Chitosan-based films filled with nanoencapsulated essential oil: Physical-chemical characterization and enhanced wound healing activity.

The economic burden of chronic wounds, the complexity of the process of tissue repair and the possibility of resistant bacterial infections, have triggered a significant research interest in the application of natural alternative therapies for wound healing. Biomolecules are intrinsically multi-active, as they affect multiple mechanisms involved in tissue repair phenomenon, including immunomodulatory, anti-inflammatory, cell proliferation, extra cellular matrix remodeling and angiogenesis. Chitosan features a unique combination of attributes, including intrinsic hemostatic, antimicrobial, and immunomodulatory properties, that make it an exceptional candidate for wound management, in the development of wound dressings and scaffolds. In this study, we produced nanoemulsions (NE) loaded with SFO, characterized them, and evaluated their tissue repairing properties. Dynamic light scattering (DLS) analysis confirmed the formation of a nanoemulsion with a droplet size of 21.12 ± 2.31 nm and a polydispersity index (PdI) of 0.159, indicating good stability for up to 90 days. To investigate the potential wound healing effects, SFO-loaded NE were applied on male C57BL/6 mice for seven consecutive days, producing a significantly higher wound closure efficiency (p < 0.05) for the group treated with SFO-loaded NE compared to the control group treated with the saline solution. This finding indicates that the SFO-loaded NE exhibits therapeutic properties that effectively promote wound healing in this experimental model. Then, SFO-loaded NE were incorporated into chitosan:polyvinyl alcohol (PVA)-based films. The inclusion of NE into the polymer matrix resulted in increased lipophilicity reflected by the contact angle results, while decreasing moisture absorption, water solubility, and crystallinity. Moreover, FTIR analysis confirmed the formation of new bonds between SFO-NE and the film matrix, which also impacted on porosity properties. Thermal analysis indicated a decrease in the glass transition temperature of the films due to the presence of SFO-NE, suggesting a plasticizing role of NE, confirmed by XRD results, that showed a decrease in the crystallinity of the blend films upon the addition of SFO-NE. AFM images showed no evidence of NE droplet aggregation in the Chitosan:PVA film matrix. Moisture absorption and water content decreased upon incorporation of SFO-loaded NE. Although the inclusion of NE increased hydrophobicity and water contact angle, the values remained within an acceptable range for wound healing applications. Overall, our results emphasize the significant tissue repairing properties of SFO-loaded NE and the potential of Chitosan:PVA films containing nanoencapsulated SFO as effective formulations for wound healing with notable tissue repairing properties.

In Vitro and In Vivo Cell-Interactions with Electrospun Poly (Lactic-Co-Glycolic Acid) (PLGA): Morphological and Immune Response Analysis.

Random electrospun three-dimensional fiber membranes mimic the extracellular matrix and the interfibrillar spaces promotes the flow of nutrients for cells. Electrospun PLGA membranes were analyzed in vitro and in vivo after being sterilized with gamma radiation and bioactivated with fibronectin or collagen. Madin-Darby Canine Kidney (MDCK) epithelial cells and primary fibroblast-like cells from hamster's cheek paunch proliferated over time on these membranes, evidencing their good biocompatibility. Cell-free irradiated PLGA membranes implanted on the back of hamsters resulted in a chronic granulomatous inflammatory response, observed after 7, 15, 30 and 90 days. Morphological analysis of implanted PLGA using light microscopy revealed epithelioid cells, Langhans type of multinucleate giant cells (LCs) and multinucleated giant cells (MNGCs) with internalized biomaterial. Lymphocytes increased along time due to undegraded polymer fragments, inducing the accumulation of cells of the phagocytic lineage, and decreased after 90 days post implantation. Myeloperoxidase+ cells increased after 15 days and decreased after 90 days. LCs, MNGCs and capillaries decreased after 90 days. Analysis of implanted PLGA after 7, 15, 30 and 90 days using transmission electron microscope (TEM) showed cells exhibiting internalized PLGA fragments and filopodia surrounding PLGA fragments. Over time, TEM analysis showed less PLGA fragments surrounded by cells without fibrous tissue formation. Accordingly, MNGC constituted a granulomatous reaction around the polymer, which resolves with time, probably preventing a fibrous capsule formation. Finally, this study confirms the biocompatibility of electrospun PLGA membranes and their potential to accelerate the healing process of oral ulcerations in hamsters' model in association with autologous cells.

In Vitro Degradation of Electrospun Poly(Lactic-Co-Glycolic Acid) (PLGA) for Oral Mucosa Regeneration.

Poly(lactic-co-glycolic acid) (PLGA) has been used in the field of tissue engineering as a scaffold due to its good biocompatibility, biodegradability and mechanical strength. With the aim to explore the degradability of PLGA electrospun nonwoven structures for oral mucosa tissue engineering applications, non-irradiated and gamma irradiated nonwovens were immersed in three different solutions, in which simulated body fluid (SBF) and artificial saliva are important for future oral mucosa tissue engineering. The nonwovens were immersed for 7, 15 and 30 days in SBF, culture media (DMEM) and artificial saliva at 37 °C. Before immersion in the solutions, the dosage of 15 kGy was applied for sterilization in one assay and compared with non-irradiated samples at the same timepoints. Samples were characterized using different techniques such as scanning electron microscopy (SEM), differential scanning calorimetric (DSC) and gel permeation chromatography (GPC) to evaluate the nonwoven degradation and Fourier-transform infrared spectroscopy (FTIR) to evaluate the chain scissions. Our results showed that PLGA nonwovens were constituted by semicrystalline fibers with moderate degradation properties up to thirty days. The non-irradiated samples exhibited slower kinetics of degradation than irradiated nonwovens. For immersion times longer than 7 days in the three different solutions, the mean diameter of irradiated fibers stayed in the same range, but significantly different from the control sample. On non-irradiated samples, the degradation kinetics was slower and the plateau in the diameter value was only attained after 30 days of immersion in the fluids. Plasticization (fluid absorption into the fiber structure) occurred in the bulk material, as confirmed by a decrease in Tg observed by DSC analyses of non-irradiated and irradiated nonwovens, in comparison with the respective controls. In addition, artificial saliva showed a higher capacity of influencing PLGA crystallization than SBF and DMEM. FTIR analyses showed typical PLGA chemical functional groups changes. These results will be important for future application of those PLGA electrospun nonwovens for oral mucosa regeneration.

Controlling burst effect with PLA/PVA coaxial electrospun scaffolds loaded with BMP-2 for bone guided regeneration.

Biocompatible scaffolds have been used to promote cellular growth and proliferation in order to develop grafts, prostheses, artificial skins and cartilage. Electrospinning is widely studied as a method capable of producing nanofibers which enables cell attachment and proliferation, generating a functional scaffold that is suitable for many types of organs or tissues. In this study, electrospinning was used to obtain core-shell and monolithic fibers from the biocompatible poly (lactic acid) and poly (vinyl alcohol) polymers. The main purpose of this work is to produce core-shell nanofiber based scaffolds that works as a sustained delivery vehicle for BMP-2 protein, allowing those fibers to be used in the recovery of alveolar bone tissue without further bone surgery. Then, polymer nanofibers were manufactured by optimizing process parameters of coaxial electrospinning with emphasis on the most relevant ones: voltage, internal and external flows in an attempt to correlate fibers properties with protein releasing abilities. All nanofibers were characterized according to its morphology, thermal behaviour, crystallinity and release profile. For the release tests, bovine albumin was added into internal fiber for future periodontal restorage application. Obtained results demonstrate that fibers were formed with diameters up to 250 nm. According to electronic microscopy images, one could observe surface of nanofibers, thickness and core-shell morphology confirmed. X-ray diffraction analysis and contact angle tests showed fibers with low crystal degree and low hydrophobicity. Nanofibers structure affected in vitro release model tests and consequently the cellular assays.