Preparation and characterization of carboxymethyl chitosan sulfate/oxidized konjac glucomannan hydrogels.

Hydrogel wound dressing is a new type of biomaterial with performance that is better than traditional and biological dressings. It has been extensively researched and the application in the field of biomedicine is common. In this study, we developed a simple and nontoxic method for preparing a new type of composite hydrogel, which formed through the Schiff-base reaction between the aldehyde of oxidized konjac glucomannan (OKGM) and the amino of carboxymethyl chitosan sulfate (CMSS). The chemical structures of this composite hydrogel were characterized by transform infrared spectroscopy (FT-IR). The micro-morphology of hydrogels were analyzed by scanning electron microscopy (SEM). Meanwhile, the properties of composite hydrogels including gelation time, swelling ability, water evaporation rate, hemolytic potential and biological compatibility were also investigated in different means. The results gained from these studies show that this composite hydrogels have a series of properties such as short gelation time, good swelling ability, appropriate water evaporation rate, excellent hemocompatibility and well biological compatibility. Considering these excellent performance, this composite hydrogels can be used as a wound dressing to treat injured skin.

Preparation and characterization of chitosan - collagen peptide / oxidized konjac glucomannan hydrogel.

In this paper, the microbial transglutaminase (MTGase) was used as a catalyst to graft the collagen peptide (COP) molecules on the amino group of chitosan to obtain water-soluble chitosan-collagen peptide (CS-COP) derivatives. The preparation of composite hydrogel was via the Schiff-base reaction between the amino of CS-COP and the aldehyde of oxidized konjac glucomannan (OKGM). The hydrogels were characterized by various techniques including Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The results of SEM showed that the hydrogel sample had a clear and stable three-dimensional network structure. Meanwhile, these effects of the addition of OKGM on gelation time, swelling behaviors, water evaporation rate and blood coagulation capacity were investigated. The shortest gelation time for hydrogels was 99.3s. The hydrogels showed a good swelling ability and appropriate water retention capacity. The maximum swelling ratio of the hydrogel was 265%. Dynamic blood clotting test showed that the hydrogels materials had good blood coagulation capacity. Moreover, The biocompatibility of hydrogels was evaluated with NIH-3T3 cells by MTT method. The results indicated that the hydrogels exhibited better biocompatibility. Therefore, this hydrogel has a promising potential to be applied as wound dressing.

Preparation and characterization of aminoethyl hydroxypropyl starch modified with collagen peptide.

The preparation of aminoethyl hydroxypropyl starch collagen peptide (AEHPS-COP) was via an enzyme-catalyzed reaction between amino groups in aminoethyl hydroxypropyl starch (AEHPS) and γ-carboxamide groups in collagen peptide (COP) by using microbial transglutaminase (MTGase) as biocatalyst. As an intermediate reactant, AEHPS was synthesized from hydroxypropyl starch (HPS) and 2-chloroethylamine hydrochloride (CEH). The chemical structures of HPS, AEHPS and AEHPS-COP were characterized by Fourier transform infrared spectroscopy (FT-IR) and 13C nuclear magnetic resonance (13C NMR). The reaction conditions that influenced the degree of substitution (DS) of AEHPS-COP were optimized, which included the reaction temperature, the reaction time, the mass ratio of collagen peptide to aminoethyl hydroxypropyl starch and the pH value. In addition, in vitro antioxidant activities of AEHPS-COP were evaluated through the scavenging activity of hydroxyl and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. Furthermore, the methylthiazol tetrazolium (MTT) assay was applied to investigate the cell viability of AEHPS-COP. The results indicated that the AEHPS-COP exhibited better cell viability to L929 mouse fibroblast cells. Therefore, the AEHPS-COP showed a promising potential application in cosmetic, biomedical and pharmaceutical fields.

Enzymatic synthesis of N-succinyl chitosan-collagen peptide copolymer and its characterization.

Collagen peptide (COP) grafted N-succinyl chitosan (NSC) was prepared by using microbial transglutaminase (MTGase) as biocatalyst. The catalyzed reaction displayed high efficiency, high selectivity, mild reaction condition and environmental friendliness. The degree of substitution (DS) of N-succinyl chitosan-collagen peptide (NSC-COP)depended on the reaction time, the reaction temperature, the mass ratio of COP to NSC and the mass ratio of MTGase to NSC. NSC-COP showed excellent moisture absorption and retention properties. Antioxidant activities of varying DS and concentration of NSC-COP were evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl. Methylthiazol tetrazolium (MTT) assay exhibited that at a suitable concentration NSC-COP with different DS value could promote L929 mouse fibroblasts effectively. The animal experiment indicated that the wound covered with NSC-COP were completely filled with new epithelium within 2 weeks without any significant adverse side reactions. Therefore, the results may contribute to finding the application of NSC-COP in pharmaceutical and biomedical fields.

Sodium alginate conjugated graphene oxide as a new carrier for drug delivery system.

The biomedical applications of graphene-based materials, including drug delivery, have grown rapidly in the past few years. The aim of this present study is to enhance the efficiency and specificity of anticancer drug delivery and realize intelligently controlled release and targeted delivery. Graphene oxide (GO) was first prepared from purified natural graphite according to a modified Hummers' method. Then GO was functionalized with adipic acid dihydrazide to introduce amine groups, and sodium alginate (SA) was covalently conjugated to GO by the formation of amide bonds. The resulting GO-SA conjugate was characterized and used as a carrier to encapsulate the anticancer drug doxorubicin hydrochloride (DOX·HCl) to study in vitro release behavior. The maximum loading capacity of DOX on GO-SA was 1.843mg/mg and the drug release rate under tumor cell microenvironment of pH 5.0 was significantly higher than that under physiological conditions of pH 6.5 and 7.4. Methylthiazol tetrazolium (MTT) assay was applied to evaluate the Hela cells and NIH-3T3 cells cytotoxicity of GO-SA. Results showed that GO-SA had no obvious toxicity and GO-SA/DOX exhibits notable cytotoxicity to Hela cells. Cell uptake studies indicated that GO-SA could specifically transport the DOX into Hela cells over-expressing CD44 receptors and showed enhanced toxicity.

Preparation and characterization of hydroxypropyl chitosan modified with collagen peptide.

Collagen peptide (COP) had been grafted to hydroxypropyl chitosan (HPCS) by using microbial transglutaminase (MTGase) as biocatalyst. HPCS was synthesized from chitosan and propylene oxide under alkali condition. The chemical structures of derivative were characterized by FT-IR and 1H NMR spectroscopy. The process conditions were optimized from the aspects of the reaction time, the reaction temperature, the molar ratio of COP and the mass ratio of MTGase to HPCS. In this study, HPCS-COP could serve not only to reduce the loss of moisture but also to absorb the moisture, and the moisture absorption and moisture retention abilities were closely related to the degree of substitution (DS) values. In addition, with the DS and concentration increase of HPCS-COP, the radical scavenging activity increased in vitro antioxidant activity. Furthermore, the methyl thiazolyl tetrazolium assay (MTT) was applied to evaluate the biocompatibility of HPCS-COP, and the result indicated that HPCS-COP with the DS of 0.34 displayed pronounced cell viability at 50ppm. Therefore, the results suggest that HPCS-COP could be potential wound dressings for clinical applications.

Preparation and characterization of oxidized konjac glucomannan/carboxymethyl chitosan/graphene oxide hydrogel.

Polysaccharide hydrogels have been widely used as biomaterials in biomedical field. In this article, composite hydrogels were prepared through the Schiff-base reaction between the aldehyde of oxidized konjac glucomannan (OKGM) and the amino of carboxymethyl chitosan (CMCS). Meanwhile, different amount of graphene oxide (GO) was added as nano-additive. The hydrogels have been characterized by various methods including Fourier transform infrared spectroscopy (FT-IR) and Surface morphology (SEM). Through the observation of SEM, the hydrogels' scaffolds present a homogeneous interconnected pore structure after lyophilizing. In addition, the influence of different GO content on properties including gelation time, swelling ability, water evaporation rate and mechanical properties was investigated. The results indicate that the hydrogels have short gelation time, appropriate swelling ability and water evaporation rate. Especially, the compressive strength and modulus increase 144% and 296% respectively as the GO content increase from 0 to 5mg/ml. Moreover, MTT assay was applied to evaluate the biocompatibility of hydrogels. The result indicate that hydrogels with GO show better biocompatibility. Therefore, due to the appropriate water absorption capacity, the similar compressive modulus with soft tissue and excellent biocompatibility, the composite hydrogels have potential application in wound dressings.

Preparation and characterization of aminoethyl hydroxypropyl methyl cellulose modified with nisin.

Nisin grafted aminoethyl hydroxypropyl methyl cellulose (AEHPMC) was prepared by an enzyme-catalyzed reaction in the presence of microbial transglutaminase (MTGase). AEHPMC was synthesized with 2-chloroethylamine hydrochloride (CEH) which was as an intermediate reactant. The parameters, which influenced the NH2% and the degree of substitution (DS), including reaction time, reaction temperature and the mass ratio of the reactants were investigated. Antioxidant activities of AEHPMC-nisin were evaluated by the scavenging activity of hydroxyl and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. With the DS and concentration increasing of AEHPMC-nisin, the radical scavenging activity increased. The Methylthiazol tetrazolium (MTT) assay indicated that AEHPMC-nisin had low-toxicity to L929 cells. Therefore, the derivative of HPMC may show a promising potential application in biomedical, food and pharmaceutical fields.