Hydrogel Based on Chitosan/Gelatin/Poly(Vinyl Alcohol) for In Vitro Human Auricular Chondrocyte Culture.

Three-dimensional (3D) hydrogels provide tissue-like complexities and allow for the spatial orientation of cells, leading to more realistic cellular responses in pathophysiological environments. There is a growing interest in developing multifunctional hydrogels using ternary mixtures for biomedical applications. This study examined the biocompatibility and suitability of human auricular chondrocytes from microtia cultured onto steam-sterilized 3D Chitosan/Gelatin/Poly(Vinyl Alcohol) (CS/Gel/PVA) hydrogels as scaffolds for tissue engineering applications. Hydrogels were prepared in a polymer ratio (1:1:1) through freezing/thawing and freeze-drying and were sterilized by autoclaving. The macrostructure of the resulting hydrogels was investigated by scanning electron microscopy (SEM), showing a heterogeneous macroporous structure with a pore size between 50 and 500 µm. Fourier-transform infrared (FTIR) spectra showed that the three polymers interacted through hydrogen bonding between the amino and hydroxyl moieties. The profile of amino acids present in the gelatin and the hydrogel was determined by ultra-performance liquid chromatography (UPLC), suggesting that the majority of amino acids interacted during the formation of the hydrogel. The cytocompatibility, viability, cell growth and formation of extracellular matrix (ECM) proteins were evaluated to demonstrate the suitability and functionality of the 3D hydrogels for the culture of auricular chondrocytes. The cytocompatibility of the 3D hydrogels was confirmed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, reaching 100% viability after 72 h. Chondrocyte viability showed a high affinity of chondrocytes for the hydrogel after 14 days, using the Live/Dead assay. The chondrocyte attachment onto the 3D hydrogels and the formation of an ECM were observed using SEM. Immunofluorescence confirmed the expression of elastin, aggrecan and type II collagen, three of the main components found in an elastic cartilage extracellular matrix. These results demonstrate the suitability and functionality of a CS/Gel/PVA hydrogel as a 3D support for the auricular chondrocytes culture, suggesting that these hydrogels are a potential biomaterial for cartilage tissue engineering applications, aimed at the regeneration of elastic cartilage.

Slow-release microencapsulates containing nanoliposomes for bioremediation of soil hydrocarbons contaminated.

Encapsulation and nutrient addition in bacterial formulations have disadvantages concerning cell viability during release, storage, and under field conditions. Then, the objective of this work was to encapsulate a bacterial consortium with hydrocarbon-degrading capacities in different matrices composed of cross-linked alginate/ polyvinyl alcohol /halloysite beads (M1, M2, and M3) containing nanoliposomes loaded with or without nutrients and evaluate their viability and release in a liquid medium, and soil (microcosmos). Also, evaluate their capacity to remove total petroleum hydrocarbons (TPH) for 165 days and matrices characterization. The encapsulate consortium showed a quick adaptation to contaminated soil and a percentage of removal (PR) of TPH up to 30% after seven days. All the matrices displayed a PR of up to 90% after 165 days. The matrix M2 displayed significant resistance to degradation and higher cell viability with a PR of 94%. This result supports the encapsulation of bacteria in a sustainable matrix supplemented with nutrients as a well-looked strategy for improving viability and survival and, therefore, enhancing their effectiveness in the remediation of hydrocarbon-contaminated soils.

Enzymatic Crosslinked Hydrogels of Gelatin and Poly (Vinyl Alcohol) Loaded with Probiotic Bacteria as Oral Delivery System.

Probiotic bacteria are widely used to prepare pharmaceutical products and functional foods because they promote and sustain health. Nonetheless, probiotic viability is prone to decrease under gastrointestinal conditions. In this investigation, Lactiplantibacillus plantarum spp. CM-CNRG TB98 was entrapped in a gelatin−poly (vinyl alcohol) (Gel−PVA) hydrogel which was prepared by a "green" route using microbial transglutaminase (mTGase), which acts as a crosslinking agent. The hydrogel was fully characterized and its ability to entrap and protect L. plantarum from the lyophilization process and under simulated gastric and intestine conditions was explored. The Gel−PVA hydrogel showed a high probiotic loading efficiency (>90%) and survivability from the lyophilization process (91%) of the total bacteria entrapped. Under gastric conditions, no disintegration of the hydrogel was observed, keeping L. plantarum protected with a survival rate of >94%. While in the intestinal fluid the hydrogel is completely dissolved, helping to release probiotics. A Gel−PVA hydrogel is suitable for a probiotic oral administration system due to its physicochemical properties, lack of cytotoxicity, and the protection it offers L. plantarum under gastric conditions.

Sterilized chitosan-based composite hydrogels: Physicochemical characterization and in vitro cytotoxicity.

Gelatin/chitosan/polyvinyl alcohol hydrogels were fabricated at different polymer ratios using the freeze-drying and sterilized by steam sterilization. The thermal stability, chemical structure, morphology, surface area, mechanical properties, and biocompatibility of hydrogels were evaluated by simultaneous thermal analysis, Fourier transform infrared spectroscopy, X-ray diffraction, confocal microscopy, adsorption/desorption of nitrogen, rheometry, and 3-4,[5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide cell viability assay (MTT assay), respectively. The samples showed a decomposition onset temperature below 253.3 ± 4.8°C, a semicrystalline nature, and a highly porous structure. Hydrogels reached the maximum water uptake in phosphate-buffered saline after 80 min, showing values from nine to twelve times their dry mass. Also, hydrogels exhibiting a solid-like behavior ranging from 2,567 ± 467 to 48,705 ± 2,453 Pa at 0.1 rad/s (low frequency). The sterilized hydrogels showed low cytotoxicity (cell viability > 70%) to the HT29-MTX-E12 cell line. Sterilized hydrogels by steam sterilization can be good candidates as scaffolds for tissue engineering applications.

Effect of doping in carbon nanotubes on the viability of biomimetic chitosan-carbon nanotubes-hydroxyapatite scaffolds.

This work describes the preparation and characterization of biomimetic chitosan/multiwall carbon nanotubes/nano-hydroxyapatite (CTS/MWCNT/nHAp) scaffolds and their viability for bone tissue engineering applications. The cryogenic process ice segregation-induced self-assembly (ISISA) was used to fabricate 3D biomimetic CTS scaffolds. Proper combination of cryogenics, freeze-drying, nature and molecular ratio of solutes give rise to 3D porous interconnected scaffolds with clusters of nHAp distributed along the scaffold surface. The effect of doping in CNT (e.g. with oxygen and nitrogen atoms) on cell viability was tested. Under the same processing conditions, pore size was in the range of 20-150 µm and irrespective on the type of CNT. Studies on cell viability with scaffolds were carried out using human cells from periosteum biopsy. Prior to cell seeding, the immunophenotype of mesenchymal periosteum or periosteum-derived stem cells (MSCs-PCs) was characterized by flow cytometric analysis using fluorescence-activated and characteristic cell surface markers for MSCs-PCs. The characterized MSCs-PCs maintained their periosteal potential in cell cultures until the 2nd passage from primary cell culture. Thus, the biomimetic CTS/MWCNT/nHAp scaffolds demonstrated good biocompatibility and cell viability in all cases such that it can be considered as promising biomaterials for bone tissue engineering.

New insights into the bactericidal activity of chitosan-Ag bionanocomposite: the role of the electrical conductivity.

The relationship between electrical conductivity, structure and antibacterial properties of chitosan-silver nanoparticles (CS/AgnP) biocomposites has been analyzed. To test the film's antimicrobial activity, Gram-positive and Gram-negative bacteria were studied. The interactions between silver nanoparticles with chitosan suggest the formation of silver ions which plays a major role in nanocomposite's bactericidal potency. In CS/AgnP biocomposites, the bactericide effectiveness increases by increasing AgnP concentrations up to 3 wt%, which is close to the electrical percolation threshold of ca. 3 wt%. As the AgnP concentration increases above this threshold, the bactericidal potency is greatly diminished. The elucidated correlation between electrical conductivity and antibacterial activity could be useful in the design of other nanocomposites that involve polymeric-based matrices.