聚乳酸-羟基乙酸/改性纳米羟基磷灰石复合多孔支架材料的研制

聚乳酸-羟基乙酸(PLGA)/改性纳米羟基磷灰石(MHA)复合多孔组织工程支架材料的制备主要包含以下步骤:首先通过室温化学共沉淀法制备纳米羟基磷灰石,然后通过L-丙交酯在二甲苯溶液中聚合接枝纳米羟基磷灰石得到改性的纳米羟基磷灰石;最后通过改进的热致相分离两步初化法制备PLGA/MHA复合多孔支架.X射线衍射仪(XRD)显示纳米羟基磷灰石合成成功,透射电子显微镜(TEM)结果显示其为半径为30～50nm的球形,红外光谱显示聚乳酸成功的接枝到纳米羟基磷灰石表面;扫描电子显微镜(SEM)结果表明改进的热致相分离两步初化法制备的PLGA/MHA复合多孔支架的孔径在100～450μm.     

羟基磷灰石基多孔复合支架的制备及其表征

研究利用造孔剂法制备高度贯通的多孔羟基磷灰石(HA)支架,孔隙率约为78%,并利用聚己内酯(PCL)分别复合纳米HA(nHA)或微纳米生物玻璃(nBG)粉末对其进行涂覆改性,粉末的添加量均为10%~40%(质量分数)。4种类型支架分别记为HA、PCL/HA、nHA-PCL/HA和nBG-PCL/HA。实验结果发现,nHA-PCL/HA和nBG-PCL/HA复合支架最大抗压强度分别为1.41~1.98 MPa和1.35~1.78MPa。4类支架矿化实验显示,浸泡21d后nBG-PCL/HA表面促进生成较多的磷灰石矿化物;细胞实验结果显示细胞在4类支架上均生长良好,说明支架具有良好的生物相容性。支架在实验犬背部肌肉组织内植入2个月的组织学检测显示,4种支架内均有新骨形成,尤其是nHA-PCL/HA和nBG-PCL/HA孔内有更多的新生骨组织,说明这两种支架表面复合涂层中的生物活性纳米颗粒对诱导新骨生成具有积极的促进作用。     

羟基磷灰石的表面改性对羟基磷灰石/聚醚醚酮复合材料力学和摩擦性能的影响

采用共沉淀法制备纳米羟基磷灰石（HA）,并用硅烷偶联剂KH560对其进行表面改性;然后,以聚醚醚酮（PEEK）为基体,通过热压成型工艺制备原始HA/PEEK与改性HA/PEEK复合材料。考察两种HA的引入对复合材料结构、力学性能和摩擦性能的影响。利用XRD、FTIR、FESEM、拉伸测试、DMA和摩擦测试对两种HA/PEEK复合材料的结构和性能进行了表征。结果表明：HA表面引入了硅烷偶联剂KH560;改性前后HA的晶型结构没有明显改变;两种HA对PEEK基体的结晶结构也没有产生影响;改性HA在PEEK基体中分散均匀;与纯PEEK相比,10wt%改性HA/PEEK复合材料的储能模量增加了55.56%,玻璃化温度增加了3.6℃,磨痕深度降低了31.1%,有效改善了复合材料的热力学性能和摩擦性能;改性HA/PEEK拉伸强度为68.33 MPa,能够满足人骨的强度要求。     

羟基磷灰石(HA)表面改性对HA/聚乳酸复合材料力学性能的影响

采用三种高分子有机物聚乙二醇(PEG)、聚乙烯醇(PVA)和聚丙烯酸(PAA)对羟基磷灰石(HA)颗粒表面进行改性处理,以便改善两相在复合时的界面结合强度,从而获得力学性能优良的复合材料.首先,将三种高分子聚合物分别溶于含HA颗粒的水溶液中,均匀分散后经喷雾干燥获得改性的粉体;然后,利用流延法获得HA/PLLA复合材料薄膜.研究了3种高分子表面改性HA颗粒后复合材料的力学性能,以及自然断面的界面结合情况.结果表明HA表面经PEG改性后,HA与PLLA间的界面结合状态优良,HA/PEG/PLLA的断裂强度较未经表面改性处理的HA颗粒与PLLA的复合材料的断裂强度提高了31%.     

改性聚乳酸/羟基磷灰石复合材料的制备及性能研究

以羟脯氨酸改性后聚乳酸(PLA)作为基体材料,以羟基磷灰石(HA)为改性材料,制备了聚乳酸/羟基磷灰石复合材料(PLA/HA)。通过X射线(XRD)表征可知,改性后的PLA和HA的混合为物理混合,混合的过程中并没有改变HA的结晶性。TG分析结果表明,HA的加入能够提高材料的热稳定性能。扫描电子显微镜(SEM)观察可知纳米级HA粒子未发生团聚现象,两种物质的界面相容性良好。力学性能测试得出:材料的力学强度在HA的含量为10%时为最佳,此时的拉伸强度为45.7MPa、弯曲强度为127.7MPa、弯曲模量为2.34GPa,能够满足人体骨组织的强度要求。     

纳米羟基磷灰石/聚乳酸多孔生物工程材料的制备与性能

纳米羟基磷灰石(n HA)/聚乳酸(PLA)生物工程材料可作为骨的替代材料,在医学上有较大的应用价值。n HA是骨组织的主要成分,有良好的生物活性,可作为骨组织工程材料的填充物;而PLA在生物体内可完全降解,有良好的生物相容性。文中通过制备多孔n HA/PLA复合材料,探讨最佳的n HA添加量以及高效的致孔方法。实验发现,n HA分散在PLA的过程中,通过乙醇溶剂的引入制备出多孔复合材料,制备方法简单高效无毒,所得样品有较好的孔结构;而XRD测试结果表明n HA可以促进PLA的结晶,为PLA的结晶研究提供了借鉴。同时,观察SEM图发现,实验中以m(n HA)∶m(PLA)≤3∶10比例改性为宜,而最佳的添加比例为m(HA)∶m(PLA)=1∶10,此时制得的样品具有较好的成孔性。     

羟基磷灰石聚乳酸多孔复合材料的制备与表征

羟基磷灰石陶瓷(HA)与人体具有良好的生物相容性,能够与骨结合,可用于骨代替材料,但其机械性能欠佳,还有待提高。聚乳酸(PLA)具有良好的生物相容性和降解性能。现将二者复合制备了HA/PLA复合物,采用超声分散法制备不同比例的HA/PLA多孔复合材料,并对该材料进行了相关的表征。结果表明HA/PLA比例在70:100时获得孔隙率及综合性能较好的多孔材料。     

聚乳酸/聚乙二醇/羟基磷灰石多孔骨支架的3D打印制备及其生物相容性

聚乳酸(PLA)是一种应用广泛的生物高分子材料,但在应用过程中存在韧性、亲水性、生物活性差等缺点。用聚乙二醇(PEG)和羟基磷灰石(HA)对PLA进行改性。通过熔融共混制备不同质量比的PLA/PEG/HA复合3D打印线材,并通过分析PLA/PEG/HA线材的力学性能、结晶性能、热性能、流变性能等,筛选更适合熔融沉积成型(FDM)的3D打印成型线材,进而利用3D打印制备精度高的力学性能试样及生物相容性好、细胞可增殖和分化的生物多孔支架。结果表明:PEG的添加提高了PLA的韧性,降低了PLA的熔点。HA的添加则提高PLA/PEG/HA复合材料的弹性模量和冷结晶温度,同时HA也可以改善复合材料的加工性能。SEM与荧光标记结果表明多孔支架与细胞具有良好的生物相容性。生物支架对体外细胞的成功培养,为进一步发掘生物多孔支架在动物体内、生物医学及定制化应用方面提供了潜在可能。     

硬脂酸对纳米羟基磷灰石表面的改性机理

用硬脂酸对羟基磷灰石进行了表面改性处理,采用XRD、TEM、FTIR以及XPS等方法研究了表面改性的机理及硬脂酸含量对羟基磷灰石活化率的影响。结果表明,羟基磷灰石的晶体结构及微观形貌没有发生变化。硬脂酸通过硬脂酸根离子（CH3（CH2）16COO^-）与羟基磷灰石表面的钙离子结合形成离子键而接枝在羟基磷灰石表面。当硬脂...     

硬脂酸对纳米羟基磷灰石表面的改性机理

用硬脂酸对羟基磷灰石进行了表面改性处理,采用XRD、TEM、FTIR以及XPS等方法研究了表面改性的机理及硬脂酸含量对羟基磷灰石活化率的影响。结果表明,羟基磷灰石的晶体结构及微观形貌没有发生变化。硬脂酸通过硬脂酸根离子(CH_3(CH_2)_(16)COO~-)与羟基磷灰石表面的钙离子结合形成离子键而接枝在羟基磷灰石表面。当硬脂酸含量为3%时,羟基磷灰石的活化率超过99%,继续增加硬脂酸含量,活化率基本保持不变。通过硬脂酸的表面改性处理,使羟基磷灰石表面的亲水性成功地转变为疏水性。     

Scaffolds for drug delivery,part I: electrospun porous poly(lactic acid) and poly(lactic acid)/poly(ethylene oxide) hybrid scaffolds

This is the first in a series of papers, focused on the development of a biodegradable, controlled, and potentially targeted drug delivery system. In this paper, we describe the production of highly porous biodegradable fibrous structures suitable for biomedical applications and as a matrix for drug delivery. Two structures are described below. The first structure is composed of electrospun poly(lactic acid) (PLA) fibers and is unique due to (1) the uniformity if its constitute fibers’ diameter, (2) consistent surface pore dimensions of each fiber, (3) the use of only a single solvent, (4) interior nano-size porosity throughout each individual fiber, and (5) the independency of surface pore dimensions on fiber diameter. The produced matrix will be further impregnated with cargo loaded nanoparticles—Red clover necrotic mosaic virus (RCNMV)—to achieve a controlled drug delivery system (described in Part III) for cancer treatments. Such a structure can also be used as tissue engineering scaffolds and filter media. The second electrospun structure has enhanced hydrophilicity compared to PLA matrix and is formed by blending poly(lactic acid)/poly(ethylene oxide) (PEO) polymers. The incorporation of PEO in the matrix introduces preferable sites for aqueous compounds to be attached to while retaining the overall structural integrity and porous morphology. It is hypothesized that the existence of alternative hydrophilic and hydrophobic segments in the structure may reduce post-implantation complications such as platelet adhesion.     

Characterisation and modelling of the elastic properties of poly(lactic acid) nanofibre scaffolds

The aim of this study is to predict the elastic response of poly(lactic acid) (PLA) electrospun nanofibre scaffolds through mathematical models based on homogenisation and the differential replacement method (DRM). These models principally seek to determine and analyse the effects of the internal morphology of the nanofibres on the effective Young’s modulus of polymer nanofibre scaffolds. The microstructure of the nanofibres was first characterised by SEM, XRD, DSC, AFM, and TEM techniques. From this characterisation, strong evidence of a hierarchical core–shell structure was found. With the experimental data, it was possible to design and validate better models than those currently used. In addition, the effects of the electrospinning parameters, such as take-up velocity and thermal treatment, were analysed and correlated with the morphology and the elastic properties of the nanofibres and their scaffolds. To validate the models’ results, we conducted a series of uniaxial tensile tests on the PLA nanofibre scaffolds. Using the data from the nanofibre measurements, the homogenisation approximations and the model based on the DRM predicted an effective Young’s modulus of 667 and 835 MPa, respectively. The predicted data were in excellent agreement with the experimental results (685–880 MPa). These models will be useful in understanding and evaluating the structure–property relationships of oriented nanofibre scaffolds for medical or biological applications.     

In vitro degradation of porous poly(lactic acid)/quantum dots scaffolds

In this study, cadmium selenide/zinc sulfide (CdSe/ZnS) quantum dots (QDs) were introduced into poly(lactic acid) (PLA) for fabrication of photoluminescent PLA/QDs scaffolds. TEM images revealed that the QDs were uniformly dispersed in the PLA. Compressive modulus and thermal stability of the PLA/QDs scaffolds are higher than those of the unfilled PLA scaffold. Cytotoxicity test results confirmed the non-cytotoxicity of the PLA/QDs scaffolds. During the process of in vitro degradation, the degradation rate of the PLA was accelerated by the presence of the QDs, and the molecular weight distributions of the PLA/QDs scaffolds were much broader when compared with the unfilled PLA ones. During the first 84 weeks of the degradation process, the photoluminescence (PL) intensity of the PLA/QDs scaffolds decreased with almost the same degradation ratio. The results suggested that the CdSe/ZnS QDs have potential applications for monitoring in vivo degradation of tissue engineering scaffolds.     

Nanodiamond/poly (lactic acid) nanocomposites: Effect of nanodiamond on structure and properties of poly (lactic acid)

Nanodiamond (ND)/poly (lactic acid) (PLA) nanocomposites with potential for biological and biomedical applications were prepared by using melting compound methods. By means of transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Thermogravimetric analyses (TGA), Dynamic mechanical analyses (DMA), Differential scanning calorimetry (DSC) and Tensile test, the ND/PLA nanocomposites were investigated, and thus the effect of ND on the structural, thermal and mechanical properties of polymer matrix was demonstrated for the first time. Experimental results showed that the mechanical properties and thermal stability of PLA matrix were significantly improved, as ND was incorporated into the PLA matrix. For example, the storage modulus (E′) of 3 wt% ND/PLA nanocomposites was 0.7 GPa at 130 °C which was 75% higher than that of neat PLA, and the initial thermal decomposition was delayed 10.1 °C for 1 wt% ND/PLA nanocomposites compared with the neat PLA. These improvements could be ascribed to the outstanding physical properties of ND, homogeneous dispersion of ND nanoclusters, unique ND bridge morphology and good adhesion between PLA matrix and ND in the ND/PLA nanocomposites.     

Novel porous scaffolds of poly(lactic acid) produced by phase-separation using room temperature ionic liquid and the assessments of biocompatibility

Here we prepared three-dimensional (3D) porous-structured biodegradable polymer scaffolds for tissue regeneration using room temperature ionic liquids (RTILs) as a novel porogen, and addressed their biological properties, including in vitro cell growth and differentiation and in vivo tissue compatibility. RTIL based on 1-butyl-3-methylimidazolium ([bmim]) bearing hydrophilic anion Cl was introduced within the polymer structure to provide a pore network. A mixture of poly(lactic acid) (PLA) with RTIL dissolved in an organic solvent formed a bi-continuous network during the drying process. Selective dissolution of the RTIL phase was facilitated in ethanol, which resulted in a porous network of the polymer phase with complete removal of the RTIL. The RTILs-assisted porous scaffolds showed a typical open-channeled network with pore sizes over 100 μm and porosities of about 86–94%. For the biocompatibility assessments of the scaffolds, mesenchymal stem cells (MSCs) derived from rat bone marrow were seeded onto the PLA scaffold, and the cell proliferation and osteoblastic differentiation behaviors were examined. Results showed a typical on-going increase in the cell population with a level comparable to that observed on the tissue culture plastic control, indicating good cell compatibility. When cultured in an osteogenic medium, the alkaline phosphatase (ALP) activity of the cells on the PLA scaffolds was stimulated to increase with time from 7 to 14 days, in a similar manner to that on the control. Moreover, the expression of genes related to osteoblasts, including collagen type I, osteocalcin and bone sialoprotein, was stimulated on the 3D PLA scaffold during culture for up to 14 days, with levels higher than those on the control, suggesting the developed scaffold provided a 3D matrix condition for osteogenesis. An in vivo pilot study conducted subcutaneously in rat for 4 weeks revealed good tissue compatibility of the scaffold, with the ingrowth of cells and formation of collageneous tissue around and deep within the pores of the scaffold and no significant inflammatory reaction. Taken together, this novel method of using RTILs as a pore generator is considered to be useful in the development of biocompatible porous polymer scaffolds for tissue regeneration.     

Biodegradable poly(lactic acid)/hydroxyl apatite 3D porous scaffolds using high-pressure molding and salt leaching

Scaffolds comprising poly(lactic acid) (PLA) and hydroxyl apatite (HA) were fabricated by combination of the high-pressure compression-molding plus salt-leaching techniques. The optimized HA content was determined in terms of the pore morphology, porosity, storage modulus, degradation behavior, hydrophilicity as well as the cell growth ability of the scaffolds. At HA content of 20 wt%, the scaffolds exhibited an interconnected open pore structure with the high porosity of 82.2 %. More importantly, the storage modulus of PLA/HA scaffolds (87.6 MPa) achieved almost three times higher compared with pure PLA scaffolds, while under low-pressure condition, the increase of modulus caused by HA does not reach 150 %. The obvious contrast indicated that HA and high pressure had a synergistic effect on enhancing mechanical properties of porous scaffolds. It was truly interesting that the hydrophilicity of PLA/HA scaffolds was significantly improved by alkaline hydrolysis treatment, which eventually led to the excellent cellular biocompatibility of the scaffolds, as revealed from the morphology and spreading of the cells cultured in our scaffolds. On the whole, the resultant PLA/HA scaffolds are well-suited candidates for the design of tailor-made matrices in tissue engineering.     

采用聚醚酯制备多孔支架的条件控制

采用热致相分离(TIPS)结合冷冻干燥技术制备了聚醚酯(聚对苯二甲酸丁二醇酯-co-聚对苯二甲酸环己烷二甲醇酯-b-聚乙二醇)(PTCG)多孔支架,研究了聚合物质量浓度、粗化温度和溶剂组成等相分离参数对多孔支架形貌结构的影响.结果表明,制备出的多孔支架孔间相互贯通,支架表面(与空气接触面)的孔径大于底面(与玻璃接触面)的孔径;随着聚合物质量浓度的增大,支架的孔径和孔隙率减小.由于分相过程中热力学推动力增大和相区融合阻力增加的相互作用,孔径随着粗化温度的降低呈现先升后降的趋势,并在0℃时出现最大值.在DO中加入不良溶剂H2O,溶液分相温度的升高导致多孔支架孔径的增大.通过控制相分离参数可以制备不同形貌结构的PTCG多孔支架.     

功能分子共聚改性聚乳酸的研究进展

为了获得降解性能、亲水性能和力学性能等更好的生物材料,各种功能分子改性聚乳酸的研究日益受到重视.本文按照官能团的不同,综述了近年来功能分子共聚改性聚乳酸的研究情况,指出利用新颖的功能分子改性聚乳酸和利用直接熔融共聚法降低共聚改性聚乳酸是未来的发展方向.     

In-depth study of mechanical properties of poly(lactic acid)/thermoplastic polyurethane/hydroxyapatite blend nanocomposites

Journal of Materials Science - The present study evaluates the effect of adding different contents of hydroxyapatite (HA) nanoparticles on the mechanical properties of poly(lactic...