3D Chitosan-Gallic Acid Complexes: Assessment of the Chemical and Biological Properties

Three-dimensional chitosan-gallic acid complexes were proposed and prepared for the first time by a simple adsorption process of gallic acid (GA) on three-dimensional chitosan structures (3D chitosan). Highly porous 3D devices facilitate a high GA load, up to 2015 mmol/kg at pH 4.0. The preservation of the redox state of GA released from 3D chitosan was confirmed by spectroscopic analyses. The antioxidant activity of 3D chitosan-GA complexes was assessed using the DPPH radical scavenging assay and was found to be dramatically higher than that of free chitosan. The mechanical property of 3D chitosan–GA complexes was also evaluated using a compression test. Finally, 3D chitosan–GA complexes showed a significant antimicrobial capacity against E. coli and S. aureus, selected, respectively, as a model strain for Gram-negative and Gram-positive bacteria. Our study demonstrated a new, simple, and eco-friendly approach to prepare functional chitosan-based complexes for nutraceutical, cosmeceutical, and pharmaceutical applications

Photopolymer-based volume holographic optical elements: design and possible applications

In this paper, Volume Holographic Optical Elements (V-HOEs), such as holographic gratings and spherical lenses, are designed and fabricated by using a prototype of photopolymer. The recording process of V-HOEs and their appropriate characterization are described. Moreover, V-HOEs possible applications as solar concentrator are investigated and results are discussed. Finally, a system that allows passive solar tracking is proposed and preliminary results are reported

High nonlinear optical response in 4-chlorothiazole-based azo dyes

Four azo dyes showing high nonlinear optical properties were prepared, based on a 4-chlorothiazole azo moiety functionalized with strong acceptor groups and/or further donor/acceptor groups along the conjugated backbone. The effects of the acceptors as well as the lateral donor/acceptor groups upon absorption properties, thermal stability and second order nonlinear optical activity were evaluated. © 2010 Elsevier Ltd. All rights reserved

Synthesis of highly regioregular poly[3-(4-alkoxyphenyl)-thiophene]s by oxidative catalysis using copper complexes

A novel, easy, and cost-effective synthetic procedure is reported for the production of very highly regioregular poly[3-(4-alkoxyphenyl)thiophene]s by means of oxidative coupling. Four copper complexes were synthesized and used as catalysts to obtain polymers with higher regioregularity compared to the previous oxidative coupling methodologies reported in the literature and similar to that obtained by McCullough and Rieke methods in the synthesis of poly-3-alkylthiophenes. The regioregularity of the synthesized polymers was investigated by UV-Visible characterization on polymer thin films and 1H NMR analysis. The remarkable potentialities of these polymers have emerged from field-effect transistor mobility measurements operated on devices with bottom-contact configuration and hexamethyldisilazane-treated SiO 2 gate dielectric, showing a well-defined p-type field-effect response and maximum mobility values in air higher than 10-4 cm 2 V-1 s-1. © 2013 Wiley Periodicals, Inc

Computational approach to design of aptamers to the receptor binding domain of sars-cov-2

The aim of the research. In this work, in silico selection of DNA-aptamers to the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein was performed using molecular modeling methods. Material and methods. A new computational approach to aptamer in silico selection is based on a cycle of simulations, including the stages of molecular modeling, molecular docking, molecular dynamic simulations, and quantum chemical calculations. To verify the obtained calculated results flow cytometry, fluorescence polarization, and small-angle X-ray scattering methods were applied. Results. An initial library consisted of 256 16-mer oligonucleotides was modeled. Based on molecular docking results, the only one aptamer (Apt16) was selected from the library as a starting aptamer to the RBD protein. For Apt16/RBD complex, molecular dynamic and quantum chemical calculations revealed the pairs of nucleotides and amino acids whose contribution to the binding between aptamer and RBD is the largest. Taking into account these data, Apt16 was subjected to the structure modifications in order to increase the binding with the RBD. Thus, a new aptamer Apt25 was designed. The procedure of 1) aptamer structure modeling/modification, 2) molecular docking, 3) molecular dynamic simulations, 4) quantum chemical calculations was performed sev-eral times. As a result, four aptamers (Apt16, Apt25, Apt27, Apt31) to the RBD were designed in silico without any preliminary experimental data. Binding of the each modeled aptamer to the RBD was studied in terms of interactions between residues in protein and nucleotides in the aptamers. Based on the simulation results, the strongest binding with the RBD was predicted for two Apt27 and Apt31aptamers. The calculated results are in good agreement with experimental data obtained by flow cytometry, fluorescence polarization, and small-angle X-ray scattering methods. Conclusion. The proposed computational approach to selection and refinement of aptamers is universal and can be used for wide range of molecular ligands and targets. Key words

Carrier capability of halloysite nanotubes for the intracellular delivery of antisense PNA targeting mRNA of neuroglobin gene

Peptide nucleic acid (PNA) is a DNA mimic that shows good stability against nucleases and proteases, forming strongly recognized complementary strands of DNA and RNA. However, due to its feeble ability to cross the cellular membrane, PNA activity and its targeting gene action is limited. Halloysite nanotubes (HNTs) are a natural and low-cost aluminosilicate clay. Because of their peculiar ability to cross cellular membrane, HNTs represent a valuable candidate for delivering genetic materials into cells. Herein, two differently charged 12-mer PNAs capable of recognizing as molecular target a 12-mer DNA molecule mimicking a purine-rich tract of neuroglobin were synthetized and loaded onto HNTs by electrostatic attraction interactions. After characterization, the kinetic release was also assessed in media mimicking physiological conditions. Resonance light scattering measurements assessed their ability to bind complementary single-stranded DNA. Furthermore, their intracellular delivery was assessed by confocal laser scanning microscopy on living MCF-7 cells incubated with fluorescence isothiocyanate (FITC)-PNA and HNTs labeled with a probe. The nanomaterials were found to cross cellular membrane and cell nuclei efficiently. Finally, it is worth mentioning that the HNTs/PNA can reduce the level of neuroglobin gene expression, as shown by reverse transcription-quantitative polymerase chain reaction and western blotting analysis

Photopolymer-based volume holographic optical elements: design and possible applications

In this paper, Volume Holographic Optical Elements (V-HOEs), such as holographic gratings and spherical lenses, are designed and fabricated by using a prototype of photopolymer. The recording process of V-HOEs and their appropriate characterization are described. Moreover, V-HOEs possible applications as solar concentrator are investigated and results are discussed. Finally, a system that allows passive solar tracking is proposed and preliminary results are reported

Photopolymer-based volume holographic optical elements: design and possible applications

In this paper, Volume Holographic Optical Elements (V-HOEs), such as holographic gratings and spherical lenses, are designed and fabricated by using a prototype of photopolymer. The recording process of V-HOEs and their appropriate characterization are described. Moreover, V-HOEs possible applications as solar concentrator are investigated and results are discussed. Finally, a system that allows passive solar tracking is proposed and preliminary results are reported