两种消毒方法对壳聚糖温敏凝胶物理性能及生物学特性影响的研究

目的:比较不同消毒方法对壳聚糖温敏凝胶物理性能及生物学特性的影响。方法:采用常规消毒法(壳聚糖-盐酸液高温高压消毒)和改进消毒法(壳聚糖粉单独高温高压消毒)制备壳聚糖温敏凝胶,分别检测其凝胶化时间、粘度;通过扫描电镜观察2组壳聚糖温敏凝胶的超微结构;在2组壳聚糖温敏凝胶表面培养第三代人牙周膜细胞,倒置荧光显微镜观察凝胶表面细胞活性;用2组壳聚糖温敏凝胶浸提液培养第三代人牙周膜细胞,MTT法检测细胞增殖情况。结果:改进组壳聚糖温敏凝胶凝胶化时间5～6 min稳定,常规组壳聚糖温敏凝胶凝胶时间为10～30 min不等;改进组的壳聚糖温敏凝胶初始粘度为(9.94±0.38)Pa.s,在37℃环境下其粘度随时间延长而增加,10 min后达(50.25±0.96)Pa.s,此后趋于平稳。常规组初始粘度为(0.90±0.45)Pa.s,其粘度随时间延长增加不明显,15 min时仅为(4.05±0.72)Pa.s,2组各时间点间均有显著差异(P<0.05);扫描电镜观察2组壳聚糖温敏凝胶均呈三维立体网状多孔结构,常规组孔径为10～48.33μm,改进组孔径为0.385～2μm。人牙周膜细胞不仅在2组壳聚糖温敏凝胶表面生长良好,而且在其浸提液中也均增殖正常。结论:改进消毒方法制备的壳聚糖温敏凝胶凝胶化时间更短,粘度更大,与常规消毒方法一样具有良好的生物相容性。     

高温高压对壳聚糖／甘油磷酸钠温敏凝胶释药性能的影响

目的：研究高温高压后的壳聚糖／甘油磷酸钠凝胶温敏、释药性能。方法：观察不同比例的壳聚糖和甘油磷酸钠混合液的凝胶时间、pH值变化。粘度测试比较不同比例壳聚糖／甘油磷酸钠混合液粘度变化。在37℃形成凝胶后,观察该体系作为奥硝唑药物模型载体的释药性能。结果：随着壳聚糖／甘油磷酸钠混合液中甘油磷酸钠的比例增加,溶液pH值增加,在37℃下,壳聚糖／甘油磷酸钠凝胶时间缩短,但当壳聚糖／甘油磷酸比例为2：1、1：1时,溶液不凝胶。粘度实验表明,4种比例（9：1、8：1、7：1、6：1）壳聚糖／甘油磷酸溶液随着时间增加,粘度明显增加,到10 min后粘度基本不变化,9：1比例组粘度最大为（53±0．9）Pa·s。药物释放实验表明,以奥硝唑为释药模型,该凝胶可持续释放200 min以上。结论：改进消毒方法后的壳聚糖／甘油磷酸钠,增加甘油磷酸钠比例可以提高溶液pH值,可在37℃下快速形成凝胶。该凝胶具有温敏性,具有缓慢释放药物能力。     

黄芩苷和牛血清白蛋白双缓释制剂的制备及释药性能检测

目的:将黄芩苷和牛血清白蛋白(bovine serum albumin,BSA)载入壳聚糖温敏凝胶,构建双缓释体系,检测凝胶对药物的体外释放情况。方法:采用乳化缩聚法制备黄芩苷-明胶微球(gelatin microspheres,GMS);用不同配比的壳聚糖溶液和β-甘油磷酸钠(β-glycerophosphate,β-GP)溶液制备壳聚糖温敏凝胶,观察在37℃的成胶情况,选择最佳配比;在此基础上,将不同浓度的黄芩苷-GMS与BSA共混于壳聚糖凝胶溶液,测定载药后的成胶情况及黄芩苷和BSA的体外释放情况。结果:成功制备了黄芩苷-GMS,载药率5.62%,包封率72.05%;1.8%壳聚糖溶液与9%的β-GP混合10min后可获得状态良好的凝胶;加载两种药物后的凝胶溶液相转变时间未发生改变;30d时低浓度组累积释放了63.79%,两个较高浓度组分别释放了74.86%、77.63%。结论:壳聚糖温敏凝胶可以同时负载黄芩苷-GMS和BSA两种药物,在室温下呈溶液状态,37℃下经过10min可转变成半固体凝胶,在体外释药可达30d。黄芩苷和牛血清白蛋白双缓释制剂的制备和释药性能检测为牙周组织修复再生药物的研制提供了基础。     

骨形成蛋白和氯己定双缓释的壳聚糖温敏凝胶用于牙周组织再生的实验研究

目的 观察双重缓释骨形成蛋白和氯己定的壳聚糖温敏载药凝胶修复牙周组织缺损的效果.方法 制备犬前磨牙Ⅱ度根分叉牙周组织缺损模型,分5组于牙周组织缺损处分别注入:①自制的双重缓释骨形态发生蛋白和氯己定的载药凝胶(T1组);②仅加载缓释骨形态发生蛋白的壳聚糖温敏凝胶(T2组);③仅加载缓释氯己定的壳聚糖温敏凝胶(T3组);④未加载任何药物的壳聚糖温敏凝胶(C1组);⑤不注射任何载体及药物(C0组).术后不使用抗生素,常规护理,8周后取材进行大体及组织学观察牙龈炎性反应及牙周组织再生情况.结果 应用壳聚糖温敏凝胶,可以方便地通过注射方式局部安放载体.T1组新生牙槽骨高度平均达到缺损高度的99.2%,T2组新生牙槽骨高度平均达到缺损高度的87.8%,T3组为63.6%,C1组为37.0%,CO组为34.3%;牙龈炎性反应细胞浸润情况显示T1及T3组炎细胞数量明显少于其他组.结论 自制双缓释壳聚糖温敏凝胶有效发挥了骨形态发生蛋白和氯己定各自的作用,并且在牙周组织再生治疗中具有简便性和有效性.     

温敏型壳聚糖/甘油磷酸钠缓释胰岛素凝胶系统的制备

目的:初步探讨制备温敏性壳聚糖/甘油磷酸钠载胰岛素凝胶系统.方法:应用壳聚糖与甘油磷酸钠制备具有温敏性的载有胰岛素的凝胶体系,从凝胶体系的pH值、粘度测定、胶凝时间研究不同配比、不同pH值对壳聚糖/甘油磷酸钠(CS/β-GP) 体系凝胶化性能的影响.结果:壳聚糖凝胶在室温(25℃)下呈液态,56% 甘油磷酸钠(β-GP)与3%壳聚糖(CS)在pH值6.8-7.2,37℃下凝胶化时间(GT) 从1h缩短到8-12min,凝胶形态良好,并且在负载胰岛素溶液后C/GP凝胶形态未受影响.结论:一定配比CS/GPS 体系在37℃具有快速凝胶化性能,在加入胰岛素后并未改变其温敏特性,为后续的温敏性壳聚糖/甘油磷酸钠载胰岛素凝胶系统的体外释药实验打下了基础.     

不同组分壳聚糖温敏凝胶材料理化性能评价

目的:评价不同组分壳聚糖温敏凝胶材料的理化性能。方法:先对壳聚糖粉高温高压消毒,然后壳聚糖溶液(0.1mol/L)和β-甘油磷酸钠(β-GP)溶液(1.83 mol/L)分别按照体积比9∶1和7∶1两种配比组分制备壳聚糖温敏凝胶。通过粘度变化、凝胶时间、溶胀率、降解率、微观结构等观察指标比较2种凝胶的性能差异。结果:凝胶时间9∶1组为(6.1±0.68)min,7∶1组为(4.98±0.5)min(P<0.05);初始粘度9∶1组为(9.95±0.40)Paos,7∶1组为(9.90±0.36)Paos(P>0.05),终粘度9∶1组为(50.05±1.06)Paos,7∶1组为(45.25±0.69)Paos(P<0.05);溶胀率9∶1组为(16.6±0.8)%,7∶1组为(16.9±0.7)%(P>0.05);含溶菌酶组的降解率(%)明显高于不含酶组(P<0.05),加酶组和不加酶组7∶1组降解均快于9∶1组(P<0.05)。扫描电镜结果显示9∶1组平均孔径为(1.01±0.62)μm,7∶1组的平均孔径为(0.79±0.44)μm(P>0.05)。结论:9∶1配比的壳聚糖温敏凝胶理化性能优于7∶1比例组。     

新型壳聚糖基引导骨再生膜的蛋白缓释性能研究

目的：制备负载牛血清白蛋白的壳聚糖/β-甘油磷酸钠(CS/β-GP)可吸收性膜,探讨其缓释蛋白的性能。方法：利用CS/β-GP体系的温敏相转变特性,同时向其中添加蛋白制成新型生物膜。进行膜厚度及拉伸强度等力学性能测试。利用BCA蛋白浓度试剂盒（加强型）检测不同时点的蛋白浓度,绘制膜的蛋白缓释曲线。结果：利用SPSS16.0统计分析软件进行分析,负载蛋白后复合膜的理化性能均未发生明显变化（P>0.05）。不同浓度的复合膜可缓慢释放蛋白12天以上,并且随着β-GP浓度的升高,蛋白缓释总量增大。结论：新型壳聚糖温敏凝胶膜可以作为蛋白缓释的载体,是在引导骨再生领域具有应用潜力的生物膜材料。     

碱性成纤维细胞生长因子/壳聚糖衍生物/胶原温敏型复合水凝胶促大鼠牙周组织再生的研究

目的 探讨不同种壳聚糖衍生物温敏型复合水凝胶作为支架材料应用于牙周组织工程的可行性。方法制备磺化壳聚糖（SCS）、磷酸化壳聚糖（PCS）及磷酸化磺化壳聚糖（PSCS） 3种具有不同生物学特性的壳聚糖衍生物,构建3种碱性成纤维细胞生长因子（bFGF）/壳聚糖衍生物/胶原温敏型复合水凝胶。选取20只雄性wistar大鼠,大鼠双侧上颌第一磨牙近中建立三壁骨袋,随机分为空白对照组、空白凝胶组、bFGF/SCS/胶原温敏型复合水凝胶组、bFGF/PCS/胶原温敏型复合水凝胶组、bFGF/PSCS/胶原温敏型复合水凝胶组,术后6周处死大鼠,采集标本,进行大体、苏木精-伊红染色、Masson染色观察。结果 术后6周,3种bFGF/壳聚糖衍生物/胶原温敏型复合水凝胶组与空白对照组在相对牙槽骨高度比值、相对上皮根向下移比及牙周组织再生分级计数等方面的差异均具有统计学意义（P<0.05）。结论 bFGF/壳聚糖衍生物/胶原温敏型复合水凝胶在牙周组织工程邻域具有良好的应用前景。     

氟化钠壳聚糖凝胶对乳牙釉质抗酸能力的影响

目的 本实验通过研究氟化钠壳聚糖温敏凝胶对乳牙牙釉质表面抗酸蚀的作用,初步探讨氟化钠壳聚糖温敏凝胶在防治早期龋中的应用可能性。方法 配制氟化钠壳聚糖温敏凝胶,观察其基本性能,使用氟离子选择电极检测壳聚糖氟化钠凝胶氟离子的释放速率。制备乳前牙试件,随机分成4组,分别为多乐氟组、氟化钠壳聚糖凝胶组、壳聚糖空白凝胶处理组和空白对照组,进行乳酸脱钙实验,离子火焰法测试洗脱出的钙离子浓度。SPSS19.0对不同组钙离子浓度进行方差分析,统计结果。结果 壳聚糖氟化钠凝胶,常温下为淡黄色清亮黏稠液体,37 ℃时转变为乳白色的果冻状凝胶。壳聚糖氟化钠凝胶4 h氟离子的释放率为70.22%。氟化钠壳聚糖凝胶处理的乳前牙釉质试件,其脱出的钙离子浓度为4.29 mg/L,低于壳聚糖空白凝胶组(7.20 mg/L)及空白对照组(7.34 mg/L),有统计学差异;但和多乐氟组(4.22 mg/L)没有统计学差异(P>0.05)。结论 氟化钠壳聚糖凝胶可以提高乳前牙的釉质抗酸能力,有应用于预防乳前牙早期龋的可能性。     

缓释骨形态发生蛋白-2的壳聚糖温敏凝胶促进牙周组织再生的实验研究

目的观察自制的加载重组人骨形态发生蛋白- 2（rhBMP- 2）的壳聚糖温敏凝胶修复牙周组织缺损的效果。方法选取3只健康雄性杂种犬制备前磨牙区人工Ⅱ度根分叉区组织缺损模型,随机分为空白对照组、空白凝胶组及载药凝胶组,术中先严密缝合组织瓣,然后对空白凝胶组及载药凝胶组区域分别注射先期配制并消毒好的空白凝胶和载药凝胶,术后8周取材行大体及组织学观察。结果载药凝胶组出现明显的牙周组织再生,而空白对照组和空白凝胶组仅有少量的牙周组织再生。载药凝胶组与空白对照组及空白凝胶组均有统计学差异（P<0.05）,空白对照组和空白凝胶组相比,没有统计学差异。结论载rhBMP- 2的壳聚糖温敏凝胶可有效促进牙周组织再生,同时简化手术操作,是一项有潜力的牙周组织再生手段。     

Growth factor release and enhanced encapsulated periodontal stem cells viability by freeze-dried platelet concentrate loaded thermo-sensitive hydrogel for periodontal regeneration

Periodontium regeneration is a highly challenging process as it requires the regeneration of three different tissues simultaneously. The aim of this study was to develop a composite material that can be easily applied and can sufficiently deliver essential growth factors and progenitor cells for periodontal tissue regeneration.Freeze-dried platelet concentrate (FDPC) was prepared and incorporated in a thermo-sensitive chitosan/β-glycerol phosphate (β-GP) hydrogel at concentrations of 5, 10, or 15?mg/ml. The viscosity of the hydrogels was investigated as the temperature rises from 25?°C to 37?°C and the release kinetics of transforming growth factor (TGF-β1), platelet-derived growth factor (PDGF-BB) and insulin-like growth factor (IGF-1) were investigated at four time points (1?h, 1?day, 1?week, 2?weeks). Periodontal ligament stem cells (PDLSCs) were isolated from human third molars and encapsulated in the different hydrogel groups. Their viability was investigated after 7?days in culture in comparison to standard culture conditions and non FDPC-loaded hydrogel.Results showed that loading FDPC in the hydrogel lowered the initial viscosity in comparison to the unloaded control group and did not affect the sol-gel transition in any group. All FDPC-loaded hydrogel groups exhibited sustained release of TGF-β1 and PDGF-BB for two weeks with significant difference between the different concentrations. The loading of 10 and 15?mg/ml of FDPC in the hydrogel increased the PDLSCs viability significantly compared to the unloaded hydrogel and was comparable to the standard culture conditions.Accordingly, it may be concluded that loading FDPC in a chitosan/β-GP hydrogel can offer enhanced injectability, a sustained release of growth factors and increased viability of encapsulated stem cells which can be beneficial in periodontium tissue regeneration.     

盐酸多西环素微球温敏凝胶剂的表征及对大鼠牙周炎的药效评价

目的：评价盐酸多西环素（ Doxycycline Hydrochloride,DXY）微球温敏凝胶剂（ DXY-MS-GEL）的体外特性和对大鼠实验性牙周炎的治疗效果。方法：通过胶凝化温度和体外释药曲线评价DXY-MS-GEL的体外特性。采用内毒素隔日注射法建立Wistar大鼠牙周炎动物模型。将大鼠随机分为3组,空白对照组不予处理,实验组给以自制的DXY微球温敏性凝胶,阳性对照组给以盐酸米诺环素（派丽奥）软膏,隔日注射1次×5。末次给药后1 d测定牙龈出血指数、牙周指数、牙周探诊深度、菌斑指数、牙槽骨丧失量,观察组织病理学切片。结果：DXY-MS-GEL在室温下为自由流动的液体,37℃的平均凝胶时间为1.1±0.3 min,可持续释药24 h,体外释药曲线符合Higuchi方程,R2＝0.9948。与空白对照组相比,实验组和阳性对照组各观测指标差异均具有统计学意义（ P＜0.05）,而实验组和阳性对照组之间对比差异无统计学意义。结论：DXY微球温敏性凝胶对牙周炎的局部治疗效果显著。     

钛种植体表面新型DNA水凝胶递送地塞米松诱导巨噬细胞M2极化的研究

目的:构建壳聚糖DNA水凝胶负载递送地塞米松(Dex),探索其在钛种植体表面对巨噬细胞M2极化的作用.方法:阳极氧化法(20 V)在钛表面制备纳米管(NT);将鲑鱼精双链DNA变性-退火-交叉配对形成预凝胶,与壳聚糖交联形成水凝胶,采用真空抽吸将凝胶加载到纳米管的管腔中;通过SEM、FTIR和体外释放试验检测其结构特征...     

pH‐Responsive Hydrogel With an Anti‐Glycation Agent for Modulating Experimental Periodontitis

Background: Stimulus‐responsive devices have emerged as a novel approach for local drug delivery. This study investigates the feasibility of a novel chitosan‐based, pH‐responsive hydrogel loaded with N‐phenacylthiazolium bromide (PTB), which cleaves the crosslinks of advanced glycation end products on the extracellular matrix. Methods: A chitosan‐based hydrogel loaded with PTB was fabricated, and the in vitro release profile was evaluated within pH 5.5 to 7.4. BALB/cJ mice and Sprague‐Dawley rats were used to evaluate the effects during the induction and recovery phases of periodontitis, respectively, and animals in each phase were divided into four groups: 1) no periodontitis induction; 2) ligature‐induced experimental periodontitis (group PR); 3) experimental periodontitis plus hydrogel without PTB (group PH); and 4) experimental periodontitis plus hydrogel with PTB (group PP). The therapeutic effects were evaluated by microcomputed tomographic imaging of periodontal bone level (PBL) loss and histomorphometry for inflammatory cell infiltration and collagen density. Results: PTB was released faster at pH 5.5 to 6.5 and consistently slower at pH 7.4. In the induction phase, PBL and inflammatory cell infiltration were significantly reduced in group PP relative to group PR, and the loss of collagen matrix was significantly reduced relative to that observed in group PH. In the recovery phase, PBL and inflammatory cell infiltration were significantly reduced, and significantly greater collagen deposition was noted in group PP relative to groups PR and PH at 4 and 14 days after silk removal. Conclusion: Chitosan‐based, pH‐responsive hydrogels loaded with PTB can retard the initiation of and facilitate the recovery from experimental periodontitis.     

Antibacterial properties of electron beam-sterilized Gutta-Percha cones

The purpose of the study was to determine the effect of electron beam sterilization on gutta-percha cones (GPCs) at different times after sterilization. An agar diffusion test was used with -one aerobic bacterium (Bacillus subtilis) and five oral anaerobic bacteria (Fusobacterium nucleatum, Peptostreptococcus micros, Porphyromonas gingivalis, Propionibacterium acnes, and Veillonella parvula). With each microorganism 30 agar plates were prepared, evenly distributed among three groups (group 1: unsterilized GPCs; groups 2 and 3: GPCs sterilized by electron beam irradiation 5 months and 5 yr before, respectively). One GPC of the selected group was placed in each plate. After incubation the area of inhibition was read on the agar plates. Inhibition of growth was significantly different for the tested microorganisms. However no significant difference was observed between the sterilized and unsterilized GPCs. Both the tested sterilized and unsterilized GPCs impair the growth of endodontic pathogens, with no influence of the time elapsed since sterilization.     

Experimental evaluation of cyclic fatigue resistance of four different nickel-titanium instruments after immersion in sodium hypochlorite and/or sterilization

NiTi instruments have a high risk of separation due to torsional or flexural fatigue (cyclic fatigue). Chemomechanical preparation, cleaning procedures, chemical disinfection and sterilization cause the corrosion of endodontic instruments that may weaken the fracture resistance of the instruments.

Objective

To assess the effects of NaOCl immersion and autoclave sterilization on the cyclic fatigue resistance of ProFile, FlexMaster, Mtwo and TwistedFiles NiTi instruments (tip size 25, 0.06 taper, n=160).

Material and Methods

The instruments (n=10 for each subgroup) were dynamically immersed in NaOCl; immersed in NaOCl and sterilized in one autoclave cycle; 5 cycles immersed in NaOCl and sterilized in autoclave and not immersed in NaOCl and not sterilized (control group). Dynamic cyclic fatigue resistance was tested. The number of cycles to failure (NCF) were statistically analyzed (P<0.05).

Results

Kruskall-Wallis test indicated significant differences among the tested instruments in terms of NCF (P=0.000). The mean NCF of Mtwo (556.75) was higher than that of the Twisted File, Flexmaster and ProFile, 483.1, 376.12, 365.25, respectively. NaOCl immersion and autoclave sterilization have no effect on the NCF values of the tested instruments (P>.05).

Conclusions

Cyclic fatigue resistance of the tested NiTi instruments cannot be adversely affected by NaOCl immersion and autoclave sterilization. Production process (TwistedFiles) or design (Twisted Files, FlexMaster, Mtwo and ProFile) of the instruments can influence their cyclic fatigue resistance.