Surface assisted laser desorption/ionization on two-layered amorphous silicon coated hybrid nanostructures

Abstract

Matrix-free laser desorption/ionization was studied on two-layered sample plates consisting of a substrate and a thin film coating. The effect of the substrate material was studied by depositing thin films of amorphous silicon on top of silicon, silica, polymeric photoresist SU-8, and an inorganic-organic hybrid. Des-arg 9 -bradykinin signal intensity was used to evaluate the sample plates. Silica and hybrid substrates were found to give superior signals compared with silicon and SU-8 because of thermal insulation and compatibility with amorphous silicon deposition process. The effect of surface topography was studied by growing amorphous silicon on hybrid micro-and nanostructures, as well as planar hybrid. Compared with planar sample plates, micro-and nanostructures gave weaker and stronger signals, respectively. Different coating materials were tested by growing different thin film coatings on the same substrate. Good signals were obtained from titania and amorphous silicon coated sample plates, but not from alumina coated, silicon nitride coated, or uncoated sample plates. Overall, the strongest signals were obtained from oxygen plasma treated and amorphous silicon coated inorganic-organic hybrid, which was tested for peptide-, protein-, and drug molecule analysis. Peptides and drugs were analyzed with little interference at low masses, subfemtomole detection levels were achieved for des-arg 9 -bradykinin, and the sample plates were also suitable for ionization of small proteins. (J Am Soc Mass

Oxygen and nitrogen plasma hydrophilization and hydrophobic recovery of polymers

“…These results agree well with previous reports of highly hydrophilic oxygen plasma treated PS surfaces. The initial contact angles of nitrogen plasma treated surfaces were around 10 and after 100 days the contact angles of dry stored and rewashed samples had recovered to around 42 and 60 , respectively. Overall, PS was the material which kept its hydrophilicity for the longest time, although most of the samples seem to still be ongoing slow hydrophobic recovery after 100 days.…”

“…40 Applications of ORMOCERs include abrasion resistant transparent coatings, 40 barrier layers for food packaging, 40 elements for optical applications, 40 microchip capillary electrophoresis, 15,41 and surface assisted laser desorption ionization mass spectrometry. 42 We have recently studied the hydrophilization and pore formation process of ORMOCOMP by an oxygen plasma process using a different oxygen plasma process (reactive ion etching). 43 In that study, we found that the contact angles of all but the most clearly porous samples recovered to around 45 in three weeks, while the strongly porous samples retained complete wetting during that period.…”

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.…”

Functionalized Nanoparticles and Nanostructured Surfaces for Surface-Assisted Laser Desorption/Ionization Mass Spectrometry

“…Double-or multilayer-coated hybrid substrates, such as metal-coated porous alumina (platinum/alumina), 41,44 two-layered amorphous silicon, 64 titania-printed aluminum foils (titania/aluminum), 65 layer-by-layer (LBL) self-assembled films, 66,67 and DVDs coated with diamond-like carbon 68 are considered to be promising materials for SALDI-MS because the layer properties of these substances can be varied using diffrernt layer combinations.…”

“…64 With regard to the coating layer, an amorphous silicon coating was superior to other coatings because of its UV absorptivity and favorable surface chemistry. Good signals were obtained from the combination of a titania substrate with an amorphous silicon coating, but not from alumina-coated, silicon-nitride-coated, or uncoated sample plates.…”