Carboxymethyl Chitosan Concentration Research Articles

Optimization of the synthesis process of β‐galactosidase/carboxymethylchitosan‐silica biocatalyst powders, stabilized with lyoprotectants for potential dietary applications

Abstractβ‐galactosidase dosing and transport powders offer benefits for people with specific digestive deficiencies. They can be produced by immobilization in solid materials by sol–gel methods. The challenge is to maintain enzyme activity under processing conditions. The objective here is to design and optimize the calcium chloride and carboxymethylchitosan concentrations at 25°C and 7.3 pH for preparing active β‐galactosidase powders. This optimization was performed using a Response Surface Methodology with Central Composite Design, selecting lyoprotectants for preserving activity during the lyophilization. Glucose, galactose, maltose, sucrose, and β‐cyclodextrin lyoprotectants were assayed in different weight proportions. The optimal conditions to obtain a biocatalyst with maximum expressed activity were 473 mM CaCl2 and 402 ppm carboxymethylchitosan, obtaining a biocatalyst with 57.8% ± .7% recovered activity and 92.3% ± 2.1% immobilization yield. The galactose, maltose, and sucrose in a 1:5 ratio increased 1.2 times the expressed activity of this biocatalyst, protecting the active site during lyophilization due to favorable interactions with the enzyme as shown by docking analysis.Practical applicationsThis work shows the implementation of production methodologies of mixed enzyme‐mineral biocatalysts, based on the experimental, statistical, and docking studies of β‐galactosidase interactions with mono‐, di‐ and polysaccharides under ionic and thermal stress. The obtained powders could be candidates as dietary supplements of calcium, silicon minerals, and β‐galactosidase.

Double network structure via ionic bond and covalent bond of carboxymethyl chitosan and poly(ethylene glycol): Factors affecting hydrogel formation

The factors were studied that affect the formation of DN hydrogel, which was prepared using a water-based, environmental-friendly system. The DN hydrogel was designed and prepared based on a cross-linked, polysaccharide-based, polymer carboxymethyl chitosan (CMCS) via an ionic crosslinking reaction for the first network structure. UV irradiation created a radical crosslinking reaction of poly(ethylene glycol) from a double bond at the chain end for the second network structure. It was found that the optimum hydrogel was produced using 9.5 %v/v of 1000PEGGMA, CMCS 5%w/v, and CaCl2 3%w/v. The results showed the highest percentage of the gel fraction was 87.84 % and the hydrogel was stable based on its rheological properties. Factors affecting the hydrogel formation were the concentration and molecular weight of PEGGMA and the concentrations of CMCS and calcium chloride (CaCl2).The DN hydrogel had bioactivity due to its octacalcium phosphate (OCP) hydroxyapatite crystal form. In addition, the composite DN scaffold with a conductive polymer of chitosan-grafted-polyaniline (CS-g-PANI) had conduction of 2.33 × 10−5 S/cm when the concentration of CS-g-PANI was 3 mg/ml, confirming the semi-conductive nature of the material. All the results indicated that DN hydrogel could be a candidate to apply in tissue-engineering applications.

The Effect of Polymers Ratio Carboxymethyl Chitosan, Polyvinyl Pyrolidone K-30, and Ethyl Cellulose N22 on Physico-Chemical Characteristics and Drug Release from Matrix Type Diclofenac Potassium Patch

Background: Diclofenac potassium is an NSAID drug that is used in the treatment of mild to moderate pain. The use of this drug orally can cause side effects in the gastrointestinal tract, and the drug will undergo extensive first-pass metabolism in the liver. Therefore, preparations for transdermal patches were made. Objective: Determining the effect of the polymer ratios of carboxymethyl chitosan, polyvinyl pyrolidone K-30, and ethyl cellulose N22 on the physicochemical characteristics and drug release of a matrix type diclofenac potassium patch. Methods: In this study, matrix type diclofenac potassium patches were made using a combination of carboxymethyl chitosan (CMC), polyvinyl pyrrolidone (PVP) K-30 polymer, and ethyl cellulose (EC) N22 in a ratio of 2:3:7 and 3:2:7. Patches are made by mixing the entire polymer matrix and diclofenac potassium together, which are then evaporated and dried. Results: The results showed that the different polymer compositions of CMC, PVP K-30, and EC N22 resulted in patches with physicochemical characteristics that were not significantly different. The combination of these polymers is able to control the release of the drug from the patch for a long time. It was also found that increasing the concentration of CMC was able to increase the rate of release of diclofenac potassium. Formula 2 with a ratio of 3:2:7 is claimed to be the best formula in terms of physical, chemical, and drug release characteristics from the patch. Further studies are needed, such as drug penetration tests into the skin.

Development of food-grade oleogel via the aerogel-templated method: Oxidation stability, astaxanthin delivery and emulsifying application

Templates for the fabrication of food-grade oleogels were prepared by freeze-drying of whey protein isolate (WPI)–carboxymethyl chitosan (CMCS) heat-set hydrogels, and the effect of the concentration of CMCS on aerogel properties was explored. It was observed that both the oil adsorption capacity and oil binding capacity were significantly improved when the CMCS concentration was up to 0.75% (w/w). With the further increase of CMCS concentration, the oil absorption capacity decreased. Scanning electric microscopy images exhibited that the corresponding aerogel showed dense and uniform porous networks. Compared with bulk oil, WPI–CMCS aerogel gel showed excellent oxidation stability. In addition, the delivery efficiency of aerogel-based oleogels as nutraceutical delivery carriers for astaxanthin (AST) was assessed. The bioaccessibility of AST in WPI–CMCS oleogels was significantly higher than that of bulk oil. Finally, the emulsification of aerogel-based oleogels was tested by TSI and droplet size. In comparison with WPI oleogel, the WPI–CMCS oleogel exhibited better physical stability and smaller droplet size. This work indicates that the path of oil structuring is not limited to the selection of existing oleogelators. The construction of aerogel templates from various protein/polysaccharide for oil absorption is also a promising path. • Oleogel could be prepared from whey protein isolate–carboxymethyl chitosan aerogel. • Aerogel-based oleogels (AOs) exhibited superior oxidation stability. • AOs could serve as efficacious vehicles for hydrophobic nutraceuticals. • AOs improved the lipolysis rate and the bioaccessibility of astaxanthin. • The prepared AO-based emulsion showed superior physical stability.

Development of a Self-Assembled Hydrogels Based on Carboxymethyl Chitosan and Oxidized Hyaluronic Acid Containing Tanshinone Extract Nanocrystals for Enhanced Dissolution and Acne Treatment.

This study aimed to construct a pH-responsive nanocrystalline hydrogel drug delivery system for topical delivery of insoluble drugs based on the self-assembly behavior of carboxymethyl chitosan (CMC) and oxidized hyaluronic acid (OHA). The tanshinone nanocrystal (TNCs) extract was prepared by dielectric milling method, the type and ratio of stabilizer of the drug were investigated to optimize the prescription, and the effector surface method was used to optimize the preparation process. OHA was prepared by the sodium periodate oxidation method, and the concentration of CMC and OHA was optimized using gel formation time as an indicator. OHA was dissolved in TNCs and self-assembled with CMC solution to form tanshinone extract nanocrystal hydrogels (CMC-OHA/TNCs), of which the physicochemical properties and in vitro antibacterial activity were evaluated. Results showed that the optimized prescription and process could produce tanshinone extract nanocrystals with a particle size of (223.67 ± 4.03) nm and a polydispersity index (PDI) of 0.2173 ± 0.0008. According to SEM and XRD results, TNCs were completely wrapped in the hydrogel as nanoparticles, and the crystallinity of TNCs was reduced and the diffraction peaks in CMC-OHA/TNCs almost disappeared. In vitro, transdermal test results showed that CMC-OHA/TNCs could release the drug continuously at the acne lesions. The cell-counting kit-8 (CCK-8) assay confirmed that the CMC-OHA/TNCs had no obvious cytotoxicity. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of CMC-OHA/TNCs against Propionibacterium acnes and Staphylococcus aureus were significantly lower and the diameter of the inhibition circle was obviously higher than that of TNCs and tanshinone extract crude suspension. This study demonstrated that CMC-OHA/TNCs was a promising delivery system for topical delivery of insoluble drugs, which could improve the solubility of tanshinone extract and enhance its in vitro bacterial inhibitory activity.

Antibacterial activity and bonding performance of carboxymethyl chitosan–containing dental adhesive system

ObjectivesDevelop an antibacterial adhesive by adding appropriate concentration of carboxymethyl chitosan (CMC), to prevent secondary caries on the bonding surface, meanwhile, ensuring the bonding performance. The addition of polyelectrolyte into the bonding system will provide a new idea for the development of antibacterial adhesives. MethodsCMC was incorporated into the primer at the concentration of 5, 10, and 20 mg/ml. An etched-and-rinse adhesive without CMC was used as the negative control. Antibacterial activity against Streptococcus mutans was evaluated using the direct contact test, XTT assay, live/dead bacteria staining and fluorescence analysis. The degree of conversion, microtensile bond strength (μTBS) before and after thermocycling were also evaluated. The results were compared at the significant level of 0.05 (α = 0.05). ResultsThe polymerized CMC-modified adhesive significantly decreased the adherent S. mutans amount. The inhibitory effect was more significant when the CMC concentration increased; There was no significant difference observed between the 10 and 20 mg/mL groups. The XTT and live/dead bacteria staining results indicated that the polymerized CMC-modified adhesive interfered with the adherence of S. mutans poliand biofilm integrity. Reduction in metabolic activity was more significant when the CMC concentration increased. The ratio of green/red fluorescence mean intensity showed no significant difference between the experiment group and control group, but the fluorescence area and bacterial viability of CMC-containing group was significantly lower than control group. There were no significant differences in the degree of conversion and μTBS among each group before or after thermocycling. ConclusionsThe adhesive system containing 20 mg/mL CMC demonstrated reliable antibacterial activity against S. mutans and did not adversely affect bonding performance. Clinical significanceThe CMC-modified adhesive inhibits S. mutans whilst preserving bond strength to dentine. Incorporation of the antibacterial agent endows the modified adhesive with the potential of combating secondary caries.

Carboxymethyl chitosan prolongs adenovirus-mediated expression of IL-10 and ameliorates hepatic fibrosis in a mouse model.

Effective and safe liver‐directed gene therapy has great promise in treating a broad range of liver diseases. While adenoviral (Ad) vectors have been widely used for efficacious in vivo gene delivery, their translational utilities are severely limited due to the short duration of transgene expression and solicitation of host immune response. Used as a promising polymeric vehicle for drug release and nucleic acid delivery, carboxymethyl chitosan (CMC) is biocompatible, biodegradable, anti‐microbial, inexpensive, and easy accessible. Here, by exploiting its biocompatibility, controlled release capability and anti‐inflammatory activity, we investigated whether CMC can overcome the shortcomings of Ad‐mediated gene delivery, hence improving the prospect of Ad applications in gene therapy. We demonstrated that in the presence of optimal concentrations of CMC, Ad‐mediated transgene expression lasted up to 50 days after subcutaneous injection, and at least 7 days after intrahepatic injection. Histologic evaluation and immunohistochemical analysis revealed that CMC effectively alleviated Ad‐induced host immune response. In our proof‐of‐principle experiment using the CCl4‐induced experimental mouse model of chronic liver damage, we demonstrated that repeated intrahepatic administrations of Ad‐IL10 mixed with CMC effectively mitigated the development of hepatic fibrosis. Collectively, these results indicate that CMC can improve the prospect of Ad‐mediated gene therapy by diminishing the host immune response while allowing readministration and sustained transgene expression.

In vitro and in vivo study of carboxymethyl chitosan/polyvinyl alcohol for wound dressing application

AbstractAntibacterial, good biosafety, and wound healing enhancers, are the most favorable factors for wound dressing. Designing nanomaterial of the scaffold for supporting skin regeneration is a complicated process. Carboxymethyl chitosan (CMC) structure similar to the glycosaminoglycan and antibacterial activity combined with polyvinyl alcohol (PVA) (PVA/CMC) can lead to satisfactory properties for wound management. In this study, a collection of electrospun nanofibrous scaffolds are fabricated by blending the constant PVA concentration (9%) with a limited area of CMC concentration (2%, 3%, 4%, and 5%). PVA/CMC scaffolds characteristic was investigated through a scanning electron microscope, Fourier‐transform infrared spectroscopy, and contact angle tests. The fiber diameter values were measured for PVA (144.60 nm), chitosan (131.57 nm), and average different concentration of CMC in PVA/CMC (104.7 ± 2.45 nm). In vitro potential of the scaffolds were evaluated by using human dermal fibroblast cells and human placental‐derived mesenchymal stem cells. According to in vitro results, PVA/CMC4% scaffold was selected as the optimized wound dressing for skin tissue engineering. The in vivo wound healing data in rat models illustrated more healing capacity of PVA/CMC4% dressing in which accelerating wound closure and freshly healed tissue with high similarity to the normal skin was reorganized.

Effects of carboxymethyl chitosan on physicochemical, rheological properties and in vitro digestibility of yam starch

The effects of carboxymethyl chitosan (CMCS) on the pasting, rheological, and physical properties of yam starch (YS) were investigated. Different concentrations of CMCS were added to the YS, followed by heating paste treatment at 95 °C. Then the blends were subjected to the determination of physicochemical, rheological properties and in vitro digestibility. Our results showed that CMCS reduced the paste viscosity of YS and the addition of CMCS did not effectively inhibit the movement of water molecules. Rheological measurements results showed that YS-CMCS blends exhibited shear thinning behavior. Furthermore, because of the presence of amylose inhibited the swelling of the starch and leaching of amylose, the addition of CMCS had no significant difference between solubility and swelling power of YS.

Preparation and hydrophobic modification of carboxymethyl chitosan aerogels and their application as an oil adsorption material

Carboxymethyl chitosan (CMCS) aerogels were prepared through sol-gel combining with freeze drying technology. The effects of CMCS concentration on the gelation time, volume shrinkage, density, porosity, compressive strength and hygroscopicity were investigated. Meanwhile, the CMCS aerogel was characterized by Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). Then the CMCS aerogel was hydrophobic, modified through cold plasma modification technology, and oil absorbency of hydrophobic modified CMCS (HMCMCS) aerogel was researched. The results showed that the CMCS aerogel had the lowest density of 0.022 g/cm3, the maximum porosity of 95.34%, the highest compressive strength reached 1.74 MPa and a three-dimensional (3D) network heterogeneous porous structures in the inner areas. After hydrophobic modification, the water contact angle of 2% for HMCMCS aerogel with 20 min under 60 W reached 117 °. Besides, the HMCMCS aerogel represented excellent oil adsorbing property and outstanding recyclability, for the oil adsorption rate was up to 31.6 g/g and stable in multiple cycles.

Interpenetrating polysaccharide-based hydrogel: A dynamically responsive versatile medium for precisely controlled synthesis of nanometals

Herein, we reported an interpenetrating polysaccharide-based hydrogel in which carboxymethyl chitosan (CMC) chains were physically dispersed throughout the thermoplastic elastomer gel network has been developed as a versatile platform for precisely controlled synthesis of nanometals. Results indicated the interpenetrated CMC chains could serve as multifunctional fillers for metal ions adsorption and stabilization while the thermally reconfigurable agarose (Agar) gel medium provides three-dimensional semi-solid framework for entrapping and recollecting of the fabricated nanometals. Specifically, the CMC chains were found to strongly coordinate with silver ions as a dynamically responsive metal-biopolymer complex within the bulk gel network as confirmed by the enhanced mechanical properties and regulated shape memory performances. Moreover, by varying CMC concentrations and coupling with a layer-stacking approach, multiple biochemical gradients could be facilely generated for in-situ synthesis of silver nanoparticles, achieving a narrow size of ~7 nm, confined sphere-shape and high concentrations. The monodispersed nanometals are confirmed to be highly active (e.g., considerable catalytic performance), and which could be easily recycled from the bulk gel system via a heating treatment. Thus, this work would provide a generic methodology for the multifunctional metallogel assembly and great possibility for controllable and largescale synthesis of noble nanometals toward biomedical applications.

CONCENTRATION DEPENDENT EFFECTS OF CARBOXYMETHYL CHITOSAN ON DENTIN REMINERALIZATION WITH AMORPHOUS CALCIUM PHOSPHATE

Objective: Carboxymethyl chitosan (CMC) is a non-collagenous protein analog which has a similar role as dentin matrix protein 1. CMC stabilizes amorphous calcium phosphate (ACP); hence forming nanocomplexes of CMC-ACP. The purpose of this study was to evaluate the effect of CMC concentration in CMC-ACP on dentin remineralization.Methods: Cavities were formed on the occlusal surfaces of freshly extracted premolar teeth. All samples were demineralized and immersed in phosphate-buffered saline and stored in a shaking incubator at 37°C. The teeth were randomly divided into five groups. Group 1 was control group (no treatment), whereas Groups 2, 3, 4, and 5 were treated with CMC-ACP containing 1%, 2.5%, 5%, and 10% CMC. The remineralized layer on the dentin surface was evaluated using scanning electron microscopy and energy-dispersive X-ray analysis.Results: The highest dentin remineralization capacity was achieved in Group 5 (10% CMC), whereas diminishing effects were observed in Group 4 (5% CMC), Group 3 (2.5% CMC), and Group 2 (1% CMC). Although no significant differences in calcium levels were observed between 2.5%, 5%, and 10% CMC groups, phosphate levels differed significantly in all treatment groups.Conclusion: Optimal dentin remineralization was achieved by the application of CMC–ACP containing 2.5% CMC.

Mechanical strong stretchable conductive multi-stimuli-responsive nanocomposite double network hydrogel as biosensor and actuator

Multi-stimuli- responsive mechanical strong stretchable hydrogel has grabbed extensive attention in recent years. Here, a novel stretchable conductive biocompatible near-infrared light(NIR)-/thermal-/pH-/ionic concentration- responsive carboxymethyl chitosan (CMCTs)/graphene oxide (GO)/poly(N-isopropylacrylamide)(PNIPAm) nanocomposite double network hydrogel was fabricated through a simple one-pot in situ free radical polymerization, which is initiated by ultraviolet (UV) light and using N-(3-dimethylaminopropyl)-N-ethylcarbodiimidehydrochloride (EDC) and N,N’-bis(acryloyl)cystamine (BAC) as cross-linkers respectively, instead of toxic organic molecules. When the concentration of CMCTs, GO, EDC and BAC is 22.50, 0.103, 7.50 and 0.467 mg/mL respectively, the obtained hydrogel sample owns the highest tensile strength of 1046 kPa at failure strain of 1286% and a corresponding compressive stress of 2.37 MPa at deformation of 90%. Besides, these hydrogels have an obvious pH-/thermal-/ionic concentration-responsive properties depending on the concentration of the above mentioned factors, and their good conductive property makes them as candidate material for healthcare biosensors. Finally, we attempt to design a novel thermal-/NIR-responsive double network structure bilayer hydrogel, which has the potential use as remote actuator in dangerous places in the future.

Effects of carboxymethyl chitosan on the growth and nutrient uptake in Prunus davidiana seedlings.

To determine the effects of carboxymethyl chitosan on plant growth and nutrient uptake, Prunus davidiana seedlings were treated with various concentrations of carboxymethyl chitosan. The biomass, physiological characteristics, and nutrient uptake of the treated P. davidiana seedlings were then examined. Compared with the control seedlings, the carboxymethyl chitosan-treated seedlings had a higher biomass and a greater abundance of photosynthetic pigments (i.e., chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid), with the best concentration as 2g/L carboxymethyl chitosan, which increased the shoot biomass and total chlorophyll content by 26.75% and 24.64%, respectively. Moreover, the application of carboxymethyl chitosan enhanced superoxide dismutase and catalase activities, increased the soluble protein content, and decreased the malondialdehyde and proline contents of the P. davidiana seedlings to some extent. Additionally, the carboxymethyl chitosan treatments decreased the total nitrogen content, but increased the total phosphorus and potassium contents in P. davidiana seedlings to some extent. The minimum of total nitrogen content and the maximum of total phosphorus and potassium contents in shoots of P. davidiana seedlings were the concentration of 2g/L carboxymethyl chitosan, which was decreased by 12.96% and increased by 15.45% and 22.53%, respectively, compared with the control. Therefore, the application of a carboxymethyl chitosan solution may promote the growth, enhance the stress resistance, and alter the nutrient uptake of P. davidiana seedlings, especially at 2g/L carboxymethyl chitosan.

Enhanced fluorescence of carboxymethyl chitosan via metal ion complexation in both solution and hydrogel states

Recently, biopolymer-based non-traditional luminogens had attracted a great deal of interest because of their potential applications in biomedical field. Herein, we report for the first time that carboxymethyl chitosan (CMCh) can exhibit strong blue fluorescence at λ = 436.8 nm when brought in contact with zinc ion (Zn2+) in both solution and hydrogel states. The resultant CMCh-Zn sample exhibits a typical fluorescence lifetime of 3.68 ns and a quantum yield of 6.8%. The fluorescence behaviors of CMCh-Zn samples at different excitation wavelengths, CMCh concentrations, temperature, and pH values, are also investigated. The results clearly indicate clustering-triggered emission characteristic of the CMCh-Zn. In order to further elucidate the chemical nature of this new fluorescence system, a series of CMCh-Zn samples are characterized by using ultraviolet-visible spectrometer, Fourier-transform infrared spectrometer and X-ray diffractometer. The data suggest that the metal-ligand complexation of CMCh with Zn2+ account for the generation of such an enhanced fluorescence.

Influence of molecular weight and concentration of carboxymethyl chitosan on biomimetic mineralization of collagen.

The objective of the present study was to systematically investigate the influence of molecular weight (MW) and concentration of carboxymethyl chitosan (CMC), which served as non-collagenous protein (NCP) surrogates, on biomimetic mineralization of type I collagen. Supersaturated CMC-stabilized amorphous calcium-phosphate (CMC-ACP) dispersions containing different MWs (20 kDa, 60 kDa, 150 kDa) and concentrations (25, 50, 100, 200, 400 μg ml−1) of CMC were prepared. After mineralization in the aforementioned dispersions for 7 days, the pattern and extent of biomimetic mineralization of collagen scaffolds were investigated. Our study showed that increasing CMC concentration resulted in increasing stability and decreasing particle size of CMC-ACP dispersions. Images from scanning and transmission electron microscopy revealed that intrafibrillar mineralization of collagen was obtained with 20k-200, 60k-100, 60k-200 and 150k-200 CMC-ACP dispersions, with hydroxyapatite (HAp) formation confirmed by Fourier transform infrared spectroscopy and X-ray diffraction measurements, whereas HAp formed extrafibrillar clusters in other collagen scaffolds. Thermogravimetric analysis showed that the combined effect of MW and concentration of CMC contributed to different extents of biomimetic mineralization, and was correlated with the stability and particle size of CMC-ACP dispersions, and the size-exclusion characteristics of type I collagen. The results of this work support the effective function of CMC as NCP analogs, and provide parameters of MWs and concentrations of CMC for applications in hard tissue engineering as well as insights into intersections of mechanisms in biomimetic mineralization.

Formulation, Physical Characterization and Wound Healing Activity Evaluation of Carboxymethyl Chitosan-Curcumin Carbomer-Based Hydrogel

The aim of this study was to determine the effect of different concentration of carboxymethyl chitosan and curcumin on physical characteristics and wound healing activity of carboxymethyl chitosan-curcumin hydrogel. Hydrogels were prepared using carbomer as a gelling agent and TEA was added to neutralize the carbomer hydrogel in order to make it swell. The obtained hydrogels were evaluated for its physical characterization such as organoleptic, viscosity, spreadability, drying time, pH, and wound healing activity on the burned wound in Wistar rats. The results showed that higher concentration of carboxymethyl chitosan significantly reduces viscosity and pH while its spreadability and drying time are significantly increased. Curcumin only affected two out of five physical characteristics: organoleptic and pH. Higher concentration of curcumin reduces its pH but statistical analysis showed no interaction between carboxymethyl chitosan and curcumin. The wound healing activity in Wistar rats with 2nd degree burn wound model indicates that carboxymethyl chitosan-curcumin hydrogel can significantly improve wound healing activity in rats compared to control group. Higher concentration of carboxymethyl chitosan can affect the physical characteristics of carboxymethyl chitosan-curcumin hydrogel i.e. a decrease in viscosity and pH, as well as an increase in spreadability and drying time. On the other hand, higher concentration of curcumin only affected the pH of the preparation. In the wound healing activity test, macroscopic observation showed that the combination of carboxymethyl chitosan-curcumin significantly increased the wound healing activity of 2nd degree burn in Wistar rats. However, the use of this hydrogel preparation statistically did not give significant improvement in wound healing process when compared with G1, G2, G3, G4, and positive control. Based on histopathology test results, it can be concluded that after 14 days of treatment the value of collagen deposition and PMN between groups 1, 2, 3, 4, and positive control and intergroup replication (1, 2, 3, 4, and positive controls) are in uniformity which indicates that the wound has undergone healing process. In addition, the four groups possess better results than negative controls which didn’t receive any treatment.

The combined effects of Carboxymethyl chitosan and Cryptococcus laurentii treatment on postharvest blue mold caused by Penicillium italicum in grapefruit fruit

The blue mold caused by Penicillium italicum in grapefruit fruit was controlled by the antifungal activities of Carboxymethyl chitosan (CMCS) alone and combined with Cryptococcus laurentii treatments in this study. According to the study results spore germination of P. italicum can be inhibited by both CMSC and C. laurentii treatment. Moreover, the growth of C. laurentii can be maintained by low CMCS concentration in vitro. The blue mold in grapefruit fruit inoculated with P. italicum was decreased in all treatments compared with the control fruit. The combination of CMSC and C. laurentii treatment resulted in a significantly synergistic effects in smallest lesion diameter and decay incidence. The defense enzyme activities, such as phenylalanine ammonia-lyase, polyphenol oxidase, peroxidase and antifungal compounds like total phenolic related to disease resistance can be induced by combined treatment. Furthermore, the commercial quality parameters of the CMCS combined with C. laurentii treatment which were measured by ascorbic acid, titratable acidity, weight loss and total soluble solid, were better than those treated with treatments alone. According to the results, the combination of CMSC and C. laurentii treatment can maintain fruit quality and control postharvest decay more effectively than single treatment, and can be commercially used in grapefruit fruit.

Synthesis, Characterization, and Sludge Dewaterability Evaluation of the Chitosan-Based Flocculant CCPAD.

Carboxymethyl chitosan (CMCS), acrylamide, and methacryloxyethyltrimethyl ammonium chloride were used as co-monomers to produce a sludge dewatering agent carboxymethyl chitosan-graft-poly(acrylamide-methacryloxyethyltrimethyl ammonium chloride) (CCPAD) by UV-induced graft polymerization. Single-factor experiments and response surface methodology were employed to investigate and optimize the grafting rate, grafting efficiency, and intrinsic viscosity influenced by the total monomer concentration, CMCS concentration, cationic degree, pH value, and illumination time. The structure, surface morphology, and thermal stability of CCPAD were characterized by infrared spectroscopy, hydrogen nuclear magnetic resonance, X-ray diffraction, scanning electron microscopy, and differential thermal-thermogravimetry. The raw sludge with 97.9% water content was sourced from the concentrated tank of a sewage treatment plant and used in the sludge condition experiments. In addition, CCPAD was applied as the sludge conditioner to investigate the effects of cationic degree, intrinsic viscosity, and pH on the supernatant turbidity, moisture content, specific resistance to filtration, and sludge settling ratio. Moreover, the mechanism of sludge conditioning by CCPAD was discussed by examining the zeta potential and extracellular polymeric substance (EPS) content of the supernatant. The sludge dewatering results confirmed that CCPAD had excellent performance for improving sludge dewaterability.

Size controllable one step synthesis of gold nanoparticles using carboxymethyl chitosan

Gold nanoparticles (AuNPs) were synthesized by reducing chloroauric acid with nontoxic and biodegradable carboxymethyl chitosan (CMC) as dual roles of reducing agent and stabilizer. Several CMC with different molecular parameters, i.e., degree of substitution (DS), substitution position, degree of deacetylation (DD) and molecular weight (MW) have been investigated for their reducing and stabilizing ability on the synthesis of AuNPs. The obtained AuNPs were characterized with UV-vis spectroscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. The resulting AuNPs displayed controllable size and shape not only depending on the molecular parameters of CMC but experimental parameters, such as reaction temperature, time, pH, concentration of NaOH, HAuCl4 and CMC in solution. The results indicated the addition of NaOH to a solution containing HAuCl4 and CMC is essential to synthesize individual spherical AuNPs with a rather uniform size distribution. The –OH at C-6 and –NH2 at C-2 of CMC played important roles in the reduction of Au(III) to Au(0) and –COO– groups were accountable for the stabilizing ability of CMC to AuNPs.