Polysaccharide films are alternative sources to replace fossil‐based compounds. This study aimed to use rice starch modified by gelatinization and oxidation processes. Different properties were ...observed after blending it with chitosan and polyols, as evaluated on the film‐forming solutions by rheology. The interaction between chitosan and oxidized starch appeared higher, as the plasticizers exhibited a low effect on the rheological behavior. Polyols played an essential role in chitosan/gelatinized associations, driven by the number of OH groups. Films were evaluated by thermogravimetry (TGA), differential scanning calorimetry (DSC), water vapor permeability (WVP), water solubility, and tensile tests. The effect of the plasticizer type on chitosan/gelatinized starch was related to an increase in the temperature of the endothermic peak observed by DSC, confirming the role of hydroxyl groups of polyols in the polymer–polymer chain associations. The WVP and solubility decreased with starch oxidation due to increased chitosan–starch interactions. The decrease in tensile strength with adding polyols was correlated to reduced direct interactions between chitosan and starch chains. A drop of about 77% in elongation at break was observed in chitosan/oxidized starch film. On the other hand, elongation at break increased by around 14% in films with sorbitol (SO).
Highlights
Starch oxidation reduces the viscosity of film‐forming solutions.
The number of OH groups influences the gelation point measured by rheology.
The WVP is reduced in oxidized starch/chitosan associations.
Plasticizers enhanced the elongation at break of polysaccharide films.
The OH polyol groups mainly controls film‐forming and film properties.
In this study, chitosan and gelatin materials incorporated with grape seed (Vitis vinifera L.) (VSE) and jabuticaba peel (Plinia cauliflora) (PPE) extracts were developed with potential application ...as food coatings. It was evaluated how the concentration of the extracts and their addition order in the polymeric matrix affect its properties. Samples with VSE presented a higher total phenolic content and also a more elastic behavior than samples with PPE. The addition order effect over viscosity was the opposite for the extracts, and for the samples with VSE a lower viscosity was obtained when the extract was added before gelatin. All samples were hydrophilic, a good result for application as coatings. Films with PPE were less soluble than chitosan/gelatin film, and CG5P sample was chosen as the most suitable for the desired application, due to its lower water vapor permeation value. The microbial permeation test showed that all samples avoid microorganism growth, extending shelf life of food. The results of this study revealed the extracts concentration was the main factor which influenced the studied parameters; however, their addition order had significant importance on rheological and barrier properties, the ones most influenced by the availability of extract compounds in the polymeric system.
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•Extracts of grape seed (VSE) and jabuticaba peel (PPE) are rich in phenolics.•Phenolics addition functionalized the properties of chitosan/gelatin mixtures.•Mixtures with VSE were more elastic and presented a higher phenolic content.•Higher extracts concentrations led to a reduction in initial viscosity of the samples.•Films properties were more influenced by extracts concentration than addition order.
Lesions with bone loss may require autologous grafts, which are considered the gold standard; however, natural or synthetic biomaterials are alternatives that can be used in clinical situations that ...require support for bone neoformation. Collagen and hydroxyapatite have been used for bone repair based on the concept of biomimetics, which can be combined with chitosan, forming a scaffold for cell adhesion and growth. However, osteoporosis caused by gonadal hormone deficiency can thus compromise the expected results of the osseointegration of scaffolds. The aim of this study was to investigate the osteoregenerative capacity of collagen (Co)/chitosan (Ch)/hydroxyapatite (Ha) scaffolds in rats with hormone deficiency caused by experimental bilateral ovariectomy. Forty-two rats were divided into non-ovariectomized (NO) and ovariectomized (O) groups, divided into three subgroups: control (empty defect) and two subgroups receiving collagen/chitosan/hydroxyapatite scaffolds prepared using different methods of hydroxyapatite incorporation, in situ (CoChHa1) and ex situ (CoChHa2). The defect areas were submitted to macroscopic, radiological, and histomorphometric analysis. No inflammatory processes were found in the tibial defect area that would indicate immune rejection of the scaffolds, thus confirming the biocompatibility of the biomaterials. Bone formation starting from the margins of the bone defect were observed in all rats, with a greater volume in the NO groups, particularly the group receiving CoChHa2. Less bone formation was found in the O subgroups when compared to the NO. In conclusion, collagen/chitosan/hydroxyapatite scaffolds stimulate bone growth in vivo but abnormal conditions of bone fragility caused by gonadal hormone deficiency may have delayed the bone repair process.
This study compares a wound dressing based on bacterial cellulose/collagen (BC/COL) hydrogel in rat dorsum with commercial collagenase ointment and untreated wound. The hydrogel was characterized by ...Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA), Fourier transformed - Infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). According to the In vivo test and macroscopic evaluation, BC/COL hydrogel showed a better repair of wounds and promoted statistically significant differences of tissue repair between treatments on the 7th day after surgery. Better quality, quantity and orientation evaluation of collagen fibers (p=0.0001) were observed in the BC/COL hydrogel and collagenase ointment groups in relation to the control group. The BC/COL hydrogel promoted better wound healing than collagenase and the control group, therefore, it can be considered a potential wound dressing for skin regeneration.
The physicochemical properties of nanoparticles (NPs) directly influence the colloidal stability and bio‐nano interface, which makes the study of these factors extremely important for NPs ...applicability. Here, we report the influence of pH and ionic strength in the size, surface charge, and antimicrobial activity of chitosan/rhamnolipid nanoparticles (C/RL‐NPs), synthesized by mixing C and RL in the proportion of 1:1, with the dropwise addition of TPP (sodium tripolyphosphate) in the molar ratio of 1:2.5:1.3, respectively. The obtained NPs were resuspended in different solvents to investigate the ionic strength effect on their stability and antimicrobial activity. By decreasing pH and ionic strength, NPs size was reduced while their surface charge increased. Chitosan nanoparticles (C‐NPs) remained stable in the presence of TPP at acidic pH and low ionic strength, indicating that the modulation of physicochemical conditions for the crosslinking between the two ionic components was an efficient approach to enhance C/RL‐NPs colloidal stability. Thermogravimetric analysis confirmed the interaction between rhamnolipid and chitosan in C/RL‐NPs. The antibacterial activity of C/RL‐NPs against Staphylococcus aureus increased significantly, demonstrating the importance of investigating size and surface charge to dictate the bioactivity properties of such hybrid natural‐based nanomaterial.
A comprehensive framework to assess the factors driving chitosan/rhamnolipid nanoparticles stability and aggregation and how these can dictate bacteria responses and interactions are provided. Nanoparticles colloidal stability is dependent on the solution chemistry and the modulation of ionic cross‐linkers. Smaller particles with high charge density and very potent antimicrobial activity are linked to low pH and ionic strength.
This study aims to evaluate the incorporation, addition order and concentration of grape seed extract (Vitis vinifera L.) in chitosan and gelatin solutions, candidates as food coatings due to their ...excellent antioxidant and barrier properties. This study originally assesses how such variables can affect the rheological parameters of this particular combination of materials. Initially, 1% (w/w) solutions of chitosan (C) and gelatin (G) are mixed at a 1:1 ratio (CG). For grape seed extract addition, ethanolic solutions (50%, v/v) are prepared in different concentrations, with two incorporation orders: 1) addition to CG and 2) addition to the chitosan gel (C), followed by G mixing. The addition order reveals a direct influence on the rheological properties, and low extract concentrations leads to solutions with adequate viscosity for coating applications. The findings of this study confirm that it is essential to standardize the addition procedures during the preparation of the materials.
O compósito à base de hidroxiapatita, quitosana e nanotubo de carbono foi desenvolvido com o intuito de auxiliar na consolidação óssea. Estudos anteriores sugerem que a combinação de substitutos ...ósseos e células-tronco mesenquimais (CTM) podem auxiliar a potencializar e promover a regeneração óssea. No presente estudo, o biomaterial foi desenvolvido e a viabilidade e a citotoxicidade de células Vero (ATCC CCL-81) e CTM obtidas de medula óssea provenientes de ovinos utilizando ensaios metil-tiazol-tetrazólio, MTT e iodeto de propídeo (PI) foram avaliadas em diferentes concentrações de extrato desse compósito. O compósito demonstrou ausência de citotoxicidade com comportamento semelhante ao grupo controle. Amostras com 50% e 10% de concentração de extrato do compósito mostraram resultados maiores comparados ao grupo controle (ensaio MTT). Esses resultados também sugerem que a presença do biomaterial pode ser utilizada em associação a CTM. Assim, esse estudo conclui que o compósito apresentado de hidroxiapatita, quitosana e nanotubo de cabono não foi considerado citotóxico e pode ser utilizado em teste in vivo.
Tissue engineering represents a promising alternative for reconstructive surgical procedures especially for the repair of bone defects that do not regenerate spontaneously. The present study aimed to ...evaluate the effects of the elastin matrix (E24/50 and E96/37) incorporated with hydroxyapatite (HA) or morphogenetic protein (BMP) on the bone repair process in the distal metaphysis of rat femur. The groups were: control group (CG), hydrolyzed elastin matrix at 50°C/24h (E24/50), E24/50 + HA (E24/50/HA), E24/50 + BMP (E24/50/BMP), hydrolyzed elastin matrix at 37°C/96h (E96/37), E96/37 + HA (E96/37/HA), E96/37 + BMP (E96/37/BMP). Macroscopic and radiographic analyses showed longitudinal integrity of the femur in all groups without fractures or bone deformities. Microtomographically, all groups demonstrated partial closure by mineralized tissue except for the E96/37/HA group with hyperdense thin bridge formation interconnecting the edges of the ruptured cortical. Histologically, there was no complete cortical recovery in any group, but partial closure with trabecular bone. In defects filled with biomaterials, no chronic inflammatory response or foreign body type was observed. The mean volume of new bone formed was statistically significant higher in the E96/37/HA and E24/50 groups (71.28 ± 4.26 and 66.40 ± 3.69, respectively) than all the others. In the confocal analysis, it was observed that all groups presented new bone markings formed during the experimental period, being less evident in the CG group. Von Kossa staining revealed intense calcium deposits distributed in all groups. Qualitative analysis of collagen fibers under polarized light showed a predominance of red-orange birefringence in the newly regenerated bone with no difference between groups. It was concluded that the E24/50 and E96/37/HA groups promoted, with greater speed, the bone repair process in the distal metaphysis of rat femur.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Blending chitosan and gelatin, two biodegradable and non-toxic polymers, is a recurrent choice in food coating or biomaterials development. The incorporation of vegetal extracts into chitosan/gelatin ...films can improve or introduce some properties to these materials. Jatobá resin is a product of Hymenaea genus trees with antimicrobial and anti-inflammatory activities, interesting properties for films applied in several areas. The chitosan degree of acetylation (DA) influences the inter and intramolecular interactions of this polymer and, therefore, also implicates in changes of its properties. This research aims to study the influence of jatobá resin inclusion and chitosan DA modification on chitosan/gelatin films properties. Both jatobá resin and chitosan DA affected physicochemical, antimicrobial and barrier properties of the films, allowing the control of these properties by changes in these parameters. Jatobá resin incorporation and the decrease in chitosan DA significantly improved antimicrobial activity and water vapor permeability of films with the reduction of water solubility and swelling.
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•Controlling films properties is feasible by jatobá resin inclusion and DA changes.•Resin addition increases water resistance and permeability of chitosan/gelatin films.•Chitosan/gelatin/jatobá resin films demonstrate high water vapor transmission rate.•Both DA and vegetal resin influence antimicrobial efficacy of chitosan/gelatin films.•Chitosan-based films properties make them ideal candidates as bioactive systems.
This investigation used materials based on synthetic hydroxyapatite and mineralized bovine tendon as a framework for bone regeneration and evaluated the osteoconductivity of these materials in the ...calvaria of Wistar rats in comparison to Bio-Oss/Geistlich. Micro-computed tomography (µ-CT) analyses were performed non-invasively using three-dimensional image reconstruction to evaluate new bone formation; in addition, conventional histological analysis was used. The µ-CT results showed that Bio-Oss resulted in higher volume, density and bone percentage than the other materials. Based on the three-dimensional reconstructed images, the lowest resorption rates were observed in the Bio-Oss group, and the materials remained in larger quantities inside the defect at thirty days. In the synthetic hydroxyapatite group, intense resorption of the material and slight bone formation on the defect margins were noted, yielding an irregular edge. The mineralized bovine tendon group showed discrete new bone formation, and the material was fully resorbed. The Bio-Oss and synthetic hydroxyapatite groups yielded similar amounts of blood vessels and osteoblastic cells, and these were higher than the amounts found in the mineralized bovine tendon group. Synthetic hydroxyapatite was present within the defect and exhibited osteoconductive properties that were similar to the commercial brand, Bio-Oss. Mineralized bovine tendon did not exhibit good osteoconductivity and is contraindicated for maintaining bone space. Moreover, µ-CT yielded lower specificity; that is, µ-CT was not able to distinguish bone tissue from Bio-Oss, although it exhibited high sensitivity. Based on these results, it appears that synthetic hydroxyapatite has great potential for use in filling bone defects, unlike mineralized bovine tendon
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