羟基磷灰石/聚醚酯聚氨酯支架的体外降解行为和细胞相容性研究

采用XRD、DSC、体外降解实验和细胞相容性实验等方法对羟基磷灰石/聚醚酯聚氨酯(HA/PU)多孔支架的结构和性能进行了研究。结果表明,HA粒子添加到聚醚酯聚氨酯基体中,在一定程度上降低了聚氨酯软段的结晶,提高了聚氨酯基体的力学性能。体外降解实验表明HA/PU复合支架的降解不会引起浸泡液pH值较大的波动,且降解初期的力学性能衰减缓慢。MG63细胞与HA/PU复合支架共培养的实验表明,细胞生长良好,牢固地黏附在支架表面,并在支架表面充分伸展,复合支架具有良好的细胞相容性。这些结果表明HA/PU支架有望用于骨组织工程修复。     

亲水性聚氨酯复合材料的体外降解性和细胞相容性

采用摇床法和体外细胞培养法对亲水性羟基磷灰石/聚氨酯(HA/PU)纳米复合材料的体外降解性和体外细胞相容性进行了评估。结果表明:HA/PU纳米复合材料在磷酸缓冲溶液中浸泡不同时间后,材料发生了不同程度的降解。纳米HA含量对复合材料的降解性有一定影响,纳米HA含量较高的复合材料表现出较缓的降解速率。体外细胞相容性实验表明,MG63细胞在纯PU上成球型,抱团生长;而MG63细胞在HA/PU复合材料上生长良好,牢固地黏附在表面,并借助伪足在材料表面充分伸展,这说明HA/PU复合材料为细胞的黏附、增殖以及生存活力的维持提供了有利的环境。这些结果表明该HA/PU纳米复合材料有望用于骨组织工程修复。     

两步氧化法制备ZnO薄膜及其光催化特性研究

本文采用热蒸发法在玻璃衬底上沉积Zn膜,然后在氧气中通过两步热氧化制备ZnO薄膜。利用X射线衍射（XRD）、扫描电子显微镜（SEM）和紫外透过光谱等表征技术,研究了氧化温度对ZnO薄膜结晶质量和光学性能的影响。研究结果表明,两步氧化法在400℃下氧化1 h后的样品中除含有ZnO成份外,还有少量金属Zn存在;525℃下氧化1 h可以制备出疏松多孔的ZnO薄膜,其在紫外光和可见光范围内的透过率可达85%。通过太阳光和紫外光（254 nm）催化降解苯酚实验,发现两步氧化法制备的ZnO薄膜具有良好的光催化特性：太阳光照10 h后苯酚降解率达到56%,紫外灯下苯酚降解率高达86%。此外,ZnO薄膜的光催化重复利用实验表明,经过H2O2溶液清洗干燥处理后,ZnO薄膜可以基本恢复其光催化能力,此特性为ZnO薄膜的重复利用提供了很好的实验依据。     

钛酸钾生物薄膜/钛合金生物复合材料的制备及其体外生物相容性

用仿生化学方法制备钛酸钾生物薄膜/Ti-15Mo-3Nb生物复合材料,然后通过模拟体液培养试验、动态凝血试验及体外细胞培养试验对Ti-15Mo-3Nb和钛酸钾生物薄膜/Ti-15Mo-3Nb生物复合材料的体外生物相容性进行研究,以验证钛酸钾作为一种新型的生物活性涂层材料的可行性.对比试验的结果表明:(1)在模拟体液培养实验中,Ti-15Mo-3Nb表面未见钙磷沉积,表现为生物惰性,而呈多孔网状结构的钛酸钾生物薄膜具有很强的钙磷吸附能力,表现出很好的生物活性;(2)以动态凝血时间为指标,钛酸钾生物薄膜＞Ti-15Mo-3Nb,表现出良好的血液相容性;(3)细胞培养实验表明,二者均具有良好的细胞相容性,但在细胞培养初期钛酸钾生物薄膜具有更好的细胞附壁生长趋势,这将有利于损伤部位的早期愈合.钛酸钾生物薄膜/Ti-15Mo-3Nb生物复合材料表现出更好的生物相容性和生物活性.     

TiN／Ag多层膜的生物相容性研究

使用离子束辅助沉积（IBAD）的方法，在医用不锈钢317L的基底上制备TiN／Ag多层膜．在TiN／Ag多层膜具有良好的抗茵性和抗腐蚀性的研究基础上，通过细胞毒性试验和溶血试验评价了TiN／Ag多层膜的生物相容性．试验结果表明：TiN／Ag多层膜样品的细胞毒性等级在0～1之间；溶血率〈5％，符合生物医学材料的标准．这些说明TIN／Ag多层膜不仅具有抗菌性和抗腐蚀性，而且具有良好的生物相容性．     

a—C：H（N）薄膜的生物相容性

采用射频－直流等离子增强化学气相沉积法用Ｃ２Ｈ２与Ｎ２的混合气体制备了ａ－Ｃ：Ｈ（Ｎ）薄膜,用动物急性实验法和细胞毒性实验法研究了ａ－Ｃ：Ｈ（Ｎ）薄膜的生物相容性。结果表明,ａ－Ｃ：Ｈ（Ｎ）薄膜的生物相容性优于常用生物材料纯Ｔｉ,且能为细胞的生长提供合适的生长表面。     

魔芋葡甘聚糖/羧甲基纤维素钠共混膜的制备及其性能表征

以魔芋葡甘聚糖和羧甲基纤维素钠为主要原料,添加丙三醇为增塑剂,乳酸为改性剂,结合微波处理工艺,采用流延成型的方法制备出魔芋葡甘聚糖/羧甲基纤维素钠共混膜。通过FT-IR、X-射线衍射对共混膜进行性能表征,同时测定了共混膜的吸水率、力学性能和降解率。结果表明:膜有较好的降解性能和细胞相容性,作为一种潜在的术后防粘连材料将具有良好的应用前景。     

Ti-O/Ti-N复合薄膜的离子束合成及人工心脏瓣膜材料表面改性研究

采用离子束增强沉积（ＩＢＥＤ）等方法在热解碳、钛及钴合金等人工心脏瓣膜材料表面制备Ｔｉ－Ｏ、Ｔｉ－Ｎ及其复合薄膜。对薄膜的成分、结构进行了研究，测定了材料的电阻率，对薄膜材料的血液相容性和力学性能进行了系统的研究。结果表明：合成薄膜具有优于热解碳的血液相容性和力学性能，提出了材料的血液相容性机理模型。     

CdSe-ZnS QDs/PLGA纳米复合材料的性能及体外降解行为

采用溶液浇铸法制备了不同CdSe-ZnS量子点(Quantum dots QDs)含量的QDs/乳酸-乙醇酸共聚物(PLGA)复合材料薄膜,通过傅里叶变换红外光谱仪、透射电子显微镜(TEM)、光致发光光谱仪(PL)及紫外-可见吸收光谱仪(UV-Vis)等对薄膜的微观结构与光学性能进行了表征,并对不同降解时间后降解液的pH值、薄膜的发光情况和相对分子质量及其分布进行了测试。PL及UV-Vis结果显示,QDs/PLGA纳米复合材料的发光性能良好,吸光度随QDs含量增加而增大;TEM结果显示,QDs在基体中分散良好;在体外降解过程中,凝胶渗透色谱和缓冲液p H值测试结果说明,量子点催化了PLGA的降解;复合材料的荧光效应随着降解时间的延长逐渐减弱。以上结果说明,采用简单的溶液浇铸法制备的CdSe-ZnS QDs/PLGA复合材料发光性能稳定优异,且可以通过检测荧光效应变化以实现动态监测QDs/PLGA复合材料的降解进程。     

防粘连壳聚糖衍生物共混膜的生物学性质研究

将甲壳素、羧甲基壳聚糖和羟丙基壳聚糖按一定比例共混交联,流延成膜法制备CM-C-HP共混膜.利用细胞培养、扫描电镜、HE染色等方法对共混膜的吸水率、溶胀比、细胞相容性、细胞贴附性、皮内刺激反应、急性全身毒性、体内外降解性和生物相容性进行了评价.结果表明,该共混膜具有一定吸水率,溶胀比小,无皮内刺激反应和急性全身毒性,具有良好的细胞相容性,生物可降解性和生物相容性,对成纤维细胞的生长有较强的抑制作用,是一种极具潜力的具有良好生物安全性的可吸收防粘连膜片.     

Effects of material thickness and processing method on poly(lactic-co-glycolic acid) degradation and mechanical performance

In this study, the effects of material thickness and processing method on the degradation rate and the changes in the mechanical properties of poly(lactic-co-glycolic acid) material during simulated physiological degradation were investigated. Two types of poly(lactic-co-glycolic acid) materials were considered: 0.12?mm solvent-cast films and 1?mm compression-moulded plates. The experimental results presented in this study were compared to the experimental results of Shirazi et al. (Acta Biomaterialia 10(11):4695–703, 2014) for 0.25?mm solvent-cast films. These experimental observations were used to validate the computational modelling predictions of Shirazi et al. (J Mech Behav Biomed Mater 54: 48–59, 2016) on critical diffusion length scale and also to refine the model parameters. The specific material processing methods considered here did not have a significant effect on the degradation rate and the changes in mechanical properties during degradation; however, they influenced the initial molecular weight and they determined the stiffness and hardness of the poly(lactic-co-glycolic acid) material. The experimental observations strongly supported the computational modelling predictions that showed no significant difference in the degradation rate and the changes in the elastic modulus of poly(lactic-co-glycolic acid) films for thicknesses larger than 100?μm.     

Degradation behaviors of surface modified magnesium alloy wires in different simulated physiological environments

The degradation behaviors of the novel high-strength AZ31B magnesium alloy wires after surface modification using micro-arc-oxidization （MAO） and subse- quently sealing with poly-L-lactic acid （PLLA） in different simulated physiological environments were investigated. The results show the surface MAO micropores could be physically sealed by PLLA, thus forming an effective protection to corrosion resistance for the wires. In simulated gastric fluid （SGF） at a low pH value （1.5 or 2.5）, the treated wires have a high degradation rate with a rapid decrease of mass, diameter, mechanical properties and a significant increase of pH value of the immersion fluid. However, surface modification could effectively reduce the degradation rate of the treated wires in SGF with a pH value above 4.0. For the treated wires in simulated intestinal fluid at pH =8.5, their strength retention ability is higher than that in strong acidic SGF. And the loss rate of mass is faster than that of diameter, while the pH value of the immersion fluid decreases. It should be noted that the modified wires in simulated body environment have the best strength retention ability. The wires show the different degradation behaviors indicating their different degradation mechanisms, which are also proposed in this work.     

Effect of different processings on mechanical property and corrosion behavior in simulated body fluid of Mg-Zn-Y-Nd alloy for cardiovascular stent application

The biomagnesium alloys have been considered to be one of the most potential biodegradable metal materials due to its good mechanical compatibility, biological compatibility, biological security and biodegradable characteristics. However, the two major problems of high degradation rates in physiological environment and low mechanical properties prevent the development of biomagnesium alloys. In the present work, the samples of Mg-Zn-Y-Nd alloy were prepared by cyclic extrusion compression （CEC） and equal channel angular pressing （ECAP）. The microstructures, mechanical properties of alloy and its corrosion behavior in simulated body fluid （SBF） were evaluated. The results reveal that Mg-Zn-Y-Nd alloy consists of equiaxial fine grain structure with the homogeneous distribution of micrometer size and nano-sized second phase, which was caused by the dynamic recrystallization during the ECAP and CEC. The corrosion resistance of alloy was improved. The tensile and corrosion resistance were improved, especially the processed alloy exhibit uniform corrosion performances and decreased corrosion rate. This will provide theoretical ground for Mg-Zn-Y-Nd alloy as vascular stent application.     

Deposition behavior and properties of silk fibroin scaffolds soaked in simulated body fluid

Porous 3D silk fibroin (SF) scaffolds were prepared directly from the SF solution with the addition of methanol and glutaraldehyde by a freeze-drying method. The scaffolds were then soaked in the simulated body fluid (SBF) for the deposition of hydroxyapatite (HA) crystals. The XRD and FTIR results showed that the SF were in β-sheet structure, resulting in the high thermal stability and mechanical properties of scaffolds. The XRD and AAS data revealed that the SF scaffolds could induce the continuous growth and enrichment of HA crystals onto the scaffolds with the extension of soaking time. The mechanical properties of scaffolds increased first with the HA-deposition within 3 d of soaking, then it declined. During the full soaking period, no significant change was observed on the porosity and water-binding ability, which were kept at about 84% and 800%, respectively. The cell cultivation results showed that the scaffolds have the satisfied cell biocompatibility, which was promoted after the HA-deposition. This work suggests that the porous 3D SF scaffolds may be a potential candidate in the bone engineering.     

Bovine pericardium coated with biopolymeric films as an alternative to prevent calcification: In vitro calcification and cytotoxicity results

Bovine pericardium, for cardiac valve fabrication, was coated with either chitosan or silk fibroin film. In vitro calcification tests of coated and non coated bovine pericardium were performed in simulated body fluid solution in order to investigate potential alternatives to minimize calcification on implanted heart valves. Complementary, morphology was assessed by scanning electron microscopy — SEM; X-ray diffraction (XRD) and infrared spectroscopy (FTIR-ATR) were performed for structural characterization of coatings and biocompatibility of chitosan. Silk fibroin films were assayed by in vitro cytotoxicity and endothelial cell growth tests. Bovine pericardium coated with silk fibroin or chitosan did not present calcification during in vitro calcification tests, indicating that these biopolymeric coatings do not induce bovine pericardium calcification. Chitosan and silk fibroin films were characterized as non cytotoxic and silk fibroin films presented high affinity to endothelial cells. The results indicate that bovine pericardium coated with silk fibroin is a potential candidate for cardiac valve fabrication, since the affinity of silk fibroin to endothelial cells can be explored to induce the tissue endothelization and therefore, increase valve durability by increasing their mechanical resistance and protecting them against calcification.     

Advances in DLC coatings by hybrid PSII and PECVD as a barrier to corrosion in simulated body fluid*

In this study, diamond-like carbon (DLC) films were deposited on biomedical AISI316L stainless steel by hybrid plasma source ion implantation (PSII) and plasma-enhanced chemical vapour deposition (PECVD). Potentiodynamic polarization tests and Electrochemical Impedance Spectroscopy (EIS) have been employed to investigate the corrosion performance of different DLC films in Tyrode's simulated body fluid (pH = 7.4). The corrosion resistance of the DLC films by PECVD deteriorated rapidly after 24 h of immersion, but those made by hybrid PSII and PECVD offered more effective barrier for AISI316L stainless steel during 72 h of immersion. The test results demonstrated that the DLC film by hybrid PSII and PECVD possessed less corrosion current density, greater corrosion resistance, and more positive breakdown potential in simulated body fluid.     

Viscoelastic monitoring of starch-based biomaterials in simulated physiological conditions

Dynamic mechanical analysis (DMA) was used to investigate the solid-state rheological behaviour in a starch-based thermoplastic aimed to be used in different biomedical applications. The tested samples were processed by different injection moulding procedures. The dry samples were immersed in a simulated physiological solution and the relevant viscoelastic parameters were monitored against time. The decrease of stiffness due to swelling can be followed in real time, being less pronounced for the composite sample with hydroxyapatite (HA). The temperature control of the liquid bath was found to be very good. Frequency scans were also performed in wet conditions in samples previously immersed during different times, indicating that DMA is a suitable method to control in-vitro the changes on the viscoelastic properties of biomaterials during degradation.     

Effect of particle size on the in vitro bioactivity,hydrophilicity and mechanical properties of bioactive glass-reinforced polycaprolactone composites

Polycaprolactone (PCL) composite films containing 5 wt.% bioactive glass (BG) particles of different sizes (6 μm, 250 nm, < 100 nm) were prepared by solvent casting methods. The ultra-fine BG particles were prepared by high-energy mechanical milling of commercial 45S5 Bioglass® particles. The characteristics of bioactive glass particles were studied by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), and X-ray diffraction (XRD) methods. In vitro bioactivity of the PCL/BG composite films was evaluated through immersion in the simulated body fluid (SBF). The films were analyzed by FE-SEM, energy dispersive spectrometry (EDS), XRD, and atomic force microscopy (AFM). The mechanical properties of highly-porous PCL/BG composites were examined on cylindrical specimens under quasi-static compression load. It was found that partial crystallization of amorphous BG particles during a prolonged mechanical milling occurred and calcium silicate (CaSiO₃) and sodium calcium silicate (Na₂CaSiO₄) phases were formed. The introduction of submicron BG particles (250 nm) was shown to improve the bioactivity of PCL films. In contrast to BG microparticles, the submicron BG particles were distributed on the film surfaces, providing a high surface exposure to SBF with an improved nanotopography. A notable increase in the stiffness and elastic modulus of the composite was also obtained. As compared to submicron BG particles, lower bioactivity and elastic modulus were acquired for PCL/BG nanoparticles. It was also shown that in spite of high specific surface area of the nanoparticles, partial crystallization during mechanical milling and agglomeration of the nanoparticles during processing decrease the bioactivity, hydrophilicity and mechanical response of the BG-reinforced PCL composites.     

Preparation and characterization of polypropylene/sodium propionate (PP/SP) composite films for bread packaging application

To prolong the shelf life of bread, polypropylene/sodium propionate (PP/SP) composite films were prepared via a melt‐extrusion process. To investigate the feasibility of using PP/SP composite films as a bread packaging material, their chemical structure, morphology, mechanical properties, barrier properties against water, surface properties, and antimicrobial properties were investigated. A storage test for bread was also conducted. The mechanical and thermal stability of the PP/SP composite films enhanced with increasing SP content. Compared with pure PP, the PP/SP composites had increased hydrophilicity that increased with increasing SP content. These composite films showed enhanced antimicrobial activity against both Gram‐negative and Gram‐positive microorganisms. This was due to the interaction of SP and water originating from the bread, which modifies the pH of the bread and causes destruction of the cellular structures of fungi and also reduces the growth rate of bacteria. The enhanced thermal, mechanical, antifungal, and antimicrobial properties achieved by the addition of SP can be beneficial for maintaining the freshness of bread and prolonging its shelf life.     

β-偏磷酸钙晶须增强左旋聚乳酸材料的体外降解

对用于骨折内固定的β-偏磷酸钙晶须/左旋聚乳酸(β-CMP_W/PLLA)复合材料在体外降解过程中强度的变化、 分子量和微观形貌进行了初步研究。结果表明: 在人体模拟体液(SBF)中浸泡, 前8周材料的强度变化较小, 25wt%β-CMP_W/75wt%PLLA降解20周后的抗压强度值仍高达103MPa; 45wt%β-CMP_W/55wt%PLLA降解12周后抗压强度约为初始值的88%。扫描电镜图表明, 随降解时间的延长, 因聚乳酸溶解而在样品中形成孔洞。在降解周期内, SBF溶液的pH值随β-CMP_W/PLLA降解时间的延长基本保持稳定。凝胶渗透色谱检测结果表明, PLLA的数均相对分子质量和重均相对分子质量随降解时间的延长而降低, 降解20周后数均相对分子质量约为20万, 重均相对分子质量下降了32%。