壳聚糖/介孔生物活性玻璃多孔膜的制备和表征

背景：壳聚糖和介孔生物玻璃都具有良好的生物相容性和止血性能,但壳聚糖止血作用有限,介孔生物玻璃粉体方式止血,给应用带来不便。 目的：制备壳聚糖/介孔生物玻璃复合多孔膜并检测材料的性能。 方法：采用冷冻干燥法制备壳聚糖/介孔生物玻璃复合多孔膜。 结果与结论：通过冷冻干燥法可以实现壳聚糖和介孔生物玻璃的均匀复合。制备的复合多孔膜的孔隙分布较均匀;多孔膜具有很好的吸水性,吸水率的大小与壳聚糖和介孔生物玻璃质量比相关;多孔膜的孔隙率高。     

壳聚糖/磷酸三钙复合组织工程支架材料的制备及其性能*

背景：通过适当的工艺混合、加工来制备复合支架材料,可以弥补单一材料的不足,最大限度地满足组织工程的需要。 目的：制备壳聚糖/磷酸三钙复合支架,探讨其作为牙髓组织工程支架材料的可行性。 方法：壳聚糖粉末溶于微量冰醋酸溶液中,搅拌均匀,静置脱泡,预冷冻,交联,再次冷冻制成海绵状多孔壳聚糖/磷酸三钙支架。 结果与结论：冻干法制备的壳聚糖/磷酸三钙多孔支架平均孔隙率达85.78%,最高孔隙率达90%以上,孔径在100~300 μm,复合后的支架材料具有良好的韧性,当轴向压缩变形量超过5 mm时,材料仍然没有发生破坏。材料浸提液与牙髓细胞复合培养后,细胞毒性均为0级,由此可见壳聚糖/磷酸三钙复合材料具有良好的生物相容性、细胞亲和性和一定的力学性能,满足生物材料基本要求。     

酸性成纤维细胞生长因子/胶原蛋白复合海绵的研制及其组织相容性

我们以牛跟腱和酸性成纤维细胞生长因子(acidic fibroblast growth factor,aFGF)为原料,研制了一种新型的创伤敷料--aFGF/胶原蛋白复合海绵,并检测了其物理性能和组织相容性,特别是在血液相容性方面,研究其作为医用生物材料的安全性.结果显示:制备的高剂量和低剂量aFGF/胶原蛋白复合海绵的急性毒性试验、刺激性试验结果均为阴性;复钙试验表明aFGF/胶原蛋白复合海绵复钙时间较长,具有较好的抗凝特性;溶血试验表明复合海绵对红细胞的破坏很小,符合生物材料的溶血性要求;血小板黏附试验表明aFGF/胶原蛋白复合海绵的血小板黏附量较少且未被激活,对血小板没有明显的破坏作用.结果表明,aFGF/胶原蛋白复合海绵具有较好的组织相容性,具备临床应用的可能性.     

海藻酸钠/壳聚糖复合凝胶的制备与细胞毒性评价

背景：海藻酸钠和壳聚糖分别是聚阳离子和聚阴离子的天然高分子材料,二者可以互为交联剂形成复合凝胶,避免使用普通交联剂产生的细胞毒性。 目的：制备海藻酸钠壳聚糖复合凝胶并评价其体外细胞毒性。 方法：以0.25 mol/L乙酸溶解壳聚糖,制成质量浓度30 g/L溶液,再以0.1 mol/L的NaOH中和酸性得到壳聚糖絮状沉淀,将壳聚糖絮状沉淀与质量浓度3%海藻酸钠等比例混合,高频振动混匀,使二者形成复合凝胶。使用傅里叶变换红外光谱、扫描电镜分析观察凝胶成分和交联纤维网络结构。分别以海藻酸钠壳聚糖复合凝胶24,72 h浸提液、聚乙烯24,72 h浸提液及苯酚溶液培养L-929细胞,体外检测其细胞毒性。 结果与结论：傅里叶变换红外光谱检测到海藻酸钠壳聚糖复合凝胶特征性峰值改变,扫描电镜显示其内部形成丰富间隙的空间网络结构。浸提液法检测海藻酸钠壳聚糖复合凝胶的细胞毒性为合格,表明海藻酸钠/壳聚糖复合凝胶具有成为组织工程支架材料的良好条件。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

温敏性壳聚糖止血膜的止血作用及体内降解吸收

背景：尽管温敏性壳聚糖是壳聚糖的一种,但其止血效果、组织相容性及体内代谢吸收情况还需要验证。目的：探讨温敏性壳聚糖止血膜的止血作用、体内降解和组织相容性。方法：取SD大鼠48只,随机均分为4组,同时进行两种实验：①制作肝脏创面出血模型,其中3组分别采用温敏性壳聚糖止血膜、纤维素止血棉和明胶海绵止血材料贴敷大鼠肝创面止血,以不做任何处理的为空白对照。记录出血时间及出血量。②在上述3组大鼠的股四头肌内分别再植入对应的止血材料,空白对照组不植入任何材料。术后1,2,3,4,6周取两处创面行大体观察,术后4周行苏木精-伊红染色和电镜观察。结果与结论：温敏性壳聚糖组、纤维素组止血时间和出血量少于空白对照组、明胶海绵组(P < 0.05)。温敏性壳聚糖止血膜于术后6周完全降解,纤维素止血棉于术后3周完全降解,明胶海绵于术后2周完全降解。温敏性壳聚糖组肝小叶结构完整,肝细胞结构基本正常,肿胀轻,炎症细胞浸润程度轻,电镜显示整个肝细胞外形结构清楚,细胞核无破损,细胞器良好;肌肉纤维结构完整,炎症细胞浸润程度轻,电镜显示肌纤维走向整齐,肌细胞核形态正常,细胞器良好。可见温敏性壳聚糖止血膜具有较好的止血作用和组织相容性。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

胶原/壳聚糖复合纳米纤维膜引导骨再生的细胞学研究

采用静电纺丝技术制备胶原/壳聚糖复合纳米纤维膜,研究其作为引导骨再生生物膜的细胞生物相容性及诱导成骨性。以乙酸为溶剂,聚环氧乙烯(PEO)为增塑剂,采用静电纺丝技术制备胶原纳米纤维膜及不同比例的胶原/壳聚糖复合纳米纤维膜(胶原、壳聚糖、PEO质量比5∶1∶4,5∶2∶3,5∶4∶1),电子显微镜观察4种纳米纤维膜的表面形态;将骨髓间充质干细胞种植于胶原纳米纤维膜及表面形态较好的胶原/壳聚糖纳米纤维膜上,通过MTT法、碱性磷酸酶检测、细胞内胶原检测、免疫荧光染色及茜素红染色法观察,研究其细胞生物相容性及诱导成骨性。扫描电子显微镜观察胶原纳米纤维膜及质量比为5∶1∶4的胶原/壳聚糖复合纳米纤维膜的纤维光滑,直径均一。MTT法检测显示,胶原纳米纤维膜和胶原/壳聚糖复合纳米纤维膜均可促进骨髓间充质干细胞的粘附和增殖。细胞培养14 d后,胶原/壳聚糖复合纳米纤维膜上细胞内胶原含量检测为2.02 mg/gport,高于胶原纳米纤维膜组的1.63 mg/gport胶原含量(P<0.05),且胶原/壳聚糖复合纳米纤维膜上细胞内碱性磷酸酶、骨钙素及钙化结节的形成均高于胶原纳米纤维膜组。胶原/壳聚糖复合纳米纤维膜可促进骨髓间充质干细胞的增殖和分化,有望应用于骨再生的研究。     

碱性成纤维细胞生长因子/双层胶原基复合材料制备及其生物安全性

背景：胶原特殊的分子结构和生物活性有利于多种细胞黏附、增殖和分化,并可降解为新生组织提供足够空间。 目的：制备一种复合负载碱性成纤维细胞生长因子的壳聚糖-肝素纳米粒子双层胶原基复合材料,并评价其生物安全性。 方法：制备交联风干胶原膜和交联冻干胶原膜。将壳聚糖-肝素纳米粒滴于交联冻干胶原膜上,再将湿态交联风干胶原膜置于复合纳米粒子的交联冻干胶原膜上风干,即碱性成纤维细胞生长因子/双层胶原基复合材料。采用急性全身毒性试验、溶血试验、热原试验和细胞毒性试验评价其生物安全性。 结果与结论：碱性成纤维细胞生长因子/双层胶原基复合材料为双层结构,一侧表面致密,另一侧疏松多孔。在其中间负载碱性成纤维细胞生长因子的壳聚糖-肝素纳米粒子呈不规则球形分布于胶原膜内侧面;急性全身毒性试验、热原试验、溶血试验均为阴性,细胞毒性为0级。说明碱性成纤维细胞生长因子/双层胶原基复合材料具有良好的生物安全性,对机体无毒,符合ISO 10993-1评价标准。     

藻酸钙敷料的促凝血机制

背景：藻酸钙敷料近年来被广泛应用于手术止血、外伤止血、鼻腔术后止血、穿刺部位止血等,但有关其止血机制的国内外研究较少。 目的：初步探讨藻酸钙敷料的促凝血机制。 方法：将人抗凝血分别滴加至藻酸钙敷料、纳吸棉与医用棉纱布上,室温静置2 min,扫描电镜下观察材料与血液的相互作用;在人红细胞悬液中分别加入藻酸钙敷料、纳吸棉与医用棉纱布,静置15 s,扫描电镜下观察材料与红细胞的相互作用;在人红细胞中分别加入10,5,2.5 g/L的藻酸钙敷料浸提液,观察作用30,60,120 min的红细胞沉降率;在人富血小板血浆中分别加入10,5,2.5 g/L的藻酸钙敷料浸提液,37 ℃孵育10 min,流式细胞仪检测CD62P阳性血小板百分率。 结果与结论：藻酸钙敷料与抗凝血接触后可见致密的纤维蛋白网形成,其中网罗大量血细胞;纳吸棉组与医用棉纱布组仅见少量红细胞及血小板黏附。藻酸钙敷料与红细胞相互作用后可见红细胞变形,有伪足样改变,纳吸棉组与医用棉纱布组红细胞形态无变化。藻酸钙敷料浸提液呈剂量与时间依赖性提高红细胞沉降率,组间两两比较差异有显著性意义(P < 0.01);藻酸钙敷料浸提液呈剂量依赖性提高CD62P阳性血小板百分率,组间两两比较差异有显著性意义(P < 0.01)。表明藻酸钙敷料可通过释放钙离子、引起红细胞聚集和变形、活化血小板等促进止凝血过程。 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

明胶海绵颗粒和壳聚糖α,β-甘油磷酸凝胶微球在肺结核咯血应用中的对比北大核心

背景:文献报道显示,明胶海绵颗粒和壳聚糖/α,β-甘油磷酸凝胶微球在肺结核咯血中具有较高的应用前景。目的:观察明胶海绵颗粒和壳聚糖/α,β-甘油磷酸凝胶微球在肺结核咯血中的应用效果。方法:取40只昆明小鼠,采用雾化吸入感染装置构建肺结核咯血模型,随机分为2组,分别采用明胶海绵颗粒、壳聚糖/α,β-甘油磷酸凝胶微球进行栓塞止血治疗,治疗后15,30 d,观察体质量变化、止血时间、止血有效率、心肌相关指标及肺结核组织病理变化。结果与结论:(1)壳聚糖/α,β-甘油磷酸凝胶微球组治疗后15 d的体质量高于明胶海绵组(P<0.05);(2)壳聚糖/α,β-甘油磷酸凝胶微球组止血有效率高于明胶海绵组(P<0.05),止血时间短于明胶海绵组(P<0.05);(3)两组N端BNP前体、肌酸激酶同工酶及肌酸激酶水平比较差异无显著性意义(P>0.05);(4)壳聚糖/α,β-甘油磷酸凝胶微球组材料周围淋巴细胞浸润,存在坏死病灶,材料上存在大量活性细胞;明胶海绵颗粒组材料上存在少许淋巴细胞,存在坏死病灶;(5)结果表明,将壳聚糖/α,β-甘油磷酸凝胶微球应用于肺结核小鼠动物模型中可获得更好的止血效果。     

聚乳酸-羟基乙酸共聚物/Ⅰ型胶原/壳聚糖人工硬脊膜在兔脊髓损伤模型中的应用*☆

背景：自体组织、异体组织、动物来源的硬脊膜替代材料都难达到降低脊髓损伤后致残率与致死率的修复结果。 目的：观察聚乳酸-羟基乙酸共聚物/Ⅰ型胶原/壳聚糖人工硬脊膜修复大白兔脊髓损伤的疗效。 方法：70新西兰大白兔随机分为4组：假手术组(n=10)：单纯切除椎板,不损伤脊髓;模型组(n=20)：脊髓损伤硬脊膜缺损后未进行修复;壳聚糖组(n=20)：脊髓损伤硬脊膜缺损处植入壳聚糖人工硬脊膜;复合膜组(n=20)：脊髓损伤硬脊膜缺损处植入聚乳酸-羟基乙酸共聚物/Ⅰ型胶原/壳聚糖人工复合膜。 结果与结论：脊髓损伤24 h后,壳聚糖组和复合膜组运动功能评分均明显高于模型组(P < 0.01),复合膜组运动功能评分高于壳聚糖组(P < 0.05)。脊髓损伤之后潜伏期均有明显延长,模型组、壳聚糖组、复合膜组潜伏期明显高于假手术组,在6 h各组潜伏期有明显增加,在24 h左右到达高峰,而后开始逐渐下降,脊髓损伤2 d后模型组、壳聚糖组、复合膜组潜伏期差异无显著性意义。各组细胞凋亡率均大于假手术组(P < 0.05),损伤后6,24 h壳聚糖组和复合膜组细胞凋亡率均明显低于模型组(P < 0.05)。结果提示在大白兔脊髓损伤模型中应用聚乳酸-羟基乙酸共聚物/Ⅰ型胶原/壳聚糖人工硬脊膜有利于脊髓损伤恢复。       

胶原/壳聚糖复合膜的制备及止血效果的研究

目的以胶原和壳聚糖制备复合膜,检验其止血效果,并探讨其止血原因.材料与方法以酸解法从牛腱中提取胶原,用甲壳素制得壳聚糖,以胶原和壳聚糖制成复合膜,通过动物实验测不同配比的复合膜对出血创面的止血时间,并与其它止血材料做对比.结果各种配比的复合膜的止血效果均比明胶等一般止血材料好.结论胶原/壳聚糖复合膜有良好的止血作用,可望在外科手术上得到广泛应用.     

Development of a chitosan-based wound dressing with improved hemostatic and antimicrobial properties

Hemorrhage remains a leading cause of early death after trauma, and infectious complications in combat wounds continue to challenge caregivers. Although chitosan dressings have been developed to address these problems, they are not always effective in controlling bleeding or killing bacteria. We aimed to refine the chitosan dressing by incorporating a procoagulant (polyphosphate) and an antimicrobial (silver). Chitosan containing different amounts and types of polyphosphate polymers was fabricated, and their hemostatic efficacies evaluated in vitro. The optimal chitosan-polyphosphate formulation (ChiPP) accelerated blood clotting (p = 0.011), increased platelet adhesion (p=0.002), generated thrombin faster (p = 0.002), and absorbed more blood than chitosan (p < 0.001). Silver-loaded ChiPP exhibited significantly greater bactericidal activity than ChiPP in vitro, achieving a complete kill of Pseudomonas aeruginosa and a > 99.99% kill of Staphylococcus aureus consistently. The silver dressing also significantly reduced mortality from 90% to 14.3% in a P. aeruginosa wound infection model in mice. Although the dressing exerted severe cytotoxicity against cultured fibroblasts, wound healing was not inhibited. This study demonstrated for the first time, the application of polyphosphate as a hemostatic adjuvant, and developed a new chitosan-based composite with potent hemostatic and antimicrobial properties.     

几丁糖/海藻酸敷料止血性能的实验研究

目的研究一种新型敷料：几丁糖／海藻酸敷料（本项目组自行研制，已申请国家专利）的止血性能。方法取新西兰兔4只，在背部两侧对称性剪5个直径1cm的圆型创口，分别与创面大小相当的几丁糖／海藻酸敷料和明胶海绵止血，观察与创面的粘附情况，记录出血时间：止血停止后，将几丁糖／海藻酸敷料和明胶海绵放入预先配制好的氰化高铁血红蛋白检测试剂中仔细清洗，用分光光度计在540nm波长处光度比色，测出的Hb光度吸收值表示出血量。结果几丁糖／海藻酸敷料与创面粘附较好，几丁糖／海藻酸敷料、明胶海绵组的出血时间分别为87.7±19.1妙、170.7±22.6妙，Hb光度吸收值分别为1.131±0.44、1.733±0.733，经统计学分析，两组数据都有显著性差异（P〈0.01），几丁糖／海藻酸敷料组明显优于明胶海绵组。结论几丁糖／海藻酸敷料具有较好的止血性能。     

Fabrication and characterization of Chinese giant salamander skin composite collagen sponge as a high-strength rapid hemostatic material

Chinese giant salamander (CGS) has high medicinal value and long history of clinical use in ancient China. In this study, CGS skin (CGSS) collagen was extracted and purified to prepare collagen sponge by freeze-drying. TEMPO oxidized microfibrillated cellulose (TEMPO-MFC) and genipin were adopted to improve the mechanical properties of collagen sponge. The hygroscopicity, porosity, mechanical properties, hemostatic performance, morphology, and biodegradability of the resultant sponges were investigated in detail. The results indicated that CGSS collagen was type I collagen with intact triple-helical structure, and the prepared sponge had porous structure and excellent hemostatic performance with procoagulant ratio of 53.28%. However, the CGSS collagen sponge showed low tensile strength (TS) of 98.80?KPa, compression strength (CS) of 1.48?KPa, and elongation at break (E) of 4.72%. Incorporating 2.5% TEMPO-MFC into the native CGSS collagen sponge resulted in an increase of 188.26% in TS to 284.80?KPa, 166.89% in CS to 3.95?KPa, and 73.52% in E to 8.19%. The improvements were attributed to the physical filling of TEMPO-MFC in cavity and cavity wall of collagen sponge and the stable chemical linkage between carboxyl of TEMPO-MFC and amino group of collagen which effectively improved the toughening of sponge and formed good interface bonding, respectively. Subsequent 0.3% genipin treatment further improved the TS to 605.00?KPa and the CS to 8.66?KPa as a result of crosslinking reaction. Moreover, the composite reinforcing also improved the anti-degradation ability and procoagulant ratio of collagen sponge. All results suggested that the TEMPO-MFC toughened and genipin crosslinked CGSS composite collagen sponge is a promising rapid hemostatic material with high-strength and can be applicated in biomedical field.     

生物止血材料在妇产科手术中的应用

背景：良好的生物敷料或纱布可直接促进凝血过程,不仅可用于广泛渗血创面,且在一些常用的妇产科手术中能有效降低渗血率。 目的：评价不同生物止血敷料及纱布的材料学性能及应用于妇产科切口的生物相容性,寻找符合不同切口创面需要的止血材料。 方法：采用电子检索的方式,在万方数据库(http://www.wanfangdata.com.cn/)中检索1999-01/2011-04有关妇产科生物止血材料应用的研究文章,关键词为“妇产科,生物材料,止血敷料,纱布,胶原/壳聚糖”,排除重复研究、普通综述或Meta分析类文章,筛选纳入30篇文献进行评价。 结果与结论：近几年国内外生物医用可吸收止血材料主要包括纤维蛋白胶、壳聚糖、明胶海绵、氰基丙烯酸酯类组织胶、氧化纤维素和氧化再生纤维素等。各种止血性伤口急救材料都有各自的特点,但在妇产科应用的选择上,应考虑多方面因素,包括手术部位、出血部位、切口形态大小、不同渗/出血情况的填塞要求、不同止血材料的自身性能及与机体的相容性等。但因目前尚无完全符合理想标准的材料,因此开发新的快速止血和与宿主相容性良好的止血材料及复合材料势在必行。     

The inhibition of glioma growth in vitro and in vivo by a chitosan/ellagic acid composite biomaterial

This study has developed a chitosan-based delivery system to locally administer ellagic acid for brain cancer treatment. We fabricated chitosan/ellagic acid composite films with various concentrations of ellagic acid. In vitro release study was performed by using a UV spectrophotometer, and enzymatic degradation rate was determined by analyzing the increased free amino groups. Viability of brain cancer cells (human U87 glioblastomas and rat C6 glioma cells) was measured via direct and indirect cell culture on the films by MTS assay. Caspase-3 activation, Western blot for p53, and anti-angiogenesis assays were also examined. In the in vivo study, GFP-tagged rat C6 glioma cells were implanted subcutaneously at the right flank region of nude mice and treatments were initiated by implanting the films subcutaneously. Tumor growth was evaluated by measuring tumor volume using a caliper, an ultrasound machine, and an optical imaging system. The chitosan/ellagic acid composite films were enzymatically degradable and exhibited a sustained slow release of ellagic acid. These materials could inhibit the cancer cell growth in an ellagic acid concentration-dependent manner by inducing apoptosis of cancer cells as well as suppressing angiogenesis. These materials also significantly suppressed tumor tissue growth in vivo.     

介孔二氧化硅微球的淀粉复合止血敷料

背景：止血是外伤急救的重要环节。 目的：研制一种新型的介孔二氧化硅微球/淀粉复合止血敷料,并观察其止血效果。 方法：采用溶胶-凝胶法,以三嵌段共聚物pluronic(P123)为模板剂,合成孔径在5 nm左右的介孔氧化硅微球,将其与淀粉复合,制备介孔氧化硅微球/淀粉复合止血敷料,通过动物实验观察复合材料的止血性能。 结果与结论：介孔氧化硅微球/淀粉复合材料不仅具有很强的吸水性能,而且还具有明显的体外凝血性能,能显著地缩短部分凝血活酶时间和凝血酶原时间。介孔氧化硅微球/淀粉复合材料能够阻止兔背部皮肤及肝脏伤口的流血和缩短其流血时间,具有明显的止血效果。     

胶原/壳聚糖止血敷料在外科伤口中的应用

背景：壳聚糖与胶原联合可更有效地止血。 目的：评价胶原/壳聚糖止血敷料的材料学性能及应用于外科伤口的生物相容性。 方法：以“生物材料,止血敷料,纱布,胶原/壳聚糖,生物相容性”为中文关键词,以“biomaterial;hemostatic material;bioresorbable material;hemostasis effect;hemostatic mechanism”为英文关键词,采用计算机检索2000-01/2010-06与生物敷料、胶原/壳聚糖止血材料在伤口或创面止血过程中应用相关的文献。 结果与结论：壳聚糖独特的生物学特性,具有广谱抑菌、促进上皮细胞生长及止血,促进创面愈合的作用,在体内具有良好的生物降解性与组织相容性,可用于指端损伤和肉芽创面的治疗,如制成伤口敷料、可吸收缝线、止血材料、防粘连剂、药物缓释及组织工程支架,用于平战时伤口的处理。     

烷基化壳聚糖的制备及止血效果

BACKGROUND: 18-Alkylated-chitosan has been proved to exhibit a good coagulation capacity through hydrophobic modification. OBJECTIVE: To improve the adhesion between the material and the wound through the introduction of alkylated-chitosan molecules. METHODS: The alkyl group was introduced in the chitosan by potentiodynamic method to prepare the alkylated-chitosan with different substitution degrees (7%,16%, 26% and 40%), and then their structure, viscosity, porosity, water absorption, contact angle and in vitro coagulation capacity were detected. Thirty New Zealand rabbits were enrolled, modeled into the left femoral artery hemorrhage, and randomized into six groups, including four experimental groups, positive control and control groups, followed by treated with alkylated-chitosan sponges with different degrees of substitution, absorbable hemostatic gauze and chitosan sponge, respectively. Afterwards, the blood loss and clotting time were observed. RESULTS AND CONCLUISON: With the degree of substitution increased, the viscosity of alkylated-chitosan increased firstly and then decreased, the porosity and water absorption decreased gradually, and the contact angle on a rise. Compared with chitosan, different alkylated-chitosans showed a better henostatic effect in vitro, especially the alkylated-chitosan with 16% substitution degree. The blood loss and clotting time in the experimental groups except that the alkylated-chitosan with 7% substitution degree were significantly lower than those in the control group (P < 0.05); the bold loss in the alkylated-chitosan with 40% substitution degree group was significantly lower than that in the positive control group (P < 0.05). These findings suggest that the alkylated-chitosan with 40% substitution degree exhibits the best hemostatic effect in vivo.