title: Monitoring intermediate states of bacteriorhodopsin monolayers using near-field optical microscopy.
abstract: We demonstrate single-molecule-level features using near-field optical microscopy on bacteriorhodopsin (bR), a membrane protein that functions as a light-driven proton pump. The photophysical properties of bR are utilized in this imaging technique, using a combination of photoexcitation sources, to accurately identify the active regions and quantify the optical parameters. The studies of bR monolayers are carried out on inert quartz substrates as well as active conducting polymer (polyaniline) substrates. The substrate also plays an important role in the photocycle quantum efficiencies. We speculate on mechanisms governing the higher near-field absorption strength of bR molecules.
authors.affiliation: Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India.
authors.forename: Narasimhan
authors.initials: N
authors.lastname: Arun
authors.forename: Sabyasachi
authors.initials: S
authors.lastname: Mukhopadhyay
authors.forename: K S
authors.initials: KS
authors.lastname: Narayan
mesh_terms: D000814:Aniline Compounds; D001436:Bacteriorhodopsins / Q000737:chemistry*; D008853:Microscopy / Q000379:methods*; D018625:Microscopy, Atomic Force; D055620:Optical Phenomena; D010777:Photochemistry; D045663:Quantum Dots; D011791:Quartz
chemical_list: D000814:Aniline Compounds; C416807:polyaniline; D011791:Quartz; D001436:Bacteriorhodopsins