Bio-hybrid acrylic hydrogels containing metronidazole – loaded poly(acrylic acid-co-methyl methacrylate) nanoparticles and Aloe vera as natural healing agent

Bio-Hybrid Hydrogels Incorporated into a System of Salicylic Acid-pH/Thermosensitive Nanocarriers Intended for Cutaneous Wound-Healing Processes

In this paper, the preparation method of bio-hybrid hydrogels incorporated into a system of salicylic acid-pH/thermosensitive nanocarriers to speed up the wound-healing process was developed. This combination creates a dual drug delivery system, which releases the model hydrophobic active substance—salicylic acid—in a gradual and controlled manner for an extended time. Our research team has determined the various properties of bio-hybrid hydrogels based on their physicochemical (swelling degree, and degradation), structural (FT-IR), morphological (SEM), and mechanical (elongation tests) traits. Moreover, empty pH/thermosensitive nanocarriers and their salicylic acid-containing systems were characterized using the following methods: DLS, TG/DTG, and DSC. Additionally, salicylic acid release profiles directly from thermosensitive nanocarriers were compared to the bio-hybrid matrix. These studies were conducted in PBS (pH = 7.4) for 7 days using the USP4 method. To evaluate the antibacterial properties of the obtained materials, the inhibition of growth of Staphylococcus aureus, Escherichia coli, Candida albicans, and Aspergillus niger—as the main microorganisms responsible for human infections—were tested. The obtained results indicated that the pH/thermosensitive nanocarrier–salicylic acid system and bio-hybrid hydrogels are characterized by antibacterial activity against both S. aureus and E. coli.

The Effect of Glycerin Content in Sodium Alginate/Poly(vinyl alcohol)-Based Hydrogels for Wound Dressing Application

The impact of different amounts of glycerin, which was used in the system of sodium alginate/poly(vinyl alcohol) (SA/PVA) hydrogel materials on the properties, such as gel fraction, swelling ability, degradation in simulated body fluids, morphological analysis, and elongation tests were presented. The study shows a significant decrease in the gel fraction from 80.5 ± 2.1% to 45.0 ± 1.2% with the increase of glycerin content. The T₅ values of the tested hydrogels were varied and range from 88.7 °C to 161.5 °C. The presence of glycerin in the matrices significantly decreased the thermal resistance, which was especially visible by T₁₀ changes (273.9 to 163.5 °C). The degradation tests indicate that most of the tested materials do not degrade throughout the incubation period and maintain a constant ion level after 7-day incubation. The swelling abilities in distilled water and phosphate buffer solution are approximately 200-300%. However, we noticed that these values decrease with the increase in glycerin content. All tested matrices are characterized by the maximum elongation rate at break in a range of 37.6-69.5%. The FT-IR analysis exhibits glycerin changes in hydrogel structures, which is associated with the cross-linking reaction. Additionally, cytotoxicity results indicate good adhesion properties and no toxicity towards normal human dermal fibroblasts.

Advanced SA/PVA-based hydrogel matrices with prolonged release of Aloe vera as promising wound dressings

This work focuses on the influence of different amounts (5, 10, 15, 20 and 25%, v/v) of solution of Aloe vera on the chemical structure and properties of sodium alginate/poly(vinyl alcohol) hydrogel films. The polymeric matrix was prepared following the chemical cross-linking method using poly(ethylene glycol) diacrylate (PEGDA, Mn = 700 g/mol) as a cross-linking agent. First, the gel fractions of the modified hydrogels were determined and their swelling behavior in distilled water and phosphate-buffered saline (PBS) was tested. Subsequently, the following properties of the modified hydrogel materials were studied: structural (FT-IR spectra analysis), morphological (SEM analysis) and mechanical (tensile strength, elongation at break and hardness). Moreover, a thermal analysis (TG/DTG and DSC) confirmed that the SA/PVA hydrogels containing Aloe vera exhibited slightly higher thermal stability than the unmodified hydrogels, which allows concluding that a rigid and thermally stable three-dimensional structure had been obtained. Additionally, the release profile of polysaccharides from the hydrogel matrix was evaluated in PBS at 37 °C. The results show that the active substance was released in a prolonged manner, gradually, even for a week. It was found that the presence of Aloe vera inside the cross-linked polymeric network improved the active substance delivery properties of the hydrogel films. When greater amounts of Aloe vera were applied, the hydrogel had an irregular surface structure, as revealed by SEM images. The chemical structure was confirmed on the basis of an FT-IR spectral analysis. Concluding, SA/PVA/Aloe vera matrices are promising compounds and deserve further studies towards application in interactive wound dressings. Additionally, the cytotoxicity of the materials was studied and the results indicated good adhesion properties and no toxicity. In vitro experiments performed on normal human dermal fibroblasts proved excellent cell attachment on the Aloe vera hydrogel discs, which promoted cells spreading and proliferation.