(639d) Label-Free Colorimetric Detection of Matrix Metalloproteinases on Nanoporous Silicon Photonic Crystals

Matrix metalloproteinases (MMPs) are degradative enzymes that play an important role in tumor invasion and metastasis. Current MMPs detection methods include zymography, ELISA, western blot, and immuno-histochemistry. However, all of these methods are facing enormous challenges to have the high sensitivity and specificity of MMPs detection required for routine clinical detection of tumors. For example, zymography detection is time consuming and cumbersome; ELISA, western blot, and immuno-histochemistry are not able to detect the activity of MMPs. Here we present the fabrication of a MMPs sensor on a nanoporous silicon photonic crystal platform. The sensor is made by spin-coating a thin gelatin-layer on a nanoporous silicon chip. MMPs present in the sample will digest the gelatin layer and induce a significant change of the rugate peak position on the reflection spectrum of the porous silicon, which can be detected by naked eyes when the chip is illuminated with white light. This method can detect both the presence and the activities of the MMPs, which corresponds to the expression level of MMPs in tumor growth and metastasis. Detection of MMPs at a concentration as low as 1 ng/ml has been demonstrated using this method.