Binding of glycine and L-cysteine on Si(111)-7 x 7.
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.
Huang
Jing Yan
JY
Department of Chemistry, National University of Singapore, 10 Kent Ridge, Singapore.
Ning
Yue Sheng
YS
Yong
Kian Soon
KS
Cai
Ying Hui
YH
Tang
Hai Hua
HH
Shao
Yan Xia
YX
Alshahateet
Solhe F
SF
Sun
Yue Ming
YM
Xu
Guo Qin
GQ
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
D020099:Coated Materials, Biocompatible; D003545:Cysteine; D005998:Glycine; D012825:Silicon