组织工程微构建与Bottom-up构建思路的研究进展

天然组织结构是由高度复杂化的组织微结构体组成,现今组织工程学的巨大挑战就是在体外重现这些微结构体的结构和功能。微构建技术为组织构建提供了一条新途径。对微工程化水凝胶技术作了相关的介绍,举例阐述了其中的微流体技术和微孔技术在形成细胞集落、促进细胞-细胞与细胞-细胞外基质间作用等方面的影响。此外,还提出了一种通过自下而上的构建方式制备水凝胶微结构的新技术,利用微囊化细胞与生物凝胶材料进行体外组织工程构建。     

图案化金属铜纳米线阵列的制备与表征

采用紫外线光刻技术与电化学沉积相结合的方法,成功制备了不同图案的铜纳米线阵列:一种是圆形图案;另一种是QDU图案.首先利用紫外线光刻技术在多孔阳极氧化铝模板(AAO)生成预设图案,以此作为"二次模板";再利用电化学方法将铜纳米线沉积到"二次模板"的开孔中.扫描电镜(SEM)测试结果表明,大面积、高规整的铜纳米线图案阵列各自独立地立在基底上, 同时,用电子能谱(EDS)分析了铜纳米线的化学成分.透射电镜(TEM)也探测到了铜纳米线的微结构.     

基于壳聚糖/β-甘油磷酸钠(CS/β-GP)温敏型水凝胶的细胞表面壳化及对癌细胞行为的影响研究

制备了壳聚糖/β-甘油磷酸钠(CS/β-GP)复合物水凝胶,测试其温敏特性及其SEM、FTIR性质,并研究人卵巢癌细胞、人宫颈癌细胞和小鼠成纤维细胞在包裹CS/β-GP水凝胶后的运动迁移性能和生理活性,进一步探究温敏性水凝胶在肿瘤治疗领域的潜在应用。方法制备CS/β-GP水凝胶,并将该水凝胶包裹于生长良好的人卵巢癌细胞、人宫颈癌细胞和小鼠成纤维细胞表面继续培养,通过细胞划痕实验和活死荧光染色检测水凝胶对癌细胞的迁移性和生理活性的影响。结果制备出的CS/β-GP水凝胶在室温下呈透明液体,在37℃发生凝胶化现象;细胞划痕实验结果显示,未涂覆水凝胶的癌细胞随培养时间的延长细胞不断向划痕区迁移生长,而涂覆了水凝胶之后,细胞迁移明显受到抑制;活死荧光染色结果表明,水凝胶可抑制癌细胞(人卵巢癌细胞、人宫颈癌细胞)生理活性,但对正常细胞(小鼠成纤维细胞)的生理活性影响较小,故此CS/β-GP水凝胶的温敏特性可以作为癌细胞与正常细胞的初筛,有望用于生物安全的癌症治疗。     

光聚合PEXS-A水凝胶材料的合成及包埋活细胞的性能

光聚合水凝胶材料在组织工程中发挥着重要作用。本研究合成了一种可快速光聚合的水凝胶材料——丙烯酸酯封端聚乙二醇聚木糖醇癸二酸共聚物(PEXS-A),从聚乙二醇投量、酰化剂选择和透析时间三个方面对合成工艺进行了探索并对水凝胶的细胞相容性和降解性能进行表征。通过比较预聚物水溶性确定聚乙二醇投量,采用核磁共振氢谱图(1H-NMR)对材料进行结构分析并计算材料丙烯酸酯化程度;将透析0 h、24 h、48 h、72 h的水凝胶材料与细胞一同培养,采用CCK-8细胞毒性检测试剂盒对细胞存活率进行检测;将细胞包埋于水凝胶材料中置于细胞培养基中培养48 h后用活/死细胞双染试剂盒荧光染色观察细胞存活情况,并测试了PEXS-A水凝胶在磷酸缓冲液(PBS)中37℃下降解28 d过程中的质量变化。结果表明,聚乙二醇质量分数为60%时得到易溶于水和最高羟基比例的PEXS预聚物,PEXS-A丙烯酸酯化程度可达91. 61%,在紫外光照下1 min内能聚合成水凝胶,PEXS-A预聚物水透析48 h后合成的水凝胶细胞毒性较低,与对照材料PDLLA相当,细胞包埋于PEXS-A水凝胶培养48 h后有极高的存活率,PEXS-A水凝胶还具有生物降解性能,其在体外28 d可降解52. 85%±0. 64%(质量分数)。     

高力学强度水凝胶的研究进展

传统的水凝胶由于力学强度差而大大限制了其应用。近年来,从分子水平上改进水凝胶内部微结构提高水凝胶力学强度的方法越来越受到关注。文中综述了提高水凝胶力学强度的各种有效方法,期望研究者们能够在这些方法的基础上进一步深入探讨并扩展其应用领域。     

胶原/海藻酸钙互穿网络水凝胶的构建及其对细胞行为的影响

利用溶液共混法制备了胶原/海藻酸钠混合液,建立了制备胶原/海藻酸钙互穿网络水凝胶的方法,并证实互穿网络凝胶中,胶原与海藻酸钙二者共存且相互独立,胶原结构保持完好。与传统海藻酸钙水凝胶相比,本文建立的胶原/海藻酸钙互穿网络水凝胶表面疏水性增强且凝胶结构更加疏松,更利于细胞粘附与物质传递。以人源成纤维细胞为模型,通过考察细胞在凝胶表面与凝胶内部的形态,进一步证实胶原分子在胶原/海藻酸钙互穿网络水凝胶的表面与内部均有分布。细胞迁移实验结果也表明该胶原/海藻酸钙互穿网络水凝胶不仅能有效保持细胞活性,且为细胞迁移行为的研究提供了一种新的研究模型。     

透明质酸/胶原蛋白/聚乙二醇复合水凝胶的研究

针对透明质酸、胶原蛋白水凝胶力学性能差的问题,采用两步交联法将透明质酸、胶原蛋白与聚乙二醇双丙烯酸酯制备成一种兼具生物相容性和高强度的复合水凝胶。研究制备了具有相同胶原蛋白和聚乙二醇双丙烯酸酯质量分数,不同透明质酸质量分数的水凝胶,从微观结构和力学强度调控了复合水凝胶的理化性能,并用L-赖氨酸对复合凝胶进行改性。SEM结果表明,三元复合水凝胶具有蜂窝状的内部结构,孔径范围在80~180μm,赖氨酸浓度达40 mmol/L时,水凝胶的压缩模量达414 k Pa,是改性前模量的19倍。细胞毒性和体内植入实验表明该水凝胶浸提环境对细胞生长无明显抑制作用,产生较低的免疫排斥反应,有望用于软骨等组织的修复。     

磁诱导高取向水凝胶的构筑及功能

磁诱导制备高取向水凝胶可赋予其各向异性的支持、驱动、传输、结构等特殊功能,从而使得高取向水凝胶成为生物工程材料应用的理想候选者.同时,磁诱导制备方法不受限于材料尺寸且取向方向容易控制,是目前较为简单、有效的制备高取向水凝胶的方法之一.本文主要从各向异性偶极-偶极作用力和磁能角度分析了磁性纳米填料及非磁性材料在磁场作用下的取向机理;阐述了磁诱导取向水凝胶在仿生学领域的最新研究进展;最后,对磁诱导构建取向水凝胶的未来研究和发展进行了展望.     

用光刻、软刻和氧化硅球晶体模板制备表面微结构

表面微结构的制备对获得超疏水性表面和改善生物医学材料性能具有重要意义. 为了制备微米、亚微米和纳米级表面微结构, 本文采用光刻(photo-lithography)和软刻技术(soft lithography) 制备了微米尺寸长方体或圆柱体的阵列, 压印出变形长方体(塔状)或圆柱体(圆盘状)阵列的微结构表面; 采用单分散氧化硅球自集聚紧密堆积而成的胶体晶体为模板, 制备了亚微米/纳米 尺寸网状微结构的表面. 用光学和扫描电子显微镜表征了所获得的表面微结构.     

不同体系的双网络水凝胶及其增强机理

双网络水凝胶是由两种不同性质的聚合物形成的互穿网络,第一层为紧密交联的刚而脆聚电解质网络,第二层为松散交联的软而韧中性网络.双网络水凝胶具有极高的机械强度和韧性,甚至可以与橡胶相媲美.其中,刚而脆聚电解质网络为双网络水凝胶提供了“牺牲键”,起到分散外界应力的作用;而软而韧的中性聚合物填补于剐性网络中,为双网络水凝胶提供了支架,保持水凝胶外形.基于上述机理,研究者设计合成了具有高强度、良好生物相容性、低摩擦和低磨损等特性的双网络水凝胶.着重讨论了不同体系双网络水凝胶的力学性能和增强机理,并展望了双网络水凝胶研究前景.     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Assessment of intakes of mixtures of radionuclides

Australia has several uranium mines and a large number of mineral sand mines, with associated processing facilities. Exposures resulting from these mining and processing operations usually involve intakes of mixtures of radionuclides. This work describes the development of a suite of first order, linear compartment models, based on the ICRP Publication 66 respiratory tract model, and an analytical solution to the decay equations, for assessing the consequences of such intakes. The computer programs based on these models directly compute excretion, organ retention and organ and whole-body doses for intakes of either single radionuclides or any mixture of radionuclides belonging to the same radioactive decay chain. The intake can be via inhalation, ingestion or injection, and can be acute, chronic or of limited duration. The starting concentration and degree of secular (dis)equilibrium can be specified for each radionuclide. No assumptions need to be made about the relative magnitudes of the radioactive half-lives of the different nuclides.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Numerical study of methods of linearization of the output characteristics of radio-frequency sensors of the level of dielectric media

Different constructions of the sensing elements of radio-frequency level sensors based on sections of long lines are numerically investigated by means of the Matlab program for the purpose of minimizing the measurement error caused by the nonlinearity of the output characteristic. It is shown that the nonlinearity is lowest for U-shaped designs. The nonlinearity factor KN may be regulated by varying the capacitance of a correcting capacitor connected to the input of the sensing element and (or) the length of one of the sections of the long line. In selecting an optimal capacitance of the correcting capacitor KN ≤ 0.15% for control media with dielectric permittivity in the range 2.2–30.