Nanostructured Electrospun Polycaprolactone-Propolis Mats Composed of Different Morphologies for Potential Use in Wound Healing.

This study aimed to investigate different types of morphologies obtained using the electrospinning process to produce a material that enables wound healing while performing a controlled release. Using benign solvents, the authors prepared and characterised electrospun polycaprolactone mats loaded with propolis, a popular extract in traditional medicine with potential for skin repair. Different morphologies were obtained from distinct storage periods of the solution before electrospinning to investigate the effect of PCL hydrolysis (average diameters of fibres and beads: 159.2-280.5 nm and 1.9-5.6 µm, respectively). Phytochemical and FTIR analyses of the extract confirmed propolis composition. GPC and viscosity analyses showed a decrease in polymer molecular weight over the storage period (about a 70% reduction over 14 days) and confirmed that it was responsible for the nanostructure diversity. Moreover, propolis acted as a lubricant agent, affecting the spun solutions' viscosity and the thermal properties and hydrophilicity of the mats. All samples were within the value range of the water vapour transpiration rate of the commercial products (1263.08 to 2179.84 g/m2·day). Even though the presence of beads did not affect the propolis release pattern, an in vitro wound-healing assay showed that propolis-loaded mats composed of beaded fibres increased the cell migration process. Thus, these films could present the potential for use in wound dressing applications.

Structure and thermal behavior of biobased vitrimer of lactic acid and epoxidized canola oil.

Biobased vitrimers were obtained from epoxidized canola oil (ECO) and lactic acid (LA) using zinc acetate (ZnAc) and ZnAl-layered double hydroxide (ZnAl) in the proportions of 1 and 2 wt% as transesterification catalysts. Reactions containing ECO and LA showed an average enthalpy of cure of approximately 85 mJ mg-1 and materials cured in the presence of the catalysts showed lower enthalpies of cure and decrease in the material gel content. ECO-LA reaction generated materials with rubber-like properties with Tg ranging from -15 °C to -23 °C, where the material without a catalyst showed the higher Tg value. The presence of catalysts gave the material vitrimer properties, with the softening point associated with transesterification reactions and topology freezing temperature transition at temperatures (Tv) between 195-235 °C.

Novel polycaprolactone (PCL)-type I collagen core-shell electrospun nanofibers for wound healing applications.

Type I collagen (Col_1) is one of the main proteins present in the skin extracellular matrix, serving as support for skin regeneration and maturation in its granulation stage. Electrospun materials have been intensively studied as the next generation of skin wound dressing mainly due to their high surface area and fibrous porosity. However, the electrospinning of collagen-based solutions causes degradation of its structure. In this work, a coaxial electrospinning process was proposed to overcome this limitation. The production of mats of polycaprolactone (PCL)-Col_1/PVA (collagen/poly(vinyl alcohol)) composed of core-shell nanofibers was investigated. PCL solution was used as the core solution, while Col_1/PVA was used as the shell solution. PVA was used to improve the processability of collagen, while PCL was employed to improve the mechanical properties and morphology of Col_1/PVA fibers. The morphology and the cytotoxicity of the fibers were highly dependent on the processing parameters. Defect-free core-shell nanofibers were obtained with a shell/core flow rates ratio = 4, flight distance of 12 cm, and an applied voltage of 16 kV. Using this strategy, the triple helix structure characteristic of the collagen molecule was preserved. Moreover, the common post-processing of solvent removal could be suppressed, simplifying the manufacturing processing of these biomaterials. The nanostructured mats showed no cytotoxicity, high liquid absorption, structural stability, hydrophilic character, and collagen release capacity, making them a potential novel dressing for skin damage regeneration, in special in the case of chronic wounds treatment, in which exogenous collagen delivery is necessary.

Electrospinning: New Strategies for the Treatment of Skin Melanoma.

Recent studies have shown a significant growth of skin cancer cases in northern regions of the world, in which its presence was not common. Skin cancer is one of the cancers that mostly affects the world's population, ranking fifth in studies conducted in the United States (USA). Melanoma is cancer that has the highest number of deaths worldwide since it is the most resistant skin cancer to current treatments. This is why alternatives for its treatment has been investigated considering nanomedicine concepts. This study approaches the role of this field in the creation of promising electrospun devices, composed of nanoparticles and nanofibers, among other structures, capable of directing and/or loading active drugs and/or materials with the objective of inhibiting the growth of melanoma cells or even eliminating those cells.

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.

Biodegradable nanoparticles from prosopisylated cellulose as a platform for enhanced oral bioavailability of poorly water-soluble drugs.

Bio-inspired nanotechnology-based strategies are potential platforms for enhanced dissolution and oral biovailability of poorly water-soluble drugs. In this study, a recently patented green biopolymer (Prosopis africana gum, PG) was compatibilized with microcrystalline cellulose (MCC), a conventional polysaccharide, via thermo-regulated coacervation to obtain PG-MCC (1:0, 1:1, 1:2, 2:1, and 0:1) rational blends and the nanoparticles developed with optimized (1:1) biocomposites (termed "prosopisylated cellulose") by combined homogenization-nanoprecipitation technique was engineered as a high circulating system for improved oral bioavailability of griseofulvin (GF), a model Biopharmaceutics Classification System (BCS) Class-II drug. The effects of biopolymer interaction on morphological and microstructural properties of drug-free biocomposites obtained were investigated by Fourier transform infra-red spectroscopy, scanning electron microscopy and x-ray diffractometry, while the physicochemical properties and in-vivo pharmacokinetics of GF-loaded nanoparticles were also ascertained. Optimized biocomposites revealed inter-molecular and intra-molecular hydrogen bonding between the hydroxyl group of MCC and polar components of PG, as well as reduction in crystallinity of MCC. Griseofulvin-loaded nanoparticles were stable, displayed particles with relatively smooth surfaces and average size of 26.18 ± 0.94 . nm, with zeta potential and polydispersity index of 32.1 ± 0.57 mV and 0.173 ± 0.06, respectively. Additionally, the nanoparticles showed good entrapment efficiency (86.51 ± 0.93 %), and marked improvement in griseofulvin dissolution when compared to free drug, with significantly (p < 0.05) higher GF release in basic than acidic PEG-reinforced simulated bio-microenvironments. Besides, x-ray diffractogram of GF-loaded nanoparticles showed amorphization with few characteristic peaks of GF while infra-red spectrum indicated broader principal peaks of GF and components compatibility. Furthermore, GF-loaded nanoparticles showed low plasma clearance with three-fold increase in systemic bioavailability of griseofulvin compared with free drug. These results showed that prosopisylated cellulose nanoparticles would be a facile approach to improve oral bioavailability of BCS class-II drugs and can be pursued as a new versatile drug delivery platform.

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.