RESUMEN
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.
RESUMEN
Flame-resistant polymer composites were prepared based on polyvinyl alcohol (PVA) as a polymer matrix and a polyphosphonate as flame retardant. Oxalic acid was used as crosslinking agent. LiClO4, BaTiO3, and graphene oxide were also incorporated into PVA matrix to increase the ionic conductivity. The obtained film composites were investigated by infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry and microscale combustion tests. Incorporating fire retardant (PFRV), BaTiO3, and graphene oxide (GO) into a material results in increased resistance to fire when compared to the control sample. A thermogravimetric analysis revealed that, as a general trend, the presence of PFRV and BaTiO3 nanoparticles enhances the residue quantity at a temperature of 700 °C from 7.9 wt% to 23.6 wt%. Their dielectric properties were evaluated with Broad Band Dielectric Spectroscopy. The electrical conductivity of the samples was determined and discussed in relation to the LiClO4 content. The electrical properties, including permittivity and conductivity, are being enhanced by the use of LiClO4. Additionally, a relaxation peak has been observed in the dielectric losses at frequencies exceeding 103 Hz. The electrical properties, including permittivity and conductivity, are being enhanced by the use of LiClO4. Additionally, a relaxation peak has been observed in the dielectric losses at frequencies exceeding 103 Hz. Out of the various composites tested, the composite containing 35 wt% of LiClO4 exhibits the highest alternating current (AC) conductivity, with a measured value of 2.46 × 10-3 S/m. Taking into consideration all the aspects discussed, these improved composites are intended for utilization in the manufacturing of Li-Ion batteries.
RESUMEN
The excellent biological properties of chitosan (CS) together with the increased oxygen permeability of polyvinyl alcohol (PVA) were the prerequisites for the creation of a wound healing dressing that would also function as a system for L-arginine (L-arg) and caffeine (Caff) delivery. Using the freezing/thawing method, 12 hydrogels were obtained in PVA:CS polymer ratios of 90:10, 75:25, and 60:40, and all were loaded with L-arg, Caff, and the mixture of L-arg and Caff, respectively. Afterwards, an inorganic material (zeolite-Z) was added to the best polymeric ratio (75:25) and loaded with active substances. The interactions between the constituents of the hydrogels were analyzed by FTIR spectroscopy, the uniformity of the network was highlighted by the SEM technique, and the dynamic water vapor sorption capacity was evaluated. In the presence of the inorganic material, the release profile of the active substances is delayed, and in vitro permeation kinetics proves that the equilibrium state is not reached even after four hours. The synergy of the constituents in the polymer network recommends that they be used in medical applications, such as wound healing dressings.
RESUMEN
The development of intelligent materials for protective equipment applications is still growing, with enormous potential to improve the safety of personnel functioning in specialized professions, such as firefighters. The design and production of such materials by the chemical modification of biodegradable semisynthetic polymers, accompanied by modern manufacturing techniques such as electrospinning, which may increase specific properties of the targeted material, continue to attract the interest of researchers. Phosphorus-modified poly(vinyl alcohol)s have been, thus, synthesized and utilized to prepare environmentally friendly electrospun mats. Poly(vinyl alcohol)s of three different molecular weights and degrees of hydrolysis were phosphorylated by polycondensation reaction in solution in the presence of phenyl dichlorophosphate in order to enhance their flame resistance and thermal stability. The thermal behavior and the flame resistance of the resulting phosphorus-modified poly(vinyl alcohol) products were investigated by thermogravimetric analysis and by cone calorimetry at a micro scale. Based on the as-synthesized phosphorus-modified poly(vinyl alcohol)s, electrospun mats were successfully fabricated by the electrospinning process. Rheology studies were performed to establish the optimal conditions of the electrospinning process, and scanning electron microscopy investigations were undertaken to observe the morphology of the phosphorus-modified poly(vinyl alcohol) electrospun mats.
RESUMEN
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).
RESUMEN
The sensitivity and selectivity properties of three phenylquinoxaline derivatives to different metal ions were investigated by absorption and fluorescence spectroscopy. The absorption and fluorescence responses of the phenylquinoxaline derivatives were examined towards the following metal ions Ag+, Mg2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+ and Hg2+, in THF solution. All investigated samples exhibit sensitivity and selectivity to Ag+, Co2+ and Cu2+ ions compared to other metal ions (Mn+â¯=â¯Mg2+, Ni2+, Zn2+, Cd2+ and Hg2+). The gradual addition of Ag+, Co2+ and Cu2+ ions to a Q-Ox sample solution generates new absorption bands (with maxima at 244, 675 and 294â¯nm, in presence of the Ag+, Co2+ and Cu2+ ions, respectively) while the emission intensities were weakly quenched, except in presence of Ag+ ions, when the emission was almost completely quenched (quenching efficiency at 426â¯nm, (I0â¯-â¯I)â¯/â¯I0â¯×â¯100%â¯=â¯91%). Absorption and fluorescence results show the formation of 1:2 metal complexes with Ag+ ions and 1:1 stoichiometry for a complexation between Q-Ox and Co2+ or Cu2+ ions. The following characteristics of these phenylquinoxaline derivatives have been calculated and discussed: the effects of the interfering ions, the binding constants and the detection limit of Ag+, Co2+ and Cu2+ ions.
RESUMEN
Optical characteristics of some fluorinated poly(1,3,4-oxadiazole-ether)s in presence of SnO2, NiO and SnO2/NiO mixed-oxide nanoparticles (NPs) was investigated. The interactions between polymers and metal oxide NPs were studied by steady-state UV-Vis absorption and fluorescence spectroscopy techniques. The absorption and fluorescence signals of all investigated polymers was modified by presence of both pure and mixed-oxide nanoparticles. The moderate values of Stern-Volmer quenching constant and non-linear trend of Scott plot indicate the less affinity between metal oxide NPs and polymers. The solvation behavior of some fluorinated poly(1,3,4-oxadiazole-ether)s in chloroform-N,N-dimethylformamide and N,N-dimethylformamide-dimethylsulfoxide mixtures was discussed.
