Comparative Study of the Antibacterial, Biodegradable, and Biocompatibility Properties of Composite and Bi-Layer Films of Chitosan/Gelatin Coated with Silver Particles.

The dressings are materials that can improve the wound-healing process in patients with medical issues. Polymeric films are frequently used as dressings with multiple biological properties. Chitosan and gelatin are the most used polymers in tissue regeneration processes. There are usually several configurations of films for dressings, among which the composite (mixture of two or more materials) and layered ones stand out (layers). This study analyzed the antibacterial, degradable, and biocompatible properties of chitosan and gelatin films in 2 configurations, composite and bilayer, composite. In addition, a silver coating was added to enhance the antibacterial properties of both configurations. After the study, it was found that the bilayer films have a higher antibacterial activity than the composite films, having inhibition halos between 23% and 78% in Gram-negative bacteria. In addition, the bilayer films increased the fibroblast cell proliferation process, reaching up to 192% cell viability after 48 h of incubation. On the other hand, composite films have greater stability since they are thicker, with 276 µm, 243.8 µm, and 239 µm compared to 236 µm, 233 µm, and 219 µm thick for bilayer films; and a low degradation rate compared to bilayer films.

O-carboxymethyl chitosan/gelatin/silver-copper hydroxyapatite composite films with enhanced antibacterial and wound healing properties.

Wound dressing composite films of O-carboxymethyl chitosan (OCMC) and gelatin were prepared and mixed with hydroxyapatite (HA) composited with Silver (Ag) and Copper (Cu) at different concentrations. The chemical, thermal, morphological, and biological properties of the composite films were studied. The analysis by FTIR confirmed the presence of interactions between gelatin and OCMC, and at the same time, the polymer matrix interactions with Ag-Cu/HA complex. The inclusion of nanoparticle to the composite was associated with an improvement of the thermal stability, morphological roughness, a 9-12% more hydrophobic behavior (composite C1, C5, and C8), increase in antibacterial activity from 23.2 to 33.1% for gram negative bacteria and from 37.28 to 40.59% for gram positive bacteria, and with a cell viability greater than 100% for 24 and 72 h. The films obtained can serve as a wound healing dressing and regenerating biomaterial.

High Resistance of a Sludge Enriched with Nitrogen-Fixing Bacteria to Ammonium Salts and Its Potential as a Biofertilizer.

The increasing use of chemical fertilizers causes the loss of natural biological nitrogen fixation in soils, water eutrophication and emits more than 300 Mton CO2 per year. It also limits the success of external bacterial inoculation in the soil. Nitrogen fixing bacteria can be inhibited by the presence of ammonia as its presence can inhibit biological nitrogen fixation. Two aerobic sludges from wastewater treatment plants (WWTP) were exposed to high ammonium salts concentrations (>450 mg L-1 and >2 dS m-1). Microbial analysis after treatment through 16S pyrosequencing showed the presence of Fluviicola sp. (17.70%), a genus of the Clostridiaceae family (11.17%), and Azospirillum sp. (10.42%), which were present at the beginning with lower abundance. Denaturing gradient gel electrophoresis (DGGE) analysis based on nifH genes did not show changes in the nitrogen-fixing population. Nitrogen-Fixing Bacteria (NFB) were identified and associated with other microorganisms involved in the nitrogen cycle, presumably for survival at extreme conditions. The potential use of aerobic sludges enriched with NFB is proposed as an alternative to chemical fertilizer as this bacteria could supplement nitrogen to the plant showing competitive results with chemical fertilization.

The effect of Allium cepa extract on the chitosan/PLGA scaffolds bioactivity.

Allium cepa extracts (AC) allow the fabrication of a biomaterial that, together with chitosan and PLGA, could be osteoconductive and promote a better and faster regeneration of bone tissue, with biocompatibility and biomineralization properties. In this work, scaffolds were developed by the thermally induced phase separation (TIPS) technique. An in vitro bioactivity analysis was performed using simulated body fluid (SBF). Scanning electron microscopy (SEM), energy dispersion spectroscopy, and infrared spectroscopy were used for the scaffolds characterization. The results showed a structure with a pore size distribution between 50 and 100 µm, which allowed the uniform formation of biological apatite crystals on the surface of the scaffolds. The chitosan/policaprolactone/Allium cepa scaffold (ChPAC) showed the most promising results with a ratio of P/Ca between 1.6 and 1.7, a value very close to that of hydroxyapatite.

Mucoadhesive polymeric systems for vaginal drug delivery: a systemic review / Sistemas poliméricos mucoadhesivos para la liberación vaginal de fármacos: revisión sistemática

ABSTRACT Intravaginal drug administration has many advantages in comparison to other delivery routes: its local and systemic effect, lower dosages, and easiness of administration. Furthermore, makes it a reliable and comfortable way of therapy. This route can be used to prevent and treat a wide range of conditions including, sexually transmitted infections (STIs), hormonal treatment, birth control, and cancer treatment. The dosage forms may vary from ovules, tablets, rings, gels, creams, films and many more; lately adding the mucoadhesiveness to the characteristics to reduce the waste of active molecules. This review focuses on the way mucoadhesive polymeric systems have been applied in vaginal delivery. This review presents a bibliographical compilation of results from various investigations published in scientific databases: Science Direct, SciELO, and PubMed Central. Results compiled demonstrate that the intravaginal drug administration can be an alternative form of medication for women with more stable and prolonged results than traditional routes requiring lower doses and avoiding the first-pass effect.

RESUMEN La administración de fármacos por vía intravaginal cuenta con múltiples ventajas a comparación de otras rutas, puede lograr un efecto tanto local como sistémico, las dosis requeridas son menores, facilidad de administración entre otras, hacen que esta forma de administración sea confiable y cómoda. Esta vía de administración puede ser empleada para prevenir y tratar diferentes trastornos, como enfermedades de transmisión sexual, desordenes hormonales, anticonceptivos y tratamiento contra el cáncer. La presentación de las dosis puede variar, desde óvulos, tabletas, anillos, geles, cremas, películas entre otros, agregando a esta, en los últimos tiempos, la característica de mucoadhesividad para reducir el desecho de moléculas activas. Este trabajo se enfoca en las aplicaciones que han tenido los sistemas poliméricos mucoadhesivos en la vía intravaginal. La bibliografía recolectada se obtuvo de bases de datos como Science direct, SciELO, y PubMed Central. Los resultados obtenidos demuestran que la administración de fármacos por vía intravaginal puede ser una forma alternativa para medicación en mujeres, con resultados más estables y prolongados que otras rutas, requiriendo menores dosis y evitando el efecto de primer paso.

Chitosan/Mimosa tenuiflora films as potential cellular patch for skin regeneration.

Bio-composites films were prepared by casting and drying of aqueous solutions containing different weight ratios of chitosan and bark of Mimosa tenuiflora. The physico-chemical and functional properties of the films were characterized by scanning electron microscopy, dynamical mechanical analysis, wettability, cytotoxicity and in vitro antibacterial activities. The morphology studies confirmed that the presence of Mimosa tenuiflora change the surface of films. Moreover, the incorporation of Mimosa tenuiflora improved the thermal stability of the films, as it was indicated by the changes in the glass temperatures obtained. Water-uptake ability changed in relation to polymeric composition of film. This property increased by the addition of Mimosa tenuiflora to the film. Improved antibacterial properties were measured against Escherichia Coli and Micrococcus lysodeikticus or luteus. Finally, cytotoxicity was studied by MTT assay and the films were non-toxic. These preliminary results provide a cheap way to prepare chitosan/Mimosa tenuiflora films for wound healing and skin regeneration.