Development of a peptide microarray-based metal-enhanced fluorescence assay for ultrasensitive detection of multiple matrix metalloproteinase activities by using a gold nanorod-polymer substrate

Matrix metalloproteinases (MMPs) are attractive biomarkers for cancer diagnosis and treatment, while it is still a challenge to precise analysis of MMP activities owing to their very low abundance in the biological samples, especially at the early stages of tumors. Herein, a peptide microarray-based metal-enhanced fluorescence assay (PMMEFA) is proposed to simultaneously detect MMP-1, -2, -3, -7, -9, and -13 activities. The assay involves immobilization of Fo center dot rster resonance energy transfer dye pair decorated peptides (FRET-peptides) on a poly (glycidyl methacrylate-co-2-hydroxyethyl methacrylate) coated gold nanorod modified glass slide (GNR@P (GMA-HEMA)). To fabricate the GNR@P(GMA-HEMA) slide, GNRs are self-assembled onto an aminated glass slide, and a polymer brush (P(GMA-HEMA)) is grown through a surface-initiated atom transfer radical polymerization reaction (SI-ATRP). Upon the addition of MMPs, the FRET pairs are broken due to the specific cleavage of FRET-peptides by enzymes, resulting in the recovery of fluorescence signals and further enhancement by the MEF of GNRs. The fluorescence recovery degree provides a direct indicator for MMP activity. The PMMEFA exhibits excellent sensitivity, which enables to detect MMP-1, -2, -3, -7, -9, and -13 activities, with low limits of detection (LODs) of 1.7 fg mL-1, 0.3 fg mL-1, 2.0 fg mL-1, 1.8 fg mL-1, 2.2 fg mL-1 and 14.0 fg mL-1, respectively. To substantiate the practicability of PMMEFA, MMP activities were measured in a range of matrices, encompassing cell culture medium, serum, and tumor tissue homogenate, and MMP activities can be detected only in 0.15 mu L serum and 0.025 mg tumor tissue.

Automated summary

Matrix metalloproteinases (MMPs) are attractive biomarkers for cancer diagnosis and treatment, but their low abundance in biological samples, especially in the early stages of tumors, makes it challenging to precisely analyze MMP activities. In this study, a peptide microarray-based metal-enhanced fluorescence assay (PMMEFA) is proposed as a sensitive and specific method to simultaneously detect MMP-1, -2, -3, -7, -9, and -13 activities. The PMMEFA showed excellent sensitivity and was capable of detecting MMP activities in various matrices.