Influence of chemical reaction conditions in P(St-MMA-AA) synthesis: variation in nanoparticle size, color and deposition methods

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Antibacterial nanocomposites based on Ag NPs and HMDSO deposited by atmospheric pressure plasma

The development of new multifunctional coatings with antimicrobial properties has a special interest in several applications for pharmaceutical and medical products. This work reports on the deposition of antimicrobial coatings based on silver nanoparticles (Ag NPs) embedded in an organosilicon film onto woven and nonwoven textiles. The Ag nanoparticles admixed with hexamethyldisiloxane (HMDSO) vapours are introduced by means of an atomizer system in the remote discharge of an atmospheric pressure plasma source operating in argon. The chemical properties and the surface morphology of the coatings with antimicrobial potential are discussed.This work was performed within the M-ERA-NET project PlasmaTex, contract 31/2016/ UEFISCDI. The financial support from the Ministry of Research and Innovation under the Nucleus contract 4N/2016 is gratefully acknowledged.info:eu-repo/semantics/publishedVersio

Atmospheric plasma immobilization of antimicrobial Zeolite loaded silver nanoparticles on medical textiles

1. Introduction Nosocomial infections, in particular problematic chronic wounds, are a ubiquitous general concern. This apprehension was acuted by the prevalence of multidrug resistant bacteria and emergence of Pandemics. Therefore, the development of novel and highly effective antimicrobial wound dressing comprising marginal or absent cytotoxicity to the patient is crucial. Plasma plays a key role in improving the functionalization of surfaces, in particular of textiles [1]. Thus, in this work we used atmospheric double dielectric discharge (DBD) plasma activated woven polyester (PES) functionalized with silver nanoparticles (AgNPs), enzymes as antimicrobial agents, immobilized using mordenite (MOR) zeolites and polysaccharide-based matrixes to mitigate cytotoxicity. 2. Methodology and results MOR was used with the objective of improving the concentration, stability, and immobilization efficiency of AgNPs and enzymes in the functionalized fabric. Therefore, a solution combining the AgNPs, and/or antimicrobial enzymes was prepared. Afterwards, this solution was mixed with a polysaccharide matrix, consisting of alginate or chitosan. Woven PES surface was activated using DBD and was impregnated with the prepared formulation. The antimicrobial activity of the functionalized fabrics was characterized using bacteria commonly associated to nosocomial infections as well as a virus that is a potential surrogate of severe acute respiratory coronavirus 2 (SARS-COV-2). The antimicrobial tests performed comprised the evaluation of antimicrobial efficacy when in contact with the composites during 1 to 2 hours, by adapting the following standards: AATCC TM100-100 and ISO18184. The microorganisms used were S. aureus, E. coli, and bacteriophage MS2. The formulated composites containing alginate as matrix displayed a high antibacterial activity (higher than 99.999 %) which was stable for over than 15 days of storage. However, it did not exhibit any antiviral activity. The alginate composites also did not hinder the activity of protease, which may have an important antifouling activity. Whereas, the composites containing chitosan exhibited a highly effective antimicrobial activity against the bacteria and the virus (higher than 99.9999 %) when zeolite was present in the formulation

Effect of dopants and DBD plasma treatment on the conductivity of fabrics impregnated with PEDOT:PSS

Conductive properties are paving the way to produce smart textiles with a robust framework, so the development of electroconductive textiles is an area with growing interest. Poly (3,4-ethylene dioxythiophene):polystyrene sulfonate (PEDOT:PSS), is a conductive polymer widely used to impart conductivity to textiles. An increase of the conductivities is possible through the addition of secondary dopants to the conductive polymers, such as glycerol (GLY) or dimethyl sulfoxide (DMSO). Dielectric barrier discharge (DBD) plasma treatment improves the adhesion of coatings by modifying the surface of textiles. Herein, electrically conductive textiles for heat generation were prepared and characterized. Polyester (PES, DBD plasma-treated and not treated) fabrics were impregnated in a padding system with five layers of conductive solutions: PEDOT:PSS; PEDOT:PSS + GLY 5%; and, PEDOT:PSS + DMSO 7%

Application of Dielectric Barrier Discharge (DBD) atmospheric pressure plasma for pretreatment of medical textiles

Conventional pretreatment by wet chemistry and/or low-pressure plasma have several drawbacks [1]. Atmospheric plasma is an alternative and cost-competitive method to low-pressure plasma and wet chemical pretreatments, allowing continuous and uniform processing of fibers, substrates and films surfaces, improving its functionalization performance [2]. This technology has been studied in the field of the R&D project - PLASMAMED. The main objective of this project is to produce a new generation of coatings containing nanoparticles (NPs) and enzybiotics, with controllable antibacterial activity, on medical textiles, with special emphasis in antimicrobial dressing for pressure injury and hernia meshes. To achieve this goal, a dielectric barrier discharge (DBD) atmospheric pressure plasma was used as a pretreatment sustainable alternative. In this sense, medical-grade 100% polyester (PES) fabrics were pretreated by atmospheric plasma technology, where various processing conditions were tested. Different treatment speeds and discharges powers were tested, as well as the application of various gases (such as helium, oxygen and nitrogen) and a corona treatment (air), with a carrier gas (argon). The characterization of these pretreated textiles was carried out by contact angle (CA), through the sessile drop technique, with 3 µL water droplets on the surface of the textile. In general, contact angles exhibit a significant decrease (between 40º and 60º for all studied gases), when compared with the standard values for substrate without treatment (around 120º). Therefore, plasma pretreatment significantly improved the hydrophilicity of these fabrics (Figure 1), which reveals to be an advantage for the further functionalization step

Comparative study of the synthesis and characterization of reduced graphene oxide (RGO) using an eco friendly reducing agent

In this work, the reducing action of four reducing agents—ascorbic acid, inorganic salt, sodium hydrosulfte and polysaccharide—was investigated. Some reducing agents, in addition to being environmentally friendly, are good substitutes for dangerous chemicals used industrially. Graphene oxide (GO) was synthesized by the modifed Hummers method and was reduced with ascorbic acid (RGO-AA), inorganic salt (RGO-SI), sodium hydrosulfte (RGO-HS) and polysaccharide (RGO-PS). The microstructural, morphological, optical, electrochemical and thermal properties of GO, RGO-AA, RGOSI, RGO-HS and RGO-PS were characterized by x-ray difraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy/attenuated total refectance (FTIR-ATR), x-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM)/energy-dispersive x-ray spectroscopy (EDS), feld-emission scanning electron microscopy (FEG-SEM), UV–Vis, zeta potential, thermogravimetric analysis (TGA) and diferential scanning calorimetry (DSC). The conclusive results showed that the four agents demonstrated reducing capability. It was observed that the reducing agent derived from inverted sugar (polysaccharide) was the most efcient because it presented a reduction in GO with fewer microstructural defects, a lower number of sheets, and electrochemical and thermal properties superior to the properties obtained from conventional reducing agents. Therefore, with these impressive results obtained with polysaccharide, it was concluded that an efective GO reducing agent was obtained using this green and ecological product, resulting in a reduced graphene oxide (RGO) with few sheets and fewer defects and, consequently, with greater supercapacitor application potential.CNPq -Conselho Nacional de Desenvolvimento Científico e Tecnológico(45034/2020-3