Effects of thin-film structural parameters on laser desorption/ionization from porous alumina.
Nanoporous aluminum oxide layers, grown by anodization of aluminum thin films on glass and then sputter-coated with gold, were used to study the effects of the thin-film structural parameters on laser desorption/ionization (LDI) mass spectrometry (MS) of peptides. Variation of MS signal intensity was examined as a function of alumina pore depth, pore width, and gold layer thickness. Peptide molecular ion intensity was optimal with porous alumina formed from aluminum films of approximately 600-nm thickness; thinner or thicker films gave significantly lower signals. Signals decreased when pore sizes were increased beyond the as-formed width of approximately 100 nm. The MS signal also varied with the thickness of the sputtered gold layer with an optimum thickness being approximately 90 nm. The results of these studies provide values for empirical optimization of LDI MS performance as well as potential clues to the LDI mechanism.
Nayak
Ranu
R
Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, 173 Ashley Avenue, Charleston, South Carolina 29425, USA.
Knapp
Daniel R
DR
D000535:Aluminum / Q000737:chemistry*; D000537:Aluminum Oxide / Q000737:chemistry*; D005898:Glass / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D007477:Ions; D008855:Microscopy, Electron, Scanning / Q000379:methods; D010316:Particle Size; D010455:Peptides / Q000032:analysis / Q000737:chemistry*; D016062:Porosity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013499:Surface Properties
D007477:Ions; D010455:Peptides; D006046:Gold; D000535:Aluminum; D000537:Aluminum Oxide