title: Matrix-free laser desorption/ionization-mass spectrometry using self-assembled germanium nanodots.
abstract: A novel ionization platform for matrix-free laser desorption/ionization-mass spectrometry (LDI-MS) was developed using self-assembled germanium nanodots (GeNDs) of uniform size (approximately 150 - 200-nm width and approximately 50-nm height) grown on a silicon wafer produced by molecular beam epitaxy. The performance of LDI-MS using GeNDs (GeND-MS) was investigated through measurements of a broad range of analytes, including peptides, proteins, synthetic oligomers, and polymer additives. Mass spectra of tryptic digests were clearly observed even for the mass range lower than m/z 800 without obstructive peaks. A detection limit of subfemtomole level was achieved for angiotensin-I. The upper limit of detectable mass range was approximately 17 kDa (myoglobin). GeND-MS also has potential for application to the characterization of industrial compounds. Almost accurate molecular weight distribution was obtained for a nonionic surfactant (Triton X-100) and for poly(ethylene glycol) oligomer. Furthermore, a brominated flame retardant, tetrabromobisphenol-A bis(2,3-dibromopropyl ether), was successfully ionized with less fragmentation, a result not obtainable by matrix-assisted laser desorption/ionization-mass spectrometry or desorption/ionization on porous silicon-mass spectrometry.
authors.affiliation: New Energy and Industrial Technology Development Organization (NEDO), 1310 Omiya, Saiwai, Kawasaki 212-8554, Japan.
authors.forename: Teruyuki
authors.initials: T
authors.lastname: Seino
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Sato
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yamamoto
authors.forename: Atsushi
authors.initials: A
authors.lastname: Nemoto
authors.forename: Masaki
authors.initials: M
authors.lastname: Torimura
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Tao
mesh_terms: D000803:Angiotensin I / Q000032:analysis; D005411:Flame Retardants / Q000032:analysis; D005857:Germanium / Q000737:chemistry*; D006801:Humans; D007834:Lasers; D008027:Light; D008970:Molecular Weight; D009211:Myoglobin / Q000032:analysis; D049329:Nanostructures / Q000737:chemistry*; D017830:Octoxynol / Q000032:analysis; D011075:Polybrominated Biphenyls / Q000032:analysis; D011092:Polyethylene Glycols / Q000032:analysis; D012680:Sensitivity and Specificity; D012825:Silicon / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013501:Surface-Active Agents / Q000032:analysis; D014357:Trypsin / Q000378:metabolism
chemical_list: D005411:Flame Retardants; D009211:Myoglobin; D011075:Polybrominated Biphenyls; D013501:Surface-Active Agents; D005857:Germanium; D011092:Polyethylene Glycols; D017830:Octoxynol; D000803:Angiotensin I; D014357:Trypsin; C020806:tetrabromobisphenol A; D012825:Silicon