We demonstrate a way to conjugate a light-harvesting complex, peridinin-chlorophyll-protein, with silver nanowires using biotin-streptavidin linker. In the case of conjugated structure we observe slight increase of the fluorescence intensity of the chlorophyll emission followed by the gradual decrease of the intensity due to photobleaching. For a non-conjugated mixture of peridinin-chlorophyll-protein with silver nanowires only the photobleaching takes place. The results suggest a possible way to fabricate hybrid nanostructures comprising light-harvesting complexes and metallic nanoparticles for achieving the efficient plasmon-induced enhancement of absorption of the light-harvesting complexes.
We use a seed-mediated growth to fabricate gold nanorods in water solution. By changing the amount of silver salt we demonstrate the control of aspect ratio of the obtained rods. The microscopic and spectroscopic analyses provide ways to characterize the morphology and the optical properties of the gold nanorods. Nanorods synthesized using this approach feature length of the order of 50-60 nm, which translates into longitudinal plasmon resonances in the near infrared spectrum region.
We report on confocal microscopy imaging of hybrid nanostructures composed of silver nanowires and corroles. Both nanomaterials were separated by a 30 nm thick SiO_2 spacer in order to inhibit fluorescence quenching. The results show that for such a hybrid nanostructure the average enhancement of the fluorescence intensity reached 2.5. Importantly, the coupling to plasmon excitations in metallic nanowires leaves no effect on the fluorescence spectrum of the organic molecules.
We study the effect of plasmon excitations in silver island film on the optical properties of peridinin-chlorophyll-protein light-harvesting complex using scanning fluorescence microscopy. With this technique we can unambiguously locate areas where the biomolecules are deposited on the metallic nanostructures from the areas where they stick to the glass surface. The enhancement factor of fluorescence intensity obtained for such a hybrid nanostructure is found to be 3. Plasmon excitations in the SIF layer also influence the dynamics of the emission, but in this case the interpretation of the results is more complex.
In this work we demonstrate confocal fluorescence imaging of hybrid nanostructures composed of silver nanowires and peridinin-chlorophyll-protein light-harvesting complexes. The length of silver nanowires, which reaches 10 μm, allows for determination of the nanowire position and consequently direct correlation with the fluorescence image. In this way we probe the influence of plasmon induced electromagnetic field on the fluorescence of light-harvesting complexes. When the nanowires are spaced from the light-harvesting complexes by a 10 nm thick dielectric layer, we observe a fluorescence enhancement, which depends upon the laser excitation wavelength. The measured enhancement values are 2.5 and 1.9 for 405 nm and 485 nm, respectively. Larger enhancement for the 405 nm excitation is attributed to direct creation of plasmon excitations in the silver nanowires.
We report on the influence of plasmon resonance in spherical gold nanoparticles on the optical properties of light-harvesting complex LH2 from the purple bacteria Rhodopseudomonas palustris. Systematic studies as a function of the excitation energy and the separation distance indicate that metal enhanced fluorescence shows strong dependence upon both of these parameters. We observe substantial increase of the fluorescence from LH2 complex in a hybrid nanostructure with 12 nm silica spacer. On the other hand, the enhancement measured with laser tuned into the plasmon resonance is almost threefold compared to the off-resonance configuration. The enhancement of fluorescence intensity originates in both cases from the increase of carotenoid absorption in the LH2 complex.
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