AVS 47th International Symposium
    Biomaterial Interfaces Tuesday Sessions
       Session BI-TuM

Paper BI-TuM9
Desorption/Ionization Mass Spectrometry on Porous Silicon Surfaces

Tuesday, October 3, 2000, 11:00 am, Room 202

Session: Protein-Surface Interactions
Presenter: Z. Shen, University of California, San Diego
Authors: Z. Shen, University of California, San Diego
J.E. Crowell, University of California, San Diego
G. Siuzdak, The Scripps Research Institute
Correspondent: Click to Email
A new desorption/ionization strategy for biomolecular mass spectrometry has been developed based on pulsed laser desorption/ionization from a porous silicon surface. Desorption/ionization on silicon (DIOS) uses porous silicon to trap analytes deposited on the surface and laser radiation to vaporize and ionize these molecules. DIOS is demonstrated for a wide range of small molecules as well as biomolecules at the femtomole and attomole level with little or no fragmentation, in contrast to what is typically observed with other direct desorption/ionization approaches. Porous silicon surfaces were prepared using electrochemical etching. While DIOS has been universally applicable for a range of mass analyses, its success is highly dependent upon the preparation of the sample and the nature of the porous silicon surface. Different etching parameters, including silicon wafer crystal orientation, dopant type, dopant level, light intensity, current density, etching solution, and etching time were studied to optimize DIOS-MS performance. Scanning Electron Microscopy (SEM) was used to examine the pore structure and correlate it with DIOS-MS performance. We will also demonstrate the application of DIOS-MS to small molecule analysis and quantitation, protein identification, on-chip reaction monitoring, on-chip separation and post-source decay structure analysis. DIOS offers many unique advantages including good sensitivity, low background ion interference, and high salt tolerance. Desorption/ionization on porous silicon (DIOS) permits analysis of a wide range of molecules with very good sensitivity and a demonstrated potential for automation, as well as compatibility with microfluidics and microchip technology on silicon.