Structure and properties of biodegradable PLLA/ZnO composite membrane produced via electrospinning

These days, composite materials based on polymers and inorganic nanoparticles (NPs) are widely used in optoelectronics and biomedicine. In this work, composite membranes of polylactic acid and ZnO NPs containing 5–40 wt.% of the latter NPs were produced by means of electrospinning. For the first time, polymer material loaded with up to 40 wt.% of ZnO NPs (produced via laser ablation in air and having non-modified surface) was used to prepare fiber-based composite membranes. The morphology, phase composition, mechanical, spectral and antibacterial properties of the membranes were tested by a set of analytical techniques including SEM, XRD, FTIR, UV-vis, and photoluminescence spectroscopy. Antibacterial activity of the materials was evaluated following standard procedures (ISO 20743:2013) and using S. aureus and E. coli bacteria. It is shown that incorporation of 5–10 wt.% of NPs led to improved mechanical properties of the composite membranes, while further increase of ZnO content up to 20 wt.% and above resulted in their noticeable deterioration. At the same time, the antibacterial properties of ZnO-rich membranes were more pronounced, which is explained by a larger number of surface-exposed ZnO NPs, in addition to those embedded into the bulk of fiber material

Antibacterial ferroelectric hybrid membranes fabricated via electrospinning for wound healing

n the present study, wound healing ferroelectric membranes doped with zinc oxide nanoparticles were fabricated from vinylidene fluoride-tetrafluoroethylene copolymer and polyvinylpyrrolidone using the electrospinning technique. Five different ratios of vinylidene fluoride-tetrafluoroethylene to polyvinylpyrrolidone were used to control the properties of the membranes at a constant zinc oxide nanoparticle content. It was found that an increase of polyvinylpyrrolidone content leads to a decrease of the spinning solution conductivity and viscosity, causing a decrease of the average fiber diameter and reducing their strength and elongation. By means of X-ray diffraction and infrared spectroscopy, it was revealed that increased polyvinylpyrrolidone content leads to difficulty in crystallization of the vinylidene fluoride-tetrafluoroethylene copolymer in the ferroelectric β-phase in membranes. Changing the ratio of vinylidene fluoride-tetrafluoroethylene copolymer and polyvinylpyrrolidone with a constant content of zinc oxide nanoparticles is an effective approach to control the antibacterial properties of membranes towards Staphylococcus aureus. After carrying out in vivo experiments, we found that ferroelectric hybrid membranes, containing from five to ten mass percent of PVP, have the greatest wound-healing effect for the healing of purulent wound

Restoration and conservation of old low-quality book paper using aqueous colloids of magnesium oxyhydroxide obtained by pulsed laser ablation

Magnesium-containing nanocolloids were synthesized by nanosecond pulsed laser ablation (PLAL) of a Mg target in water. As-prepared colloids contained 2-D lamellar nanostructures of magnesium oxyhydroxide Mg5O(OH)8 (Mg-NSs) with a thickness of 5–10 nm and a length/width up to one micron. The colloids obtained were used for the first time to restore old, low-quality paper (a Russian book from the beginning of the 20th century). All results were compared to conventional treatment with basic magnesium carbonate. It was found that Mg-NSs facilitated effective deacidification and conservation treatment of the paper. Paper pH increased after treatment and remained stable upon artificial aging. Moreover, treatment led to an increase in paper whiteness of up to 10% and paper strengthening up to 25%. In general, the treated paper became more resistant to the deterioration processes during aging. Thus, colloid of Mg5O(OH)8 lamellar nanostructures obtained by PLAL in water is a promising agent for paper restoration and conservation

Highly defective dark nano titanium dioxide: preparation via pulsed laser ablation and application

The development of methods to synthesize and study the properties of dark titania is of the utmost interest due to prospects for its use, primarily in photocatalysis when excited by visible light. In this work, the dark titania powder was prepared by pulsed laser ablation (Nd:YAG laser, 1064 nm, 7 ns) in water and dried in air. To study the changes occurring in the material, the thermal treatment was applied. The structure, composition, and properties of the obtained powders were studied using transmission electron microscopy, low-temperature N2 adsorption/desorption, X-ray diffraction, thermogravimetry/differential scanning calorimetry, X-ray photoelectron, Raman and UV-vis spectroscopies, and photoluminescence methods. The processes occurring in the initial material upon heating were studied. The electronic structure of the semiconductor materials was investigated, and the nature of the defects providing the visible light absorption was revealed. The photocatalytic and antibacterial activities of the materials obtained were also studied. Dark titania obtained via laser ablation in liquid was found to exhibit catalytic activity in the phenol photodegradation process under visible light (>420 nm) and showed antibacterial activity against Staphylococcus aureus and bacteriostatic effect towards Escherichia coli. View Full-Tex

Cu2O water dispersions and nano-Cu2O/fabric composite: preparation by pulsed laser ablation, characterization and antibacterial properties

Colloidal solutions of copper (I) oxide, Cu2O, were obtained by pulsed laser ablation of metallic copper target in distilled water using fundamental harmonic of Nd:YAG laser (1064 nm, 7 ns, 20 Hz). Nanocolloids obtained were applied to cotton fabric. Nanoparticles composition and structure were studied by UV-Vis and Raman spectroscopy, transmission and scanning electron microscopy, and XRD. Antibacterial activity of Cu2O nanoparticles on cotton fabric to E.coli bacteria was demonstrated in comparison with zinc oxide nanoparticles

Cu2O water dispersions and nano-Cu2O/fabric composite: preparation by pulsed laser ablation, characterization and antibacterial properties

Colloidal solutions of copper (I) oxide, Cu2O, were obtained by pulsed laser ablation of metallic copper target in distilled water using fundamental harmonic of Nd:YAG laser (1064 nm, 7 ns, 20 Hz). Nanocolloids obtained were applied to cotton fabric. Nanoparticles composition and structure were studied by UV-Vis and Raman spectroscopy, transmission and scanning electron microscopy, and XRD. Antibacterial activity of Cu2O nanoparticles on cotton fabric to E.coli bacteria was demonstrated in comparison with zinc oxide nanoparticles

Implementation of differential scanning calorimetry when studying polymerization of compounds based on glycolic acid ether

Using differential scanning calorimetry and synchronous thermal analysis under dynamic conditions, kinetic regularities of copolymerization of α- glycolide and a mixture of α-β-glycolide with D,L-lactide in the presence of stannous octoate as a catalyst have been investigated. Some thermodynamic and kinetic parameters of cationic copolymerization of monomers have been determined

Implementation of differential scanning calorimetry when studying polymerization of compounds based on glycolic acid ether

Using differential scanning calorimetry and synchronous thermal analysis under dynamic conditions, kinetic regularities of copolymerization of α- glycolide and a mixture of α-β-glycolide with D,L-lactide in the presence of stannous octoate as a catalyst have been investigated. Some thermodynamic and kinetic parameters of cationic copolymerization of monomers have been determined

Comparative Study of Physicochemical and Antibacterial Properties of ZnO Nanoparticles Prepared by Laser Ablation of Zn Target in Water and Air

Here, we report on ZnO nanoparticles (NPs) generated by nanosecond pulsed laser (Nd:YAG, 1064 nm) through ablation of metallic Zn target in water and air and their comparative analysis as potential nanomaterials for biomedical applications. The prepared nanomaterials were carefully characterized in terms of their structure, composition, morphology and defects. It was found that in addition to the main wurtzite ZnO phase, which is conventionally prepared and reported by others, the sample laser generated in air also contained some amount of monoclinic zinc hydroxynitrate. Both nanomaterials were then used to modify model wound dressings based on biodegradable poly l-lactic acid. The as-prepared model dressings were tested as biomedical materials with bactericidal properties towards S. aureus and E. coli strains. The advantages of the NPs prepared in air over their counterparts generated in water found in this work are discussed