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目的:探讨不同粒径大小对γ辐照中脱钙骨基质（demineralized bone matrix，DBM）中胶原结构的影响以及辐照保护剂的有效性。方法:取同一供体的冻干皮质骨，依据Urist改良法制备不同粒径的（0.5~1.0 mm、1.2~2.8 mm、3.3~4.7 mm及5.7~7.0 mm）DBM样品，按照不同剂量分为：0 kGy、15 kGy、25 kGy及25 kGy（辐照保护剂），真空密封后储存于-80℃冰箱待用。通过扫描电镜观察胶原表面形态，大体观察胶原表面结构损伤的程度；将样品按照0.2 g/ml生理盐水比例在50℃条件下72 h，利用浸提液颜色深度观察胶原被辐照损伤的程度；使用2，4-二硝基苯肼（吸光光度计法）测定样品中羰基含量；十二烷基硫酸钠聚丙烯酰胺钠凝胶电泳法（Sodium dodecyl sulfatepolyacrylamide gel electrophoresis，SDS-PAGE）测定样品中胶原分子量的变化；利用差示热量扫描法（differential scanning calorimetry，DSC）检测样品热变性温度以观察胶原热稳定性。结果:样品浸提液颜色与γ辐照剂量相关度较高，未辐照样品浸提液颜色清亮，而在同粒径下随辐照剂量加大浸提液黄色逐渐加深，5.7~7.0 mm粒径组颜色相对较浅；25 kGy组相比于25 kGy+保护剂组浸提液颜色加深。扫描电镜观察到γ辐照导致胶原结构紊乱，纤维断裂，随着辐照剂量增大损伤区域增多，当粒径增大时，损伤区域有减少的趋势；相比于25 kGy组，25 kGy+保护剂组胶原结构性破坏减少。差示热量扫描法得出样品热交换曲线，随着粒径增大，热变性温度有增高的趋势，粒径间对比有统计学差异（n F=189.4，n P<0.001）；同粒径间差异不明显。SDS-PAGE发现同粒径下γ辐照剂量愈大，胶原分子量愈小；同辐照条件下随粒径较小，高分子量胶原含量减少明显；225 kGy+保护剂组相比于25 kGy组，高分子量增多。羰基含量结果显示在同一粒径下，γ辐照使羰基含量增多，0.5~1.0 mm组（n F=13.631，n P=0.002），1.2~2.8 mm组（n F=6.390，n P=0.016），3.3~4.7 mm组（n F=5.630，n P=0.023），5.7~7.0 mm组（n F=4.150，n P=0.048）的差异均有统计学意义，不同粒径间随着粒径增大羰基含量逐渐减小但差异统计学意义（n F=0.560，n P=0.650）。n 结论:γ辐照与胶原的氧化损伤具有明显的剂量反应关系，随着γ辐照剂量的增加，胶原损伤程度逐渐增加；DBM的粒径大小影响着胶原对γ辐照的敏感度，随着粒径的减小，DBM颗粒更易被γ辐照损伤；辐照保护剂在辐照过程中对胶原有一定程度的保护作用。“,”Objective:To investigate the effects of different particle sizes on the collagen structure of demineralized bone matrix (DBM) and the effectiveness of dry ice as an irradiation protectant in the procedure of gamma irradiation.Methods:DBM samples with different particle sizes (0.5-1.0 mm, 1.2-2.8 mm, 3.3-4.7 mm and 5.7-7.0 mm) were prepared, and sterilized with several doses of gamma irradiation (0 kGy, 15 kGy and 25 kGy) at room temperature. Additionally, another group of DBM samples were sterilized with 25 kGy gamma irradiation with protective agent. Changes in surface and characteristics of collagen were observed by using scanning electron microscope (SEM), Sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE), differential scanning calorimetry (DSC) and carbonyl content.Results:The color of collagen extract indicated that oxidative damage is directly related to irradiation dose. SEM showed that the gamma irradiation caused collagen structure disorder and fiber breakage. As the irradiation doses increased, the damage area significantly increased. When the particle size increased, the damage area tended to decrease. The DSC showed that the thermal denaturation temperature of 5.7-7 mm, 3.3-4.7 mm, 1.2-2.8 mm and 0.5-1.0 mm were 142.8℃, 97.3℃,84.3℃ and 83.9℃, respectively. The differences of the thermal denaturation temperatures among the four particle sizes were statistically significant (n F=0.560, n P=0.650). Collagen structure was destroyed by gamma irradiation, resulting in a decrease in collagen molecular weight. While, large particle DBM had a tendency to resist radiation damage. There was a significant difference on the contents of carbonyl in collagen from same particle sizes of DBM with different irradiation dose. The carbonyl content gradually decreased with the increase of particle size, but the difference was not statistically significant (n F=0.560, n P=0.650).n Conclusion:The gamma irradiation and collagen oxidative damage have obvious dose-response relationship. With the increase of gamma irradiation dose, the degree of collagen damage increases. The sizes of DBM could affect the sensitivity of collagen to gamma irradiation. With the decrease of particle sizes, DBM particles are more susceptible to gamma irradiation damage. Additionally, dry ice, as a radiation protection agent, has a certain degree protection effect against radiation.