Light waveguiding in bioinspired peptide nanostructures

Abstract

Basic optical properties of bioinspired peptide nanostructures are deeply modified by thermally mediated refolding of peptide secondary structure from α-helical to βsheet. This conformational transition is followed by the appearance in the β-sheet structures of a wideband optical absorption and fluorescence in the visible region.We demonstrate that a new biophotonic effect of optical waveguiding recently observed in peptide/protein nanoensembles is a structure-sensitive bimodal phenomenon. In the primary α-helical structure input, light propagates via optical transmission window demonstrating conventional passive waveguiding, based on classical optics.In the β-sheet structure, fluorescent (active) light waveguiding is revealed. The latter can be attributed to completely different physical mechanism of exciton-polariton propagation, characterized by high effective refractive index, and can be observed in nanoscale fibers below diffraction limit. It has been shown that peptide material requirements for passive and active waveguiding are dissimilar. Original biocompatibility and biodegradability indicate high potential future applications of these bioinspired waveguiding materials in precise photobiomedicine towards advanced highly selective bioimaging, photon diagnostics, and optogenetics. KEYWORDS optical absorption, passive and active peptide optical waveguides, peptide nanophotonics, refolding of peptide secondary structure, requirements to peptide waveguiding materials, visible fluorescence

Selected Advances of Quantum Biophotonics – a Short Review

“…The generated light can be routed into waveguiding systems, allowing for functionalization and implementation of various detection strategies inside a PICs architecture. Waveguiding strategies in biophotonic systems can be divided into active, usually realized by means of fluorescence inside the waveguide material, excited by an external light source, and passive waveguiding, which can be realized in various ways, e.g., using air-clad, biocompatible spider silk [46] or peptide nanostructures (which could be used either as active or passive waveguides, depending on the fabrication steps taken) [47].…”

Biological Photonic Devices Designed for the Purpose of Bio-Imaging with Bio-Diagnosis

“…The natural abundance of biomaterials and biological entities has long served as a source of inspiration for designing tracers/devices as well as photonic structures that are capable of manipulating incident light [29]. Biological cells, microorganisms, and their derivatives, encompassing DNA, proteins, silk, biomaterials, and polysaccharides, exhibit diverse interactions with light, facilitating their use as photonics components like waveguides, micro lenses, lasers, and even gratings [30][31][32][33][34][35][36]. These innate biological materials and biological beings possess immense potential for innovating novel photonics tracers/devices tailored for biological imaging, detection, and restorative uses [20].…”

Amyloid-like Prep1 peptides exhibit reversible blue-green-red fluorescence in vitro and in living cells

“…5 Interestingly, independently of their natural or synthetic origin, amyloid-like peptides generally emit fluorescence with a maximum in the blue field upon excitation with near-UV radiation (B370 nm). [6][7][8][9][10][11][12][13][14] Although the physicochemical determinants of these spectroscopic properties remain quite elusive, it has been recently shown that these assemblies can also emit in the red and near-infrared region when excited with radiation with wavelengths in the range 600-670 nm. 15 In this scenario, we have recently found that the human protein Pbx-regulating protein-1 (PREP1) [16][17][18] contains two cytotoxic amyloidogenic fragments, spanning residues 117-132 and 297-311.…”

“…A remarkable number of studies have shown that these assemblies, independently of their natural or synthetic origin, frequently present some spectroscopic properties whose underlying physicochemical determinants remain still quite elusive. [6][7][8][9][10][11][12][13][14] In particular, they can emit a blue fluorescence upon excitation with near-UV radiation (B370 nm). Very recently, it has been shown that these assemblies are also able to emit at much higher wavelengths extending to the red and near-infrared region when excited with radiation with wavelengths in the range 600-670 nm.…”