Since the SARS-CoV-2 pandemic, the interest in applying nanofibers t air filtration and personal protective equipment has grown significantly. Due to their morphological and structural properties, nanofibers have potential applications for air filtration in masks and air filters. However, most nanofiber membrane materials used for these purposes are generally non-degradable materials, which can contribute to the disposal of plastic waste into the environment. Hence, this work aims to produce polyvinyl alcohol (PVA) and chitosan (CS) biodegradable nanofibers with controlled morphology and structure via electrospinning. An experimental design was used to investigate the effects of the PVA|CS ratio and concentration on the properties of the electrospinning compositions and electrospun nanofiber mat. The electrospinning parameters were constant for all experiments: Voltage of 20 kV, a feed rate of 0.5 mL·h−1, and a distance of 10 cm between the needle and a drum collector. CS proved to be an efficient adjuvant to the PVA’s electrospinning, obtaining a wide range of nanofiber diameters. Furthermore, 6.0% PVA and 1% CS were the best compositions after optimization with the response surface methodology, with a mean fiber diameter of 204 nm. The addition of biocide agents using the optimized condition was also investigated, using surfactants, citric acid, and pure and encapsulated essential oils of Lippia sidoides. Pure oil improved the material without enlarging the nanofiber sizes compared to the other additives. The nanofiber membranes produced have the potential to be used in air filtration or wound-dressing applications where biocidal activity is needed.

Purposes The objective of this work was to produce and characterise biodegradable poly (vinyl alcohol) (PVA) nanofibre loaded with green propolis extract (GPE), chitosan (CS) and nystatin (NYS) alone and in mixtures as a potential wound dressing material. Methods The GPE, NYS and CS1% were loaded in electrospinning compositions based on PVA 7%, 8% and 12% solubilised in milli-Q water or a mixture of water and glacial acetic acid. The electrospinning compositions without actives (blank) and those loaded with actives were characterised by determining the pH, electrical conductivity and rheological properties. An image analysis procedure applied to photomicrographs obtained by scanning electronic microscopy (SEM) allowed the determination of the nanofibres’ diameter distribution and average surface porosity. The disintegration time and swelling ratio of the nanofibre mats were also determined. Results The physicochemical parameters of the electrospinning compositions (pH, electrical conductivity and rheology) and the incorporated active ingredients (GPE, CS and NYS) affected the electrospun nanofibre mats properties. The electrospun nanofibres’ mean diameters and surface porosity ranged from 151.5 to 684.5 nm and from 0.29 ± 0.04 to 0.50 ± 0.05. The PVA/CS electrospun nanofibres fibres exhibited the smallest diameters, high surface porosity, water absorption capacity and disintegration time. The characteristics of the PVA/CS nanofibres mat associated with the biodegradability of the polymers make them a novel material with the potential to be applied as wound and burn dressings.

Disposable surgical masks emerged as a solution to the increasing protection demands against fine/ultrafine particulate matter. It was prompted by the SARS-CoV-2 pandemic and the escalating levels of air pollution...

A minha família, seja ela, a que nasceu comigo, a nascida de mim ou a escolhida por mim, que me ajudou chegar até aqui.Vocês são e sempre serão a minha força!