Evaluation of Poly(vinyl alcohol)–Xanthan Gum Hydrogels Loaded with Neomycin Sulfate as Systems for Drug Delivery

In recent years, multidrug-resistant bacteria have developed the ability to resist multiple antibiotics, limiting the available options for effective treatment. Raising awareness and providing education on the appropriate use of antibiotics, as well as improving infection control measures in healthcare facilities, are crucial steps to address the healthcare crisis. Further, innovative approaches must be adopted to develop novel drug delivery systems using polymeric matrices as carriers and support to efficiently combat such multidrug-resistant bacteria and thus promote wound healing. In this context, the current work describes the use of two biocompatible and non-toxic polymers, poly(vinyl alcohol) (PVA) and xanthan gum (XG), to achieve hydrogel networks through cross-linking by oxalic acid following the freezing/thawing procedure. PVA/XG-80/20 hydrogels were loaded with different quantities of neomycin sulfate to create promising low-class topical antibacterial formulations with enhanced antimicrobial effects. The inclusion of neomycin sulfate in the hydrogels is intended to impart them with powerful antimicrobial properties, thereby facilitating the development of exceptionally efficient topical antibacterial formulations. Thus, incorporating higher quantities of neomycin sulfate in the PVA/XG-80/20-2 and PVA/XG-80/20-3 formulations yielded promising cycling characteristics. These formulations exhibited outstanding removal efficiency, exceeding 80% even after five cycles, indicating remarkable and consistent adsorption performance with repeated use. Furthermore, both PVA/XG-80/20-2 and PVA/XG-80/20-3 formulations outperformed the drug-free sample, PVA/XG-80/20, demonstrating a significant enhancement in maximum compressive stress

Simultaneous Enhancement of Flame Resistance and Antimicrobial Activity in Epoxy Nanocomposites Containing Phosphorus and Silver-Based Additives

The design and manufacture of innovative multifunctional materials possessing superior characteristics, quality and standards, rigorously required for future development of existing or emerging advanced technologies, is of great importance. These materials should have a very low degree of influence (or none) on the environmental and human health. Adjusting the properties of epoxy resins with organophosphorus compounds and silver-containing additives is key to the simultaneous improvement of the flame-resistant and antimicrobial properties of advanced epoxy-based materials. These environmentally friendly epoxy resin nanocomposites were manufactured using two additives, a reactive phosphorus-containing bisphenol derived from vanillin, namely, (4-(((4-hidroxyphenyl)amino)(6-oxido-6H-dibenzo[c,e][1,2]oxaphosphinin-6-yl)methyl)-2-methoxyphenyl) phenylphosphonate (BPH), designed as both cross-linking agent and a flame-retardant additive for epoxy resin; and additional silver-loaded zeolite L nanoparticles (Ze–Ag NPs) used as a doping additive to impart antimicrobial activity. The effect of BPH and Ze–Ag NPs content on the structural, morphological, thermal, flame resistance and antimicrobial characteristics of thermosetting epoxy nanocomposites was investigated. The structure and morphology of epoxy nanocomposites were investigated via FTIR spectroscopy and scanning electron microscopy (SEM). In general, the nanocomposites had a glassy and homogeneous morphology. The samples showed a single glass transition temperature in the range of 166–194 °C and an initiation decomposition temperature in the range of 332–399 °C. The introduction of Ze–Ag NPs in a concentration of 7–15 wt% provided antimicrobial activity to epoxy thermosets

Organophosphorus Reinforced Poly(vinyl alcohol) Nanocomposites Doped with Silver-Loaded Zeolite L Nanoparticles as Sustainable Materials for Packaging Applications

The sustainable development of innovative eco-friendly multifunctional nanocomposites, possessing superior characteristics, is a noteworthy topic. Novel semi-interpenetrated nanocomposite films based on poly(vinyl alcohol) covalently and thermally crosslinked with oxalic acid (OA), reinforced with a novel organophosphorus flame retardant (PFR-4) derived from co-polycondensation in solution reaction of equimolar amounts of co-monomers, namely, bis((6-oxido-6H-dibenz[c,e][1,2]oxaphosphorinyl)-(4-hydroxyaniline)-methylene)-1,4-phenylene, bisphenol S, and phenylphosphonic dichloride, in a molar ratio of 1:1:2, and additionally doped with silver-loaded zeolite L nanoparticles (ze-Ag), have been prepared by casting from solution technique. The morphology of the as prepared PVA-oxalic acid films and their semi-interpenetrated nanocomposites with PFR-4 and ze-Ag was investigated by scanning electron microscopy (SEM), while the homogeneous distribution of the organophosphorus compound and nanoparticles within the nanocomposite films has been introspected by means of energy dispersive X-ray spectroscopy (EDX). It was established that composites with a very low phosphorus content had noticeably improved flame retardancy. The peak of the heat release rate was reduced up to 55%, depending on the content of the flame-retardant additive and the doping ze-Ag nanoparticles introduced into the PVA/OA matrix. The ultimate tensile strength and elastic modulus increased significantly in the reinforced nanocomposites. Considerably increased antimicrobial activity was revealed in the case of the samples containing silver-loaded zeolite L nanoparticles

Tunable Properties via Composition Modulations of Poly(vinyl alcohol)/Xanthan Gum/Oxalic Acid Hydrogels

The design of hydrogel networks with tuned properties is essential for new innovative biomedical materials. Herein, poly(vinyl alcohol) and xanthan gum were used to develop hydrogels by the freeze/thaw cycles method in the presence of oxalic acid as a crosslinker. The structure and morphology of the obtained hydrogels were investigated by means of scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and swelling behavior. The SEM analysis revealed that the surface morphology was mostly affected by the blending ratio between the two components, namely, poly(vinyl alcohol) and xanthan gum. From the swelling study, it was observed that the presence of oxalic acid influenced the hydrophilicity of blends. The hydrogels based on poly(vinyl alcohol) without xanthan gum led to structures with a smaller pore diameter, a lower swelling degree in pH 7.4 buffer solution, and a higher elastic modulus. The antimicrobial activity of the prepared hydrogels was tested and the results showed that the hydrogels conferred antibacterial activity against Gram positive bacteria (Staphylococcus aureus 25923 ATCC) and Gram negative bacteria (Escherichia coli 25922 ATCC)

Optical and Flame-Retardant Properties of a Series of Polyimides Containing Side Chained Bulky Phosphaphenanthrene Units

Among the multitude of polymers with carbon-based macromolecular architectures that easily ignite in certain applications where short circuits may occur, polyimide has evolved as a class of polymers with high thermal stability while exhibiting intrinsic flame retardancy at elevated temperatures via a char-forming mechanism. However, high amounts of aromatic rings in the macromolecular backbone are required for these results, which may affect other properties such as film-forming capacity or mechanical properties; thus, much work has been done to structurally derivatize or make hybrid polyimide systems. In this respect, flexible polyimide films (PI(1–4)) containing bulky 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) units have been developed starting from commercial dianhydrides and an aromatic diamine containing two side chain bulky DOPO groups. The chemical structure of PI(1–4)) was characterized by 1H NMR, 13C NMR and 31P NMR spectroscopy. The optical properties, including absorption and luminescence spectra of these polymers, were analyzed. All polyimides containing DOPO derivatives emitted blue light with an emission maxima in the range of 340–445 nm, in solvents such as N,N-dimethylformamide, N-methyl-2-pyrrolidone, chloroform, and N,N-dimethylacetamide, while green light emission (λem = 487 nm for PI-4) was evidenced in a thin-film state. The thermal decomposition mechanism and flame-retardant behavior of the resulting materials were investigated by pyrolysis-gas-chromatography spectrometry (Py-GC), scanning electron microscopy (SEM), EDX maps and FTIR spectroscopy. The residues resulting from the TGA experiments were examined by SEM microscopy images and FTIR spectra to understand the pyrolysis mechanism

Thermal Properties and Flammability Characteristics of a Series of DGEBA-Based Thermosets Loaded with a Novel Bisphenol Containing DOPO and Phenylphosphonate Units

Despite a recent sustained preoccupation for developing biobased epoxies with enhanced applicability, such products have not been widely accepted for industry because of their inferior characteristics compared to classic petroleum-based epoxy thermosets. Therefore, significant effort is being made to improve the flame retardance of the most commonly used epoxies, such as diglycidyl ether-based bisphenol A (DGEBA), bisphenol F (DGEBF), novalac epoxy, and others, while continuously avoiding the use of hazardous halogen-containing flame retardants. Herein, a phosphorus-containing bisphenol, bis(4-(((4-hydroxyphenyl)amino)(6-oxido-6H-dibenzo[c,e][1,2]oxaphosphinin-6-yl)methyl)phenyl) phenylphosphonate (BPH), was synthesized by reacting bis(4-formylphenyl)phenylphosphonate with 4-hydroxybenzaldehyde followed by the addition of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) to the resulting azomethine groups. Environmentally friendly epoxy-based polymer thermosets were prepared by using epoxy resin as polymer matrix and a mixture of BPH and 4,4′-diaminodiphenylsulfone (DDS) as hardeners. A hyperbranched phthalocyanine polymer (HPc) and BaTiO3 nanoparticles were incorporated into epoxy resin to improve the characteristics of the final products. The structure and morphology of epoxy thermosets were evaluated by infrared spectroscopy and scanning electron microscopy (SEM), while the flammability characteristics were evaluated by microscale combustion calorimetry. Thermal properties were determined by thermogravimetric analysis and differential scanning calorimetry. The surface morphology of the char residues obtained by pyrolysis was studied by SEM analysis

Tailoring Thermal and Electrical Properties of Jeffamine Segmented Polyetherimide Composite Films Containing BaTiO3 particles

The continuous advancement of materials science has highlighted the ongoing need for additional studies on the main composite materials topics, particularly in the field of multifunctional nano-composites, towards improving their capability to meet multifaceted requirements in order to stimulate both scientific and technological development. In this study, we report the preparation and characterization of polyetherimides (PEIs) derived from 4,4′-(4,4′-isopropylidenediphenoxy) bis (phthalic anhydride) following a two-step polycondensation reaction using either 4,4′-(1,3-phenylenedioxy) dianiline, or Jeffamine ED-600 as comonomers, or a mixture of the two diamines. Based on the PEI containing flexible Jeffamine segments, polymer composite films were developed by incorporating BaTiO3 particles. The chemical structure and morphology of the composite films were investigated by FTIR spectroscopy and scanning electron microscopy. Thermal properties were determined by thermogravimetric analysis and differential scanning calorimetry. The influence of Jeffamine segments on the thermal decomposition process was investigated by TG/MS/FTIR measurements under air and nitrogen atmospheres. Based on the obtained data, the thermal decomposition mechanism was established and is discussed in accordance with the chemical structures of the polymers. The surface properties of the PEI and PEI-composite films were characterized by performing contact angle measurements. The addition of BaTiO3 increased the wettability of the surfaces. The dielectric characteristics of polymer composite films were investigated by broad band dielectric spectroscopy measurements. It was noticed that the addition of BaTiO3 nanoparticles to the copolymer matrix gradually enhanced the dielectric constant of the composites

Effects of Phosphorus and Boron Compounds on Thermal Stability and Flame Retardancy Properties of Epoxy Composites

While plastics are regarded as the most resourceful materials nowadays, ranging from countless utilities including protective or decorating coatings, to adhesives, packaging materials, electronic components, paintings, furniture, insulating composites, foams, building blocks and so on, their critical limitation is their advanced flammability, which in fire incidents can result in dramatic human fatalities and irreversible environmental damage. Herein, epoxy-based composites with improved flame-resistant characteristics have been prepared by incorporating two flame retardant additives into epoxy resin, namely 6-(hydroxy(phenyl)methyl)-6H-dibenzo[c,e][1,2]oxaphosphinine-6-oxide (PFR) and boric acid (H3BO3). The additional reaction of 9,10-dihydro-oxa-10-phosphophenanthrene-10-oxide (DOPO) to the carbonyl group of benzaldehyde yielded PFR, which was then used to prepare epoxy composites having a phosphorus content ranging from 1.5 to 4 wt%, while the boron content was 2 wt%. The structure, morphology, thermal stability and flammability of resulted epoxy composites were investigated by FTIR spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis, differential scanning calorimetry, and microscale combustion calorimetry (MCC). Thermogravimetric analysis indicated that the simultaneous incorporation of PFR and H3BO3 improved the thermal stability of the char residue at high temperatures. The surface morphology of the char residues, studied by SEM measurements, showed improved characteristics in the case of the samples containing both phosphorus and boron atoms. The MCC tests revealed a significant reduction in flammability as well as a significant decrease in heat release capacity for samples containing both PFR and H3BO3 compared to the neat epoxy thermoset

Electrospun Polyvinyl Alcohol Loaded with Phytotherapeutic Agents for Wound Healing Applications

In this paper, hydroalcoholic solutions of Thymus vulgaris, Salvia officinalis folium, and Hyperici herba were used in combination with poly (vinyl alcohol) with the aim of developing novel poly (vinyl alcohol)-based nanofiber mats loaded with phytotherapeutic agents via the electrospinning technique. The chemical structure and morphology of the polymeric nanofibers were investigated using Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The addition of Thymus vulgaris, Salvia officinalis folium, and Hyperici herba extracts to the pure polyvinyl alcohol fibers led to changes in the morphology of the fibers and a reduction in the fibers’ diameter, from 0.1798 µm in the case of pure polyvinyl alcohol to 0.1672, 0.1425, and 0.1369 µm in the case of polyvinyl alcohol loaded with Thymus vulgaris, Salvia officinalis folium, and Hyperici herba, respectively. The adapted Folin–Ciocalteu (FC) method, which was used to determine the total phenolic contents, revealed that the samples of PVA–Hyperici herba and PVA–Thymus vulgaris had the highest phenol contents, at 13.25 μgGAE/mL and 12.66 μgGAE/mL, respectively. Dynamic water vapor measurements were used in order to investigate the moisture sorption and desorption behavior of the developed electrospun materials. The antimicrobial behavior of these products was also evaluated. Disk diffusion assay studies with Escherichia coli, Staphylococcus aureus, and Methicillin-resistant Staphylococcus aureus were conducted on the developed nanofibers in order to quantify their phytotherapeutic potential

Fabrication of Poly(vinyl alcohol)/Chitosan Composite Films Strengthened with Titanium Dioxide and Polyphosphonate Additives for Packaging Applications

Eco-innovation through the development of intelligent materials for food packaging is evolving, and it still has huge potential to improve food product safety, quality, and control. The design of such materials by the combination of biodegradable semi-synthetic polymers with natural ones and with some additives, which may improve certain functionalities in the targeted material, is continuing to attract attention of researchers. To fabricate composite films via casting from solution, followed by drying in atmospheric conditions, certain mass ratios of poly(vinyl alcohol) and chitosan were used as polymeric matrix, whereas TiO2 nanoparticles and a polyphosphonate were used as reinforcing additives. The structural confirmation, surface properties, swelling behavior, and morphology of the xerogel composite films have been studied. The results confirmed the presence of all ingredients in the prepared fabrics, the contact angle of the formulation containing poly(vinyl alcohol), chitosan, and titanium dioxide in its composition exhibited the smallest value (87.67°), whereas the profilometry and scanning electron microscopy enlightened the good dispersion of the ingredients and the quality of all the composite films. Antimicrobial assay established successful antimicrobial potential of the poly(vinyl alcoohol)/chitosan-reinforced composites films against Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, Pseudomonas aeruginosa, and Candida albicans. Cytotoxicity tests have revealed that the studied films are non-toxic, presented good compatibility, and they are attractive candidates for packaging applications