N-乙烯基吡咯烷酮接枝改性聚乳酸组织工程支架的制备与性能

利用热致相分离技术制备了N-乙烯基吡咯烷酮接枝改性聚乳酸（M-PLA）组织工程支架。在36%接枝率下,讨论了聚合物浓度、水/二氧六环比例和粗化温度对支架孔隙度和微孔结构的影响;并进一步探讨了在相同制备工艺条件下,不同接枝率对支架结构的影响,并对M-PLA支架的亲水性和蛋白粘附性能进行测试。结果显示,在一定接枝率下,支架孔隙度随聚合物浓度增大而降低;水的添加有利于规则孔径的形成;粗化温度降低,支架孔径和孔隙度提高。与PLA支架相比,随着接枝率提高,共聚物支架孔隙度变化不大,孔径略减小,但孔隙规整性和连通性较好,亲水性和蛋白粘附率明显增大,生物相容性提高。     

60Co-γ射线引发聚氨酯接枝N-乙烯基吡咯烷酮的性能研究

利用60 Co-γ辐照接枝技术,在医用聚氨酯弹性体(TPU)表面接枝亲水性N-乙烯基吡咯烷酮(NVP),制备了TPU-g-PVP接枝共聚物。通过傅里叶变换红外光谱和扫面电子显微镜表征了接枝共聚物结构,研究了吸收剂量、溶剂组成、单体浓度和介质pH值对共聚物接枝率的影响。结果表明,在一定条件下,随着吸收剂量和单体浓度的增大,共聚物接枝率逐渐增大;当溶剂中乙醇含量为60%(体积分数,下同)时,接枝效率最高;在中性和碱性条件下,NVP接枝率较高。亲水性及润滑性能测试表明,接枝改性后,材料的亲水性和润滑性随着接枝率的增大显著提高。接枝体系最佳工艺条件为:乙醇含量60%、pH值为7、NVP浓度20%、吸收剂量为10kGy、体系接枝率为20%。     

线形低密度聚乙烯粉料固相光接枝丙烯酸的研究

采用接枝率测定、红外光谱、光电子能谱、接触角、剥离强度等测试，研究了紫外线（UV）引发丙烯酸（AA）固相表面接枝线形低密度聚乙烯（PBLLD）粉料的影响因素（温度、单体浓度和反应时间），接枝PE—LLD表面结构、微观形态和性能。结果表明：UV能高效地引发AA在PE-LLD材料表面接枝聚合，随辐照时间延长、温度升高和单体浓度增大，接枝率增大，在实验条件下达到满足实际应用所需接枝率（约0．5％质量含量）的反应时问可达分钟数量级。接枝改性后，PE-LLD与水的接触角下降，亲水性增强；对钢材和聚乙烯黏接强度提高。     

铸膜液结构对PVC/PMMA合金微滤膜性能的影响

通过高分子合金化,以L-S相转化法制备了PVC/PMMA非对称型合金微滤膜,考察了铸膜液结构对微滤膜结构与性能的影响.结果表明:随聚合物浓度、铸膜液温度升高合金膜水通量降低,平均孔径减小;增大PMMA含量,水通量上升,平均孔径增大;随添加剂量的增加,合金膜水通量上升,平均孔径减小.     

溶聚丁苯橡胶接枝MAH的改性研究

为提高溶聚丁苯橡胶(SSBR)与极性物质的相容性,以马来酸酐(MAH)为极性单体对SSBR进行接枝改性。研究了MAH用量、引发剂过氧化苯甲酰(BPO)用量、反应时间和反应温度等对接枝聚合物(SSBR-g-MAH)的接枝率和凝胶率的影响。结果发现,随MAH、BPO用量增加和反应时间延长,接枝聚合物的接枝率呈现先增大后降低的变化趋势,而凝胶率变化则与之相反;随反应温度的升高,接枝率依然先增大后降低,但凝胶率却一直增大。热重分析表明接枝橡胶与SSBR具有相同的耐热性,分解温度均在360℃左右,并采用傅里叶红外法对接枝产物的结构进行了表征。     

PP-g-MBA的制备与结构性能表征

利用电子束预辐照粉末聚丙烯,水溶液中引发N.N-甲叉基双丙烯酰胺(MBA)接枝共聚合,制备了PP-g-MBA接枝共聚物。研究预辐照剂量、反应时间、单体浓度对接枝率的影响,用FTIR和接触角测量仪分析其结构和表面性能。结果表明:辐照剂量为5kGy,反应时间为3h,单体浓度为0.1~0.3mol·L-1时,接枝率较高。FTIR结果证明,BMA已接枝到聚丙烯中,并随接枝率增加相应峰面积增大,对水接触角减小,亲水性明显改善。     

聚乳酸多孔支架材料的制备研究

以聚L-乳酸(PLLA)为原料、四氢呋喃和异丁醇的混合物为溶剂,采用热诱导相分离法结合冷冻萃取法,制备了聚乳酸多孔支架材料,探讨了陈化温度、淬火温度对支架材料形态的影响。结果表明,随着陈化温度的降低,支架材料的平均孔径先增大后减小,在30℃下陈化所得支架材料的平均孔径最大;支架材料的形态也随淬火温度的改变而发生变化,其中在-30℃下淬火所得支架材料的平均孔径最大,孔的形态最好,而在液氮下淬火所得支架材料无孔。     

线型低密度聚乙烯固相接枝丙烯酸丁酯的研究

利用固相接枝共聚的方法,制备了线型低密度聚乙烯接枝丙烯酸丁酯(LLDPE-g-BA)共聚物。讨论了反应温度、反应时间、引发剂用量、单体浓度对接枝率的影响,结果表明:随着反应温度的升高,反应时间的延长,引发剂用量以及单体/聚合物比例的增加,接枝率提高,最高接枝率达到10.12%。并用红外光谱表征产物的结构。LLDPE-g-BA可明显改善PET/LLDPE复合材料的界面相容性及力学性能。     

聚乳酸接枝丙烯酸纳米孔纤维膜制备及其细胞相容性研究

以V(二氯甲烷)/V(N,N-二甲基甲酰胺)=4∶1为溶剂,通过电纺制备直径为(650±60)nm,孔径为96 nm×72 nm聚乳酸(PLLA)纳米孔纤维膜。利用氧等离子体处理将亲水性单体丙烯酸(AA)接枝到纤维表面制备聚乳酸接枝丙烯酸(PLLAg-PAA)纳米孔纤维膜。与PLLA纳米孔纤维膜相比,PLLA-g-PAA纳米孔纤维膜的水接触角从(119.4±1.2)°降低到(42.3±0.6)°,拉伸强度、杨氏模量和断裂伸长率略有降低。将牙髓干细胞(DPSCs)在纤维膜支架上培养,细胞生长密度顺序为PLLA-g-PAA纳米孔纤维膜PLLA纳米孔纤维膜PLLA纤维膜。由于PLLA-g-PAA纳米孔纤维膜表面粗糙,比表面积大,孔隙率高和表面亲水性好,更有利于细胞的粘附、迁移、分化和繁殖。PLLA-g-PAA纳米孔纤维膜有望成为优良的组织工程支架材料。     

果胶-甲基丙烯酸丁酯接枝共聚结肠靶向骨架片的制备与研究

果胶-甲基丙烯酸丁酯在引发剂KPS的作用下接枝共聚,疏水性提高,为研究和开发新型结肠靶向载体材料开辟了新的途径。考察了共聚物的制备条件、物化特性和结构特征,制备了结肠靶向骨架片,评价了其释药性能。结果表明,果胶在KPS浓度为0.008 mol/L,BMA浓度为0.14 mol/L,温度为50℃和反应时间为4 h条件下的接枝率最高,可达284.87%。DSC表明,果胶与BMA接枝共聚后热稳定性降低,热焓增大;不同p H缓冲液的水溶性和溶液黏度随接枝率的增大而减小。SEM表明,PT-BMA颗粒表面呈现凹凸不平的蜂窝状结构,同时有颗粒连接的突起。FT-IR、~1HNMR结果表明,疏水单体BMA成功接枝到果胶分子。PT-BMA骨架片的制备条件为:PT-BMA3为0.025 g,BSA为0.006 g,甲基纤维素为0.025 g,硬脂酸镁为0.001 g,压片压力为8 kg/mm~2。此时骨架片的结肠释药性较好。     

Fabrication and characterization of poly(l-lactic acid) 3D nanofibrous scaffolds with controlled architecture by liquid-liquid phase separation from a ternary polymer-solvent system

Poly(l-lactic acid) (PLLA) three-dimensional (3D) scaffold with macro/micropores and nanofibrous structure was fabricated by phase separation from a ternary PLLA/dioxane/water system. The pore size was mainly determined by the coarsening effects in the phase separation process, while the nanofibrous structure was due to the formation of PLLA microcrystallite domains in the gelation process. Increasing the gelation temperature or the content of water in the mixed solvent system, the pore size definitely increased and macropores up to 300 μm were observed. However, coalescence of nanofibers occurred, even platelet-like structure appeared at gelation temperatures higher than 12 °C or the proportion of water exceeded 12%. X-ray diffraction (XRD) and Differential Scanning Calorimetry (DSC) analyses demonstrated that the crystallinity degree increased with increasing the gelation temperature or the non-solvent volume ratio in the mixed system. Moreover, the results indicated that α′ was mainly corresponding to the nanofibers structure, while α crystal was detected in the platelet-like structure. Scanning electron micrograph (SEM) and methyl thiazolyl tetrazolium (MTT) assays indicated that the nanofibrous scaffold provided a better attachment and viability of MSCs (rat derived mesenchymal stem cells) than the platelet-like scaffold.     

Fabrication of porous scaffolds with a controllable microstructure and mechanical properties by porogen fusion technique

Macroporous scaffolds with controllable pore structure and mechanical properties were fabricated by a porogen fusion technique. Biodegradable material poly (d, l-lactide) (PDLLA) was used as the scaffold matrix. The effects of porogen size, PDLLA concentration and hydroxyapatite (HA) content on the scaffold morphology, porosity and mechanical properties were investigated. High porosity (90% and above) and highly interconnected structures were easily obtained and the pore size could be adjusted by varying the porogen size. With the increasing porogen size and PDLLA concentration, the porosity of scaffolds decreases, while its mechanical properties increase. The introduction of HA greatly increases the impact on pore structure, mechanical properties and water absorption ability of scaffolds, while it has comparatively little influence on its porosity under low HA contents. These results show that by adjusting processing parameters, scaffolds could afford a controllable pore size, exhibit suitable pore structure and high porosity, as well as good mechanical properties, and may serve as an excellent substrate for bone tissue engineering.     

Preparation of interconnected poly(ε-caprolactone) porous scaffolds by a combination of polymer and salt particulate leaching

This paper examines a new technique for the preparation of porous scaffolds by combining selective polymer leaching in a co-continuous blend and salt particulate leaching. In the first step of this technique, a co-continuous blend of two biodegradable polymers, poly(ε-caprolactone) (PCL) and polyethylene oxide (PEO), and a certain amount of sodium chloride salt particles are melt blended using a twin screw extruder. Subsequently, extraction of the continuous PEO and mineral salts using water as a selective solvent yields a highly porous PCL scaffold with fully interconnected pores. Since, the salt particles and the co-continuous polymer blend morphology lead to very different pore sizes, a particular feature of this technique is the creation of a bimodal pore size distribution. Scanning electron microscopy, mercury intrusion porosimetry and laser diffraction particle size analysis were carried out to characterize the pore morphology. The prepared scaffolds have relatively homogeneous pore structure throughout the matrix and the porosity can be controlled between 75% and about 88% by altering the initial volume fraction of salt particles and to a lesser extent by changing the PCL/PEO composition ratio. Compared to the conventional salt leaching technique and to its different variants, the proposed process allows a better interconnection between the large pores left by the salt leaching and a fully interconnected porous structure resulting from the selective polymer leaching. The average compressive modulus of the different porous scaffolds was found to decrease from 5.2 MPa to about 1 MPa with increasing porosity, according to a power-law relationship. Since, the blending and molding of the scaffold (prior to leaching) can be made using conventional polymer processing equipment, this process seems very promising for a large scale production of porous scaffold of many sizes and in an economic way.     

壳聚糖-明胶-透明质酸-硫酸肝素复合支架的制备及性能评价

采用冷冻干燥法制备一种新型三维壳聚糖-明胶-透明质酸-硫酸肝素(chitosan-gelatin-hyaluronate-heparansulfate,C-G-Ha-HS)复合支架,分别测定支架的孔径、孔隙率、吸水率和降解率等物理性质,同时以壳聚糖-明胶(chitosan-gelatin,C-G)支架作为对照组,考察了神经干/祖细胞(neural stem/progenitor cells,NS/PCs)在该支架上的粘附率、生长状态以及细胞生存力等生物相容性指标。扫描电镜观察及CCK-8分析表明,C-G-Ha-HS支架孔径主要分布于90~130μm,孔隙率明显增大,吸水率大于95%且能够体外降解;C-G-Ha-HS支架明显改善了NS/PCs的粘附性及生存力,细胞在支架内相互交织成网状,C-G-Ha-HS支架(5:5)上的细胞粘附率提高至对照的(200.8±8.0)%,培养6天以后,细胞的存活率增加至对照的(357.7±8.9)%。这些结果初步显示,C-G-Ha-HS支架可以用于构建体外NS/PCs的三维培养,为进一步应用于神经组织工程和药物筛选提供了实验依据。     

3D打印骨组织支架孔隙结构对支架性能影响的研究进展

从骨组织工程支架孔隙形状、孔径大小、孔隙率、表面粗糙度、连接通路5方面对支架孔的微观结构的研究现状进行了综述。发现梯度结构的支架孔隙形状更接近天然骨,粗糙的表面可以改善细胞的黏附和增殖,非正交连接通路的内部结构可以为后期骨再生提供一个动态的生长空间。     

A simple pathway in preparation of controlled porosity of biphasic calcium phosphate scaffold for dentin regeneration

A simple pathway in preparation of biphasic calcium phosphate scaffold of hydroxyapatite/beta-tricalcium phosphate with controlled pore size, shape and porosity using phosphoric acid and calcium carbonate was successfully developed. Microporosity was controlled by adjusting temperature and soaking time of the sintering process while macroporosity was obtained through addition of polyethylene spherical particles. The advantage of this method is that a highly pure biphasic calcium phosphate scaffold consisting of hydroxyapatite/beta-tricalcium phosphate in a controlled ratio of 20/80 with a mean pore size of 300 μm and 65% porosity can be produced. These properties of scaffold are of high potential for use in dentin regeneration.     

Fabrication of Macroporous Alumina with Tailored Porosity

Macroporous alumina materials were fabricated via colloidal processing using polymer spheres as the template and ceramic particles as the building blocks. The influence of the suspension conditions and volume ratio of the polymer/ceramic particles on the formation of the pore structure has been investigated. The results showed that the suspension conditions have a significant effect on the pore morphology. A well-defined three-dimensional, ordered porous structure with a controllable pore size and porosity could be obtained through the hetero-coagulation, self-assembled processing of the polymer/ceramic particles. The pore size and porosity could be easily tailored by varying the polymer size and the volume ratio of the polymer/ceramic particles.     

Synthesis of poly(ε-caprolactone)-based polyurethane semi-interpenetrating polymer networks as scaffolds for skin tissue regeneration

A new biodegradable poly(ε-caprolactone)-polyurethane semi-interpenetrating polymer network (PCL-PU-semi-IPNs) was synthesized through the reaction of hydroxyl-terminated four-armed star-shaped PCL, 1,4-diisocyanatobutane, and ethylenediamine. Afterwards, the three-dimensional (3D) porous structure of the polymer was prepared through particulate leaching and freeze-drying methods. The chemical structure of star-shaped block PCL-PU polymer was confirmed by ¹H NMR and IR spectroscopy. The morphology of the fabricated PCL-PU-semi IPN scaffolds was identified by scanning electron microscopy. Results indicated that lower polymer concentration can lead to formation of an isolated pore with a small size, while increasing polymer concentration increases the pore size. Fibroblast cells culturing on the scaffold suggests that the fabricated PU-based scaffold is biocompatible and can be considered as a suitable scaffold material for skin tissue engineering applications.     

Solvent-Free Fabrication of Tissue Engineering Scaffolds With Immiscible Polymer Blends

A completely organic solvent-free fabrication method is developed for tissue engineering scaffolds by gas foaming of immiscible polylactic acid (PLA) and sucrose blends, followed by water leaching. PLA scaffolds with above 90% porosity and 25–200 µm pore size were fabricated. The pore size and porosity was controlled with process parameters including extrusion temperature and foaming process parameters. Dynamic mechanical analysis showed that the extrusion temperature could be used to control the scaffold strength. Both unfoamed and foamed scaffolds were used to culture glioblastoma (GBM) cells M059 K. The results showed that the cells grew better in the foamed PLA scaffolds. The method presented in the paper is versatile and can be used to fabricate tissue engineering scaffolds without any residual organic solvents.