Prof. Michael Sailor, UC San Diego
“Simultaneous separation, processing, and detection of biomolecules in silicon-based
optical nanostructures"
Separation, concentration, and detection of the analyte are key aspects of bioanalytics.
Nanostructured optical films constructed from porous silicon provide a versatile platform
that can incorporate all three of these components within a 5 nL volume. This
presentation will illustrate the enabling aspects of the electrochemical synthesis and
optical properties of porous silicon for label-free biosensing applications. Focusing on
the preparation of chemically modified porous multilayers and the optical interferometric
means of monitoring these nanostructures, several examples of protein and enzyme
detection will be highlighted. The ability to manipulate proteins within porous silicon
nanostructures through the selective application of electric fields will be discussed. The
approach uses a high surface area, highly porous optical electrode based on a
carbonized porous silicon Fabry-Perot film. Application of a negative bias induces
concentration of a positively charged protein such as lysozyme within the porous
nanostructure to a level ~ 9600 times the free solution concentration. Diffusion and
adsorption of protein within the 40nm-diameter pores can be monitored by optical
interferometry, providing a means to identify the protein based on its characteristic
charge, size, and diffusion characteristics. The captured protein can be held for several
hours, and it is released when the sensory electrode is returned to zero bias. The
released protein retains its enzymatic activity, and the optical electrode can undergo
multiple adsorption/desorption cycles.