PCL/HA骨组织工程多孔支架的制备及其理化性能研究

以聚己内酯和羟基磷灰石粉体为原料,通过溶剂浇铸/真空挥发/粒子沥滤法(SC/VV/PL)成功制备出复合多孔PCL/HA支架,并通过X射线衍射仪(XRD)、扫描电镜(SEM)、红外分析仪(FT-IR)等对制备所得的支架物相成分、微观形貌等进行表征,研究了支架的相关理化性能,成功制备出具有较高孔隙率且力学性能良好的PCL/HA复合多孔支架,孔径大小在100～300μm之间,孔隙率达到83%～89%,满足骨组织工程支架对多孔结构的要求;研究同时表明,HA的复合可提高了支架的结晶度及其力学强度,抗压强度达到3.6～5.1MPa。     

超临界二氧化碳中聚(丁二酸-丁二醇/乙二醇)酯(PBES)多孔聚合物的制备与表征

在超临界二氧化碳(scCO2)条件下,制备了可生物降解性的聚(丁二酸-丁二醇/乙二醇)酯(PBES)多孔材料,研究了scCO2的压力、温度对多孔材料的结构形貌和结晶度的影响。 结果表明,材料的孔洞分布、结构形态和结晶度与处理样品的压力、温度关系密切;经过scCO2处理后材料的结晶度有所降低。 孔径均匀分布,为50~200 μm,131 ℃处理样品的孔隙率为55.63%。     

树莓状超疏水多孔复合棉纤维的制备及油水分离性能

基于聚多巴胺（PDA）的化学性质和树莓状纳米粒子的粗糙结构,以聚多巴胺包覆的棉纤维为基底,制备了具有多重粗糙度的树莓状超疏水多孔复合棉纤维材料.通过扫描电子显微镜观察树莓状超疏水多孔复合棉纤维表面的微观形貌,PDA-SiO₂纳米粒子稳定地固定在聚多巴胺涂覆的棉纤维表面.经过氟化改性的树莓状超疏水多孔复合棉纤维具有超疏水性,水接触角为158.2°,油接触角为0°.油/水分离实验结果表明,树莓状超疏水多孔复合棉纤维对己烷/水混合物的分离效率可达99.4%以上,使用20次后仍维持较高的分离效率.同时,其具有较高的溶剂吸附能力（13~34 g/g）、重复使用性及机械稳定性,吸油能力可与硅气凝胶相媲美.     

PDA/SiO2大孔复合材料固定化荧光假单胞菌脂肪酶

以具有三维骨架结构的大孔聚合物为模板制备SiO_2大孔材料,通过多巴胺在SiO_2大孔材料孔道表面的原位聚合制得聚多巴胺表面功能化修饰的二氧化硅大孔材料(PDA/SiO_2)。应用SEM、EDX、MIP、BET、TG-DTA和FTIR等技术对修饰前后的材料进行表征。以PDA/SiO_2为载体固定荧光假单胞菌脂肪酶(PFL),优化固定化条件并对比游离脂肪酶和固定化脂肪酶的性质。结果表明SiO_2大孔材料具有三维连续贯通的孔道结构,孔径分布在300~500 nm,聚多巴胺修饰后形成聚多巴胺/二氧化硅复合纳米薄膜构筑的大孔材料。在固定化时间为14 h、p H值为8、初始脂肪酶浓度为0.4 mg·m L-1时,固定化效果最佳,酶活回收率达246%。与游离脂肪酶相比,固定化脂肪酶有更宽的温度和p H适用范围、热稳定性显著提高,并展现出良好的储存稳定性和操作稳定性,固定化脂肪酶的Km低于游离脂肪酶的,酶与底物的亲和性较好。     

HA/GCPU复合多孔支架的可控制备及细胞相容性

以脂肪族异佛尔酮二异氰酸酯(IPDI)作为硬段、蓖麻油甘油酯(GCO)作为软段,通过原位聚合法制备了羟基磷灰石/蓖麻油甘油酯基聚氨酯(HA/GCPU)复合多孔支架.利用红外光谱和扫描电子显微镜对复合支架进行表征,并测试其力学性能及孔隙率.研究结果表明,HA/GCPU复合多孔支架的孔隙率和抗压强度依赖羟基磷灰石的含量,并具有明显的可控性.HA质量分数分别为0,20%和40%时,HA/GCPU复合多孔支架孔隙率分别为(61±3)%,(68±2)%和(57±3)%,抗压强度分别为(605±61),(2125±58)和(4588±260)k Pa,可见HA质量分数为20%时,HA/GCPU复合多孔支架具有与松质骨较为匹配的孔隙率和抗压强度.将MG63细胞与多孔支架共培养,通过倒置显微镜和扫描电子显微镜观察,用噻唑蓝(MTT)法表征HA/GCPU复合多孔支架的细胞相容性,结果表明,HA/GCPU复合多孔支架表面细胞黏附,生长良好,无细胞毒性,在骨组织工程领域具有一定的应用前景.     

聚多巴胺/聚乙烯亚胺共沉积中间层增强薄膜复合正渗透膜性能

以聚多巴胺/聚乙烯亚胺(PDA/PEI)共沉积于三醋酸纤维素(CTA)多孔支撑膜表面形成中间层,再结合界面聚合法获得聚酰胺薄膜,构建了PDA/PEI共沉积中间层改性薄膜复合(TFC)正渗透(FO)膜.通过傅里叶变换衰减全反射红外光谱法、扫描电子显微镜、原子力显微镜、溶质截留法、水接触角仪等研究了PDA/PEI共沉积中间层对CTA膜和TFC膜的表面结构和性质的影响.研究结果表明,PDA/PEI共沉积使得CTA膜表面变得更为平滑,表面孔径减小至(30.0±4.1) nm,且表面孔径分布趋于均一.同时,在PDA/PEI共沉积改性CTA膜表面界面聚合得到的聚酰胺层呈现出更均匀的叶片状结构和优异的亲水性.基于此,具有PDA/PEI共沉积中间层的TFC正渗透膜显著提高了水通量(FO模式:(7.1±2.3) L/(m^2·h)),较空白TFC膜提升了57.6%.同时,中间层改性TFC膜具有更低的反向盐通量(FO模式:1.4±0.1 g/(m^2·h))和"净盐通量"(FO模式:(0.2±0.06) g/L),与空白TFC膜相比分别下降了83.9%和90.6%.说明PDA/PEI共沉积中间层不仅能有效提升TFC正渗透膜的水渗透性,而且大幅提升了膜的截盐性和渗透选择性.     

基于聚多巴胺/铜微粒自组装多层膜的无酶葡萄糖传感器

利用多巴胺易于在电极表面发生自聚反应,且聚多巴胺膜中富含邻苯二酚等反应性基团,可通过二次反应实现电极表面的进一步功能化修饰的特点,在玻碳电极(GCE)表面,将多巴胺自聚膜(PDA)与铜微粒(Cu)进行层-层自组装,构建了无酶葡萄糖电化学传感器(GCE/(PDA/ Cu) n )。传感器的灵敏度可通过控制多层膜的组装层数进行调控。采用紫外-可见光谱跟踪表征了多层膜的组装过程,结果表明,多层膜的生长是逐步且均匀的过程。采用循环伏安法和电流-时间曲线法研究了修饰电极对葡萄糖的电催化氧化性能。对于GCE/(PDA/ Cu)4,检测葡萄糖的线性范围为0.5~9.0 mmol/ L,检出限为5.8μmol/ L(S/ N=3)。本传感器具有良好的重现性、稳定性和较强的抗干扰能力。将本传感器用于血清中葡萄糖的测定,结果令人满意。     

生物3D打印PLCL/PPDO基骨修复支架

通过生物3D打印将聚L-丙交酯-己内酯PLCL(摩尔比:LLA/CL=90/10)和聚对二氧环己酮PPDO共混物制备成平均孔径约为500μm,孔隙率为60%的骨修复支架,并进行了15 w的降解实验。通过DSC测试分析材料和支架的热力学性能;通过SEM照片分析骨修复支架。结果表明:PPDO的加人明显缩短了PLCL/PPDO复合支架的降解时间;当支架中 PPDO的含量超过10%时,PLCL和PPDO的相容性越差,支架表面的粗糙程度越高,且支架内部相分离越明显。     

基于聚多巴胺的表面改性方法研究现状

多巴胺具有与贻贝粘附蛋白类似的性能。它可以沉积在几乎所有物质表面对其进行改性,且能与氨基、巯基、金属离子等官能团反应,所以将多巴胺修饰在材料表面不但可以赋予材料表面依赖于聚多巴胺(PDA)的仿生特性,而且PDA的反应活性为材料表面的二次修饰提供了理想的平台。这种基于PDA的表面修饰方法不但简单、绿色且适用性非常广,可应用于化学、生物、医药、材料等多个领域。本文从多巴胺的结构以及聚合、粘附机理研究入手,对近几年在材料表面修饰PDA,且以其为平台再二次修饰的报道进行了归纳总结,进一步认识和理解了多巴胺的性能,并为设计和构建新型的、高性能化的PDA仿生功能材料提供思路,推动研究者们在此基础上将PDA应用于更多的领域,使其向着绿色化和多样化方向发展。     

PDA/PVDF紫外线屏蔽复合膜的制备及性能表征

利用多巴胺在溶液中自聚得到聚多巴胺(PDA)颗粒, 然后将其作为填料加入聚偏氟乙烯(PVDF)中, 采用溶液成膜法制备具有紫外线屏蔽功能的PDA/PVDF复合膜. 通过傅里叶变换红外光谱(FTIR)、 扫描电子显微镜(SEM)和紫外可见分光光度计(UV-Vis)对制备的PDA颗粒的结构、 形貌以及吸光度进行表征, 并且进一步利用X 射线衍射仪(XRD)、 差示扫描量热仪(DSC)、 热失重分析仪(TGA)、 接触角测量仪(CA)以及紫外老化箱等对PDA/PVDF复合膜的结构、 热性能、 润湿性能与紫外线屏蔽性能进行测试. 结果表明, 制备的PDA颗粒的粒径约为160 nm; 掺杂PDA之后的PVDF膜的结晶度以及接触角均减小; 并且PDA质量分数为5%时得到的PDA/PVDF复合膜在200400 nm范围内的透过率均低于1%, 能够吸收所有的紫外线, 表现出优异的紫外线屏蔽功能.     

Fabrication and Evaluation of Alginate/Bacterial Cellulose Nanocrystals–Chitosan–Gelatin Composite Scaffolds

It is common knowledge that pure alginate hydrogel is more likely to have weak mechanical strength, a lack of cell recognition sites, extensive swelling and uncontrolled degradation, and thus be unable to satisfy the demands of the ideal scaffold. To address these problems, we attempted to fabricate alginate/bacterial cellulose nanocrystals-chitosan-gelatin (Alg/BCNs-CS-GT) composite scaffolds using the combined method involving the incorporation of BCNs in the alginate matrix, internal gelation through the hydroxyapatite-d-glucono-δ-lactone (HAP-GDL) complex, and layer-by-layer (LBL) electrostatic assembly of polyelectrolytes. Meanwhile, the effect of various contents of BCNs on the scaffold morphology, porosity, mechanical properties, and swelling and degradation behavior was investigated. The experimental results showed that the fabricated Alg/BCNs-CS-GT composite scaffolds exhibited regular 3D morphologies and well-developed pore structures. With the increase in BCNs content, the pore size of Alg/BCNs-CS-GT composite scaffolds was gradually reduced from 200 μm to 70 μm. Furthermore, BCNs were fully embedded in the alginate matrix through the intermolecular hydrogen bond with alginate. Moreover, the addition of BCNs could effectively control the swelling and biodegradation of the Alg/BCNs-CS-GT composite scaffolds. Furthermore, the in vitro cytotoxicity studies indicated that the porous fiber network of BCNs could fully mimic the extracellular matrix structure, which promoted the adhesion and spreading of MG63 cells and MC3T3-E1 cells on the Alg/BCNs-CS-GT composite scaffolds. In addition, these cells could grow in the 3D-porous structure of composite scaffolds, which exhibited good proliferative viability. Based on the effect of BCNs on the cytocompatibility of composite scaffolds, the optimum BCNs content for the Alg/BCNs-CS-GT composite scaffolds was 0.2% (w/v). On the basis of good merits, such as regular 3D morphology, well-developed pore structure, controlled swelling and biodegradation behavior, and good cytocompatibility, the Alg/BCNs-CS-GT composite scaffolds may exhibit great potential as the ideal scaffold in the bone tissue engineering field.     

Generation of Haploid Spermatids on Silk Fibroin-Alginate-Laminin-Based Porous 3D Scaffolds

In vitro production of sperm is a desirable idea for fertility preservation in azoospermic men and prepubertal boys suffering from cancer. In this study, a biocompatible porous scaffold based on a triad mixture of silk fibroin (SF), alginate (Alg), and laminin (LM) is developed to facilitate the differentiation of mouse spermatogonia stem cells (SSCs). Following SF extraction, the content is analyzed by SDS-PAGE and stable porous 3D scaffolds are successfully prepared by merely Alg, SF, and a combination of Alg-SF, or Alg-SF-LM through freeze-drying. Then, the biomimetic scaffolds are characterized regarding the structural and biological properties, water absorption capacity, biocompatibility, biodegradability, and mechanical behavior. Neonatal mice testicular cells are seeded on three-dimensional scaffolds and their differentiation efficiency is evaluated using real-time PCR, flow cytometry, immunohistochemistry. Blend matrices showed uniform porous microstructures with interconnected networks, which maintained long-term stability and mechanical properties better than homogenous structures. Molecular analysis of the cells after 21 days of culture showed that the expression of differentiation-related proteins in cells that are developed in composite scaffolds is significantly higher than in other groups. The application of a composite system can lead to the differentiation of SSCs, paving the way for a novel infertility treatment landscape in the future.     

Silk fibroin microfibers and chitosan modified poly (glycerol sebacate) composite scaffolds for skin tissue engineering

Porous mSF/PGS and CS/PGS composite scaffolds were prepared by the combination of poly(glycerol sebacate) (PGS) with silk fibroin microfibers (mSF) and chitosan (CS) as modifiers through particulate leaching and freeze-drying techniques. Both mSF/PGS and CS/PGS scaffolds show highly interconnected and open porous structures, and the crosslink density and water absorption of PGS were obviously enhanced by the modifiers. Moreover, the silk fibroin microfiber and chitosan can slow down and control the degradation rate of PGS. The biocompatibility of these porous PGS based composite scaffolds for skin tissue engineering was evaluated by cell culture experiments, and the results indicate of the good attachment, proliferation and deep penetration of cells into these composite scaffolds.     

Porous nano-minerals substituted apatite/chitin/pectin nanocomposites scaffolds for bone tissue engineering

In the current study, a porous 3D scaffold using Gallium-Apatite/chitin/pectin (Ga-HA/C/P) nanocomposites scaffolds (NCS) were fabricated by freeze-drying process with applications in orthopedics (bone tissue engineering). Various NCSs (0%, 30%, 50 and 70%) were prepared and characterized for its chemical structure, crystalline phase, surface texture by using various techniques such as FT-IR, XRD and SEM-EDX, respectively. The analyses of physicochemical properties proved that the formulated scaffolds were highly porous, and mechanically stable with superior density. The nanocomposite scaffolds also presented with increased swelling ability, lower biodegradation rate and higher mechanical strength. Further, biocompatibility and cytotoxicity of Ga-HA/C/P nanocomposite scaffolds were studied using NIH3T3 cells and MG-63 cells revealed no toxicity and cells attached and proliferated on scaffolds. Further implantation of prepared NCS showed mature bone formation through formation of new bone cells and osteoblast differentiation. Also, Ga-HA/C/P nanocomposites scaffolds proved to be more effective than chitin-pectin composite scaffolds. Taking results together it can be inferred that the prepared nanocomposite scaffolds possesses the prerequisites and showed great potential for treating orthopedic applications.     

Biodegradable highly porous interconnected poly(ε-caprolactone)/poly(L-lactide-co-ε-caprolactone) scaffolds by supercritical foaming for small-diameter vascular tissue engineering

Biodegradable ?4 mm tubular porous poly(ε-caprolactone)/poly(L-lactide-co-ε-caprolactone) (PCL/PLCL) scaffolds are fabricated successfully via one-step microcellular supercritical carbon dioxide foaming process. The effect of blending ratio on the rheology, pore structures, mechanical property, wettability, and biocompatibility of PCL/PLCL blends tubular scaffold are reported. Rheological results show that PCL matrix and PLCL dispersed phase has good compatibility. The melt strength of PCL can be enhanced obviously by adding PLCL. With an increase of PLCL content from 10 to 30 wt%, the pore size increases from 7.6 to 24.9 μm due to the homogeneous nucleation effect. The maximum open-cell content can reach 77% for PCL/PLCL foamed sample. Cyclical tensile and compliance tests show that few content of dispersed PLCL (10–20 wt%) improves the flexibility and recoverability. Cell viability results demonstrate that human umbilical vein endothelial cells (HUVECs) cultured on all PCL/PLCL porous scaffolds exhibit a typical spindle-like cell morphology. Moreover, HUVECs have a higher density and spreading areas on surface of 10% PLCL scaffold. The results gathered in this paper may open a new perspective for the fabrication of small-diameter vascular tissue engineering scaffold.     

Porous poly(glycerol sebacate) (PGS) elastomer scaffolds for skin tissue engineering

Poly (glycerol sebacate) (PGS) elastomer scaffolds with different porosity for skin tissue engineering were fabricated via particulate leaching. The introduction of pores lowers the hydrophilicity but improves the water uptake capability of PGS. The gel content of PGS increases with the increase of salt mass ratio, but the degree of swelling goes the opposite way due to the existence of the porous structure. The degradation rate of PGS can be tailored and controlled by the porous structure, which is of great value for its applications in tissue engineering. The feasibility of these porous PGS scaffolds for skin tissue engineering was evaluated by seeding mouse dermal fibroblasts (MDFs) onto the scaffold. In vitro cell culture results indicate good attachment, proliferation and deep penetration of MDFs into porous PGS scaffolds, which confirms the excellent biocompatibility of these scaffolds.     

Development of sodium alginate-xanthan gum based nanocomposite scaffolds reinforced with cellulose nanocrystals and halloysite nanotubes

Sodium alginate (Alg) and xanthan gum (XG) based nanocomposite scaffolds reinforced with various amounts of cellulose nanocrystals (CNCs) and/or halloysite nanotubes (HNTs) were prepared by freeze-casting/drying method. In this study, the structure-property-performance relationship was mainly focused and analysed. Morphological analysis showed high porosity and pore-interconnectivity (pore channels) in all obtained scaffolds. Structural analysis demonstrates the good interfacial interactions and uniform dispersion of the CNCs and HNTs, involving partial orientation within the polymeric network. The water uptake capacity (from 14.73.7 ± 0.46 g/g to 11.34 ± 0.32 g/g) and porosity (from 91.7 ± 0.81% to 88.5 ± 0.64%) were reduced. The compressive strengths (in dry state from 91.1 ± 1.2 kPa to 114.4 ± 0.6 kPa and in wet state from 9.0 ± 0.8 kPa to 10.6 ± 0.8 kPa), thermal stability, cytocompatibility (MC3T3-E1 osteoblastic cells) of the nanocomposite scaffolds improved as compared to Alg and AlgX scaffolds without CNCs and/or HNTs. The obtained scaffolds may be appropriate as scaffolding material in bone tissue engineering.     

Preparation of 3D fibroin/chitosan blend porous scaffold for tissue engineering via a simplified method

In this work, we developed a simple and flexible method to manufacture a 3D porous scaffold based on the blend of regenerated silk fibroin (RSF) and chitosan (CS). No crosslinker or other toxic reagents were used in this method. The pores of resulted 3D scaffolds were connected with each other, and their sizes could be easily controlled by the concentration of the mixed solution. Compared with pure RSF scaffolds, the water absorptivities of these RSF/CS blend scaffolds with significantly enhanced mechanical properties were greatly increased. The results of MTT and RT-PCR tests indicated that the chondrocytes grew very well in these blend RSF/CS porous scaffolds. This suggested that the RSF/CS blend scaffold prepared by this new method could be a promising candidate for applications in tissue engineering.     

Characterization on Modification and Biocompatibility of PCL Scaffold Prepared with Near-field Direct-writing Melt Electrospinning

In this study, orthogonal experiments were designed to explore the optimal process parameters for preparing polycaprolactone(PCL) scaffolds by the near-field direct-writing melt electrospinning(NFDWMES) technology. Based on the optimal process parameters, the PCL scaffolds with different thicknesses, gaps and structures were manufactured and the corresponding hydrophilicities were characterized. The PCL scaffolds were modified by chitosan (CS) and hyaluronic acid(HA) to improve biocompatibility and hydrophilicity. Both Fourier transform infrared spectroscopy(FTIR) analysis and antibacterial experimental results show that the chitosan and hyaluronic acid adhere to the surface of PCL scaffolds, sugges-ting that the modification plays a positive role in biocompatibility and antibacterial effect. The PCL scaffolds were then employed as a carrier to culture cells. The morphology and distribution of the cells observed by a fluorescence microscope demonstrate that the mo-dified PCL scaffolds have good biocompatibility, and the porous structure of the scaffolds is conducive to adhesion and deep growth of cells.     

Survival, migration and differentiation of retinal progenitor cells transplanted on micro-machined poly(methyl methacrylate) scaffolds to the subretinal space

Stem and progenitor cells can be combined with polymer substrates to generate tissue equivalents in culture. The replacement of retinal tissue lost to disease or trauma using retinal progenitor cells (RPCs) delivered on polymer scaffolds and transplanted into the sub-retinal space of the damaged retina is a promising therapeutic strategy. Micromachining-based, ultra-thin PMMA poly(methyl methacrylate) scaffolds may provide a suitable cytoarchitectural environment for tissue engineering and transplantation to the diseased eye. Here, adhesion of RPCs to polymer, as well as migration and differentiation in the host retina were compared for PMMA scaffolds (6 microm thickness) with either smooth or porous (11 microm diameter) surface topography. RPCs were cultured under identical conditions on smooth or porous laminin-coated polymer scaffolds and transplanted into the subretinal space of C57BL/6 mice. RPCs could be cultured on both scaffolds with similar results, although transplantation with non-porous scaffolds showed limited RPC retention. Porous scaffolds demonstrated enhanced RPC adherence during transplantation and allowed for greater process outgrowth and cell migration into the host retinal layers. Integrated cells expressed the mature neuronal marker neurofilament-200 (nf-200), the glial marker glial fibrillary acidic protein (GFAP) and the retinal-specific marker recoverin. No host foreign body response was seen. In conclusion, ultra-thin film PMMA scaffolds micromachined to contain through pores retain adherent RPCs to a considerably greater extent than unmachined versions during the transplantation process and can serve as a biocompatible substrate for cell delivery in vivo.