title: Temperature dependence of metal-enhanced fluorescence of photosystem I from Thermosynechococcus elongatus.
abstract: We report the temperature dependence of metal-enhanced fluorescence (MEF) of individual photosystem I (PSI) complexes from Thermosynechococcus elongatus (T. elongatus) coupled to gold nanoparticles (AuNPs). A strong temperature dependence of shape and intensity of the emission spectra is observed when PSI is coupled to AuNPs. For each temperature, the enhancement factor (EF) is calculated by comparing the intensity of individual AuNP-coupled PSI to the mean intensity of 'uncoupled' PSI. At cryogenic temperature (1.6 K) the average EF was 4.3-fold. Upon increasing the temperature to 250 K the EF increases to 84-fold. Single complexes show even higher EFs up to 441.0-fold. At increasing temperatures the different spectral pools of PSI from T. elongatus become distinguishable. These pools are affected differently by the plasmonic interactions and show different enhancements. The remarkable increase of the EFs is explained by a rate model including the temperature dependence of the fluorescence yield of PSI and the spectral overlap between absorption and emission spectra of AuNPs and PSI, respectively.
authors.affiliation: IPTC and LISA+ Center, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany. marc.brecht@uni-tuebingen.de.
authors.forename: Imran
authors.identifier: http://orcid.org/0000-0002-2938-6758
authors.initials: I
authors.lastname: Ashraf
authors.affiliation: IPTC and LISA+ Center, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany. marc.brecht@uni-tuebingen.de.
authors.forename: Alexander
authors.initials: A
authors.lastname: Konrad
authors.affiliation: Department of Chemical Physics and Optics, Charles University, Ke Karlovu 3, 12116 Prague, Czech Republic.
authors.forename: Heiko
authors.initials: H
authors.lastname: Lokstein
authors.affiliation: IPTC and LISA+ Center, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany. marc.brecht@uni-tuebingen.de.
authors.forename: Sepideh
authors.initials: S
authors.lastname: Skandary
authors.affiliation: IPTC and LISA+ Center, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany. marc.brecht@uni-tuebingen.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Metzger
authors.affiliation: Laboratory of Nanotechnology, Instrumentation and Optics, University of Technology of Troyes, 12 rue Marie Curie, 10004 Troyes, France.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Djouda
authors.affiliation: Laboratory of Nanotechnology, Instrumentation and Optics, University of Technology of Troyes, 12 rue Marie Curie, 10004 Troyes, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Maurer
authors.affiliation: Laboratory of Nanotechnology, Instrumentation and Optics, University of Technology of Troyes, 12 rue Marie Curie, 10004 Troyes, France.
authors.forename: Pierre M
authors.initials: PM
authors.lastname: Adam
authors.affiliation: IPTC and LISA+ Center, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany. marc.brecht@uni-tuebingen.de.
authors.forename: Alfred J
authors.initials: AJ
authors.lastname: Meixner
authors.affiliation: IPTC and LISA+ Center, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany. marc.brecht@uni-tuebingen.de.
authors.forename: Marc
authors.initials: M
authors.lastname: Brecht
mesh_terms: D000458:Cyanobacteria / Q000502:physiology*; D006046:Gold; D053768:Metal Nanoparticles; D045331:Photosystem I Protein Complex / Q000502:physiology*; D013050:Spectrometry, Fluorescence; D013696:Temperature
chemical_list: D045331:Photosystem I Protein Complex; D006046:Gold