Photosynthetic Bacterial Light-Harvesting Antenna Complexes Adsorbed on Silica Nanoparticles Revealed by Silica Shell-Isolated Au Nanoparticle-Enhanced Raman Spectroscopy

Abstract

Assembling of photosynthetic light-harvesting proteins with inorganic nanoparticles can be a promising strategy for developing artificial solar cells. However, characterization of protein adsorption and its spatial orientation with respect to the interface is still a challenging task. Here we report surface-enhanced Raman spectra of light-harvesting antenna complexes (LH2) from two different photosynthetic bacteria adsorbed onto Au core silica shell (Au@SiO2) nanoparticles to illustrate LH2 adsorption and orientation at the interface. The surface plasmon enhanced Raman spectra of typical vibrational modes of carotenoids are used as the intrinsic reporter of LH2 adsorbed on Au@SiO2. Carotenoid molecules are asymmetrically located inside the disk-like LH2 closest to cytoplasmic side, leading to an orientation-dependent surface-enhanced Raman gain when the LH2 binds to the interface with one of its two end surfaces. We find that the Raman gain factors for LH2 from Rba. sphaeroides are larger than those from Rps. acidophila, suggesting that these two different LH2s adsorbed on the negatively charged silica shell with opposite orientation of their end surfaces carrying opposite charges. This is further supported by the observed difference in the B850 excited-state lifetime change for these two different LH2s when adsorbed onto silica nanoparticles, where the lifetime of B850 acts as an intrinsic reporter for nanoparticle-induced protein deformation which is also orientation-dependent, owing to the asymmetrical location of B850 ring inside the LH2.Natural Science Foundation of China [20925313]; National Basic Research Program of China [2009CB930700]; Chinese Academy of Sciences [KJCX2-YW-W25

Shell‐Isolated Nanoparticle‐Enhanced Raman and Fluorescence Spectroscopies: Synthesis and Applications

“…In direct detection method, the biomolecules are adsorbed or anchored on the surface of detection substrate and the functional groups of the molecules can be detected by collecting the Raman spectra. Weng group investigated the adsorption and the orientation of light‐harvesting antenna complexes (LH2) on the surface of Au@SiO 2 through the Raman spectra ( Figure ) . The LH2s obtained from two kinds of bacteria exhibited different Raman gain factors, indicating the different vibrational modes for carotenoid molecules and opposite adsorption orientation of the LH2s from the two different bacteria.…”

“…Acidophila (gray dash−dot lines), respectively. Reproduced with permission . Copyright 2012, American Chemical Society.…”

Large scale synthesis of pinhole‐free shell‐isolated nanoparticles (SHINs) using improved atomic layer deposition (ALD) method for practical applications

“…The rapid development of SHINERS technique offsets the longstanding limitations of SERS such as substrate and morphology generality to a certain extent. Therefore, SHINERS has been widely accepted by different fields such as surface science, [14,15] analytical science, [16] electrochemistry, [17][18][19][20][21][22] material science, [23][24][25] life science [26,27] and other fields. [28][29][30][31] Chemical method is the conventional protocol to prepare metal nanoparticles with thin layer of inert dielectric shell; the shell thickness can be adjusted between 1 and 5 nm with controlled reaction time.…”

“…The rapid development of SHINERS technique offsets the long‐standing limitations of SERS such as substrate and morphology generality to a certain extent. Therefore, SHINERS has been widely accepted by different fields such as surface science, analytical science, electrochemistry, material science, life science and other fields …”

Efficient light harvesting via sequential two-step energy accumulation using a Ru–Re5 multinuclear complex incorporated into periodic mesoporous organosilica

“…1,3 Photosynthetic LH systems have widely interested scientists in not only biology-related elds but also those investigating the construction of articial solar-energy conversion systems. [14][15][16][17][18][19][20] For the development of efficient solar-energy conversion systems using photofunctional molecular devices, such as photocatalysts, the small size of the molecules is problematic because of the dilute photon intensity of solar light, as described above. If these systems do not possess any LH capability, huge quantities of photofunctional molecular devices, which are usually costly and require great effort to synthesize, are necessary.…”