Biological Evaluation Of Spray External Fixation Materials-dextran-based Polyurethane

Objective:To explore the dextran-based polyurethane bio-security that might substitute plaster bandage,splints for orthopedic external fixation materials. In accordance with national standards-biological evaluation of medical devices standard requiring a series of experiments carry out its early bio-safety evaluation for clinical application to provide reliable theoretical basis.Methods:According to GB/T 16886-2,5,10,11 in national evaluate criteria of medical devices materials, we selected a serial trial in vivo to assess the safety of dextran-based polyurethane combined with dextran-based polyurethane intended for a particular purpose. In the study, four methods included acute dermal toxicity test, vitro cytotoxicity test, irritation test and the guinea pig maximization test. Acute dermal toxicity test:using the extract of acute dermal toxicity test method, observed in guinea pigs 7 d after external application of life habits,weight changes,and to line the liver histology was also examined to determine the toxicity of materials; Skin irritation test:using a direct contact method, observed skin changes after contacted after 3 d on white hair rabbit, calculated of primary stimulation index (PII), assessment of stimulation type; Sensitization experiments:using the maximum dose of allergen, observed the sensitization after stimulated guinea pigs with extracts, calculated sensitization rate, assessed the level of sensitization; Cytotoxicity test:using MTT, observed cell growth,proliferation on the L-929 mouse fibroblast, after 2,4,7 d domesticated the OD value, calculated RGR, assess toxicity levels.Result:(1) acute dermal toxicity test:The activities of animal had no significant difference, HE staining of liver was no significant difference, and body weight was no significant difference between the experimental group and negative group (P>0.05). The observed dialogue toxic response do not produce in the material extracts of guinea pigs.(2) dermal sensitization:two rabbits were barely visible erythema after removing material in 0 h at broken skin group, PII was 0.33,24 h hours after the still strained, saw a rabbit returned to normal in the 48h after the skin, PII was 0.17at 72 h Another observation of a rabbit skin to recover, no edema, erythema, PII was 0, PII were 0-0.49, indicating that the material had a very slight change stimulation. (3) skin irritation test:observed primary irritate index in rabbits at different times is very small range (0-0.49). A small amount of broken skin is observed erythema within 48 h, but the primary irritate index is still a very slight extent, experimental materials, non-irritating experimental materials, non-irritating; (4) cytotoxicity test:the relative value of the rate of cells had no difference among 50%,100% extract of different concentrations of the experimental group with control group, there were significant differences to the positive group. Cell toxicity≤1 level,evaluation normal, non-toxic effect on L-929 cells.Conclusion:A series of this study show that dextran-based polyurethane with a non-toxic, non-stimulating, non-allergenic, and having no effect on cell proliferation, had a good bio-security and can be use on clinical.