Eco-Friendly Nitrogen-Doped Graphene Preparation and Design for the Oxygen Reduction Reaction.

Four N-doped graphene materials with a nitrogen content ranging from 8.34 to 13.1 wt.% are prepared by the ball milling method. This method represents an eco-friendly mechanochemical process that can be easily adapted for industrial-scale productivity and allows both the exfoliation of graphite and the synthesis of large quantities of functionalized graphene. These materials are characterized by transmission and scanning electron microscopy, thermogravimetry measurements, X-ray powder diffraction, X-ray photoelectron and Raman spectroscopy, and then, are tested towards the oxygen reduction reaction by cyclic voltammetry and rotating disk electrode methods. Their responses towards ORR are analysed in correlation with their properties and use for the best ORR catalyst identification. However, even though the mechanochemical procedure and the characterization techniques are clean and green methods (i.e., water is the only solvent used for these syntheses and investigations), they are time consuming and, generally, a low number of materials can be prepared, characterized and tested. In order to eliminate some of these limitations, the use of regression learner and reverse engineering methods are proposed for facilitating the optimization of the synthesis conditions and the materials' design. Thus, the machine learning algorithms are applied to data containing the synthesis parameters, the results obtained from different characterization techniques and the materials response towards ORR to quickly provide predictions that allow the best synthesis conditions or the best electrocatalysts' identification.

Effects of silver and gold nanoparticles phytosynthesized with Cornus mas extract on oral dysplastic human cells.

Background: Oral cancer is highly aggressive due to difficult diagnosis, therapy resistance and increasing frequency; thus finding prevention therapies is very important. Aim: This study evaluates the use of gold and silver nanoparticles (NPs), phyto-synthesized with Cornus mas extract against oral dysplastic lesions. Methods: NPs were characterized by UV-Vis, Fourier-transform infrared spectroscopy, transmission electron microscopy, x-ray diffraction and laser Doppler microelectrophoresis. Biological testing employed two human oral cell lines: gingival fibroblasts and dysplastic keratinocytes and evaluated viability, cell death mechanisms and cellular uptake. Results: NPs induced selective toxic effects against dysplastic cells. p53/BAX/BCL2 activation and PI3K/AKT inhibition led to cell death through necrosis and apoptosis. NPs also induced antioxidant and anti-inflammatory effects. Conclusion: NPs of gold and silver showed promising beneficial effects in the therapy of oral dysplasia.

In vitro and in vivo anti-inflammatory properties of green synthesized silver nanoparticles using Viburnum opulus L. fruits extract.

A green, rapid and cost effective method for the bio-synthesis of silver nanoparticles (AgNPs), using polyphenols present in European cranberry bush fruit extracts was developed. The obtained AgNPs were characterized by ultra-violet visible spectroscopy (UV-VIS), Fourier transform - infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and X-ray diffraction patterns (XRD). The average size of the spherical AgNPs was found to be 25nm. The anti-inflammatory effect of the biomaterials was investigated, both in vitro (on HaCaT cell line, exposed to UVB radiation) and in vivo (on acute inflammation model in Wistar rats). Our results support the conclusion that the photosynthesized silver nanoparticles present a potent anti-inflammatory activity and could be successfully used as therapeutic tools for treatment of inflammation.

Green synthesis, characterization and anti-inflammatory activity of silver nanoparticles using European black elderberry fruits extract.

This research aimed at reporting the synthesis, characterization and evaluation of the anti-inflammatory effects of some new biomaterials based on silver nanoparticles and polyphenols rich natural extracts. A fast and eco-friendly extracellular biosynthesis of silver nanoparticles (AgNPs), using European black elderberry (Sambucus nigra - SN, Adoxaceae family) fruit extracts was developed. The phytosynthesized nanoparticles exhibited an absorbance peak at 426nm, characteristic for AgNPs and their sizes were ranged from 20 to 80nm. The anti-inflammatory properties of AgNPs were assessed in vitro on HaCaT cells exposed to UVB radiation, in vivo on acute inflammation model and in humans on psoriasis lesions. In vitro, our results demonstrated the anti-inflammatory effects of functionalized AgNPs by the decrease of cytokines production induced by UVB irradiation. In vivo, the pre-administration of AgNPs reduced the edema and cytokines levels in the paw tissues, early after the induction of inflammation. The present study also demonstrated the possible use of synthesized AgNPs for the treatment of psoriasis lesions.

L-Leucine for gold nanoparticles synthesis and their cytotoxic effects evaluation.

This work reports the preparation of water-soluble leucine capped gold nanoparticles by two single-step synthesis methods. The first procedure involves a citrate reduction approach where the citrate is used as reducing agent and leucine as capping/stabilizing agent. Different sizes of gold nanoparticles, citrate reduced and stabilized by leucine, Leu-AuNPs-C, with the mean diameters in the range of 21-56 nm, were obtained by varying the macroscopic parameters such as: concentration of the gold precursor solution, Au (III):citrate molar ratio and leucine pH. In the second procedure, leucine acts both as reducing and stabilizing agent, allowing us to obtain spherical gold nanoparticles, Leu-AuNPs, with a majority of 80 % (with the mean diameter of 63 nm). This proves that leucine is an appropriate reductant for the formation of water-soluble and stable gold nanoparticles colloids. The characterization of the leucine coated gold nanoparticles was carried out by TEM, UV-Vis and FT-IR analysis. The cytotoxic effect of Leu-AuNPs-C and Leu-AuNPs was also evaluated.

New nanomaterials for the improvement of psoriatic lesions.

The main purpose of the present paper is to emphasize the non-invasive effect of some new prepared nanomaterials on skin diseases (psoriasis) together with the procedures to obtain them. These new materials are based on gold nanoparticles and natural compounds extracted from native plants of the Adoxaceae family (European cranberrybush -Viburnum opulus L. and European black elderberry -Sambucus nigra L.) and possess a known anti-inflammatory activity mainly due to their high content of anthocyanins and other polyphenols. The nanomaterials were characterized by transmission electron microscopy (TEM), UV-Vis spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and thermogravimetric analysis (TGA). Studies in vivo and in vitro were made in order to determine the toxicity of the products. Based on the obtained nanomaterials, specific dermatological creams were prepared. Their effect on psoriatic lesions, in comparison with the hydrocortisone creams, was studied.