Spectrally selective fluorescence imaging of Chlorobaculum tepidum reaction centers conjugated to chelator-modified silver nanowires

Abstract

A polyhistidine tag (His-tag) present on Chlorobaculum tepidum reaction centers (RCs) was used to immobilize photosynthetic complexes on a silver nanowire (AgNW) modified with nickel-chelating nitrilo-triacetic acid (Ni-NTA). The optical properties of conjugated nanostructures were studied using wide-field and confocal fluorescence microscopy. Plasmonic enhancement of RCs conjugated to AgNWs was observed as their fluorescence intensity dependence on the excitation wavelength does not follow the excitation spectrum of RC complexes in solution. The strongest effect of plasmonic interactions on the emission intensity of RCs coincides with the absorption spectrum of AgNWs and is observed for excitation into the carotenoid absorption. From the absence of fluorescence decay shortening, we attribute the emission enhancement to increase of absorption in RC complexes.

Plasmonics with Metallic Nanowires

“…Consequently the control of the plasmon interaction with electronic states of the emitters will be limited. The range of reports where the influence of plasmon excitations in metallic nanowires on the optical properties of nearby placed emitters is rather broad [28,29,30,31,32,33,34,35], we shall concentrate here on three types of structures: where emitters are mixed together with the nanowires [29,32] or placed above them [30,31], where conjugation is used to specifically attach emitters to silver nanowires, and where the properties of single emitters are investigated [34,36,37]. This subjective overview will present a variety of structures that can be fabricated and the spectrum of effects that emerge in such systems and that can be studied using fluorescence spectroscopy and spectroscopy.…”

“…Moreover, the combination of fluorescence imaging and time-resolved fluorescence microscopy undoubtedly confirms the presence of plasmonic interactions in the structure. There are however cases, in particular those, where the primary mechanism of fluorescence enhancement is associated with the increase of the absorption rate, and where the changes of fluorescence decay are minimal or difficult to interpret [36]. In such instances the only remaining approach to prove the emergence of plasmonic coupling between emitters and nanowires should be based on wavelength-dependent imaging.…”

Correlating Plasmon Polariton Propagation and Fluorescence Enhancement in Single Silver Nanowires

“…The influence of the excitation wavelength on the SPP propagation has been demonstrated for metallic thin films and stripes, , as well as for lithographically produced wires . Likewise, it has been shown that fluorescence enhancement also depends on the excitation wavelength. , Nevertheless, it is still rather difficult to predict the scale of these effects, in particular the fluorescence enhancement which is insufficiently described by field confinement . As a field enhancement effect it is sensitive to the electric field and fluorophore distribution, both of which change with waveguide geometry .…”

Light Energy Driven Nanocommunications With FRET in Photosynthetic Systems

“…The external option might be an optical thin-film resonant cavity filter based on a Fabry-Perot or Mach-Zehnder interferometer [71]. Other possibilities are nanoparticles or nanowires filtering the energy gathered by light harvesting complexes [72,73]. All these filters can be used for the modulation of the transferred signals or control over the functions of nanomachines or other hybrid nanostructures [74].…”