Porous Silicon Resonant Microcavity Biosensor for Matrix Metalloproteinase Detection

A real-time, sensitive, and selective detection device to monitor the healing status of chronic wounds at the point of care is urgently required to render the management of this disease more effective. The photonic properties of porous silicon resonant microcavity (pSiRM) afford an excellent opportunity to be developed as a highly sensitive optical biosensor to monitor the presence of specific biomarkers found in the wound exudate, such as matrix metalloproteinases (MMPs). In this study, the pSiRM is designed, fabricated, and functionalized using a fluorogenic MMP peptide substrate featuring both a fluorophore and a quencher. The peptide-functionalized pSiRM is then employed as a fluorescence-based optical biosensor for MMPs. Active MMPs recognize and cleave the peptide sequence of the substrate, producing an immobilized peptide fragment carrying the fluorophore. The fluorescence intensity of the fluorophore embedded within the pSiRM matrix is enhanced by the photonic structure of the pSiRM compared to other pSi photonic structures. This fluorescence enhancement translates into high sensitivity, enabling detection of MMP-1 at a limit of detection as low as 7.5 × 10^-19 m after only 15 min incubation time. Finally, the biosensor also allows the detection and quantification of the concentration of MMPs in human wound fluid. An optical biosensor based on functionalized porous silicon resonance microcavity (pSiRM) using matrix metalloproteinase (MMP) substrate containing a fluorophor and a quencher is demonstrated. The presence of MMP cleaves the substrate leaving the fluorophor on the pSiRM matrix which is now emitting the fluorescence. This biosensor sensitively and selectively detects the MMP in buffer solution and human wound fluid.