In recent years, mass spectrometry techniques such as matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) have made a substantial impact on molecular biology. These tools allow detailed chemical information to be obtained on large structures at levels of sensitivity previously known only for more crude techniques such as gel electrophoresis with radiolabeled compounds. A new and inexpensive modification of MALDI has been discovered which eliminates the added matrix material that both allows MALDI to occur and limits its applicability. The new method, called laser desorption/ionization on porous silicon (DIOS), depends on the properties of chemically derivatized porous silicon to trap analyte molecules and provide an efficient mechanism for their ejection into the gas phase as intact and detectable ions upon pulsed laser irradiation. Because no added matrix is used, small molecules of molecular weight as low as 80 Daltons can be detected with high sensitivity by direct laser desorption without interference. The goals of this program are: (1) to further refine the DIOS technique, (2) to characterize porous silicon surfaces that are active in DIOS-MS and thus gain insights into the mechanisms of desorption and ionization, (3) to modify DIOS surfaces to allow a variety of chemical and biochemical reactions to be conveniently monitored by mass spectrometry, and (4) to develop porous silicon materials that both support DIOS and allow for chromatographic separation of molecules. As tests of the analytical technique, we will investigate the screening of chemical and enzymatic catalysts on DIOS-MS plates, on-plate affinity labeling, on-plate digestion and identification of proteins, and de novo sequencing using DIOS post-source decay MS. The ability to tailor surface properties by varying the conditions of preparation and modification of porous silicon, coupled with the routine use of surface science probes to examine what we make, will enable us to bring this technique to the level required for broad use by the chemistry and biochemistry communities.

Agency
National Institute of Health (NIH)
Institute
National Center for Research Resources (NCRR)
Type
Research Project (R01)
Project #
5R01RR015066-03
Application #
6639878
Study Section
Special Emphasis Panel (ZRG1-BMT (01))
Program Officer
Sheeley, Douglas
Project Start
2001-06-01
Project End
2005-05-31
Budget Start
2003-06-01
Budget End
2005-05-31
Support Year
3
Fiscal Year
2003
Total Cost
$336,730
Indirect Cost
Name
Scripps Research Institute
Department
Type
DUNS #
781613492
City
La Jolla
State
CA
Country
United States
Zip Code
92037
Meng, Jun-Cai; Siuzdak, Gary; Finn, M G (2004) Affinity mass spectrometry from a tailored porous silicon surface. Chem Commun (Camb) :2108-9
Shen, Zhouxin; Go, Eden P; Gamez, Alejandra et al. (2004) A mass spectrometry plate reader: monitoring enzyme activity and inhibition with a Desorption/Ionization on Silicon (DIOS) platform. Chembiochem 5:921-7
Meng, Jun-Cai; Averbuj, Claudia; Lewis, Warren G et al. (2004) Cleavable linkers for porous silicon-based mass spectrometry. Angew Chem Int Ed Engl 43:1255-60
Go, Eden P; Shen, Zhouxin; Harris, Ken et al. (2003) Quantitative analysis with desorption/ionization on silicon mass spectrometry using electrospray deposition. Anal Chem 75:5475-9
Yao, Sulan; Meng, Jun-Cai; Siuzdak, Gary et al. (2003) New catalysts for the asymmetric hydrosilylation of ketones discovered by mass spectrometry screening. J Org Chem 68:2540-6
Go, Eden P; Prenni, Jessica E; Wei, Jing et al. (2003) Desorption/ionization on silicon time-of-flight/time-of-flight mass spectrometry. Anal Chem 75:2504-6