title: Binding of glycine and L-cysteine on Si(111)-7 x 7.
abstract: The adsorption of glycine and l-cysteine on Si(111)-7 x 7 was investigated using high-resolution electron energy loss spectroscopy (HREELS) and X-ray photoelectron spectroscopy (XPS). The observation of the characteristic vibrational modes and electronic structures of NH3+ and COO- groups for physisorbed glycine (l-cysteine) demonstrates the formation of zwitterionic species in multilayers. For chemisorbed molecules, the appearance of nu(Si-H), nu(Si-O), and nu(C=Omicron) and the absence of nu(O-H) clearly indicate that glycine and l-cysteine dissociate to produce monodentate carboxylate adducts on Si(111)-7 x 7. XPS results further verified the coexistence of two chemisorption states for each amino acid, corresponding to a Si-NH-CH2-COO-Si [Si-NHCH(CH2SH)COO-Si] species with new sigma-linkages of Si-N and Si-O, and a NH2-CH2-COO-Si [NH2CH(CH2SH)COO-Si] product through the cleavage of the O-H bond, respectively. Glycine/Si(111)-7 x 7 and l-cysteine/Si(111)-7 x 7 can be viewed as model systems for further modification of Si surfaces with biological molecules.
authors: Department of Chemistry, National University of Singapore, 10 Kent Ridge, Singapore.
authors: Jing Yan
authors: JY
authors: Huang
authors: Yue Sheng
authors: YS
authors: Ning
authors: Kian Soon
authors: KS
authors: Yong
authors: Ying Hui
authors: YH
authors: Cai
authors: Hai Hua
authors: HH
authors: Tang
authors: Yan Xia
authors: YX
authors: Shao
authors: Solhe F
authors: SF
authors: Alshahateet
authors: Yue Ming
authors: YM
authors: Sun
authors: Guo Qin
authors: GQ
authors: Xu
mesh_terms: D000327:Adsorption; D001665:Binding Sites; D015374:Biosensing Techniques; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D003545:Cysteine / Q000737:chemistry*; D004563:Electrochemistry; D005998:Glycine / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry*; D013057:Spectrum Analysis; D014965:X-Rays
chemical_list: D020099:Coated Materials, Biocompatible; D003545:Cysteine; D005998:Glycine; D012825:Silicon