Fluorescence detection of fibrillar proteins on silicon microstructures

The biology and the structure of amyloid fibrils are under extensive investigation in many laboratories: they are co-causative agents of diseases such as Parkinson's and Alzheimer's. We are investigating the use of a silicon micromachined structure, fabricated by electrochemical etching, as a three-dimensional supporting matrix also suitable for optically monitoring the amyloid fibrils growth. The silicon device consists in a periodic array of silicon walls with high aspect-ratio. This periodic arrangement of silicon and air gives rise to one-dimensional hybrid photonic crystals, suitable for out-of-plane (top view) imaging but, potentially, also for in-plane label-free testing. Here, we present some preliminary results relative to fluorescence microscopy analysis performed to investigate the interaction among silicon microstructures and fibrillar proteins. Samples of the highly amyloidogenic variant of human β2-microglobulin (P32G β2-m) are deposited on flat silicon dice as well as inserted into the gaps of the micromachined silicon devices. After Thioflavin T labeling, a bright emission originating only from silicon devices where polymerized amyloid fibrils are present is observed.