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•Chitosan/gelatin-based materials were functionalized with pomegranate peel extract.•Extract was capable to improve the functional characteristics of the materials.•High phenolic ...extract content improved antioxidant activity of the materials.•Extract incorporation enhanced the stability against the applied strain.•Rheological properties were influenced by extract incorporation and concentration.
Biopolymer-based materials are potential candidates for food coatings application. In this study, pomegranate (Punica granatum L.) peel extract (PPE) at different concentrations was incorporated to chitosan/gelatin gels and the rheological, antioxidant and structural properties were evaluated. Due to its high phenolic content, PPE enhanced the antioxidant capacity of chitosan/gelatin mixtures. PPE addition extended linear viscoelastic range and enabled the samples to easily flow under the applied shear rate. Rheological properties indicated that both viscosity and activation energy of materials containing natural compounds are highly dependent on temperature. Scanning electron microscopy (SEM) images revealed the influence of PPE concentration in the scaffolds pores size. Findings of this study proved that PPE was capable to improve the functional characteristics of chitosan/gelatin-based materials enhancing the desired properties for their potential application as food coatings.
This study proposes the incorporation of mangosteen peel extract in chitosan and collagen gels and scaffolds, at different ratios, for fabricating materials with potential wound dressing ...applications. The extract addition increases the thermal stability of the collagen while decreasing to about one-fifth the swelling capability of its scaffolds. Oppositely, it enables chitosan and its blends to withstand high swelling percentages. Release studies showed an extract delivery of 30%, indicating that the formulation does not affect this property. Additionally, the models of Weibull and the Korsmeyer-Peppas adequately fitted the release curves, in which the last one suggested a faster release regarding extract concentration. In contrast, rheology profiling demonstrated distinct behavior associated with the formulations. Even though all the samples exhibit a shear-thinning characteristic, changes in the blend ratio increased the extension of the Newtonian plateau range. The applied Cross mathematical model showed an increase in interactions between the components.
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In this study, a potential hard tissue substitute was mimicked using collagen/mangosteen porous scaffolds. Collagen was extracted from Tilapia fish skin and mangosteen from the waste peel of the ...respective fruit. Sodium trimetaphosphate was used for the phosphorylation of these scaffolds to improve the nucleation sites for the mineralization process. Phosphate groups were incorporated in the collagen structure as confirmed by their attenuated total reflection Fourier transform infrared (ATR-FTIR) bands. The phosphorylation and mangosteen addition increased the thermal stability of the collagen triple helix structure, as demonstrated by differential scanning calorimetry (DSC) and thermogravimetry (TGA) characterizations. Mineralization was successfully achieved, and the presence of calcium phosphate was visualized by scanning electron microscopy (SEM). Nevertheless, the porous structure was maintained, which is an essential characteristic for the desired application. The deposited mineral was amorphous calcium phosphate, as confirmed by energy dispersive X-ray spectroscopy (EDX) results.
Studies indicate that hyperthermic therapy using gold nanorods and photodynamic activity with many photosensitizers can present a synergistic effect, and offer a great therapeutic potential, although ...more investigation needs to be performed before such approach could be implemented. We proposed to investigate the effect of the attachment of phthalocyanines on the surface of gold nanorods (well-characterized devices for hyperthermia generation) for the elimination of melanoma, one of the most important skin cancers due to its high lethality. Following the synthesis of nanorods through a seed-mediated method, the efficacy of photodynamic therapy (PDT) and hyperthermia was assessed separately. We chose to coat the nanorods with two tetracarboxylated zinc phthalocyanines - with or without methyl-glucamine groups. After the coating process, the phthalocyanines formed ionic complexes with the cetyltrimethylammonium bromide (CTAB) that was previously covering the nanoparticles. The nanorod-phthalocyanines complexes were analyzed by transmission electron microscopy (TEM), and their singlet oxygen and hydroxyl radical generation yields were assessed. Furthermore, they were tested in vitro with melanotic B16F10 and amelanotic B16G4F melanoma cells. The cells with nanoparticles were irradiated with laser (at 635nm), and the cell viability was assessed. The results indicate that the photodynamic properties of the phthalocyanines tested are enhanced when they are attached on the nanorods surface, and the combination of PDT and hyperthermia was able to eliminate over 90% of melanoma cells. This is a novel study because two tetracarboxylated phthalocyanines were used and because the same wavelength was irradiated to activate both the nanorods and the photosensitizers.
•The use of the same wavelength for hyperthermic and photodynamic therapies•The use of gold nanorods covered with tetracarboxylated zinc phthalocyanines•The singlet oxygen generation by the phthalocyanines attached to nanorods is increased.•Melanotic melanoma cells seem to be more susceptible to hyperthermia and combined treatments.
In traumatology, we encounter several clinical challenges that involve extensive bone loss primarily related to trauma, conditions that can be treated with autologous grafts. A good alternative is ...the use of synthetic biomaterials as substitutes. These polymers provide a suitable environment for the growth of new bone and vascular tissue, which are essential for repair. Collagen/hydroxyapatite composites have proven to be biocompatible and to behave mechanically. Furthermore, the addition of chitosan contributes to the formation of a three-dimensional structure that permits cell adhesion and proliferation, thus improving osteogenesis. The aim of this study was to evaluate bone formation during the repair of bone defects experimentally induced in the skull of rats and grafted with a polymer blend consisting of bovine tendon collagen and chitosan combined with hydroxyapatite. Thirty animals were used for the creation of a defect in the left parietal bone and were divided into three groups of 10 animals each: a control group without biomaterial implantation, a group receiving the blend of collagen and chitosan, and a group receiving this blend combined with hydroxyapatite. Each group was subdivided and the animals were sacrificed 3 or 8 weeks after surgery. After sacrifice, the skulls were removed for macroscopic photodocumentation and radiographic examination. The samples were processed for histological evaluation of new bone formation at the surgical site. Macroscopic and radiographic analysis demonstrated the biocompatibility of the blends. Histologically, the formation of new bone occurred in continuity with the edges of the defect, with the observation of higher volumes in the grafted groups compared to control. Mineralization of sponges did not stimulate bone neoformation, with bone repair being incomplete over the experimental period. In conclusion, mineralization by the addition of hydroxyapatite should be better studied. However, the collagen/chitosan sponges used in this study are suitable to stimulate osteogenesis in cranial defects, although this process is slow and not sufficient to achieve complete bone regeneration over a short period of time.
Mechanical, barrier, and thermal properties of films based on blends of corn starch and chitosan plasticized with ethylene glycol, glycerol, and sorbitol were investigated. Starch amylopectin ...variation was explored, and contents of 100% and 73% were employed to blend with chitosan and polyols. The findings showed that high amylopectin content has a significant effect (p < 0.05), resulting in films with lower tensile strength (TS) and reduced water vapor permeability (WVP). On the other hand, the incorporation of polyols showed a significantly high (p < 0.05) elongation at break (EB) for films plasticized with glycerol and sorbitol at high amylopectin content. For chitosan/73% amylopectin film, the addition of plasticizers exhibited no significant difference (p < 0.05) among the samples for TS and WVP results. The amylopectin content played no influence in the degradation stability of the films measured by thermogravimetry (TGA). However, amylopectin content influences the endothermic peak temperature observed by differential scanning calorimetry (DSC) analysis. A reduction of about 15 °C was noticed for the film prepared with high amylopectin content, a behavior correlated to its amorphous structure, capable of retaining more water than a crystalline region.
Abstract The indication of biomaterials has increased substantially in the regenerative therapy of bone defects. However, in addition to evaluating the physicochemical properties of biomaterials, the ...quality of the recipient tissue is also essential for the osseointegration of implants, as abnormalities in bone metabolism, such as gonadal hormone deficiency, can influence bone healing. This study evaluated the osteoregenerative capacity of collagen membranes derived from bovine pericardium and intestinal serosa in the repair of cranial defects in ovariectomised rats. Thirty female Wistar rats were submitted to surgical creation of a 5-mm cranial bone defect. The rats were divided into a control group (not ovariectomised) and an ovariectomised group. The non-ovariectomised group was divided into three subgroups: control (G1) in which the defect was not filled with the biomaterial, and two subgroups (G2 and G3) that received the bovine pericardium- and serosa-derived collagen membranes, respectively. The ovariectomised group was divided into the same subgroups (G4, G5, and G6). The animals were sacrificed 8 weeks after surgery. The calvaria were removed for macroscopic and radiographic photodocumentation and processed for histomorphometric analysis of bone healing at the surgical site. Macroscopic, radiological, and microscopic analyses demonstrated the biocompatibility of the implanted collagen membranes, as indicated by the absence of infiltration and signs of inflammation at the surgical site. Histologically, discrete immature bone neoformation projecting from the margins of the defect was observed at the surgical site in ovariectomised groups when compared to the non-ovariectomised groups. The volume of newly formed bone was significantly higher in the non-ovariectomised groups (G1: 7.83% ± 1.32; G2: 21.33% ± 1.96; and G3: 22.83% ± 0.98) compared to the respective ovariectomised subgroups (G4: 3.16% ± 0.75; G5: 16.83% ± 0.98; and G6: 16.16% ± 0.75), thus demonstrating the deleterious effects of ovariectomy on bone homeostasis. Higher volumes of newly formed bone were observed in the groups receiving the membrane grafts (G2, G3, G5, and G6) compared to the control groups (G1 and G4). In conclusion, the bilateral ovariectomy compromises the ability to repair bone lesions grafted with osteoconductive biomaterials as in the case of collagen membranes derived from both bovine pericardium and intestinal serosa.
Polyanionic collagen obtained from bovine pericardial tissue submitted to alkaline hydrolysis is an acellular matrix with strong potential in tissue engineering. However, increasing the carboxyl ...content reduces fibril formation and thermal stability compared to the native tissues. In the present work, we propose a chemical protocol based on the association of alkaline hydrolysis with 1,4-dioxane treatment to either attenuate or revert the drastic structural modifications promoted by alkaline treatments. For the characterization of the polyanionic membranes treated with 1,4-dioxane, we found that (1) scanning electron microscopy (SEM) shows a stronger reorientation and aggregation of collagen microfibrils; (2) histological evaluation reveals recovering of the alignment of collagen fibers and reassociation with elastic fibers; (3) differential scanning calorimetry (DSC) shows an increase in thermal stability; and (4) in biocompatibility assays there is a normal attachment, morphology and proliferation associated with high survival of the mouse fibroblast cell line NIH3T3 in reconstituted membranes, which behave as native membranes. Our conclusions reinforce the ability of 1,4-dioxane to enhance the properties of negatively charged polyanionic collagen associated with its potential use as biomaterials for grafting, cationic drug- or cell-delivery systems and for the coating of cardiovascular devices.
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