Visible‐laser desorption/ionization on gold nanostructures

Abstract

In this report, we describe the visible-laser desorption/ionization of biomolecules deposited on gold-coated porous silicon and gold nanorod arrays. The porous silicon made by electrochemical etching was coated with gold using argon ion sputtering. The gold nanorod arrays were fabricated by electrodepositing gold onto a porous alumina template, and the subsequent partial removal of the alumina template. A frequency-doubled/tripled Nd : YAG laser was used to irradiate the gold nanostructured substrate, and the desorbed molecular ions were mass-analyzed by a time-of-flight mass spectrometer. The desorption/ionization of biomolecules for both substrates was favored by the use of the 532-nm visible-laser, which is in the range of the localized surface plasmon resonance of the gold nanostructure. The present technique offers a potential analytical method for low-molecular-weight analytes that are rather difficult to handle in the conventional matrix-assisted laser desorption/ionization (MALDI) mass spectrometry.

Gold nanoparticles as assisted matrices for the detection of biomolecules in a high-salt solution through laser desorption/ionization mass spectrometry

“…Nakamura et al [28] reported similar results for the determination of asialo GM1 while 2,5-DHB was dissolved in acetonitrile/water (1:1, vol/vol). Because AuNPs have a small heating capacity, the heat diffusion from AuNPs to analyte is fast during the laser pulse [14]. Thus, the metastable heating of GM1 results in fragmentation (GM1 Ϫ Neu5Ac).…”

“…It is suggested that cobalt NPs take the advantages of a large surface area, high photoabsorption, and low heat capacity compared with those of microparticles. Inspired by Tanaka's results, a series of inorganic micro-and nanomaterials-such as graphite particles [9], gold NPs (AuNPs) [10], silver NPs [11], titanium dioxide NPs [12], silicon NPs [13], Au nanorods [14], and carbon nanotubes [15]-have been studied as potential inorganic matrices. Moreover, matrix-free LDI-MS has been proposed using porous silicon as a sample target for the analysis of small molecules such as peptides, drugs, surfactants, and carbohydrates [16].…”

Influence of Crystalline Forms of Titania on Desorption/Ionization Efficiency in Titania-Based Surface-Assisted Laser Desorption/Ionization Mass Spectrometry

“…17) Metal-oxide-based semiconductors with good UV absorbance are also promising candidates for matrix-free LDI-MS applications, such as titania sol-gel films, 18) titania nanotube arrays, 19) zinc oxide nanowires, 20) mesoporous tungsten titanium oxides, 21) and germanium nanodots. 22) In addition, double-or multilayer-coated hybrid substrates such as metal-coated porous alumina (platinum/alumina), 23), 24) two-layered amorphous silicon, 25) titaniaprinted aluminum foils (titania/aluminum), 26) silverparticle-deposited porous silicon (silver/silicon), 27) gold nanorods on porous alumina (gold/alumina), 28) layerby-layer (LBL) self-assembled films (polymer/gold), 29) Pt nanoflowers on a scratched silicon, 30) DVDs coated with diamond-like carbon, 31) and cationic-polymercoated graphite sheets (polymer/graphite) 32) are considered to be promising materials for matrix-free LDI-MS because the layer properties of these substances can be varied independently. Further, these hybridization e#ects can improve the e$ciency of matrix-free LDI-MS.…”

Nanomaterial-Assisted Laser Desorption Ionization for Mass Spectrometry-Based Biomedical Analysis

“…In addition, the a-cyano-4-hydroxycinnanic acid coating on AuN�s effectively suppressed formation of Au cluster ions and analyte fragment ions, leading to a cleaner mass spectra. Another special property of AuN�s is their ability to absorb visible light owing to localized surface plasmon resonance (S�R) and visible-LDI with the assistance of AuN�s was developed [22][23][24]. Normally, a 532-nm visible laser, corresponding to the S�R of approximately 15 nm diameter gold nanospheres, is used instead of the typical UV laser of 337 and 355 nm.…”