Protein-Coated Porous-Silicon Photonic Crystals for Amplified Optical Detection of Protease Activity


  • This project has been funded in part with Federal funds from the Air Force Office of Scientific Research (Grant# F49620-02-1-0288) and the National Science Foundation (Grant# DMR-0503006). M. J. S. is a member of the Moores UCSD Cancer Center and the UCSD NanoTUMOR Center under which this research was conducted and partially supported by NIH grant U54 CA 119335. C. P. thanks the Deutsche Forschungsgemeinschaft (PA 925/1-1) for a postdoctoral fellowship. The authors thank Anne Ruminski for experimental assistance and Prof. Farooq Azam for helpful discussions. Supporting Information is available online from Wiley InterScience or from the author.


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An optical biosensor for protease activity, capable of detecting picomole quantities of protease, is constructed from a 1D photonic crystal of porous Si. The porous Si layer is coated with a thin film of zein, a natural hydrophobic protein. Proteolytic cleavage produces small fragments that infiltrate the pores of the photonic crystal, producing a distinct color change (see figure). The amount of protease pepsin used on each of the spots is indicated.