Time-resolved methods in Biophysics. 1. A novel pump and probe surface-enhanced resonance Raman approach for studying biological photoreceptors

Abstract

This article describes a method, based on surface-enhanced resonance Raman (SERR) spectroscopy, for studying the reaction dynamics of photoreceptors immobilized on metal electrodes. Time resolution and fresh sample conditions are achieved by synchronizing the rotational and translational motion of a novel kinematic electrode with the duration and time delay between the pump and probe events. The power and sensitivity of the method is illustrated by studying the photocycle of the sensory photoreceptor NpSRII and its sensitivity to the applied electric field. The results are compared with time-resolved resonance Raman measurements in solution.

Light–Dark Adaptation of Channelrhodopsin Involves Photoconversion between the all-trans and 13-cis Retinal Isomers

“…Single beam time-resolved RR measurements at ambient temperature were based on the rotating cell technique. 1 In these experiments, the photochemical rate constant 0 is defined according to…”

“…where γ, λ (in mol −1 ⋅ L⋅cm −1 ), (in W), and λ (in nm) are the quantum yield of the photoactive proteins, its extinction coefficient at the excitation line, the laser power, and the wavelength of the laser line, respectively. 1 The radius (in m) of the laser beam, which was ca. 20 μm, and the rotational frequency of the cell ν 0 (15 Hz) determine the residence time of the sample in the laser beam ∆τ via…”

“…We therefore employed the mixing ball technique that ensures an effective mixing of the entire sample volume downstream of the irradiation point. 1 This implies that the theoretical (upper) limit for the time until an originally irradiated sample volume is probed a second time, ∆τ , is given by…”

Introducing the Time-resolved methods in biophysics series

“…The first two papers in the series appear in this issue of Photochemical & Photobiological Sciences. The first paper, by Naumann et al, 18 reports a pump and probe surface-enhanced resonance Raman approach for studying biological photoreceptors. The paper by Abbruzzetti et al 19 deals with the applications of nanosecond flash photolysis with time-resolved absorbance detection to the study of ligand binding to haem proteins.…”

Simple fabrication of Ag nanoparticle-impregnated electrospun nanofibres as SERS substrates

“…In general, it is widely accepted that the enhancement effect of SERS usually proceed via two distinct mechanisms: electromagnetic enhancement that is associated with the localized surface plasmon resonances occurring at the surfaces of roughened metal substrates or metal clusters and chemical enhancement that is associated with the direct charge transfer or indirect electron-hole pair excitation processes. 8,9 Recent studies have found that the substrates having remarkable SERS activity/sensitivity can be achieved by controlled assembly or deposition of noble metal NPs on/in the one-dimensional (1D) nanostructure due to the presence of Raman 'hotspots' by means of gap distance between particles. When deposited plasmonic NPs on the support are in close proximity, individual plasmon oscillations can couple with each other, resulting in huge local electromagnetic field enhancements in these confined junctions or these * Author for correspondence (a_amaraa1@yahoo.com) hotspots.…”