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1.
Acta Cir Bras ; 36(3): e360303, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33825787

RESUMO

PURPOSE: This study aimed to elaborate a hydrogel constituted by carboxymethyl chitosan (CMC), hyaluronic acid (HA) and silver (Ag) and to evaluate its healing effect on partial-thickness burn wounds experimentally induced in rats. METHODS: CMC was obtained by chitosan reacting with monochloroacetic acid. The carboxymethylation was confirmed by Fourier-transform infrared spectroscopy and hydrogen nuclear magnetic resonance (NMR). Scanning electron microscopy was used to determine the morphologicalcharacteristics of chitosan and CMC. After the experimental burn wound induction, the animals (n = 126) were treated with different CMC formulations, had their occlusive dressings changed daily and were followed through 7, 14 and 30 days. Morphometric, macroscopic and microscopic aspects and collagen quantification were evaluated. RESULTS: Significative wound contraction, granulation tissue formation, inflammatory infiltration and collagen fibers deposit throughout different phases of the healing process were observed in the CMC hydrogels treated groups. CONCLUSIONS: The results showed that, in the initial phase of the healing process, the most adequate product was the CMC/HA/Ag association, while in the other phases the CMC/HA association was the best one to promote the healing of burn wounds.


Assuntos
Queimaduras , Quitosana , Animais , Queimaduras/tratamento farmacológico , Colágeno , Hidrogéis , Ratos , Cicatrização
2.
Huan Jing Ke Xue ; 42(3): 1191-1196, 2021 Mar 08.
Artigo em Chinês | MEDLINE | ID: mdl-33742916

RESUMO

Rice is well known to accumulate methylmercury (MeHg) and the consumption of rice in mercury (Hg) polluted areas has been confirmed to be a primary source of MeHg exposure. Therefore, how to inhibit the formation and accumulation of MeHg in the paddy field system needs to be solved urgently. Chitosan modified biochar, a potential inhibitor, was selected in this study to explore its effect on MeHg production and accumulation in the paddy field system by analyzing the mercury content of interstitial water, soil, and rice plant tissues. The results showed that the addition of chitosan modified biochar could significantly reduce MeHg concentration in the soil with the decreased methylation rate of 51.1%-79.1%, and could also decrease the total mercury (THg) and MeHg content of interstitial water. At the maturation stage of rice, the MeHg content of rice roots treated with chitosan modified biochar (CMBC) was 73.1% lower than without biochar (CK1) and 62.0% lower than with unmodified biochar (CK2), and the rice MeHg was 75.8% lower than that of CK1 and 72.9% lower than that of CK2. In addition, the application of biochar could promote the growth of rice with the plant biomass of CMBC and CK2 of 1.6 and 1.7 times higher than that of CK1. Generally, the application of chitosan modified biochar into paddy soil could not only promote the growth of rice, but also inhibit the accumulation of MeHg in rice, suggesting that the chitosan modified biochar has a certain application value in the inhibition of the MeHg formation and accumulation in paddy field system.


Assuntos
Quitosana , Mercúrio , Compostos de Metilmercúrio , Oryza , Poluentes do Solo , Carvão Vegetal , Monitoramento Ambiental , Mercúrio/análise , Solo , Poluentes do Solo/análise
3.
J Environ Manage ; 286: 112167, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33676135

RESUMO

In this study, the cellulose sulfate/chitosan aerogel (CCA) was prepared by chitosan and sulfonated cotton, and its efficiency was assessed for lead removal from contaminated waters. The adsorbent was determined by FESEM, EDS, FTIR, and BET analysis. The batch experiments were designed by Design-Expert software. At an initial lead concentration of 300 mg L-1, the contact time of 40 min, and the temperature of 26 °C, the maximum adsorption capacity and the removal efficiency were 137.8 mg g-1 and 91.9%, respectively. Also, the effect of ions including cations and anions at 100 mg L-1 was investigated, and it was found that the presence of anions does not have much effect on adsorption, but among cations, calcium and magnesium have the inhibitor effect on adsorption due to their double plosive. Adsorption isotherms were studied at different temperatures, and the kinetics of the reaction were investigated at different concentrations. Thermodynamic parameters indicated that the adsorption process was spontaneous, endothermic, and increasing irregularity at the adsorbent level. Adsorption recovery was performed five times adsorption and de-adsorption by hydrochloric acid 1 M washing and only 10% of adsorption capacity was decreased.


Assuntos
Quitosana , Poluentes Químicos da Água , Purificação da Água , Adsorção , Celulose/análogos & derivados , Concentração de Íons de Hidrogênio , Cinética , Chumbo , Temperatura , Termodinâmica
4.
Int J Nanomedicine ; 16: 1819-1836, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33707942

RESUMO

Background: The development of vaccines is a promising and cost-effective strategy to prevent emerging multidrug-resistant (MDR) Acinetobacter baumannii (A. baumannii) infections. The purpose of this study was to prepare a multiepitope peptide nanovaccine and evaluate its immunogenicity and protective effect in BALB/c mice. Methods: The B-cell and T-cell epitopes of Omp22 from A. baumannii were predicted using bioinformatics methods and identified by immunological experiments. The optimal epitopes were conjugated in series by 6-aminocaproic acid and chemically synthesized multiepitope polypeptide rOmp22. Then, rOmp22 was encapsulated by chitosan (CS) and poly (lactic-co-glycolic) acid (PLGA) to prepare CS-PLGA-rOmp22 nanoparticles (NPs). The immunogenicity and immunoprotective efficacy of the vaccine were evaluated in BALB/c mice. Results: CS-PLGA-rOmp22 NPs were small (mean size of 272.83 nm) with apparently spherical structures, positively charged (4.39 mV) and nontoxic to A549 cells. A high encapsulation efficiency (54.94%) and a continuous slow release pattern were achieved. Compared with nonencapsulated rOmp22, CS-PLGA-rOmp22 immunized BALB/c mice induced higher levels of rOmp22-specific IgG in serum and IFN-γ in splenocyte supernatant. Additionally, lung injury and bacterial burdens in the lung and blood were suppressed, and potent protection (57.14%-83.3%) against acute lethal intratracheal A. baumannii challenge was observed in BALB/c mice vaccinated with CS-PLGA-rOmp22. Conclusion: CS-PLGA-rOmp22 NPs elicited specific IgG antibodies, Th1 cellular immunity and protection against acute lethal intratracheal A. baumannii challenge. Our results indicate that this nanovaccine is a desirable candidate for preventing A. baumannii infection.


Assuntos
Infecções por Acinetobacter/imunologia , Acinetobacter baumannii/imunologia , Vacinas Bacterianas/imunologia , Quitosana/química , Epitopos/imunologia , Nanopartículas/química , Peptídeos/imunologia , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/química , Células A549 , Infecções por Acinetobacter/sangue , Infecções por Acinetobacter/microbiologia , Sequência de Aminoácidos , Animais , Anticorpos Antibacterianos/imunologia , Carga Bacteriana , Peso Corporal , Epitopos/química , Feminino , Humanos , Imunidade Humoral , Imunização , Imunoglobulina G/imunologia , Interferon gama/metabolismo , Interleucina-4/metabolismo , Pulmão/imunologia , Pulmão/microbiologia , Pulmão/patologia , Camundongos , Camundongos Endogâmicos BALB C , Nanopartículas/ultraestrutura , Peptídeos/química , Proteínas Recombinantes/isolamento & purificação , Baço/patologia , Análise de Sobrevida
5.
Water Sci Technol ; 83(5): 1250-1264, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33724951

RESUMO

The present investigation was focused to compare chitosan based nano-adsorbents (CZnO and CTiO2) for efficient treatment of dairy industry wastewater using Response Surface Methodology (RSM) and Artificial Neural Network (ANN) models. The nano-adsorbents were synthesized using chemical precipitation method and characterized by using scanning electron microscope with elemental detection sensor (SEM-EDS) and atomic force microscope (AFM). Maximum %RBOD (96.71 and 87.56%) and %RCOD (90.48 and 82.10%) for CZnO and CTiO2 nano-adsorbents were obtained at adsorbent dosage of 1.25 mg/L, initial biological oxygen demand (BOD) and chemical oxygen demand (COD) concentration of 100 and 200 mg/L, pH of 7.0 and 2.00, contact time of 100 and 60 min, respectively. The results obtained for both the nano-adsorbents were subject to RSM and ANN models for determination of goodness of fit in terms of sum of square errors (SSE), root mean square error (RMSE), R2 and Adj. R2, respectively. The well trained ANN model was found superior over RSM in prediction of the treatment effect. Hence, the developed CZnO and CTiO2 nano-adsorbents could be effectively used for dairy industry wastewater treatment.


Assuntos
Quitosana , Purificação da Água , Indústria de Laticínios , Redes Neurais de Computação , Águas Residuárias
6.
Sheng Wu Gong Cheng Xue Bao ; 37(2): 615-624, 2021 Feb 25.
Artigo em Chinês | MEDLINE | ID: mdl-33645159

RESUMO

To effectively solve the serious impact of high oil in the kitchen wastewater on the downstream treatment process, an excellent oil-degrading strain Aeromonas allosaccarophila CY-01 was immobilized to prepare Chitosan-Aeromonas pellets (CH-CY01) by using chitosan as a carrier. Oil degradation condition and efficiency of CH-CY01 pellets were assessed. The growth of immobilized CH-CY01 was almost unaffected, and the maximum degradation rate of soybean oil was 89.7%. Especially at 0.5% NaCl concentration, oil degradation efficiency of CH-CY01 was increased by 20% compared with free cells. In the presence of a surfactant (sodium dodecylbenzene sulfonate) at 1 mg/L, the degradation efficiency of oil by CH-CY01 was increased by 40%. Moreover, using the high-oil catering wastewater as the substrate, more than 80% of the solid oil was degraded with 1% (V/V) CH-CY01 pellets treatment for 7 days, significantly higher than that of free cells. In summary, immobilized CH-CY01 significantly improved the efficiency of oil degradation.


Assuntos
Aeromonas , Quitosana , Tensoativos , Águas Residuárias
7.
Carbohydr Polym ; 260: 117808, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33712154

RESUMO

In the present study, a novel synthetic tissue adhesive material capable of sealing wounds without the use of any crosslinking agent was developed by conjugating thermosensitive hexanoyl glycol chitosan (HGC) with gallic acid (GA). The degree of N-gallylation was manipulated to prepare GA-HGCs with different GA contents. GA-HGCs demonstrated thermosensitive sol-gel transition behavior and formed irreversible hydrogels upon natural oxidation of the pyrogallol moieties in GA, possibly leading to GA-HGC crosslinks through intra/intermolecular hydrogen bonding and chemical bonds. The GA-HGC hydrogels exhibited self-healing properties, high compressive strength, strong tissue adhesive strength and biodegradability that were adjustable according to the GA content. GA-HGCs also presented excellent biocompatibility and wound healing effects. The results of in vivo wound healing efficacy studies on GA-HGC hydrogels indicated that they significantly promote wound closure and tissue regeneration by upregulating growth factors and recruiting fibroblasts compared to the untreated control group.


Assuntos
Materiais Biocompatíveis/química , Quitosana/química , Ácido Gálico/química , Animais , Materiais Biocompatíveis/farmacologia , Força Compressiva , Hidrogéis/química , Hidrogéis/farmacologia , Reologia , Suínos , Adesivos Teciduais/química , Cicatrização/efeitos dos fármacos
8.
Carbohydr Polym ; 260: 117809, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33712155

RESUMO

Gene therapy is an emerging and promising strategy in cancer therapy where small interfering RNA (siRNA) system has been deployed for down-regulation of targeted gene and subsequent inhibition in cancer progression; some issues with siRNA, however, linger namely, its off-targeting property and degradation by enzymes. Nanoparticles can be applied for the encapsulation of siRNA thus enhancing its efficacy in gene silencing where chitosan (CS), a linear alkaline polysaccharide derived from chitin, with superb properties such as biodegradability, biocompatibility, stability and solubility, can play a vital role. Herein, the potential of CS nanoparticles has been discussed for the delivery of siRNA in cancer therapy; proliferation, metastasis and chemoresistance are suppressed by siRNA-loaded CS nanoparticles, especially the usage of pH-sensitive CS nanoparticles. CS nanoparticles can provide a platform for the co-delivery of siRNA and anti-tumor agents with their enhanced stability via chemical modifications. As pre-clinical experiments are in agreement with potential of CS-based nanoparticles for siRNA delivery, and these carriers possess biocompatibiliy and are safe, further studies can focus on evaluating their utilization in cancer patients.


Assuntos
Quitosana/química , Nanopartículas/química , Neoplasias/terapia , RNA Interferente Pequeno/uso terapêutico , Antineoplásicos/química , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Portadores de Fármacos/química , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Inativação Gênica , Humanos , Neoplasias/tratamento farmacológico , Neoplasias/patologia , RNA Interferente Pequeno/química
9.
Carbohydr Polym ; 260: 117812, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33712157

RESUMO

A dual pH-/thermo-responsive hydrogel was designed based on a polyelectrolyte complex of polyacrylic acid (PAA) and norbornene-functionalized chitosan (CsNb), which was synergized with chemical crosslinking using bistetrazine-poly(N-isopropyl acrylamide) (bisTz-PNIPAM). The thermo-responsive polymeric crosslinker, bisTz-PNIPAM, was synthesized via reversible addition-fragmentation transfer polymerization of NIPAM. FTIR, XRD, rheological and morphological analyses demonstrated the successful formation of the polyelectrolyte network. The highly porous structure generated through the in-situ "click" reaction between Tz and Nb resulted in a higher drug loading (29.35 %). The hydrogel (COOH/NH2 mole ratio of 3:1) exhibited limited drug release (8.5 %) of 5-ASA at a pH of 2.2, but it provided an almost complete release (92 %) at pH 7.4 and 37 °C within 48 h due to the pH responsiveness of PAA, hydrogel porosity, and shrinkage behavior of PNIPAM. The hydrogels were biodegradable and non-toxic against human fibroblast cells, suggesting their considerable potential for a colon-targeted drug delivery system.


Assuntos
Quitosana/química , Portadores de Fármacos/química , Hidrogéis/química , Resinas Acrílicas/química , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Química Click , Portadores de Fármacos/toxicidade , Liberação Controlada de Fármacos , Humanos , Hidrogéis/farmacologia , Concentração de Íons de Hidrogênio , Mesalamina/química , Mesalamina/metabolismo , Porosidade , Temperatura
10.
Carbohydr Polym ; 260: 117815, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33712159

RESUMO

Chitosan is a versatile polysaccharide in different domains due to facile modification and good biodegradability. In this paper, taking advantage of such functional properties, we have developed a stabilizer agent [OCMCS-SB] produced from chitosan, and palladium was successfully immobilized on this designed stabilizer [OCMCS-SB-Pd(II)]. The obtained complex was illuminated by 13C CP-MAS NMR, FT-IR, TGA, XRD, XPS, SEM, TEM and ICP-OES analyses. Due to the interactions of primary hydroxyl groups on chitosan, Schiff base and carboxy groups, the Pd complex showed excellent reactivity (up to 99 %) and stability towards Suzuki reactions in eco-friendly medium. Subsequently, the reusability experiments for OCMCS-SB-Pd(II) formed from chitosan were examined in five consecutive cycles, which showed no appreciable decrease in activity. Furthermore, a reasonably trifunctional complex structure was proposed. The present bio-based system offers a promising approach in utilizing such biopolymers in organic transformations.


Assuntos
Quitosana/química , Paládio/química , Catálise , Bases de Schiff/química , Espectroscopia de Infravermelho com Transformada de Fourier
11.
Carbohydr Polym ; 260: 117828, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33712168

RESUMO

Green technique for hydrolysis of chitosan was developed using novel Brønsted Acidic Ionic Liquids (BAILs) as homogenous reusable catalysts. Efficiency of BAILs in controlling stochastic and irregular breakdown of chitosan was compared with that of mineral acids. Structural elucidation of the novel BAILs was performed using H1-NMR evaluation and supplemented using mass spectroscopy. Additionally, thermal characterization was conducted using TGA-DTA analysis, while acidity was estimated by deriving the Hammet acidity function. BAILs investigated in this work enabled consistent production of LMWCS variants, with minimum formation of residual impurities. Around 80 % reduction in molecular weight was noted as compared to original under extreme conditions employed. Further, Box-Behnken Design (BBD) was implemented to optimize effect of processing parameters for conversion of chitosan to low molecular weight congeners.


Assuntos
Quitosana/química , Líquidos Iônicos/química , Catálise , Química Verde , Hidrólise , Peso Molecular , Temperatura
12.
Carbohydr Polym ; 260: 117832, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33712170

RESUMO

Vagina atrophy is a common symptom in women after menopause owing to decreasing estrogen levels. The most conventional treatment for this condition is estrogen cream. The shortcoming is its weak adhesion to the vagina mucus, thus requiring frequent daily application. In this study, BDDE was selected to crosslink and graft chitosan with thioglycolic acid, to form thiolated chitosan (CT) and improve the mucoadhesive properties of chitosan. Genistein was selected as the bioactive molecule that could exhibit estrogen-like properties for long-term treatment of vaginal atrophy. The efficacies of the materials were characterized and evaluated both in vitro and in vivo. Results showed that the mucoadhesive property of CT was approximately two-fold stronger against the constant flow than unmodified chitosan. CT with genistein (CT-G) was administered intravaginally every three days in vivo. It showed that the developed CT-G recover 54 % of the epithelium thickness of an atrophic vagina and ease vaginal atrophy.


Assuntos
Vaginite Atrófica/tratamento farmacológico , Quitosana/química , Genisteína/uso terapêutico , Hidrogéis/química , Tioglicolatos/química , Animais , Vaginite Atrófica/patologia , Células CACO-2 , Adesão Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Portadores de Fármacos/química , Feminino , Genisteína/química , Genisteína/metabolismo , Genisteína/farmacologia , Humanos , Hidrogéis/síntese química , Hidrogéis/farmacologia , Camundongos , Ratos , Ratos Sprague-Dawley , Vagina/patologia
13.
Carbohydr Polym ; 260: 117834, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33712171

RESUMO

This study reports preparation and physicochemical characterization of natural antimicrobials (Origanum Syriacum essential oil (OSEO), shrimp chitosan nanoparticles (CSNPs)) and new imidazolium ionic liquid-supported Zn(II)Salen. These antimicrobials were separately or co-encapsulated by CSNPs to fabricate novel antimicrobial nanoplatforms "NPFs" (OSEO-loaded CSNPs (NPF-1), Zn(II)Salen-loaded CSNPs (NPF-2), and Zn(II)Salen@OSEO-loaded CSNPs (NPF-3)). The finding of loading, encapsulation, and antimicrobial release studies confirm the suitability of CSNPs for nanoencapsulation of Zn(II)Salen and OSEO. All NPFs can significantly suppress the growth of microbial species with performances dependent upon the microbial strain and nanoplatform concentration. The susceptibility of microbes toward new antimicrobials was as follows; Gram-positive bacteria > Gram-negative bacteria > fungi. The amazing physicochemical features of new nanoplatforms and their bioactive ingredients (Zn(II)Salen, OSEO, and CSNPs) signify the importance of our designs for developing a new generation of nanopharmaceuticals supported both natural products and biogenic ionic metal cofactors, targeting the multidrug resistant (MDR) pathogens.


Assuntos
Anti-Infecciosos/química , Quitosana/química , Etilenodiaminas/química , Nanopartículas/química , Óleos Voláteis/química , Anti-Infecciosos/metabolismo , Anti-Infecciosos/farmacologia , Portadores de Fármacos/química , Liberação Controlada de Fármacos , Etilenodiaminas/metabolismo , Fungos/efeitos dos fármacos , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Imidazóis/química , Óleos Voláteis/metabolismo , Origanum/metabolismo , Tamanho da Partícula , Temperatura , Zinco/química
14.
Carbohydr Polym ; 260: 117835, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33712172

RESUMO

Bacterial breeding is the main cause of food perishability, which is harmful to human health. Silver nanoparticles (AgNPs) are one of the most widely used antimicrobial agents, but they are easy to release and cause cumulative toxicity. In this work, with corn stalk as green reductant and GO as template, a simple electrostatic self-assembled sandwich-like chitosan (CS) wrapped rGO@AgNPs nanocomposite film (CS/rGO@AgNPs) was synthesized to achieve stabilizing and controlled-release of AgNPs. The results showed that the the CS/rGO@AgNPs film continued releasing AgNPs for up to 14 days, and the final release amount of silver nanoparticles was only about 1.9 %. More importantly, the nanocomposite film showed durable antibacterial effect and good antibacterial activity against E. coli and S. aureus, and they showed no toxicity to cells. Hence, the nanocomposite film has potential application as an effective and safe packaging material to prolong the shelf life of food products.


Assuntos
Antibacterianos/química , Quitosana/química , Grafite/química , Nanopartículas Metálicas/química , Nanocompostos/química , Antibacterianos/farmacologia , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/farmacologia , Escherichia coli/efeitos dos fármacos , Humanos , Nanocompostos/toxicidade , Prata/química , Solubilidade , Staphylococcus aureus/efeitos dos fármacos , Resistência à Tração
15.
Carbohydr Polym ; 260: 117836, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33712173

RESUMO

pH-sensitive polymeric dyes were fabricated by grafting phenol red (PR) and rosolic acid (RA) onto chitosan (CS) by a facile method. Successful grafting was confirmed by 1H NMR, FT-IR, UV-vis, XRD, and elemental analysis. The polymeric dyes exhibited no cell toxicity. The colorimetric pH-sensing films were fabricated by blending the polymeric dyes with CS to establish their pH-dependent color properties. The film color changed in the pH range 4-10, which may indicate food spoilage or wound status. Covalently grafting of polymeric dyes in the films led to excellent color stability, leaching resistance, and reversibility. Hence, the synthesized polymeric dyes had potential as pH-indicative colorants for food and biomedical fields.


Assuntos
Quitosana/química , Corantes/síntese química , Polímeros/química , Infecções Bacterianas/diagnóstico , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Corantes/química , Corantes/farmacologia , Armazenamento de Alimentos , Humanos , Concentração de Íons de Hidrogênio , Fenolsulfonaftaleína/química
16.
Carbohydr Polym ; 260: 117839, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33712174

RESUMO

The efficacy and mode of action of biodegradable chitosan (CS) and carboxymethyl chitosan (CMCS) organic polymer nanoparticles (NPs) on insects were studied. The prepared CS/CMCS-NPs were spherical with a particle size of 142.1 ± 2.0 nm. The swelling test showed that they were pH-sensitive, and the swelling rate was 554 % at pH 4.5. It was found that CS/CMCS-NPs had insecticidal efficacy against red fire ants (S. invicta). The mortality of red fire ants on the 6th day after treatment with 0.2 % and 0.06 % CS/CMCS-NPs suspensions was 98.33 ± 1.67 % and 48.33 ± 3.33 %, respectively. After CS/CMCS-NPs treatment, the food intake, growth, and development of red fire ants were inhibited; the midgut was significantly expanded; and the activity of digestive enzymes in the midgut was decreased. Our findings suggest that CS/CMCS-NPs mainly inhibited the digestion function of the midgut, leading to the death of red fire ants.


Assuntos
Quitosana/análogos & derivados , Quitosana/química , Inseticidas/química , Nanopartículas/química , Animais , Formigas/efeitos dos fármacos , Formigas/fisiologia , Peso Corporal/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Lipase/antagonistas & inibidores , Lipase/metabolismo , Nanopartículas/toxicidade , Peptídeo Hidrolases/química , Peptídeo Hidrolases/metabolismo
17.
Food Chem ; 352: 129325, 2021 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-33691212

RESUMO

The milk-coagulating enzyme, rennet, is widely used in cheese making. Recently stabilization of rennet, especially in accelerated cheese ripening, has received considerable interest. As we know encapsulation is one of the enzyme immobilization methods, which could increase enzyme stability. In this study, the effects of alginate, chitosan and, CaCl2 on rennet encapsulation were evaluated and optimized using RSM. Under the optimal conditions alginate, chitosan, and CaCl2 were 0.04%, 0.1%, and 0.1% respectively. At the optimum point, encapsulation efficiency, particle size, and zeta potential were evaluated to be 61.8%, 323 nm, and 25 mV, respectively. The effect of temperature and pH on the enzyme activity was evaluated, and the results showed that encapsulated enzyme had higher activity at various pH and temperature in comparison with the free enzyme. Also, the enzyme release data in all pH values were fitted to Korsmeyer-Peppas model and the n exponent indicated that the release mechanism was Fickian. The electrostatic interactions between enzyme, alginate, and chitosan were confirmed by infrared spectroscopy. No statistical difference was found between the Km and Vmax of encapsulated and free enzymes.


Assuntos
Alginatos/química , Quitosana/química , Quimosina/química , Enzimas Imobilizadas/química , Nanopartículas/química , Cloreto de Cálcio/química , Tamanho da Partícula
18.
Carbohydr Polym ; 260: 117765, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33712123

RESUMO

Chitosan (CS) combined with hydroxyapatite (HA) was injected into a composite braid, and a hierarchical pore structure scaffold was obtained by freeze drying and cold atmospheric plasma (CAP) technology. The CS/HA/braid scaffold with hierarchical pore structure was analyzed and characterized by scanning electronic microscopy, Fourier transform infrared spectroscopy, true color confocal microscopy, improved liquid replacement method, and phosphate buffer solution immersion. The mechanical properties and degradation ability of the scaffold were evaluated through compression test and degradation test. Results showed that HA addition endowed the core of the scaffold with macroscopic pore sizes of 80-180 µm, and CAP treatment endowed the shell of the scaffold with microscopic pore sizes ≤10 µm. All scaffolds exhibited high porosity and swelling rates of ≥80 % and ≥300 %, respectively. The scaffold with a hierarchical pore structure had good mechanical properties and twice the degradation rate. In addition, the treated scaffold precipitated intact spherical HA crystals. Under the synergistic effect of HA and CAP treatment, scaffolds achieved 277.6 % cell viability compared with pure CS scaffold. Overall, this method was feasible for preparing bone scaffolds with hierarchical pore structure for potential bone tissue engineering.


Assuntos
Quitosana/química , Durapatita/química , Engenharia Tecidual , Tecidos Suporte/química , Animais , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Força Compressiva , Liofilização , Camundongos , Porosidade
19.
Carbohydr Polym ; 260: 117767, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33712125

RESUMO

Wound healing is a dynamic and intricate process, and newly dressings are urgently needed to promote wound healing over the multiple stages. Herein, two water-soluble adenine-modified chitosan (CS-A) derivatives were synthesized in aqueous solutions and freeze-dried to obtain porous sponge-like dressings. The novel derivatives displayed antibacterial activities against S. aureus and E. coli. Moreover, CS-A derivatives demonstrated excellent hemocompatibility and cytocompatibility, as well as promoted the proliferation of the wound cells by shortening the G1 phase and improving DNA duplication efficiency. The ability of CS-A sponges to promote wound healing was studied in a full-thickness skin defect model. The histological analysis and immunohistochemical staining showed that the wounds treated with CS-A sponges displayed fewer inflammatory cells, and faster regeneration of epithelial tissue, collagen deposition and neovascularization. Therefore, CS-A derivatives have potential application in wound dressings and provide new ideas for the design of multifunctional biomaterials.


Assuntos
Adenina/química , Materiais Biocompatíveis/química , Quitosana/química , Animais , Bandagens , Materiais Biocompatíveis/farmacologia , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Liofilização , Masculino , Camundongos , Porosidade , Ratos , Ratos Sprague-Dawley , Pele/efeitos dos fármacos , Pele/patologia , Cicatrização/efeitos dos fármacos
20.
Carbohydr Polym ; 260: 117768, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33712126

RESUMO

Tissue engineering and regenerative medicine have entered a new stage of development by the recent progress in biology, material sciences, and particularly an emerging additive manufacturing technique, three-dimensional (3D) printing. 3D printing is an advanced biofabrication technique which can generate patient-specific scaffolds with highly complex geometries while hosting cells and bioactive agents to accelerate tissue regeneration. Chitosan hydrogels themselves have been widely used for various biomedical applications due to its abundant availability, structural features and favorable biological properties; however, the 3D printing of chitosan-based hydrogels is still under early exploration. Therefore, 3D printing technologies represent a new avenue to explore the potential application of chitosan as an ink for 3D printing, or as a coating on other 3D printed scaffolds. The combination of chitosan-based hydrogels and 3D printing holds much promise in the development of next generation biomedical implants.


Assuntos
Quitosana/química , Hidrogéis/química , Impressão Tridimensional , Materiais Biocompatíveis/química , Humanos , Medicina Regenerativa , Engenharia Tecidual
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