细菌纤维素支架的复合改性及生物性能

采用原花青素交联和仿生矿化技术,以生物相容性良好的细菌纤维素(BC)为原材料制备了BC/多肽(pol)和BC/多肽/羟基磷灰石(HAp)复合材料,并利用场发射扫描电镜、X射线衍射仪和红外光谱仪对制备材料进行分析表征,采用成骨细胞评估了几种支架材料的生物相容性。结果表明,交联和仿生矿化成功地将pol和HAp引入到BC的表面和内部,细胞实验表明,3种支架材料均具有一定的生物相容性,且复合改性提高了支架材料的生物活性,制备的材料具有优异的性能,是具有应用前景的组织工程支架材料。     

羟基磷灰石/纤维素骨仿生支架的制备及性能研究

为探究制备方法对羟基磷灰石/纤维素支架材料性能的影响,采用仿生矿化法、原位复合法和溶液共混法制备了3种羟基磷灰石(HA)/纤维素支架材料,表征了3种支架材料的结构、形貌和热稳定性,分析了制备方法对支架材料生物相容性的影响。结果表明：3种方法获得的复合支架中,HA和纤维素气凝胶(CAS)之间仅存在物理作用,且HA的引入提高了复合支架的稳定性,但仿生矿化法和原位复合法因CAS的引入限制了HA的生长,结晶度较低。3种复合材料均无细胞毒性且具有生物相容性,但仿生矿化法制备的复合支架材料具有较大的孔径、较高的比表面积,更有利于细胞的粘附及增殖。因此,仿生矿化法是制备医用骨支架材料的最佳途径。     

仿生矿化法制备双磷酸根改性的纤维素/羟基磷灰石复合支架

通过高碘酸钠的氧化以及基于席夫碱原理的阿仑膦酸缩合对支架表面进行功能化改性,最后通过仿生矿化的方式制备了一种新型的双磷酸根纤维素/羟基磷灰石三维复合支架。通过红外光谱仪、扫描电子显微镜、X射线衍射仪、X射线光电子能谱仪对磷酸化改性前后支架的矿化样品的组成、结构和形貌进行分析,结果表明改性后的凝胶支架表面沉积羟基磷灰石的含量、结晶度、晶粒尺寸、Ca/P元素比等,都更接近于天然骨骼中生物磷灰石晶体。细胞增殖毒性检测(CCK-8法)结果揭示了材料无细胞毒性,对矿化样品表面细胞的形貌分析表明,与未改性支架相比,细胞在复合支架上具有更高的活性以及更好的黏附性。因而,改性后的复合支架有望成为一种理想的支架材料。     

羟基磷灰石/ 胶原类骨仿生复合材料的制备及表征

通过体外模拟天然骨生物矿化和材料自组装的形成机制, 研究制备了类骨羟基磷灰石/ 胶原仿生复合材料并对材料进行了表征。结果表明: 纳米羟基磷灰石均匀分布在胶原基质上并择优取向排列, 该复合材料的成分和微观结构与天然骨类似。      

羟基磷灰石/纤维素复合材料在骨组织工程中的研究进展

自从使用羟基磷灰石复合材料作为生物医用替代材料以来,其制备原料和制备工艺不断得到优化,现已制备出性能接近于天然骨的复合材料。但是羟基磷灰石复合材料还存在很多不足,例如抗压强度和弹性模量达不到天然骨的要求而导致其骨兼容性和骨整合较差,这些缺点严重阻碍了它作为骨替代物的发展。羟基磷灰石/纤维素复合材料不仅具有二者的特点,而且两材料协同产生的优异性能使其更加适用于生物组织工程材料。相比传统的骨替代材料,羟基磷灰石/纤维素复合材料在力学性能、生物活性、生物相容性、生物降解性等方面都有不同程度的改善,并且具有更好的成骨活性,已经基本达到理想组织工程应用的支架材料的要求。在以纤维素为基底材料制备羟基磷灰石复合材料中,已经成功应用的纤维素类包括纳晶纤维素、细菌纤维素、羧甲基纤维素(CMC)等。但是不同的纤维素/羟基磷灰石复合材料之间也存在性能差异,有的纳米复合材料抗压强度较低,只有(1.57±0.09) MPa/cm~3,但是有的纳米复合材料的抗压强度和模量都能接近天然骨。因此近几年来,研究者们除了不断优化制备工艺,主要还在选择合适的纤维素方面不断尝试,并取得了很大的进步。目前,已经有研究者发现CMC/明胶/羟基磷灰石纳米复合材料的抗压强度和模量与人松质骨和皮质骨相似,并且它也能促进细胞的高碱性磷酸酶活性和细胞外矿化,可作为主要承载区的再生骨移植材料。本文介绍了羟基磷灰石与纤维素的特点,综述了各类羟基磷灰石/纤维素复合材料的制备方法以及研究现状,并对其性能进行了探讨,进而对羟基磷灰石/纤维素复合材料的研究发展前景予以展望,希望为制备性能更加良好的骨替代材料提供参考。     

木垛型壳聚糖多孔支架的磷酸化改性和仿生矿化

为提高壳聚糖支架材料的孔隙率及矿化程度, 通过磷酸化表面改性和仿生矿化制备了磷酸化(PCSW)和生物矿化(BMCW)木垛型壳聚糖多孔支架。FTIR结果显示, 壳聚糖分子中有磷酸根的引入。XRD结果表明, 矿化24 h后支架上形成结晶度较高的磷酸钙盐晶体, 矿化48 h后结晶度明显增加并形成单纯的羟基磷灰石(HA)结晶。SEM观察发现, 在支架的内外表面均致密地沉积了HA晶体层。压缩强度测试结果表明, 复合支架BMCW矿化48 h的压缩强度为(0.54±0.005) MPa, 压缩模量为(5.47±0.65) MPa, BMCW可用作非承重骨组织修复材料。     

透明质酸钠/魔芋葡甘聚糖多孔支架的仿生矿化研究

以魔芋葡甘聚糖(KGM)、透明质酸钠(SH)为主要原料,氨水为交联剂,制备SH/KGM多孔支架材料。将支架用钙盐溶液进行预钙化处理后,在模拟体液(Simulated body fluid,SBF)中浸泡仿生。仿生矿化后,对支架进行XRD、EDS、SEM分析。结果表明,仿生矿化后的SH/KGM多孔支架材料表面有圆球状羟基磷灰石颗粒沉积,且结晶度低、颗粒小;支架抗压强度及体外降解率均有相应的提高,是一种具有发展潜力的新型骨修复材料。     

木垛型壳聚糖多孔支架的磷酸化改性和仿生矿化

为提高壳聚糖支架材料的孔隙率及矿化程度,通过磷酸化表面改性和仿生矿化制备了磷酸化(PCSW)和生物矿化(BMCW)木垛型壳聚糖多孔支架.FTIR结果显示,壳聚糖分子中有磷酸根的引入.XRD结果表明,矿化24 h后支架上形成结晶度较高的磷酸钙盐晶体,矿化48 h后结晶度明显增加并形成单纯的羟基磷灰石(HA)结晶.SEM观察发现,在支架的内外表面均致密地沉积了HA晶体层.压缩强度测试结果表明,复合支架BMCW矿化48 h的压缩强度为(0.54±0.005) MPa,压缩模量为(5.47±0.65) MPa,BMCW可用作非承重骨组织修复材料.     

纳米羟基磷灰石/壳聚糖/羧甲基纤维素三元复合骨修复材料的制备和性能研究

用溶液共混法在常温常压下制备了不同比例的纳米羟基磷灰石/壳聚糖/羧甲基纤维素三元复合骨修复材料.用燃烧实验、IR、XRD、SEM及TEM对复合材料的组成结构及形貌进行了分析和观察,并初步研究了其力学性能.结果表明该复合材料中纳米羟基磷灰石均匀分散在壳聚糖和羧甲基纤维素网络结构中,三组分间还产生了一定的相互作用,其形态、尺寸及结构与自然骨类似,且其抗压强度比纳米羟基磷灰石/壳聚糖二元复合材料更高;同时,通过调节各组分比例,可制得不同抗压强度的复合材料.因此,该三元复合材料可望作为一种新型可降解的非承重部位骨修复材料,在生物医学材料的研究中具有重要意义.     

原位沉析羟基磷灰石-壳聚糖骨组织工程支架材料的研制

仿生构建羟基磷灰石-壳聚糖复合材料是制备骨组织修复材料的重要途径之一.本研究利用有机官能团对无机物矿化的调控作用,在壳聚糖多孔支架表面原位沉析羟基磷灰石(HAp).在仿生溶液中,采用简单的化学处理,使HAp晶体在壳聚糖多孔支架表面原位沉析.研究结果表明壳聚糖分子结构中的氨基作为成核位点,在碱性条件下首先与吸附Ca2 ,再通过静电作用力吸附仿生溶液中的PO43-、OH-等其它离子促使HAp晶体在壳聚糖支架材料表面的成核、长大.此类材料有望成为一种生物活性的骨组织工程材料.     

Preparation and characterization of 2,3-dialdehyde bacterial cellulose for potential biodegradable tissue engineering scaffolds

Bacterial cellulose (BC) is suitable for applications as scaffolds in tissue engineering due to its unique properties. However, BC is not enzymatically degradable in vivo and this has become an essential limiting factor in its potential applications. In this work, BC was modified by periodate oxidation to give rise to a biodegradable 2,3-dialdehyde bacterial cellulose (DABC). After characterization by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy, thin-film X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS), we demonstrated that the modified DABC nano-network was able to degrade into porous scaffold with micro-sized pores in water, phosphate buffered saline (PBS) and the simulated body fluid (SBF). The degradation process began from the oxidized amorphous part of the network and concurrently hydroxyapatite formed on the scaffold surface during the process in SBF. Our data also demonstrated that the tensile mechanical properties of the DABC nano-network were suitable for its use in tissue engineering scaffolds.     

Hydroxyapatite/bacterial cellulose composites synthesized via a biomimetic route

In this work, biomimetic precipitation of hydroxyapatite (HA) from simulated body fluid (SBF) on bacterial cellulose (BC) was studied. BC was firstly chemically modified by soaking in 0.1 M CaCl₂ solution at 37 °C prior to biomimetic mineralization. The resulting HA/BC composites were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and thin-film X-ray diffractometry (XRD). The results revealed that the HA minerals were homogeneously precipitated on the BC surface. Furthermore, the crystals were carbonate-containing apatites with low crystallite size and crystallinity.     

Fabrication and mechanical evaluation of hydroxyapatite/oxide nano-composite materials

In the current study, the semiconducting metal oxides such as nano-ZnO and SiO₂ powders were prepared via sol–gel technique and conducted on nano-hydroxyapatite (nHA) which was synthesized by chemical precipitation. The properties of fabricated nano-structured composites containing different ratios of HA, ZnO and SiO₂ were examined using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM) and transmission electron microscope (TEM) techniques. The effect of the variation of ratios between the three components on mechanical, microstructure and in-vitro properties was assessed to explore the possibility of enhancing these properties. The results proved that the mechanical properties exhibited an increment with increasing the ZnO content at the extent of HA. In-vitro study proved the formation and nucleation of apatite onto the surface of the fabricated composites after one week of immersion. It is concluded that HA composites containing SiO₂ or SiO₂/ZnO content had a suitable mechanical properties and ability to form apatite particles onto the composite surface. Based on bioactivity behavior, Si-HA is more bioactive than pure hydroxyapatite and nano-arrangements will provide an interface for better bone formation. Therefore, these nano-composites will be promising as bone substitutes especially in load bearing sites.     

Synthesis and characterization of hydroxyapatite/chitosan nanocomposite materials for medical engineering applications

Incorporation of hydroxyapatite (HA) with organic polymer in favor of composites would be used in biomaterial engineering. According to prior researches, because of its chemical similarity to natural bone and dental, this product could improve bioactivity and bone bonding ability. In this research, nano-hydroxyapatite/chitosan composite material was prepared via in situ Hybridization route. The surface chemical characterization on the nanocomposite was evaluated by Fourier transformed infrared (FTIR) and X-ray diffraction (XRD). Surface topography, roughness and morphology of the samples were observed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The characterization results confirmed homogeneity, interaction and integration between the HA and chitosan matrix. It was indicated that composite samples consist of homogeneous aggregations around 40–100 nm, in which many HA nanocrystals align along the chitosan molecules. HA grain gradually decreased in size when amount of chitosan increased from 0 to 6 g into 100 cc solution. It can be seen that by increasing chitosan, the aggregation of nanoparticles enhance and subsequently, improve the expected compatibility among HA filler and chitosan matrix. Furthermore, the mechanical compressive testing indicated that the synthesized composites have acceptable mechanical behavior for tissue substitution. The mechanistic of the biodegradable nanocomposite systems, their preparation and characterization for medical usage are strongly discussed.     

Fabrication of mineralized electrospun PLGA and PLGA/gelatin nanofibers and their potential in bone tissue engineering

Surface mineralization is an effective method to produce calcium phosphate apatite coating on the surface of bone tissue scaffold which could create an osteophilic environment similar to the natural extracellular matrix for bone cells. In this study, we prepared mineralized poly(d,l-lactide-co-glycolide) (PLGA) and PLGA/gelatin electrospun nanofibers via depositing calcium phosphate apatite coating on the surface of these nanofibers to fabricate bone tissue engineering scaffolds by concentrated simulated body fluid method, supersaturated calcification solution method and alternate soaking method. The apatite products were characterized by the scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR), and X-ray diffractometry (XRD) methods. A large amount of calcium phosphate apatite composed of dicalcium phosphate dihydrate (DCPD), hydroxyapatite (HA) and octacalcium phosphate (OCP) was deposited on the surface of resulting nanofibers in short times via three mineralizing methods. A larger amount of calcium phosphate was deposited on the surface of PLGA/gelatin nanofibers rather than PLGA nanofibers because gelatin acted as nucleation center for the formation of calcium phosphate. The cell culture experiments revealed that the difference of morphology and components of calcium phosphate apatite did not show much influence on the cell adhesion, proliferation and activity.     

Mechanical and microstructure of reinforced hydroxyapatite/calcium silicate nano-composites materials

In this study, the nano sized hydroxyapatite (HA) and calcium silicate (CS) powders prepared by both chemical precipitation and sol–gel methods respectively. Biphasic nano-composites materials containing different ratios of HA and CS were fabricated and assessed using X-ray diffraction (XRD), Fourier transmission infrared reflectance (FT-IR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) techniques. The effect of variation of ratios between HA and CS on mechanical properties, microstructure and in vitro study was studied. The results proved that the mechanical properties were enhanced with increasing the CS ratio in the composite. In vitro study proved the formation and nucleation of apatite onto composites surfaces which contain low content of CS after one week of immersion. Finally, it is concluded that the HACS composites containing high HA content at the expense of CS content will be promising for bone substitute’s applications, especially in load bearing sites.     

Electrospun chitosan/hydroxyapatite nanofibers for bone tissue engineering

Chitosan (CS) nanofibers were prepared by an electrospinning technique and then treated with simulated body fluid (SBF) to encourage hydroxyapatite (HA) formation on their surface. The CS/HA nanofibers were subjected to scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy, and X-ray diffraction (XRD) to confirm HA formation as well as determine the morphology of the nanofibrous scaffolds. The SEM image indicated that the distribution of HA on the CS nanofibers was homogeneous. The results from EDS and XRD indicated that HA was formed on the nanofibrous surfaces after 6-day incubation in the SBF. The calcium/phosphorus ratio of deposited HA was close to that of natural bone. To determine biocompatibility, the CS/HA scaffolds were applied to the culture of rat osteosarcoma cell lines (UMR-106). The cell densities on the CS/HA nanofibers were higher than those on the CS nanofibers, the CS/HA film, and the CS film, indicating that cell proliferation on CS/HA nanofibers was enhanced. Moreover, the early osteogenic differentiation on CS/HA was also more significant, due to the differences in chemical composition and the surface area of CS/HA nanofibers. The biocompatibility and the cell affinity were enhanced using the CS/HA nanofibers. This indicates that electrospun CS/HA scaffolds would be a potential material in bone tissue engineering.     

Scaffolds of poly (ε-caprolactone) with whiskers of hydroxyapatite

Scaffolds of Poly (ε-caprolactone)/hydroxyapatite were produced and studied for tissue engineering applications. The materials were selected due to its biodegradability (PCL) and bioactivity (HA), and above all their biocompatibility toward the human tissue. The composites produced were characterized by SEM, XRD, and EDS. By analyzing these characterizations it was possible to obtain further information about the composition and morphology aspects of all portions of the composite scaffold.     

PLGA/HA骨支架材料的降解特性

采用有机泡沫法获得了HA多孔骨架.运用溶胶浇铸法将PLGA溶胶填充入多孔骨架中,制备出骨组织工程用PLGA/HA复合支架材料,并考察了其在模拟体液中的降解性能,通过SEM观察了其表面组织形貌.结果表明,随浆料中HA含量的增加,材料降解后质量损失增大,且随降解时间的延长,PLGA/HA骨支架材料表面粘附的磷灰石相增多,表明该复合材料具有良好的生物活性.     

Synthesis,Characterization and Bioactivity Evaluation of Porous Barium Titanate with Nanostructured Hydroxyapatite Coating for Biomedical Application

Nano phase hydroxyapatite (HA) bioceramics have gained importance in the biomedical field due to their superior biological properties. In this study, nanostructured HA coating was used to increase the bioactivity of a piezoelectric bioceramic, barium titanate (BT). Early reports on the influence of collagen piezoelectricity in remodeling of bone have attracted many researchers to piezoelectric bioceramics such as BT. Hence; porous BT was used as the matrix of a new bone graft composite and then coated with nanostructured HA. BT ceramic was foamed via a direct foaming method with a spray of polyurethane foam. The surface of the foam voids was coated with HA via sol–gel and dip‐coating methods. X‐ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) techniques were used to characterize the prepared coated foam. XRD and TEM analysis showed that the HA coating had a nanostructure with crystallite size of 20–30 nm. SEM images of the prepared samples showed that the HA coating has about 25 µm thickness. The bioactivity of the prepared composite was evaluated in an in vitro study. The variation of Ca²⁺ and PO₄^3? ions versus time in simulated body fluid (SBF) solution were measured by inductively coupled plasma (ICP) analysis during 1 month and the results showed that the mineralization of calcium phosphate (Ca‐P) on HA coated porous samples was much more than that in non‐coated sample. The SEM micrographs and energy‐dispersive X‐ray spectroscopy (EDS or EDX) analysis of the samples after 1 month of immersing in SBF confirm that Ca‐P phase (bone‐like apatite) was significantly mineralized on HA coated porous BT samples. It was concluded that the nanostructured HA coating would improve the bioactivity of BT foam.