title: Single molecule studies of cyclic peptides using molecular matrix at liquid/solid interface by scanning tunneling microscopy.
abstract: We report in this work the single molecule studies of cyclic peptide, cyclosporine A (CsA), using a molecular network formed by star-shaped oligofluorene (StOF-COOH(3)) at the liquid/solid interface by scanning tunneling microscopy (STM). Individual cyclosporine A can be identified and resolved in the molecular network, and the high-resolution STM images of CsA show polygon-like characteristics with a diameter of approximately 1.7 nm. Furthermore, the complex of CsA and Mg(2+) has also been observed to adsorb inside of the molecular matrix. The STM results reveal two adsorption characteristics for the CsA-Mg(2+) complex, which is suggestive of asymmetrical configurations of the complex. The difference in binding energy between the two observed adsorption configurations is estimated to be 1.88 kJ·mol(-1). These results help set the stage for studying the fine structures and functions of various cyclic peptides at the liquid/solid interface.
authors.affiliation: National Center for Nanoscience and Technology, Beijing 100190, PR China.
authors.forename: Yibing
authors.initials: Y
authors.lastname: Wang
authors.forename: Lin
authors.initials: L
authors.lastname: Niu
authors.forename: Yibao
authors.initials: Y
authors.lastname: Li
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Mao
authors.forename: Yanlian
authors.initials: Y
authors.lastname: Yang
authors.forename: Chen
authors.initials: C
authors.lastname: Wang
mesh_terms: D000327:Adsorption; D016572:Cyclosporine / Q000737:chemistry; D005449:Fluorenes / Q000737:chemistry; D016252:Microscopy, Scanning Tunneling; D015394:Molecular Structure; D010316:Particle Size; D010456:Peptides, Cyclic / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D005449:Fluorenes; D010456:Peptides, Cyclic; D016572:Cyclosporine