草鱼鱼鳞胶原蛋白的凝胶性能研究

以草鱼鱼鳞为原料,分别提取鱼鳞中的酸溶性胶原蛋白(ASC)和酶溶性胶原蛋白(PSC),利用动态流变仪和物性分析仪开展胶原凝胶形成和凝胶性能的相关研究,并与哺乳动物来源的猪皮胶原(PC)相比较。实验结果表明,制备所得的3种胶原蛋白均为典型的Ⅰ型胶原并具有完整的3螺旋结构;蛋白浓度和体系pH值是影响胶原凝胶形成的重要因素。ASC形成凝胶的临界pH值为4.5,而PSC和PC为5,3种胶原蛋白凝胶形成的临界蛋白浓度均为0.5mg/mL。粘弹性分析和质构分析的实验结果表明,ASC容易形成一种硬度高但脆性大的凝胶,升高温度可导致其凝胶结构发生不可逆的破坏,而PSC和PC更容易形成一种硬度小但韧性好的凝胶,在低于蛋白变性温度的条件下升高温度可以有效提高凝胶硬度;胶原蛋白凝胶质构受蛋白浓度、体系pH值和蛋白的3螺旋结构影响。蛋白浓度越高,体系pH值越接近中性,形成的凝胶硬度越大,但脆性也随之增加;当胶原蛋白因受热而导致其三螺旋结构破坏后,其凝胶形成能力急剧下降。     

新型仿生聚合物材料——胶原改性聚乳酸的合成与表征

乙二胺改性聚(DL-乳酸)(EMPLA)是实验室合成的一种含有丰富氨基和羧基、具良好亲水性且降解产物不呈酸性的生物材料.研究以二环己基碳二亚胺(DCC)为缩合剂,将Ⅰ型胶原共价引入到EMPLA中,制得了新型胶原改性聚乳酸(CPLA)仿生材料,探索并建立了一套向EMPLA基质中共价引入Ⅰ型胶原的液相合成技术.采用异硫氰酸荧光素(FITC)标记技术对CPLA的结构及胶原含量进行了定性表征.结果表明,采用本研究所建立的液相反应技术能将Ⅰ型胶原共价引入到EMPLA中,且CPLA中的胶原含量随EMPLA中乙二胺接枝率(EDA%)的增大而增大.     

均布载荷对胶原纤维取向性的诱导作用及ZnO纤维的模板法生长

在分子拥挤环境及均布载荷下,利用Ⅰ型胶原蛋白制得定向有序排列的胶原纤维。以定向有序胶原纤维为模板,负载Zn~(2+),高温煅烧后制得ZnO纤维。利用扫描电镜(SEM)、X射线衍射(XRD)、物性分析仪对胶原纤维形貌和力学性能以及ZnO纤维形貌进行了表征,讨论了均布载荷作用及胶原蛋白浓度对胶原纤维定向性的影响,胶原蛋白浓度及Zn~(2+)浓度对ZnO生长形貌的影响等。结果表明,分子拥挤环境下,施加在胶原溶液上的均布载荷对成胶后的胶原纤维的取向存在诱导作用,使胶原纤维呈定向有序排列。定向排列的胶原纤维拉伸强度高于非定向胶原纤维约56%。低浓度胶原蛋白/Zn~(2+)溶液可形成保留了胶原纤维形貌的ZnO纤维。     

脱除异种骨中非胶原蛋白质的研究

为制备骨移植材料进行了脱除异种骨中非胶原蛋白的研究.方法取新鲜牛长骨(BCB)经零下20℃低温冷冻后去除软组织和骨髓,切割成80mm×10mm×3mm骨片,在索氏提取器中用1∶1氯仿/甲醇提取液在50℃下脱脂72h,把经脱脂处理的试样在4M HCl胍、0.5M CaCl2处理液(4℃,pH7.4)中下浸泡处理24h,然后在0.1%胰蛋白酶溶液(pH7.8)中浸泡处理8h(25℃,骨液比1∶1).用标准曲线法检测处理后骨中色氨酸含量和处理液中羟脯氨酸含量,对材料进行差热分析(DSC)以评价材料中有机质的去除情况.结论去除的有机质占材料重量的20.9%,溶出的羟脯氨酸量只占总含量的0.13%,该方法可脱除骨中脂肪FAT类和非胶原蛋白,未对Ⅰ型胶原造成严重破坏.     

胶原作为组织工程软骨支架材料的研究

本文报导了用胶原作为软骨组织的载体材料在组织工程化软骨中的研究情况.本研究采用冷冻干燥方法制备出了Ⅰ-型胶原(sigma)、Ⅱ-型胶原(sigma)和混合型胶原(本室提取)的胶原海绵,并将其用作软骨组织工程的载体支架,比较研究了这三种胶原材料支架在软骨组织工程应用中的效果,筛选出了较理想的软骨组织工程载体材料.     

RGDS和胶原改性聚(DL-乳酸) 的合成与表征

利用马来酸酐(MAH)、丁二胺(BDA)I、型胶原和RGDS粘附多肽依次对聚(DL-乳酸)进行了化学改性,制得了仿生细胞外基质材料——胶原改性聚乳酸(CPLA)和RGDS改性聚乳酸(RGDS-PLA)。采用FT-IR、GPC-MALLS、XPS、罗丹明比色法和茚三酮显色法对MAH改性聚乳酸(MPLA)和BDA改性聚乳酸(BDPLA)进行了定性定量表征,分别采用FITC荧光标记技术和氨基酸分析仪对CPLA和RGDS-PLA进行了定性定量测定。结果表明,按文中所述之制备技术,能将胞外基质组分如胶原和RGDS粘附多肽共价引入到PLA中,形成新型的仿生细胞外基质材料。     

Al2O3型壳与定向凝固合金IC10的界面反应

采用扫描电子显微镜、能谱分析等研究定向凝固合金IC10与Al2O3陶瓷型壳的界面反应.结果表明:Al2O3型壳与IC10合金发生界面反应,合金表面粘砂严重;IC10合金中由于含有1.5％(质量分数,下同)Hf,使其活泼程度明显增加.界面反应层厚度约5～8μm,反应区分成内、外两层,外层为HfO2,内层为富(Al,Ta,Nb)氧化物层,Al含量占80％.Hf和Al是界面反应的主导元素.     

“软模板”法调控胶原的仿生矿化研究

在模拟体内pH值=7.4的胶原溶胶-凝胶体系中,加入β-甘油磷酸钠(β-GP)作为矿化的磷源,并引入聚丙烯酸(PAA)和三聚磷酸钠(TPP)作为"软模板"模拟体内非胶原蛋白DMP-1的N端和C端的隔离功能域,调控Ⅰ型胶原的矿化,构建了纳米羟基磷灰石/胶原(n-HA/COL)复合支架材料。并以人脐带间充质干细胞hUMSCs作为种子细胞,探究了其对细胞的粘附、增殖、分化的影响。结果表明,胶原纤维组织与矿化同步进行,陈化处理有利于羟基磷灰石(HAp)晶体的结晶。自组装HAp纳米微粒不仅在胶原纤维外部沉积,也可以在原胶原分子上及胶原微纤维的末端被发现,同时纳米磷酸钙盐沿着胶原微纤维的圆柱形表面分布。细胞培养表明n-HA/COL并没有明显促进hUMSCs细胞的增殖,但能够诱导hUMSCs向成骨细胞分化,促进成骨细胞AKP的表达,并且nHA/COL复合支架材料与成骨诱导液(OICM)联用时诱导效果更加显著。这种以"bottom-up"深度矿化方法为骨支架材料的制备提供了新思路,n-HAp/collagen复合材料有望用于骨组织填充修复。     

W元素对CrWMn铁基TIG焊熔敷层耐液态PbBi腐蚀性能的影响

研究了550℃时,CrWMn铁基熔敷层在动态液态PbBi共晶合金(LBE)中的耐磨耐蚀性能以及钨化物对其的影响。4个W含量不同的试样放置在相同流速处。4个试样均出现明显的腐蚀,元素溶解,以及少量的PbBi渗透。熔敷层表面均生成双氧化层,外层为疏松多孔的Fe_3O_4,内层为致密的FeCr_2O_4和(Fe_(0.6)Cr_(0.4))_2O_3,且内外层均含少量的钨化物。WC添加量在3.73%~5.33%时,熔敷层显微硬度值最大,外层厚度较大,磨损较少,内层厚度较小。含量适中的钨化物提高了熔敷层耐蚀耐磨性能,保护熔敷层下铸造316L构件表面。     

聚乳酸表面Ⅰ型胶原纳米图案化的过程和机理

采用原子力显微镜(AFM)研究了聚乳酸(PLLA)表面Ⅰ型胶原纳米图案化的过程。发现吸附层的形态变化与干燥条件及PLLA表面的疏水性有关。经氮气快速吹干形成的吸附层较为致密;而保持较高湿度并维持较长水膜浸润时间,由于去湿作用的影响,形成纤维网状纳米图案化结构。此结构受浸润干燥时间、胶原浓度、基底疏水性等因素的影响,随浸润干燥时间延长,致密的胶原膜破裂,逐渐形成纳米图案化结构,胶原浓度由0.01mg/mL增加到1mg/mL均产生类似现象,且网状结构趋于紧密,PLLA分子量不同,胶原吸附层形成不同的结构形态,显示PLLA分子量对胶原的结构具有调控作用。     

Slanted orientations of dentine tubules on remineralized dentine surfaces

Dentine carious lesions can be remineralized under optimal conditions, while the surface characteristics of the caries-attacked area may play an important role in the remineralization process. To understand such a surface mechanism, we examined the microstructures of the remineralized area pretreated with different methods. It was found that dentinal tubules on the remineralized surface orientated differently from intrinsic dentine tubules, with the specific alignment angle determined by different surface treatments. Various surface treatments included in this study were 37% phosphoric acid treatment (the etched group), 37% phosphoric acid etching followed by the application of 10% sodium hypochlorite treatment (the deproteinized group), and untreatment (the control group). These findings are helpful for understanding the non-restorative repair of dentine lesions and the remineralization process of the caries-affected dentin surface.     

A Model of Microcrack Development in Human Tooth Dentin Using Data of Microtomography

Technical Physics Letters - The structure of dentin is characterized by the presence of microchannels—dentinal tubules (DTs) threading through the matrix composed of collagen fibris and...     

人体牙齿的显微组织及纳米力学性能

采用光学显微镜、能谱扫描电镜、高分辨透射电镜以及纳米力学探针等设备对人体牙齿的显微组织及纳米力学性能进行了研究。结果表明: 牙本质由规则排列的牙本质小管和基质组成,牙釉质由不同方向的釉柱及柱间质组成,牙本质与牙釉质之间有明显的界面;牙釉质中的Ca和P含量明显高于牙本质中的含量,而C含量明显低于牙本质中的含量。牙釉质中发现有大量的磷灰石晶体结构,而牙本质中则明显缺少。力学性能结果显示,牙釉质的纳米硬度平均为4.4 GPa,弹性模量为81 GPa,而牙本质的纳米硬度平均为1.0 GPa,弹性模量为26 GPa。牙釉质高的硬度和弹性模量与含有大量的羟基磷灰石晶体组织有关,Ca和P促进了该晶体组织形成。      

Isolation and characterization of drug delivering potential of type-I collagen from eel fish Evenchelys macrura

Acid soluble collagen (ASC) and pepsin-soluble collagen (PSC) from the outer skin waste of marine eel fish (Evenchelys macrura) were isolated and characterized. The prepared collagen was used to test its effective drug delivering potential in vitro condition. Present results were confirmed as collagen by different physico-chemical techniques like SDS-PAGE, HPLC, FTIR and SEM. Further amino acid analysis corroborates isolation of type I collagen. Both ASC and PSC comprising two different α-chains (α 1 and α 2) were characterized as type I and contained imino acid of 190-200 residues, respectively. The denaturation temperatures (T(d)) of ASC and PSC were 38.5 and 35.0?°C, respectively, which is promising as an advantage for biomedical application due to closeness in T(d) to mammalian collagen. Furthermore, the gel and film forming capability of collagen samples containing implant standard antibiotic was proved to be a suitable drug delivering system.     

Evaluation of phase, microstructure and composition of human dentine after Er,Cr:YSGG laser irradiation

This study aims to evaluate the composition, micro-structure and inorganic phase alternations of human dentine irradiated by Er,Cr:YSGG laser with water cooling spray system. X-ray diffraction (XRD) analysis indicated that the main inorganic phase of dentine before and after laser irradiation were all Hydroxyapatite (HA) structure, approximately 30 nm in size. No significant changes occurred in the average particle size after irradiation in four energy densities (6.18 J/cm2, 8.04 J/cm2, 9.89 J/cm2, 11.1 J/cm2). Atomic force microscope (AFM) phase image and the energy-dispersive spectroscope (EDS) analysis, however, demonstrated that the thermal effects of Er,Cr:YSGG laser with water-cooling spray system on the dentin surface was intense enough to induce notable decrease of the organic matter. Both scanning electron microscopy (SEM) and AFM analysis showed that the irradiated dentine presented rough surface morphology. The surface is clean and dentinal tubules are completely open. The ablation rate of both peri- and intertubular dentine increased at higher energy densities but no significant changes of gross appearance took place. Chemical analysis reveals that laser photothermal effect would decrease significantly the organic content of superficial dentinal layer. We conclude that the Er,Cr:YSGG laser, as a new type clinic laser, would not significantly influence the inorganic phase structure of the surface dentine layer, however, thermal ablation was occurred in organic component. Moreover, the rough ablated surface as well as the opened dentinal tubules induced by irradiation, might be advantageous to the infiltration of the adhesive materials, thus the adhesion of dental restoration could be enhanced. Further studies should focus on the correlation between bond strength and Er,Cr:YSGG lased dentine.     

Nanogels of carboxymethyl chitosan and lysozyme encapsulated amorphous calcium phosphate to occlude dentinal tubules

This study aimed to develop of a rapid and effective method to occlude dentinal tubules using carboxymethyl chitosan and lysozyme (CMC/LYZ) nanogels with encapsulated amorphous calcium phosphate (ACP) based on the transformation of ACP to HAP. In this work, CMC/LYZ was used to stabilize ACP and form CMC/LYZ-ACP nanogels, and then the nanogel-encapsulated ACP was applied to exposed dentinal tubule surfaces. The morphology of the nanogels was examined by transmission electron microscopy (TEM). Distribution and quantity of elements in CMC/LYZ-ACP nanogels were determined by element mapping and energy dispersive X-Ray spectroscopy (EDX). Scanning electron microscopy (SEM) images, XRD measurements and nanoindentation were applied to check the efficacy of tubular occlusion. TEM revealed that CMC/LYZ-ACP nanogels were spherical dense gel particles with size approximately 50–500?nm. Element mapping and EDX indicated that C, N, O, Ca, P, and S in the microspheres are thoroughly represented. SEM images shows that the thickness of the coating layer was approximately 1–2?μm and the depth to which the mineralized substance enters the dentinal tubule was approximately 4–8?μm. XRD measurements and nanoindentation indicated that the occluding mineralized substance observed were similar to nature dentin. CMC can form spherical dense nanogels loaded with ACP under the participation of lysozyme. The CMC/LYZ-ACP nanogels could increase the dentinal tubule occluding effectiveness. These results indicated that finding and developing novel nanomaterials of CMC/LYZ-ACP would be an effective strategy for the treatment of dentin hypersensitivity.     

海藻酸钙凝胶对牙本质小管封闭作用的实验研究

为治疗牙本质过敏症,研究了海藻酸钙对牙本质小管的封闭作用及矿化效果。以海藻酸钠(SA),碳酸钙,葡萄糖酸内酯(GDL)为原料,在牙本质上通过原位相转变制备海藻酸钙(CA)凝胶。测定了单一变量条件下不同海藻酸钠浓度、f值(钙离子与羧基的摩尔比)及n值(葡萄糖酸内酯与钙离子的摩尔比)对海藻酸钙凝胶的凝胶化时间和浸提液pH值的影响。扫描电镜观察海藻酸钠混合液处理前后牙本质微观形貌改变,并对封闭后牙本质小管进行了矿化研究。结果表明海藻酸钠浓度为2.5%、f=0.5及n=0.6为最佳配比。海藻酸钠处理后,开放的牙本质小管明显变小或封闭,显示海藻酸钠溶液可进入牙本质小管形成凝胶,并封闭牙本质小管。矿化后凝胶表面呈致密的矿化层,XRD分析为单一的高结晶羟基磷灰石,CA凝胶有利于诱导高结晶度HA的生成,为继续探索牙本质的仿生矿化提供新思路。     

The nano-hardness and elastic modulus of sound deciduous canine dentin and young premolar dentin—Preliminary study

The purpose of this study was to compare the nano-hardness and elastic modulus among deciduous and permanent dentin, buccal and lingual sides, incisal, center and cervical areas, and outer, middle and inner layers. Three premolars and three deciduous canines were bucco lingually (BL) sectioned, and three deciduous canines were mesio-distally (MD) sectioned parallel to the long axis at the center of the tooth. Hardness (H), plastic hardness (PH) and Youngs modulus (Y) were measured using a nano-indentation tester. The H, PH and Y values from the deciduous canine dentin were significantly lower than those from the premolar dentin at most sites. For deciduous canine dentin, the H and PH values of the MD sectioned dentin were significantly higher than those of the BL sectioned dentin in many layers of many areas. Generally deciduous canine dentin had H, PH and Y values that decreased from outer toward the inner layers and significant differences were obtained among the layers in many areas. For MD sectioned deciduous canine and BD sectioned premolar dentin, the H, PH and Y values of the cervical area were significantly lower than those of the incisal and center areas in many layers. It is possible that optimum bonding may require different treatments for deciduous and permanent dentin and perhaps also for different intratooth locations.     

Shear bond strengths of glass-ionomer cements to sound and to prepared carious dentine

Summary The aim of this study was determine whether bonding of glass-ionomer cements to non-carious dentine differed from that to carious dentine. Five commercial cements were used, namely Fuji IX GP, Fuji IX capsulated, Fuji IX Fast capsulated (all GC, Japan), Ketac-Molar and Ketac-Molar Aplicap (both 3M-ESPE, Germany). Following conditioning of the substrate with 10% poly (acrylic acid) for 10 s, sets of 10 samples of the cements were bonded to prepared teeth that had been removed for orthodontic reasons. The teeth used had either sound dentine or sclerotic dentine. Shear bond strengths were determined following 24 h storage. For the auto-mixed cements, shear bond strength to sound dentine was found not to differ statistically from shear bond strength to sclerotic dentine whereas for hand-mixed cements, shear bond to sound dentine was found to be higher than to carious dentine (to at least p < 0.05). This shows that the chemical effects arising from interactions of glass-ionomer cements with the mineral phase of the tooth are the most important in developing strong bonds, at least in the shorter term.