Chemically synthesized biomolecules can self-assemble to bioinspired nanostructures of different morphologies such as dots, tubes, spheres, nanofibers and more. They adopt similar basic ordering as their biological counterparts either α-helical or β-sheet peptide/protein conformations. These two fundamental biomolecular architectures exhibit dissimilar physical properties. One of the most interesting physical properties found in biological and bioinspired structures is a new biophotonic phenomenon of visible fluorescence (FL). It has been observed both in neurodegenerative disease-related amyloid fibrils and in synthetic amyloidogenic biorganic di- and tri-aromatic and aliphatic peptide nanostructures. The FL effect has been also found recently in peptide nanodots and hybrid polymer/peptide thin films. All of them have been assembled to β-sheet secondary structure. In this work we report on a new development of FL optical waveguiding in elongated bioinspired fibrillary structures, self-assembled from ultrashort amylodogenic peptides/proteins and hybrid polymer/peptides biomolecules. We show that FL propagation in these two fiber materials of different origin can be described by two completely different mechanisms. One of them is conventional FL propagation in the region of optical transparency of peptide materials in accordance with optical confinement rules. Another model is FL reabsorption mechanism where anomalous long range FL propagation has been found. We show that this intrinsic FL biophotonic waveguiding effects found in different β- sheet biomaterials is considered as a promising tool for precise biomedicine where new biocompatible visible tunable FL optical waveguides can be applied in advanced nanomedical technologies (local bioimaging, light diagnostics, therapy, optogenetitcs and health monitoring).
We investigated the morphology of polyethylene films by the Differential Evanescent Light Intensity (DELI) imaging method developed by us previously. The films were prepared by the Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique. Rough or smooth organic layers were fabricated with thickness depending on the deposition conditions. We used the DELI imaging method here as a fast, low cost method for surface morphology diagnostics of large areas (i.e., hundreds of mm2) of nano layer polyethylene films.
Photodeposition (PD) from solutions has been used for realizing various thin film patterns of sub-microscopic
thicknesses i.e., 5-500 (nm) to produce various spatially distributed components for optical applications. During PD
nanometer particles appear on the irradiated zones of any transparent substrates, such as glass used in this investigation.
In this work, Continuous Wave (CW) Photodeposition from a-Se colloid solutions onto glass substrates a Xenon UV-Visible
lamp has been employed. We evaluated the morphology of ultra-thin a-Se photodeposited nanostructures
obtained by direct deposition of a-Se on glass substrates serving as waveguides by a new technique based on capturing
the evanescent light leaking image, named Differential Evanescent Light Intensity (DELI). We obtained that deposition
fluencies of about F ≈ 300 J/cm2 were enough to produce layers up to about 340 nm thickness, similar to values needed
for CW Ar+ ion laser PD deposition at λ = 498 nm reported in previous investigations.
We evaluated the morphology of ultra-thin a-Se photodeposited nano-structures obtained by direct deposition of a-Se on glass substrates. Photodeposition (PD) from solutions has been used for realizing various thin film patterns, of sub-microscopic thicknesses i.e., 5-500 (nm) to produce various spatially distributed components for optical applications. During PD nanometer particles appear on the irradiated zones of any transparent substrates, such as glass used in this investigation. In this work, CW Photodeposition from a-Se colloid solutions onto glass substrates a Xenon UV-Visible lamp has been employed. A new technique based on capturing the evanescent light leaking image, named Differential Evanescent Light Intensity (DELI), is used to get the information about the photodeposited a-Se nanostructures profiles in the deposited zone on glass substrates serving as waveguides. The deposited particles observed on the substrates have diameters typically in the range of 100-300 nm as obtained by other microscopy methods. The morphology of the nano-structures observed by DELI during this work conditions consist of a random array of individual particles adsorbed onto the surface. The deposited material morphological profile was observed for fluences in excess of F > Fth ~ 25 J/cm2 for the particular experimental conditions of this work for a-Se. The highest merits found for the DELI technique are the fast and ease of measurements, comparable z-resolution to SEM and capability of large areas profiling and mean thickness measurements. We obtained that deposition fluences of about F 300 J/cm2 were enough to produce layers up to about 340 nm thickness, similar to values needed for CW Ar+ ion laser PD deposition at = 498 nm reported in previous investigations.
In this work, nanometer thickness dielectric layers deposited from colloid solutions using irradiation with Short
Wavelength (SW) in the visible domain have been investigated by the Differential Evanescent Light Intensity (DELI)
method. A high intensity UV filtered irradiation lamp was used for photodepositing nano-layers, directly on glass
substrates serving as waveguides. The amorphous Selenium (a-Se) nanometric thin layers were deposited as circular
zones of about ~ 1 cm2 area. Polypropylene and Polyethylene compounds melted on glass waveguides were also
analyzed by DELI.
Photo-excitation processes were investigated in Chlorophyll solutions by irradiation with various light sources. The photo-excited volume and surface effects found during bleaching experiments with Ultra Violet (UV) and Visible (VIS) spectra irradiation were recorded by dynamic optical beam diagnostics. The in-situ optical diagnotics for several spatial beams with different wavelengths was treated in a Beer-Lambert vectorial form. Bleached Porphyrins were photodeposited from Chl solutions on polymethyl-methacrylate (PMMA) surfaces using UV photons. The photodeposited material was confined by masks to simple patterns. The complex photodeposition processes of the bleached material is initiated by UV photons, followed by a VIS photons post irradiation and final fixation in the dark. Optical density profiling along with optical and scanning microscopies show a non-crystalline, bio-organic ovoid characteristic microstructure of the deposited material.
Write and erase (WE) thin film patterns obtained by in-situ consecutive photodeposition and photoablation cycles were investigated. The submicrometric structures of photodeposited and photoablated amorphous Selenium(a-Se) thin films were examined by high resolution scanning electron microscope (SEM). Magnification up to X100,000 was used to establish the morphology of the particles and islands on the substrate before and after the ablation cycle. The SEM micrographs show that the disintegration of the film during the ablation process leads to the creation of a variety of structures such as islands and particles in the nano to micrometer range. The findings indicate that similar to island film growth, viscoelastic phenomena are involved in the observed morphology in the ablation zones.
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