Peptide Nanophotonics: From Optical Waveguiding to Precise Medicine and Multifunctional Biochips

Abstract

Optical waveguiding phenomena found in bioinspired chemically synthesized peptide nanostructures are a new paradigm which can revolutionize emerging fields of precise medicine and health monitoring. A unique combination of their intrinsic biocompatibility with remarkable multifunctional optical properties and developed nanotechnology of large peptide wafers makes them highly promising for new biomedical light therapy tools and implantable optical biochips. This Review highlights a new field of peptide nanophotonics. It covers peptide nanotechnology and the fabrication process of peptide integrated optical circuits, basic studies of linear and nonlinear optical phenomena in biological and bioinspired nanostructures, and their passive and active optical waveguiding. It is shown that the optical properties of this generation of bio-optical materials are governed by fundamental biological processes. Refolding the peptide secondary structure is followed by wideband optical absorption and visible tunable fluorescence. In peptide optical waveguides, such a bio-optical effect leads to switching from passive waveguiding mode in native α-helical phase to an active one in the β-sheet phase. The found active waveguiding effect in β-sheet fiber structures below optical diffraction limit opens an avenue for the future development of new bionanophotonics in ultrathin peptide/protein fibrillar structures toward advanced biomedical nanotechnology.

Light waveguiding in bioinspired peptide nanostructures

“…Active waveguiding in the FFF fibers is observed only when the laser beam impinges on the preliminary heated β‐sheet FFF spheres and the excited FL radiation is coupled to the fibers . These results indicate effective FL wave propagation along a few FFF peptide fibers grown from the same FFF sphere (Figure O).…”

“…In this work, we report on a new category of bioinspired peptide/protein functional optical nanomaterials and describe their unique optical waveguiding phenomena . The photophysical properties were studied in ultrashort aromatic (phenylalanine, F) and aliphatic (leucine, L)‐based dipeptides and tripeptides self‐assembled into amyloidogenic nondiseased elongated nanostructures.…”

“…Both aromatic and aliphatic α‐helical peptide nanostructures are highly transmitted in a wide optical range from λ > 280 nm (for aromatic) and λ > 200 nm (for aliphatic) . In a β‐sheet structure, all these peptide architectures acquire significant OA and FL in the visible region (Figure E). These structure‐sensitive optical properties lead to different optical waveguiding phenomena.…”

“…Active waveguiding is propagation of the excited FL wave along β‐sheet peptide waveguide. Thus, these two completely different waveguiding regimes are determined by peptide/protein secondary structures …”

“…It should be noted that the FL waveguiding effect is observed in very thin tubes where the walls of 100 to 300 nm thick are by two to six times less than that the green‐yellow FL free‐space wavelength of approximately 560 to 590 nm. Found optical waveguiding in subwavelength nanostructure is a result of high contrast between refractive indexes of FFF tubes ( n approximately 1.6) and their air environment ( n = 1) and can be partially attributed to EP mechanism of light propagation …”