.61 and 32.53 pM of detection limits for MMP9, respectively. nGO-Pep-FITC was much more resistant to bovine serum albumin (BSA) than nGO/Pep-FITC, thus may be applicable to analyze clinical samples especially containing proteins.