Estudio de biocompatibilidad de matrices poliméricas combinadas, responsivas al pH, con aplicación en Ingeniería de Tejido Óseo / Biocompatibility study of combined pH-responsive polymeric matrices with application in Bone Tissue Engineering

El presente trabajo muestra la obtención de un material a partir de un polímero sintético (TerP) y otro natural, mediante entrecruzamiento físico y su caracterización fisicoquímica y biológica, con el fin de emplearlos para regeneración de tejido óseo. Las membranas fueron obtenidas por la técnica de evaporación del solvente y caracterizadas por espectroscopia FTIR, ensayos de hinchamiento, medidas de ángulo de contacto y microscopia electrónica de barrido (SEM). Se encontró que la compatibilidad entre los polímeros que la constituyen es estable a pH fisiológico y que, al incorporar mayor cantidad del TerP a la matriz, esta se vuelve más hidrofóbica y porosa. Además, teniendo en cuenta la aplicación prevista para dichos materiales, se realizaron estudios de biocompatibilidad y citotoxicidad con células progenitoras de médula ósea (CPMO) y células RAW264.7, respectivamente. Se evaluó la proliferación celular, la producción y liberación de óxido nítrico (NO) al medio de cultivo durante 24 y 48 horas y la expresión de citoquinas proinflamatorias IL-1ß y TNF-α de las células crecidas sobre los biomateriales variando la cantidad del polímero sintético. Se encontró mayor proliferación celular y menor producción de NO sobre las matrices que contienen menos proporción del TerP, además de poseer una mejor biocompatibilidad. Los resultados de este estudio muestran que el terpolímero obtenido y su combinación con un polímero natural es una estrategia muy interesante para obtener un biomaterial con posibles aplicaciones en medicina regenerativa y que podría extenderse a otros sistemas estructuralmente relacionados. (AU)

In the present work, the preparation of a biomaterial from a synthetic terpolymer (TerP) and a natural polymer, physically crosslinked, is shown. In order to evaluate the new material for bone tissue regeneration, physicochemical and biological characterizations were performed. The membranes were obtained by solvent casting and characterized using FTIR spectroscopy, swelling tests, contact angle measurements, and scanning electron microscopy (SEM). It was found that the compatibility between the polymers is stable at physiological pH and the incorporation of a higher amount of TerP into the matrix increases hydrophobicity and porosity.Furthermore, considering the intended application of these materials, studies of biocompatibility and cytotoxicity were conducted with Bone Marrow Progenitor Cells (BMPCs) and RAW264.7 cells, respectively. Cell proliferation, NO production and release into the culture medium for 24 and 48 hours, and proinflammatory cytokine expression of IL-1ß and TNF-α from cells grown on the biomaterials while varying the amount of the synthetic polymer were evaluated. Greater cell proliferation and lower NO production were found on matrices containing a lower proportion of TerP, in addition to better biocompatibility. The results of this study demonstrate that the obtained terpolymer and its combination with a natural polymer is a highly interesting strategy for biomaterial preparation with potential applications in regenerative medicine. This approach could be extended to other structurally related systems. (AU)

Applicatoin of chitosan-based hydrogel in oral tissue engineering / 中南大学学报(医学版)

Pulpitis, periodontitis, jaw bone defect, and temporomandibular joint damage are common oral and maxillofacial diseases in clinic, but traditional treatments are unable to restore the structure and function of the injured tissues. Due to their good biocompatibility, biodegradability, antioxidant effect, anti-inflammatory activity, and broad-spectrum antimicrobial property, chitosan-based hydrogels have shown broad applicable prospects in the field of oral tissue engineering. Quaternization, carboxymethylation, and sulfonation are common chemical modification strategies to improve the physicochemical properties and biological functions of chitosan-based hydrogels, while the construction of hydrogel composite systems via carrying porous microspheres or nanoparticles can achieve local sequential delivery of diverse drugs or bioactive factors, laying a solid foundation for the well-organized regeneration of defective tissues. Chemical cross-linking is commonly employed to fabricate irreversible permanent chitosan gels, and physical cross-linking enables the formation of reversible gel networks. Representing suitable scaffold biomaterials, several chitosan-based hydrogels transplanted with stem cells, growth factors or exosomes have been used in an attempt to regenerate oral soft and hard tissues. Currently, remarkable advances have been made in promoting the regeneration of pulp-dentin complex, cementum-periodontium-alveolar bone complex, jaw bone, and cartilage. However, the clinical translation of chitosan-based hydrogels still encounters multiple challenges. In future, more in vivo clinical exploration under the conditions of oral complex microenvironments should be performed, and the combined application of chitosan-based hydrogels and a variety of bioactive factors, biomaterials, and state-of-the-art biotechnologies can be pursued in order to realize multifaceted complete regeneration of oral tissue.

Advances in the structure and function of chitosanase / 生物工程学报

Chitosanases represent a class of glycoside hydrolases with high catalytic activity on chitosan but nearly no activity on chitin. Chitosanases can convert high molecular weight chitosan into functional chitooligosaccharides with low molecular weight. In recent years, remarkable progress has been made in the research on chitosanases. This review summarizes and discusses its biochemical properties, crystal structures, catalytic mechanisms, and protein engineering, highlighting the preparation of pure chitooligosaccharides by enzymatic hydrolysis. This review may advance the understandings on the mechanism of chitosanases and promote its industrial applications.

Research Advances in Medical Materials and Products for Soft Tissue Repairs / 中国医疗器械杂志

Soft tissue is an indispensable tissue in human body. It plays an important role in protecting the body from external physical, chemical or biological factors. Mild soft tissue injuries can self-heal, while severe soft tissue injuries may require related treatment. Natural polymers (such as chitosan, hyaluronic acid, and collagen) and synthetic polymers (such as polyethylene glycol and polylactic acid) exhibit good biocompatibility, biodegradability and low toxicity. It can be used for soft tissue repairs for antibacterial, hemostatic and wound healing purposes. Their related properties can be enhanced through modification or preparation of composite materials. Commonly used soft tissue repairs include wound dressings, biological patches, medical tissue adhesives, and tissue engineering scaffolds. This study introduces the properties, mechanisms of action and applications of various soft tissue repair medical materials, including chitosan, hyaluronic acid, collagen, polyethylene glycol and polylactic acid, and provides an outlook on the application prospects of soft tissue repair medical materials and products.

Biocompatible chitosan/polyethylene glycol/multi-walled carbon nanotube composite scaffolds for neural tissue engineering / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Carbon nanotube (CNT) composite materials are very attractive for use in neural tissue engineering and biosensor coatings. CNT scaffolds are excellent mimics of extracellular matrix due to their hydrophilicity, viscosity, and biocompatibility. CNTs can also impart conductivity to other insulating materials, improve mechanical stability, guide neuronal cell behavior, and trigger axon regeneration. The performance of chitosan (CS)/polyethylene glycol (PEG) composite scaffolds could be optimized by introducing multi-walled CNTs (MWCNTs). CS/PEG/CNT composite scaffolds with CNT content of 1%, 3%, and 5% (1%=0.01 g/mL) were prepared by freeze-drying. Their physical and chemical properties and biocompatibility were evaluated. Scanning electron microscopy (SEM) showed that the composite scaffolds had a highly connected porous structure. Transmission electron microscope (TEM) and Raman spectroscopy proved that the CNTs were well dispersed in the CS/PEG matrix and combined with the CS/PEG nanofiber bundles. MWCNTs enhanced the elastic modulus of the scaffold. The porosity of the scaffolds ranged from 83% to 96%. They reached a stable water swelling state within 24 h, and swelling decreased with increasing MWCNT concentration. The electrical conductivity and cell adhesion rate of the scaffolds increased with increasing MWCNT content. Immunofluorescence showed that rat pheochromocytoma (PC12) cells grown in the scaffolds had characteristics similar to nerve cells. We measured changes in the expression of nerve cell markers by quantitative real-time polymerase chain reaction (qRT-PCR), and found that PC12 cells cultured in the scaffolds expressed growth-associated protein 43 (GAP43), nerve growth factor receptor (NGFR), and class III β‍-tubulin (TUBB3) proteins. Preliminary research showed that the prepared CS/PEG/CNT scaffold has good biocompatibility and can be further applied to neural tissue engineering research.

Optimized Chitosan-Coated Gliadin Nanoparticles Improved the Hesperidin Cytotoxicity over Tumor Cells

Abstract Hesperidin is a natural compound which is found in citric fruits and presents antitumor and antimicrobial activities. However, the in vivo efficacy of Hesperidin is reduced due to its low oral bioavailability. Protein-based nanoparticles have been applied to improve biological parameters of drugs and natural compounds. Gliadin is a monomeric protein present in wheat. In this study, gliadin-based nanoparticles containing hesperidin were obtained by desolvation technique and a Taguchi orthogonal array design was employed to optimize the formulation. The independent variables were set as concentration of CaCl2 (0.5; 1 or 2%) and stabilizing agent (Pluronic F68, Tween 80 or sodium caseinate). The dependent variables consisted of mean diameter, polydispersity index, zeta potential, and encapsulation efficiency. The results showed significant effects on the dependent variables when 1% CaCl2 and Pluronic F68 were used. The optimized formulation was coated with chitosan to increase the physical stability of the nanoparticles. The final nanoparticles presented a mean diameter of 321 nm and polydispersity index of 0.217, and spherical shape. After coating, the Zeta potential was +21 mV, and the encapsulation efficiency was 73 %. The in vitro release assay showed that about 98% of the drug was released from the nanoparticles after 48 h. Moreover, the nanoparticles reduced hesperidin cytotoxicity on healthy cells (Vero cells) and improved the cytotoxicity on tumor cells (HeLa, PC-3 and Caco-2 cells). Results showed that the chitosan-coated gliadin nanoparticles are potential carriers for hesperidin delivery for cancer treatment.

Determination of the biodegradability of chitosan utilizing the most probable number technique

The present work aimed to evaluate the degradability of the chitosan polymer by soil microorganisms.This evaluation was accomplished using the Most Probable Number (MPN) method by plating in drops so that soil microorganisms capable of degrading the polymeric material could be quantified. Soil samples diluted in three specific culture media for each typeof microorganism were plated –bacteria, fungi and actinobacteria–and they were maintained at 28°C for seven days to determine the growth rate of fungi and actinobacteria, and for 48hoursfor the development of bacteria. Significant differences in the MPN of actinobacteriarelative to the other groups analyzed were observed. Thus, the method used was effective for determining the degradability of the chitosan biopolymer when observing the development of microorganisms subjected to the replacement of thecarbonsource by the addition of 2% w v-1of the chitosan biopolymer to the culture medium. The formation of clear regions around the microbial colonies was a strong indicator of biodegradation.

Application of Films Based on Chitosan and Xanthan Gum in Refrigerated Fish Conservation

Abstract This research aims to determine the efficiency of chitosan and xanthan gum films in conservation of croaker fillets kept in refrigeration for 9 days. Proximal composition, loss of mass, color, pH, TVB-N (Total Volatile Bases) and microbiological profile were assessed. The films were prepared with chitosan and xanthan gum in varying mass proportions 100:0, m:m (C100XG0); 60:40, m:m (C60XG40); 50:50, m:m (C50XG50). They presented the respective values for moisture content, water solubility, thickness and water vapor permeability: 24.59%, 19.50%, 0.086 mm and 11.45gm-1.s-1.Pa-1for C100XG0; 24.58%; 20.27%, 0.091 mm and 10.41 gm-1.s-1.Pa-1for C60XG40; 22.11%, 22.06%, 0.089 mm and 10.68 gm-1.s-1.Pa-1 forC50XG50.The films were made in small bags format capable to hold about 20 g of fish fillets. A control sample was prepared in parallel, using polyethylene bags under the same storage conditions. The results showed that the chitosan films combined with xanthan gum had excellent antimicrobial properties, capable of preserving the quality of chilled fish fillets during the studied period, since it inhibited the growth of Staphylococcus coagulase-positive, Salmonella spp and coliforms at 45 ° C. Mass loss of the croaker fillets was not significantly affected by xanthan gum addition to the films. On the other hand, xanthan gum addition affected pH and color parameters of the corvina fillets. It was also verified that the combination of these two polymers promoted the reduction of N-BVT, being the C50XG50 film that presented the best response.

Comparative effects of final canal irrigation with chitosan and EDTA

Abstract Chitosan is a natural, biocompatible chelating substance with potential for dental use. This study compared the effects of final canal irrigation with chitosan and EDTA on dentin microhardness, sealer dentin tubules penetration capacity, and push-out strength. Methodology: Fifty canine roots were distributed according to the final irrigation protocol (n=10): G1- 15% EDTA with conventional irrigation; G2- 15% EDTA with Endovac; G3- 0.2% chitosan with conventional irrigation; G4- 0.2% chitosan with Endovac; and G5- without irrigation. Specimens were obturated (AH Plus) and sectioned in 3 slices per root third. The first slice was used for microhardness and sealer penetration assessments under a laser confocal microscope. The second was utilized in a push-out strength test. The third slice was discarded. Data were analyzed using 2-way ANOVA and Tukey's post hoc test (α<0.05). Failure mode was determined at x40 magnification. Results: Microhardness reduction was more significant in groups G2 and G4 (p<0.05). Sealer penetration through dentin was significantly greater in group G2 (p<0.05). There was no significant difference between groups G1, G3, and G4 (p>0.05). In general, all experimental groups presented similar bond resistance (p>0.05) that significantly differed from the control (p<0.001). Mixed type failures were predominant. Conclusions: In general, 0.2% chitosan and 15% EDTA solutions act in a similar manner with regard to the variables studied. The use of Endovac potentiates the effect of these solutions.

Color stability and surface roughness of chitosan- and nanodiamond-modified bisacrylic resin

Abstract: The aim of this study is to evaluate the effect of chitosan or nanodiamond incorporation on the color stability and surface roughness of a bisacrylic resin subjected to artificial aging. Four bisacrylic resins were evaluated, namely, control, chitosan-modified material, nanodiamond-modified material, and chitosan-nanodiamond-modified material. Twenty-four specimens were prepared for each material. The surface roughness was determined using a profilometer with a cut-off of 0.25 mm. The baseline color was measured according to the CIE L*a*b* system using a reflectance spectrophotometer. After these tests, the specimens were individually immersed in cola soft drink, red wine, or distilled water (n = 8) for 28 days. After the aging, the surface roughness and final color were re-evaluated. The color stability was determined using the difference between the coordinates obtained before and after the aging process. The data on roughness and color change were evaluated using ANOVA and the Tukey test (α = 0.05). The results show that the incorporation of nanodiamonds and chitosan into a bisacrylic resin provided a better color stability to the materials (p = 0.007). The storage in red wine resulted in a higher variation in the surface roughness values, especially when only the nanodiamond was incorporated to the material (p < 0.05). The incorporation of both chitosan and nanodiamonds are promising in providing an improvement in the properties of the bisacrylic resin when they are simultaneously incorporated in the product.

Effect of iodonium salt and chitosan on the physical and antibacterial properties of experimental infiltrants

Abstract Resinous infiltrants are indicated in the treatment of incipient carious lesions, and further development of these materials may contribute to greater control of these lesions. The aim of this study was to analyze the physical and antibacterial properties of experimental infiltrants containing iodonium salt and chitosan. Nine experimental infiltrants were formulated by varying the concentration of the diphenyliodonium salt (DPI) at 0, 0.5 and 1 mol%; and chitosan at 0, 0.12 and 0.25 g%. The infiltrants contained the monomeric base of triethylene glycol dimethacrylate and bisphenol-A dimethacrylate ethoxylate in a 75 and 25% proportion by weight, respectively; 0.5 mol% camphorquinone and 1 mol% ethyl 4-dimethylaminobenzoate. The degree of conversion was evaluated using Fourier transformer infrared spectroscopy, and the flexural strength and elastic modulus using the three-point bending test. Sorption and solubility in water, and antibacterial analysis (minimum inhibitory concentration and minimum bactericidal concentration) were also analyzed. Data was analyzed statistically by two-way ANOVA and Tukey's test (p<0.05), with the exception of the antibacterial test, which was evaluated by visual inspection. In general, the infiltrant group containing 0.5% DPI and 0.12% chitosan showed high values of degree of conversion, higher values of elastic modulus and flexural strength, and lower sorption values in relation to the other groups. Antibacterial activity was observed in all the groups with DPI, regardless of the concentration of chitosan. The addition of DPI and chitosan to experimental infiltrants represents a valid option for producing infiltrants with desirable physical and antibacterial characteristics.

How to improve root canal filling in teeth subjected to radiation therapy for cancer

Abstract The aim of this study was to evaluate the influence of radiation therapy on root canal sealer push-out bond strength (BS) to dentin and the sealer/dentin interface after different final irrigation solutions (NaOCl, EDTA, and chitosan). Sixty-four maxillary canines were distributed into two groups (n=30): non-irradiated and irradiated with 60 Gy. Canals were prepared with Reciproc-R50 and subdivided (n=10) for final irrigation (NaOCl, EDTA, chitosan) and filled. Three dentin slices were obtained from each root third. The first slice of each third was selected for BS evaluation, and the failure mode was determined by stereomicroscopy. SEM analysis of the sealer-dentin interface was performed in the remaining slices. Two-way ANOVA and Tukey's tests (α=0.05) were used. Lower BS (P<0.0001) was obtained after irradiation (2.07±0.79 MPa), regardless of the final irrigation solution used. The NaOCl group (P<0.001) had the lowest BS in the irradiated (1.68±0.72) and non-irradiated (2.39±0.89) groups, whereas the EDTA (irradiated: 2.14±0.77 and non-irradiated: 3.92±1.54) and chitosan (irradiated: 2.37±0.73 and non-irradiated: 3.51±1.47) groups demonstrated a higher BS (P<0.05). The highest values were observed in the coronal third (3.17±1.38) when compared to the middle (2.74±1.36) and apical ones (2.09±0.97)(P<0.0001). There were more cohesive failures and more gaps in irradiated specimens, regardless of the final solution. The present study showed that radiation was associated with a decrease in BS, regardless of the final solution used, whereas chitosan increased BS in teeth subjected to radiation therapy.

Repair of Bone Defects with Chitosan-Collagen Biomembrane and Scaffold Containing Calcium Aluminate Cement

Abstract Innovative biomaterials can provide a promising new direction for the treatment of bone defects, stimulating a proper repair process, with no damage to adjacent tissues. The purpose of this in vivo study was to evaluate the biocompatibility and the osteoinductive capacity of chitosan-collagen biomembrane and scaffold containing calcium aluminate cement. Eighteen New Zealand white rabbits (Oryctolagus cuniculus) were distributed according to the experimental times of analysis (7, 15 and 30 days). Four bone defects were created in the rabbits calvaria, which were individually filled with the biomembrane, scaffold, blood clot (negative control) and autologous bone (positive control). Histopathological analysis was performed using optical microscope at 32´, 64´, 125´ and 320´ magnifications. Cell response to inflammation and new bone tissue formation was quantified using a score system. The biomembrane group presented greater inflammatory response at 15 days, with significant difference to autologous bone group (p<0.05). There was no statistically significant difference for foreign body type reaction among groups (p>0.05). Concerning new bone formation, linear closure of the defect area was observed more evidently in the group with autologous bone. The scaffold group presented similar results compared with the autologous bone group at 30 days (p>0.05). Both tested biomaterials presented similar biocompatibility compared with the control groups. In addition, the biomembrane and scaffold presented similar osteoinductive capacity, stimulating bone repair process in the course of the experimental time intervals.

Resumo Biomateriais inovadores podem fornecer uma promissora nova direção para o tratamento de defeitos ósseos, estimulando um processo de reparo adequado, sem danos aos tecidos adjacentes. O objetivo deste estudo in vivo foi avaliar a biocompatibilidade e a capacidade osteoindutora de uma biomembrana e um scaffold compostos por colágeno e quitosana, contendo cimento de aluminato de cálcio. Dezoito coelhos (New Zealand White, Oryctolagus cuniculus) foram distribuídos de acordo com os períodos experimentais de análise (7, 15 e 30 dias). Quatro defeitos foram criados na calvaria dos coelhos, que foram individualmente preenchidos com a biomembrana, scaffold, coágulo (controle negativo) e osso autólogo (controle positivo). A avaliação histopatológica foi realizada em microscópio óptico em aumentos de 32´, 64´, 125´ e 320´. A resposta celular à inflamação e à formação de novo tecido ósseo foi quantificada utilizando um sistema de escore. O grupo da biomembrana apresentou maior resposta inflamatória no período de 15 dias, com diferença significativa para o grupo do osso autólogo (p<0,05). Não houve diferença estatística significante para a reação do tipo corpo estranho entre os grupos (p>0,05). Em relação à neoformação óssea, observou-se fechamento linear da área do defeito, que foi mais evidente no grupo em que se utilizou o osso autólogo. O grupo scaffold apresentou resultados semelhantes ao grupo do osso autólogo no período de 30 dias (p>0,05). Ambos os biomateriais testados apresentaram biocompatibilidade similar em comparação com os grupos controle. Além disso, a biomembrana e o scaffold apresentaram capacidade osteoindutora similar, estimulando o reparo ósseo ao longo dos intervalos de tempo experimentais.

Desenvolvimento e análise de bandagem de bioestimulação dentino/pulpar (BBio) / Development and analysis of dental/pulpar bio-stimulation bandage ("BBIO")

O desenvolvimento de biomateriais com aplicações na área da saúde mostram-se cada vez mais importantes e a procura por novos polímeros com propriedades bioativas, biodegradabilidade, atoxicidade são o foco das principais pesquisas em diferentes aplicações médicas e odontológicas. Os materiais capeadores pulpares evoluíram rapidamente na ultima década, sendo que são disponibilizadas atualmente diversas alternativas para uso clínico odontológico. Este trabalho teve como objetivo o desenvolvimento de um novo produto bioestimulador e capeador dentino/pulpar que poderá ser base para o desenvolvimento e recobrimento de scaffolds para reparo das diferentes estruturas dentárias. O desenvolvimento das bandagens BBio e os resultados obtidos nos testes das propriedades físico-químicas (absorção de água, perda de massa e pH), bem como as análises biológicas da morfologia celular e viabilidade celular com MTT a BBio apresentaram dados favoráveis e desejáveis para sua aplicação clínica. A propriedade de liberação de cálcio foi bastante promissora, sendo esta uma condição que dará a diferenciação positiva da BBio como um produto bioestimulador pulpar. Com esses dados pode-se concluir que a mesma se encontra dentro dos parâmetros desejados para o produto final e com propriedades semelhantes aos produtos existentes no mercado, de qualidade e aprovados pelas agências reguladoras.(AU)

The development of biomaterials with applications in the health area are increasingly important and the search for new polymers with bioactive properties, biodegradability and toxicity are the focus of the main researches in different medical and dental applications. The pulp capping materials evolved rapidly in the last decade, and several alternatives are now available for clinical dental use. This project aimed to develop a new biostimulating and dentin / pulp capping product that could be the basis for the development and recoating of "scaffolds" for repair of different dental structures. The development of the BBio bandages and the results obtained in the physical-chemical properties tests (water absorption, loss of mass and pH), as well as the biological analyzes of the cellular morphology and cell viability with MTT to BBio presented favorable and desirable data for its clinical application. The calcium release property was quite promising, and this is a condition that will give BBio a positive differentiation as a pulp biostimulator product. With this data it can be concluded that it is within the parameters desired for the final product and with properties similar to the products on the market, of quality and approved by the regulatory agencies.(AU)

Effects of the protective, curative, and eradicative applications of chitosan against Penicillium expansum in apples

Abstract Apple is one of the most important temperate fruit to Brazil economy, and the use of synthetic chemicals has been the main method for reducing postharvest diseases, such as the blue mold, caused by Penicillium expansum. This work intends to evaluate the practical utilization of chitosan for blue mold control. For this purpose, fruits were treated in a preventive and curative way, immersing the fruits in chitosan solution (5 or 10 mg mL-1), or adding a single drop of this solution (10 mg mL-1) directly into the injuries. The eradicative effect of the polysaccharide was also evaluated in vitro and in vivo. Chitosan did not show a curative effect against the blue mold, and its eradicative effect was only evidenced on the higher concentration (10 mg mL-1). On the other hand, preventively, without the addition of adjuvants, chitosan reduced blue mold incidence in fruits by 24% and 93%, through the immersion or the single drop methods, respectively. Thus, it was found that, for long scale utilization, some improvements in the physico-chemical properties of the chitosan are needed, since it was only capable to prevent the infection by P. expansum when directly added on the fruit injury.

Therapeutic effect of low molecular weight chitosan containing sepia ink on ethanol-induced gastric ulcer in rats

ABSTRACT PURPOSE: To evaluate the role of low molecular chitosan containing sepia ink (LMCS) in ethanol-induced (5 ml/kg) gastric ulcer in rats. METHODS: Animals were divided into four groups (n = 12): normal group (Normal), negative control group (Con), experiment group (LMCS) and positive control Omeprazole group (OMZ). Gastric empty rate was detected in the first 7 days. Rats were sacrificed at 7, 14 and 21 day for histology and ELISA detections. RESULTS: Gastric empty was no significant differences among the groups (P > 0.05). Histological observation showed gastric mucosal LMCS treated had better healing effect. Hydroxyproline (Hyp) was significantly increased from 7 day (P < 0.05). LMCS significantly inhibited malondialdehyde (MDA) generation for lipid peroxidation from 7 day (P < 0.05). LMCS significantly promoted the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) at the earlier stage (P < 0.05). OMZ had the similar effects above. As for myeloperoxidase (MPO), LMCS significantly decreased and restored it to normal levels from 7 day (P < 0.05), it is earlier than OMZ which is from 14 day. CONCLUSION: LMCS can improve gastric mucosa tissue repair, exert significant influences on oxidative and antioxidant enzyme activities and neutrophil infiltration.

The use of chitosan in protecting wooden artifacts from damage by mold fungi

Background: Many buildings in Egypt e.g. museums, mosques and churches, do not possess controlled environments for minimizing the risks of damage of wooden artifacts due to the growth of fungi. Fungal damage usually appears as change in wood color, appearance of stains, and sometimes deformation of wooden surfaces. In this study we focused on the effect that some fungi exert on the properties of wooden artifacts and evaluated the effectiveness of different concentrations of chitosan on their protection against damage by mold fungi. Results: Samples were collected from different monuments and environments, and fungi growing on them were isolated and identified. The isolated Penicillium chrysogenum, Aspergillus flavus and /Aspergillus niger strains were used for the infestation of new pitch pine samples. The results revealed that the lightness of samples infected with any of the tested fungi decreased with increasing incubation times. XRD analysis showed that the crystallinity of incubated samples treated individually with the different concentrations of chitosan was lower than the crystallinity of infected samples. The crystallinity index measured by the first and the second method decreased after the first and second months but increased after the third and fourth months. This may due to the reducing of amorphous part by enzymes or acids produced by fungi in wooden samples. Conclusions: The growth of fungi on the treated wood samples decreased with increasing the concentration of chitosan. Hence, it was demonstrated that chitosan prevented fungal growth, and its use could be recommended for the protection of archeological wooden artifacts.

Chitosan-collagen biomembrane embedded with calcium-aluminate enhances dentinogenic potential of pulp cells

Abstract The development of biomaterials capable of driving dental pulp stem cell differentiation into odontoblast-like cells able to secrete reparative dentin is the goal of current conservative dentistry. In the present investigation, a biomembrane (BM) composed of a chitosan/collagen matrix embedded with calcium-aluminate microparticles was tested. The BM was produced by mixing collagen gel with a chitosan solution (2:1), and then adding bioactive calcium-aluminate cement as the mineral phase. An inert material (polystyrene) was used as the negative control. Human dental pulp cells were seeded onto the surface of certain materials, and the cytocompatibility was evaluated by cell proliferation and cell morphology, assessed after 1, 7, 14 and 28 days in culture. The odontoblastic differentiation was evaluated by measuring alkaline phosphatase (ALP) activity, total protein production, gene expression of DMP-1/DSPP and mineralized nodule deposition. The pulp cells were able to attach onto the BM surface and spread, displaying a faster proliferative rate at initial periods than that of the control cells. The BM also acted on the cells to induce more intense ALP activity, protein production at 14 days, and higher gene expression of DSPP and DMP-1 at 28 days, leading to the deposition of about five times more mineralized matrix than the cells in the control group. Therefore, the experimental biomembrane induced the differentiation of pulp cells into odontoblast-like cells featuring a highly secretory phenotype. This innovative bioactive material can drive other protocols for dental pulp exposure treatment by inducing the regeneration of dentin tissue mediated by resident cells.

Effect of edible quinoa protein-chitosan based films on refrigerated strawberry (Fragaria × ananassa) quality

Background Strawberries are non-climacteric fruits with a low respiration rate, but are subject to serious fungal deterioration during postharvest handling. The edible coatings based on chitosan (CH), quinoa protein-chitosan (Q/CH) and quinoa protein-chitosan-sunflower oil (Q/CH/SO) may provide a solution to this problem. Thus, in this work CH, Q/CH and Q/CH/SO were elaborated and applied to fresh strawberries, and its effect on the strawberries shelf life during storage for 15 d was evaluated by mold and yeast count, fungal decay, carbon dioxide rate, physicochemical properties, and sensory evaluation. Results On all analysis days, the strawberries coated with the film-forming CH, Q/CH and Q/CH/SO solutions presented a significant lower amount of mold and yeast growth than the uncoated strawberries. Coated strawberries with Q/CH/SO decreased the CO2 emission rate by 60% compared to the uncoated strawberries. The color of the strawberries was not influenced by the films. There was no significant difference between the different coating groups and the uncoated group in the physicochemical parameters. Sensory analysis showed that the coating application retained the total sensorial quality. Conclusions Fresh strawberries coated with CH, Q/CH/SO and Q/CH edible films had longer shelf lives than uncoated fruits.

Physicochemical and antimicrobial evaluation of chitosan and hydroxypropyl methylcellulose films forprolonged release of pilocarpine / Evaluación fisico-química y antimicrobiana de biopelículas de quitosán e hidroxipropilmetilcelulosa para liberación prolongada de pilocarpina

The use of prolonged local drug delivery to the oral cavity offers multiple benefits, such as increasing the pharmacological action in the desirable local site and reducing the usual dose and the adverse effects. Pilocarpine is a cholinergic drug approved by the FDA for the treatment of glandular hypofunction; however, the extent of its adverse effects limits its use. Objective: The main aim of this study was to analyze the physical and chemical properties of films, including pH, thickness, solubility, consistency and the ability to release pilocarpine for a prolonged time. Additionally, theantimicrobial activity in two opportunistic pathogens in hyposialia (Streptococcus mutans and Candida albicans) was also assessed. Methodology: Chitosan and HPMC (Methocel K4M CR) films were prepared in 1 percent acetic acid and pilocarpine was added under magnetic stirring. PH, thickness and time of solubility in artificial saliva, as well as diffusion and drug release kinetics per cm2 (OD=420nm) were assessed by spectrophotometry. The antimicrobialactivity was tested by disk diffusion test against St. mutans ATCC 700610 and C. albicans ATCC 90029 at concentrations of hyposalivation (1.44x1.2x106 CFU and 103 CFU, respectively). Results: All the films, except for Hydroxypropyl methylcellulose / Pilocarpine formulation, were found to have optimal physical-chemical properties for handling, maintaining drug diffusion in 76 percent per cm2 for four hours extended-release without showing antimicrobial activity at concentrations of hyposalivation. Conclusion: The films had optimum handling properties and a constant drug release; however, antimicrobial activity was not found...

El uso local de administración prolongada de fármacos en la cavidad oral proporciona múltiples ventajas, aumentando la acción farmacológica en el sitio local deseable, reducción de la dosis usual y disminución de los efectos adversos. La pilocarpina es una droga colinérgica aprobada por la FDA para el tratamiento de la hipofunción glandular, sin embargo la amplitud de sus efectos adversos limitan su uso. Objetivo: Con el objetivo de analizar las propiedades físico-químicas de las biopelículas se evaluó el pH, grosor, solubilidad, uniformidad y la capacidad de liberar prolongadamente pilocarpina, así como su actividad antimicrobiana ante los dos microorganismos patógenos oportunistas en la hiposialia (Streptococcus mutans y Candida albicans). Metodología: Se elaboraron biopelículas de Quitosán e Hidroxipropilmetilcelulosa (Methocel K4MCR) en ácido acético al 1 por ciento, adicionadas con pilocarpina bajo agitación magnética, evaluando el pH, grosor y el tiempo de solubilidad en saliva artificial, así como la uniformidad de difusión y cinética de liberación de la droga por cm2 mediante espectrofotometría (OD=420nm). Mediante difusión en disco se evaluó la actividad antimicrobiana ante Streptococcus mutans ATCC 700610 y Candida albicans ATCC 90029 en concentraciones encontradas en hiposalivación (1.44 x 106 UFC y 1.2 x 103 UFC respectivamente). Resultados: Todas las biopelículas, a excepción de la formulación Hidroxipropilmetilcelulosa e Hidroxipropilmetilcelulosa/ Pilocarpina resultaron tener las propiedades físico-químicas óptimas de manipulación, manteniendo una uniformidad de difusión de la droga en 76 por ciento por cm2 con liberación prolongada por 4 horas, sin mostrar actividad antimicrobiana en concentraciones de hiposalivación. Conclusión: Las películas obtuvieron las propiedades óptimas de manipulación, y una constante liberación del fármaco, sin embargo, ninguna formulación presentó actividad antimicrobiana...