Fabrication and characterization of surface-derivatized porous silicon "smart particles" for detection of streptavidin.

Biotin/silole-derivatized distributed Bragg reflectors porous silicon (DBR PSi) smart particles for the detection of streptavidin have been developed. DBR PSi fabricated by applying a computer-controlled periodic square current waveform was prepared for the application as a label-free biosensor based on PSi interferometer. The fabrication, optical characterization, and surface derivatization of DBR smart particles were described. Biotin/silole-derivatized DBR smart particles displaying dual optical properties such as photoluminescence (lambda(em) = 505 nm) and reflectivity (lambda(max) = 607 nm) were obtained from the DBR PSi film in organic solution by using ultra-sono method. The surface and cross sectional morphology of DBR smart particles were obtained with FE-SEM. FT-IR spectroscopy was used to characterize the oxidation and functionalization of DBR smart particles. Binding of the streptavidin into the biotin-derivatized DBR smart particles displayed a change in refractive index. A red-shift of reflectivity by 14 nm in the reflectivity spectrum was observed, when the biotin-modified DBR smart particles were exposed to a flow of PBS buffer solution containing streptavidin.