Polyvinyl alcohol-based electrospun matrix as a delivery system for nanoemulsion containing chalcone against Leishmania (Leishmania) amazonensis.

Cutaneous leishmaniasis is a worldwide public health problem. Conventional therapies, in addition to the high cost, have many adverse effects and cases of parasite's resistance. Chalcones are secondary metabolites precursors in the flavonoid pathway and can be obtained naturally, but with low yield from plant raw material. Thus, the use of synthetic chalcones has been a promising strategy for the development of molecules with leishmanicidal activity. Thus, this work aimed to develop a controlled release system of two synthetic chalcone (trans-chalcones and 3'-(trifluormethyl)-chalcone) using polyvinyl alcohol nanofibers (PVA) as scaffold. The association of chalcones to the nanofibers was made by nanoemulsions (NE) thereof, i.e., a colloidal system on a nanometric scale, which allows compounds with opposite polarities to remain miscible and stable throughout their manipulation. Chalcone nanoemulsions were developed using the spontaneous emulsification technique. The NE were characterized regarding their particle size, polydispersion index (PDI), and zeta potential. The results showed NE with spherical shape, absolute values of zeta potential were higher than 30 mV and homogeneous distribution pattern (PDI < 0.3). Dynamics light scattering (DLS) analysis showed similar hydrodynamic rays, i.e., 180 nm (trans-chalcone NE) and 178 nm (NE containing 3'-(trifluormethyl)-chalcone, in addition to presenting encapsulation efficiency values close to 100 %. Subsequently, the NE were added to a polymeric solution of polyvinyl alcohol (PVA) and processed via the electrospinning technique affording a PVA matrix (15 %, w/v) nanofiber containing the chalcones NE at 1 mg.mL-1. In a follow-up experiment, the skin permeation assay of the PVA matrix-chalcone NE was performed in vitro using Franz type diffusion cells and porcine ear as biological model of study. The results showed that the treatments with the nanofibers containing the chalcone NE were retained mainly in the stratum corneum, while the NE suspensions containing chalcone were retained in the epidermis and dermis. This result is thought to be relevant, since parasites are located mainly in the dermis. Further, in vitro assay against the amastigote form of L. (L) amazonensis, showed IC50 values to trans-chalcone and 3'-(trifluormethyl)-chalcone of 24.42 ± 6.76 µg.mL-1 and 15.36 ± 4.61 µg.mL-1, respectively. In addition to improving the solubility of the compounds tested in culture medium without using organic solvents, chalcones in nano-emulsified form reduced the IC50 to 9.09 ± 1.24 µg.mL-1 (trans-chalcone) and 10.27 ± 2.27 µg.mL-1 (3'-(trifluormethyl)-chalcone) which confirmed the potential of the nanoemulsion containing chalcone for cutaneous leishmaniasis treatment.

Nanotechnology: A Promising Tool Towards Wound Healing.

Nanotechnology is an exciting emerging field with multiple applications in skin regeneration. Nanofibers have gained special attention in skin regeneration based on their structural similarity to the extracellular matrix. A wide variety of polymeric nanofibers with distinct properties have been developed and tested as scaffolds for skin regeneration. Besides providing support for tissue repair, nanofibrous materials can act as delivery systems for drugs, proteins, growth factors, and other molecules. Moreover, the morphology, biodegradability, and other functionalities of nanofibrous materials can be controlled towards specific conditions of wound healing. Other nanostructured drug delivery systems, such as nanoparticles, micelles, nanoemulsions, and liposomes, have been used to improve wound healing at different stages. These nanoscale delivery systems have demonstrated several benefits for the wound healing process, including reduced cytotoxicity of drugs, administration of poorly water-soluble drugs, improved skin penetration, controlled release properties, antimicrobial activity, and protection of drugs against light, temperature, enzymes or pH degradation, as well as stimulation of fibroblast proliferation and reduced inflammation.

Foreign body reaction associated with PET and PET/chitosan electrospun nanofibrous abdominal meshes.

Electrospun materials have been widely explored for biomedical applications because of their advantageous characteristics, i.e., tridimensional nanofibrous structure with high surface-to-volume ratio, high porosity, and pore interconnectivity. Furthermore, considering the similarities between the nanofiber networks and the extracellular matrix (ECM), as well as the accepted role of changes in ECM for hernia repair, electrospun polymer fiber assemblies have emerged as potential materials for incisional hernia repair. In this work, we describe the application of electrospun non-absorbable mats based on poly(ethylene terephthalate) (PET) in the repair of abdominal defects, comparing the performance of these meshes with that of a commercial polypropylene mesh and a multifilament PET mesh. PET and PET/chitosan electrospun meshes revealed good performance during incisional hernia surgery, post-operative period, and no evidence of intestinal adhesion was found. The electrospun meshes were flexible with high suture retention, showing tensile strengths of 3 MPa and breaking strains of 8-33%. Nevertheless, a significant foreign body reaction (FBR) was observed in animals treated with the nanofibrous materials. Animals implanted with PET and PET/chitosan electrospun meshes (fiber diameter of 0.71 ± 0.28 µm and 3.01 ± 0.72 µm, respectively) showed, respectively, foreign body granuloma formation, averaging 4.2-fold and 7.4-fold greater than the control commercial mesh group (Marlex). Many foreign body giant cells (FBGC) involving nanofiber pieces were also found in the PET and PET/chitosan groups (11.9 and 19.3 times more FBGC than control, respectively). In contrast, no important FBR was observed for PET microfibers (fiber diameter = 18.9 ± 0.21 µm). Therefore, we suggest that the reduced dimension and the high surface-to-volume ratio of the electrospun fibers caused the FBR reaction, pointing out the need for further studies to elucidate the mechanisms underlying interactions between cells/tissues and nanofibrous materials in order to gain a better understanding of the implantation risks associated with nanostructured biomaterials.

Manipulation of chemical composition and architecture of non-biodegradable poly(ethylene terephthalate)/chitosan fibrous scaffolds and their effects on L929 cell behavior.

Microporous, non-woven fibrous scaffolds made of poly(ethylene terephthalate) and chitosan were produced by electrospinning. Fiber morphology, diameter, pore size, and wettability were manipulated by varying the chemical composition of the electrospinning solution, i.e. chitosan concentration and molecular weight, and by post-electrospinning treatment with glutaraldehyde. In vitro studies were conducted using a fibroblast cell line toward a comprehensive understanding of how scaffolds characteristics can modulate the cell behavior, i.e. viability, adhesion, proliferation, extracellular matrix secretion, and three-dimensional colonization. Substantial differences were found as a result of scaffold morphological changes. Higher levels of adhesion, spreading, and superficial proliferation were achieved for scaffolds with smaller fiber and pore diameters while cell penetration and internal colonization were enhanced for scaffolds with larger pores. Additionally, the available area for cell adhesion, which is related to fiber and pore size, was a crucial factor for the viability of L929 cells. This paper provides significant insights for the development and optimization of electrospun scaffolds toward an improved biological performance.

Anti-atherogenic effects of a phenol-rich fraction from Brazilian red wine (Vitis labrusca L.) in hypercholesterolemic low-density lipoprotein receptor knockout mice.

Moderate wine intake (i.e., 1-2 glasses of wine a day) is associated with a reduced risk of morbidity and mortality from cardiovascular disease. The aim of this study was to evaluate the anti-atherosclerotic effects of a nonalcoholic ethyl acetate fraction (EAF) from a South Brazilian red wine obtained from Vitis labrusca grapes. Experiments were carried out on low-density lipoprotein (LDL) receptor knockout (LDLr⁻/⁻) mice, which were subjected to a hypercholesterolemic diet and treated with doses of EAF (3, 10, and 30 mg/kg) for 12 weeks. At the end of the treatment, the level of plasma lipids, the vascular reactivity, and the atherosclerotic lesions were evaluated. Our results demonstrated that the treatment with EAF at 3 mg/kg significantly decreased total cholesterol, triglycerides, and LDL plus very low-density lipoprotein levels compared with control hypercholesterolemic mice. The treatment of mice with EAF at 3 mg/kg also preserved the vasodilatation induced by acetylcholine on isolated thoracic aorta from hypercholesterolemic LDLr⁻/⁻ mice. This result is in agreement with the degree of lipid deposit on arteries. Taken together, the results show for the first time that the lowest concentration of an EAF obtained from a red wine produced in southern Brazil significantly reduced the progression of atherosclerosis in mice.

Nanofibrous poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/chitosan scaffolds for skin regeneration.

The purpose of this study was to evaluate hybrid poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/chitosan nanofibrous mats as scaffolds for skin engineering. In vitro studies were carried out to test the potential of the scaffolds for fibroblasts adhesion, viability, and proliferation (L929 cell line). The in vivo performance was also studied in a full-thickness wound healing model. PHBV/chitosan 4:1 (w/w) exhibited a higher in vitro biocompatibility and a better ability for cell adhesion and growth, compared to PHBV/chitosan 2:3 (w/w). The in vivo assay also revealed the better performance of this scaffold, improving the wound healing process in rats.

Preparation and characterization of electrospun mats made of PET/chitosan hybrid nanofibers.

In this work we report the preparation and characterization of nanofibrous mats electrospun from mixed solutions of poly(ethylene terephthalate) (PET) and chitosan, with potential applications in such areas as filtration, tissue scaffolds and protective clothing. Polymer compatibility in solution was rather low due to the dissimilarity in the chemical structure of both polymers. We have defined a suitable solvent to both the synthetic, typically hydrophobic polyester, and the biopolymer, and adequate concentrations and molecular weights in order to obtained miscibility of both polymers in solution and suitable electrospinning conditions. The effect of polymer ratio and chitosan molecular weight in the electrospun mat morphology, composition, mechanical and surface properties was evaluated by SEM, ATR-FTIR spectroscopy, and uniaxial tensile tests. The presence of chitosan increased the diameter and the size distribution of the fibers. The effect on the mechanical properties of the nanofibrous mats showed a complex nature dependent on chitosan molecular weight and concentration. Phase separation during solvent evaporation and fiber formation, taking place at varied extent depending on molecular mobility of one of the components, is suggested to explain the formation of hybrid continuous or core-sheath fibers.