Development of a Sensitive Ratiometric Imprinted Hydrogel for the Detection of Matrix Metalloproteinase 7 (MMP7) Biomarker

Abstract

A dual-emissive fluorescent probe was developed for the sensitive and selective detection of matrix metalloproteinase 7 (MMP7), a protein biomarker associated with pancreatic cancer. The ratiometric probe consisting of blue emitting carbon dots (CDs) and molecularly imprinted polymers (MIPs) previously assembled around red emitting quantum dots (QDs) was successfully combined for the detection of MMP7 protein. The concept is to use MIPs that function as the biorecognition elements, conjugated to cadmium telluride QDs, as the sensing system. The fluorescence intensity of red QDs is quenched with increasing concentrations of the analyte, acting as sensitive probes, while the fluorescence intensity of blue emitting CDs remains constant, acting as internal controls. The resultant fluorescence color changed from red to blue as a function of the MMP7 concentration, under a 365 nm UV lamp. The imprinted material MIP@QDs were successfully incorporated within a cellulose hydrogel containing CDs as reference probes. The resultant materials were designated as imprinted ratiometric hydrogels (imprinted rHGs). The fluorescence quenching of the imprinted rHGs occurred with increasing concentrations of MMP7, showing linearity in the range [1.49 × 10 −11 − 1.92 × 10 −9 ] g/mL, in 1000-fold diluted human serum. The imprinted rHGs showed an imprinting factor of 1.83 and a limit of detection of 4.11 × 10 −12 g/mL. Overall, the imprinted rHGs developed in this work presented increased selectivity for the MMP7 protein over red emitting QDs nanoparticles and higher sensitivity comparatively to the non-imprinted rHGs.