Dual mode fluorometric and colorimetric detection of matrix metalloproteinase MMP-9 as a cancer biomarker based on AuNPs@gelatin/AuNCs nanocomposite

Matrix metalloproteinase (MMPs) are proteolytic enzymes which considered as important enzymes and their higher expression is associated with some malignant progression. In the present study, a novel and sensitive method was developed for detection of MMP-9 based on its gelatinase activity. Green emitting gold nanoclusters (AuNCs) has been synthesized by gelatin substrate and then AuNPs@gelatin/AuNCs nanocomposite structure were prepared through coating of gold nanoparticles (AuNPs) with gelatin/AuNCs. Characterization and morphology of synthesized nanocomposite showed successful formation of AuNPs@gelatin/AuNCs. Constructed nanocomposite exhibited internal FRET occurrence and fluorescence quenching of AuNCs due to proximity of AuNCs/AuNPs structures. Hydrolysis effect of MMPs enzyme on AuNPs@gelatin/AuNCs in saline buffer induced changes in surface plasmon resonance (SPR) of gold nanoparticles and also enhanced the emitted fluorescence by AuNCs due to inhibition of internal FRET process. The proposed platform served as the efficient approach for semi-quantitative detection of MMP-9 enzyme by naked eye and precise activity detection with LOD of 2 ng/mL calorimetrically and 0.25 ng/mL fluorometrically. The approach was also showed convenient recovery for detection of MMP-9 enzyme in human serum matrix. Our work provides an efficient, convenient and practical tool for simple identification and precise detection of MMP-9 enzyme.