title: Purple-bacterial photosynthetic reaction centers and quantum-dot hybrid-assemblies in lecithin liposomes and thin films.
abstract: Quantum dots (QDs) absorb ultraviolet and long-wavelength visible light energy much more efficiently than natural bacterial light-harvesting proteins and can transfer the excitation energy to photosynthetic reaction centers (RCs). Inclusion of RCs combined with QDs as antennae into liposomes opens new opportunities for using such hybrid systems as a basis for artificial energy-transforming devices that potentially can operate with greater efficiency and stability than devices based only on biological components or inorganic components alone. RCs from Rhodobacter sphaeroides and QDs (CdSe/ZnS with hydrophilic covering) were embedded in lecithin liposomes by extrusion of a solution of multilayer lipid vesicles through a polycarbonate membrane or by dialysis of lipids and proteins dispersed with excess detergent. The efficiency of RC and QD interaction within the liposomes was estimated using fluorescence excitation spectra of the photoactive bacteriochlorophyll of the RCs and by measuring the fluorescence decay kinetics of the QDs. The functional activity of the RCs in hybrid complexes was fully maintained, and their stability was even increased. The efficiency of energy transfer between QDs and RCs and conditions of long-term stability of function of such hybrid complexes in film preparations were investigated as well. It was found that dry films containing RCs and QDs, maintained at atmospheric humidity, are capable of maintaining their functional activity for at least some months as judged by measurements of their spectral characteristics, efficiency of energy transfer from QDs to RCs and RC electron transport activity. Addition of trehalose to the films increases the stability further, especially for films maintained at low humidity. These stable hybrid film structures are promising for further studies towards developing new phototransformation devices for biotechnological applications.
authors.affiliation: Biology Faculty, Lomonosov Moscow State University, 119991 Moscow, Russia.
authors.forename: Eugeny P
authors.initials: EP
authors.lastname: Lukashev
authors.affiliation: Biology Faculty, Lomonosov Moscow State University, 119991 Moscow, Russia.
authors.forename: Petr P
authors.initials: PP
authors.lastname: Knox
authors.affiliation: Biology Faculty, Lomonosov Moscow State University, 119991 Moscow, Russia.
authors.forename: Vladimir V
authors.initials: VV
authors.lastname: Gorokhov
authors.affiliation: Biology Faculty, Lomonosov Moscow State University, 119991 Moscow, Russia.
authors.forename: Nadezda P
authors.initials: NP
authors.lastname: Grishanova
authors.affiliation: Biology Faculty, Lomonosov Moscow State University, 119991 Moscow, Russia.
authors.forename: Nuranija Kh
authors.initials: NK
authors.lastname: Seifullina
authors.affiliation: Institut für Optik und Atomare Physik, Technische Universität Berlin, Strasse des 17 Juni 135, ER 1-1, D-10623 Berlin, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Krikunova
authors.affiliation: Charles University, Department of Chemical Physics and Optics, Ke Karlovu 3, 121 16 Prague, Czech Republic.
authors.forename: Heiko
authors.initials: H
authors.lastname: Lokstein
authors.affiliation: Biology Faculty, Lomonosov Moscow State University, 119991 Moscow, Russia. Electronic address: vz.paschenko@gmail.com.
authors.forename: Vladimir Z
authors.initials: VZ
authors.lastname: Paschenko
mesh_terms: D004587:Electrophoresis, Agar Gel; D054709:Lecithins / Q000737:chemistry*; D008081:Liposomes; D046529:Microscopy, Electron, Transmission; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism*; D020560:Proteobacteria / Q000378:metabolism*; D045663:Quantum Dots
chemical_list: D054709:Lecithins; D008081:Liposomes; D045322:Photosynthetic Reaction Center Complex Proteins
keywords: Fluorescence; Hybrid complexes; Lecithin liposomes; Light-harvesting; Pigment–protein complexes; Quantum dots; Reaction centers