| Biomedical polymeric materials played an important role in the field of functional polymer materials. Chitosan has widely applications in the medical materials for its biocompatibility and other special functions. Konjac glucomannan (KGM) was a rich resource in west China. The KGM/CHI blend materials were successfully produced by way of solution mixing. The structure and performance of the materials were evaluated by modern macromolecular research methods. The antibacterial effects and biocompatibility of the blend films and their irradiation-modified counterparts was primarily evaluated. The research provided an experimental basis for the application of the biomedical film materials.Main research results1 The condensed state structure and miscibility of the blend films were studied by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, and wide-angle X-ray diffraction. The IR spectra showed that the O-H stretching vibration (3440 cm-1) broadened and shifted to a lower wave number with the increase of konjac glucomannan, The O-H stretching vibration was shifted to 3430 cm-1 and broadened to 740 cm-1 in KC2 (KGM/CHI=8/2), it indicated that the occurrence of intermolecular hydrogen bonds between chitosan and konjac glucomannan molecules in the blend films occurred. Moreover, intermolecular hydrogen bonds were strongest in KC2. The scanning electron micrographs showed that the smooth and homogeneous cross-section morphology of KC2. However, the other blend films seemed rough and obvious phase separation took place in cross-section images. The WXRD showed that the crystallinities of the blend films increased with the increasing of the konjac glucomannan. DSC suggested that the difference in the decomposition temperature of konjac glucomannan and chitosan was the least in the KC2 curve. This also indicated that the blend film with an 80/20 mixing ratio of konjac glucomannan/chitosan derivate showed the highest miscibility and blend homogeneity, and those strong intermolecular hydrogen bonds took place between the chitosan and konjac glucomannan; thus the tensile strength also achieved the maximum in this ratio.2 The effects of radiation on the structure and the performance of the blend films were discussed in the range of 0-80KGy with emphasis on the performance of KC2. Little change in the mechanical properties was observed in the KGM film while prominently change was observed in CHI film.The mechanical properties achieved their maximum under the 10 KGy or 25 KGy dose, tensile strength of KC2 was enhanced by 40% after 10 KGy dose. IR analysis showed that no change happened in the primary group of the blend films after irradiation, the IR spectra of irradiation modified films were consistent with those of the films without radiation. SEM and XRD analysis indicated that new crystallite regions appeared because of the degradation of chitosan, and the effect of irradiation decreased with the increase of konjac glucomannan content. The results indicated that KGM has a remarkable inhibition on the deterioration of the CHI blend film during irradiation. Furthermore, the blend films could also be sterilized by irradiation.3 Antibacterial effects of the blend films were tested. The target bacteria were the primary pathogenetic bacteria in burn - E.coli, P.aeruginora and St.aereus. KGM/CHI blend film showed good antibacterial effects against E.coli, P.aeruginora and St.aereus. Antibacterial effects of the blend films decreased with the increase of the content of konjac glucomannan. After irradiation, there is no obvious change in the antibacterial effects against St.aereus of the blend films, but the antibacterial effects against E.coli and P.aeruginora increased significantly.4 The safety of KC2-25 was evaluated followed by Chinese standards (GB/T16886.1-2001). The safety evaluation results showed that KC2-25 did not have any cytotoxicity, and it was safe by in the test of the acute systemic toxicity. Skin irritation and sensitization tests showed that the skin original irritation and sensitization of KC2-25 was tiny. This indicated that KC2-25 blend film could be used as a highly safe medical dressing.5 In the KC2-25, for the intense intermolecular hydrogen bonds between the KGM and CHI in addition to good compatibility, the tensile strength of the film was prominently improved compared to the CHI film. The mechanic properties of the blend film were further improved by irradiation compared to the CHI film. At the same time, antibacterial activity against E.coli and P.aeruginora was also increased after the irradiation. By its good mechanical properties, biocompatibility, safety and low cost, the KC2-25 is a promising biomedical polymeric material.
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