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 carboxymethylated carrageenan modified with collagen peptides.

The preparation of carboxymethyl κ-carrageenan collagen peptide (CMKC-COP) was via an imide-bond forming reaction between carboxyl groups in carboxymethyl κ-carrageenan (CMKC) and amino groups in collagen peptide in the presence of 1-ethyl-(dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy sulfosuccinimide (NHS). CMKC-COP products were verified with infrared spectroscopy (FT-IR). The results of degree of substitution (DS) of CMKC-COP was presented, which are depended on reaction time, molar ratio of collagen peptide to carboxymethyl κ-carrageenan and reaction temperature. The optimal reaction conditions were studied by means of single factor experiment. Also MTT assay was applied to evaluate the effects of CMKC-COP on proliferation of chick embryo fibroblasts. The animal experiment results indicated that the wound covered with CMKC-COP were completely filled with new epithelium within 2 weeks without any significant adverse side reactions. Therefore, the CMKC-COP showed the potentiality to repair skin in cosmetic, biomedical and pharmaceutical fields.

Preparation and characterization of quaternary ammonium chitosan hydrogel with significant antibacterial activity.

Quaternary ammonium chitosan (HACC)/polyvinyl alcohol (PVA)/polyethylene oxide (PEO) hydrogels were prepared using gamma radiation. The chemical structure of the hydrogels was characterized using FT-IR. The results revealed that HACC, PVA and PEO were perfectly compatible and interacted via the hydrogen bonds. As revealed by SEM, scaffolds with a homogeneous interconnected pore structure were obtained after lyophilizing the hydrogels. The influence of different radiation doses and weight ratios on properties including gel content, swelling ability, water evaporation rate and mechanical properties were investigated. It indicated that the hydrogels had the good swelling ability, water evaporation rate and mechanical properties. In vitro antibacterial activity assessment, the hydrogels exhibited a pronounced inhibitory effect against two bacteria (Staphylococcus aureus and Escherichia coli). Therefore, the hydrogels showed a promising potential to be applied as wound dressing.

Preparation and biological activity of quaternized carboxymethyl chitosan conjugated with collagen peptide.

Tissue repair is a spontaneous process which initiated on wounding. If this complex mechanism is disturbed or impaired, the use of biomaterials might increase the chance of successful healing. In this view, a water-soluble chitosan derivative, quaternized carboxymethyl chitosan (QCMC) was prepared and collagen peptides (COPs) were grafted to the backbone by carbodiimide method. The reaction conditions affecting the degree of substitution (DS) were studied including the mass ratio of collagen peptide to QCMC, reaction temperature and reaction time. The hydrogen peroxide-scavenging activity could be different by changing the DS, concentration and molecular weight. MTT assay was used to investigate the cell viability of the derivative. The results indicated that the introduction of collagen peptide into the QCMC improved its hydrogen peroxide-scavenging activity and cell viability with the DS and concentration increased. Therefore, QCMC conjugated with collagen peptides may prove beneficial to the process of the wound-healing.