Matrix-free laser desorption/ionization mass spectrometry on silicon nanowire arrays prepared by chemical etching of crystalline silicon.
This paper reports on the use of silicon nanowires (SiNWs), easily prepared in a single step by chemical etching of crystalline silicon in HF/AgNO(3) aqueous solution, as a highly sensitive substrate for laser desorption/ionization mass spectrometry (LDI-MS) analysis. The SiNWs' diameter and length depend on the etchant concentration and dissolution time. Optimized LDI substrate consists of nanowires with an average diameter in the range of 20-100 nm and 2.5 mum in length. The optimized SiNWs' surface morphology coupled to a controlled surface chemistry allowed a significant LDI-MS performance through measurements of a broad range of analytes, including small molecules, peptides, and a bovine serum albumin (BSA) digest. A signal-to-noise ratio of 250 was ascertained for a 10 fmol bradykinin pick, in reflector mode acquisition. Likewise, the sutent, a small tyrosine kinase inhibitor, could be observed down to 10 fmol, as compared to 500 fmol limit detection using the classical matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). We have further investigated the optical properties of the nanowires, and our results suggest that they have a small or no effect on the desorption/ionization (D/I) process. On the contrary, the surface morphology and thermal properties of the silicon nanostructures are found to be the essential features contributing to the D/I performance.
Piret
Gaëlle
G
Institut de Recherche Interdisciplinaire (CNRS-USR 3078), Parc de la Haute Borne, 50 Avenue de Halley, BP 70478, 59658 Villeneuve d'Ascq, France.
Drobecq
Hervé
H
Coffinier
Yannick
Y
Melnyk
Oleg
O
Boukherroub
Rabah
R
D003460:Crystallization / Q000379:methods*; D008855:Microscopy, Electron, Scanning; D036103:Nanotechnology; D053770:Nanowires / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D012825:Silicon / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
D012825:Silicon