纳米羟基磷灰石表面接枝聚合左旋丙交酯

为了改善HA纳米粒子与有机PLGA的相容性,分别采用六亚甲基二异氰酸酯加乙二醇、左旋乳酸改性纳米粒子表面后或直接原位接枝聚合左旋丙交酯等3种不同方法,制备了表面修饰聚乳酸的纳米羟基磷灰石(PLLA-g-HA).FTIR、XPS、TEM、TGA测试表明PLLA成功接枝到HA的表面.其中六亚甲基二异氰酸酯加乙二醇改性HA纳米粒子所获得的PLLA接枝率远高于其它两种方法达25%,调整有机相和无机相的比例对PLLA接枝率的影响较小,其在氯仿中可以稳定分散2天以上.共混电纺丝后的拉伸测试表明PLLA-g-HA/PLAG复合纤维膜的力学性能高于HA/PLGA膜,当两者之间的比例为5%拉伸性能达到最大值.     

Investigations of gold nanoparticles-mediated carbon nanotube reinforced hydroxyapatite composite for bone regenerations

An excellent combination of biomaterials permits prompt features and high-throughput investigations in various fields, particularly in the biomedical applications. This article investigates the bone regeneration ability and compatibility of the Gold (Au) Nanoparticles (NPs) medicated carbon nanotube reinforced hydroxyapatite (HAP) composite. The morphologies of the synthesized Au NPs, HAP and HAP/CNT, and HAP/CNT-Au composites vary suggestively with modifying the components and the final composite showing as bone mimic extracellular matrix morphology. The structure, phase, and composition of the as-synthesized HAP were studied by FTIR, XRD, EDAX, and TEM techniques. The materials' biocompatibility was investigated in the Stimulated Body Fluid (SBF) solution, which resulted in the composite having good biocompatibility, bioactivity nature and hydroxyapatite layer formed on the composite surface. The composite shows good viability with Adipose Tissue-derived Stem Cells (ADSC) to cell growth and cell proliferation in the biological evaluation. It represented the composites having a good ability for cell formation development. Since the HAP/CNT-Au composite are useful in medicinal applications such as orthopedic and orthodontic repair/regenerations after the evaluations of animal and clinical investigations.     

原位沉析法制备磁性氧化铁羟基磷灰石/壳聚糖棒材

首先通过化学沉淀法制备磁性氧化铁羟基磷灰石(Fe3O4/HA),然后以壳聚糖(CS)为基体,利用原位沉析法将Fe3O4/HA与CS复合,制得磁性Fe3O4/HA/CS复合材料.经XRD、粒径分布和PPMS测试,结果表明了Fe3O4/HA复合物的生成.系统研究了磁性Fe3O4/HA/CS棒材力学性能的影响因素,最终确定Fe3O4与HA质量比为3∶17,磁性Fe3O4/HA与CS质量比为9∶91时,棒材的力学性能最优,弯曲强度可达到87.0 MPa,弯曲模量1.57 GPa.     

An in vivo study of the host response to starch-based polymers and composites subcutaneously implanted in rats

Implant failure is one of the major concerns in the biomaterials field. Several factors have been related to the fail but in general these biomaterials do not exhibit comparable physical, chemical or biological properties to natural tissues and ultimately, these devices can lead to chronic inflammation and foreign-body reactions. Starch-based biodegradable materials and composites have shown promising properties for a wide range of biomedical applications as well as a reduced capacity to elicit a strong reaction from immune system cells in vitro. In this work, blends of corn starch with ethylene vinyl alcohol (SEVA-C), cellulose acetate (SCA) and polycaprolactone (SPCL), as well as hydroxyapatite (HA) reinforced starch-based composites, were investigated in vivo. The aim of the work was to assess the host response evoked for starch-based biomaterials, identifying the presence of key cell types. The tissues surrounding the implant were harvested together with the material and processed histologically for evaluation using immunohistochemistry. At implant retrieval there was no cellular exudate around the implants and no macroscopic signs of an inflammatory reaction in any of the animals. The histological analysis of the sectioned interface tissue after immunohistochemical staining using ED1, ED2, CD54, MHC class II and alpha/beta antibodies showed positively stained cells for all antibodies, except for alpha/beta for all the implantation periods, where it was different for the various polymers and for the period of implantation. SPCL and SCA composites were the materials that stimulated the greatest cellular tissue responses, but generally biodegradable starch-based materials did not induce a severe reaction for the studied implantation times, which contrasts with other types of degradable polymeric biomaterials.     

碳纳米管对羟基磷灰石基复合材料力学性能的影响

将力学性能优良的碳纳米管(CNTs)与羟基磷灰石(HA)生物陶瓷相复合,发展CNTs/HA复合材料来应用于骨组织修复领域,有望解决HA生物陶瓷力学性能的不足。通过3种不同的制备方法,即通过表面活性剂将CNTs分散在HA基体中、通过酸碱中和反应将CNTs与HA共沉淀以及通过体外浸泡在CNTs上矿化生长HA等方法来获得CNTs/HA复合材料。深入研究CNTs的表面结构和分散状态对CNTs/HA复合材料力学性能的影响。结果表明,CNTs的添加改变了HA的脆性,导致复合材料抗压力学性能得到提高。但是,由于复合材料制备方法的不同,导致CNTs在HA基体中的分散状态、表面结构的完整性以及与HA的界面结合情况不同,导致其抗压力学性能不同。其中,通过表面活性剂将CNTs分散在HA基体中而获得复合材料的抗压力学性能表现最好,而CNTs与HA通过共沉淀法所获得复合材料的抗压力学性能表现最差。     

碳纳米管对羟基磷灰石基复合材料力学性能的影响

将力学性能优良的碳纳米管(CNTs)与羟基磷灰石(HA)生物陶瓷相复合,发展CNTs/HA复合材料来应用于骨组织修复领域,有望解决HA生物陶瓷力学性能的不足.通过3种不同的制备方法,即通过表面活性剂将CNTs分散在HA基体中、通过酸碱中和反应将CNTs与HA共沉淀以及通过体外浸泡在CNTs上矿化生长HA等方法来获得CNTs/HA复合材料.深入研究CNTs的表面结构和分散状态对CNTs/HA复合材料力学性能的影响.结果表明,CNTs的添加改变了HA的脆性,导致复合材料抗压力学性能得到提高.但是,由于复合材料制备方法的不同,导致CNTs在HA基体中的分散状态、表面结构的完整性以及与HA的界面结合情况不同,导致其抗压力学性能不同.其中,通过表面活性剂将CNTs分散在HA基体中而获得复合材料的抗压力学性能表现最好,而CNTs与HA通过共沉淀法所获得复合材料的抗压力学性能表现最差.     

In-Vitro Cytotoxicity Study: Cell Viability and Cell Morphology of Carbon Nanofibrous Scaffold/Hydroxyapatite Nanocomposites

Electrospun carbon nanofibers (CNFs), which were modified with hydroxyapatite, were fabricated to be used as a substrate for bone cell proliferation. The CNFs were derived from electrospun polyacrylonitrile (PAN) nanofibers after two steps of heat treatment: stabilization and carbonization. Carbon nanofibrous (CNF)/hydroxyapatite (HA) nanocomposites were prepared by two different methods; one of them being modification during electrospinning (CNF-8HA) and the second method being hydrothermal modification after carbonization (CNF-8HA; hydrothermally) to be used as a platform for bone tissue engineering. The biological investigations were performed using in-vitro cell counting, WST cell viability and cell morphology after three and seven days. L929 mouse fibroblasts were found to be more viable on the hydrothermally-modified CNF scaffolds than on the unmodified CNF scaffolds. The biological characterizations of the synthesized CNF/HA nanofibrous composites indicated higher capability of bone regeneration.     

Bone‐guided regeneration: from inert biomaterials to bioactive polymer (nano)composites

Natural bone is a unique nanostructured material made of collagen fibre matrix and hydroxyapatite (HA) nanocrystals, providing mechanical support and protection from the vertebrate skeleton. However, in severe cases like bone‐deficiencies, bone needs to be “externally” repaired. Initially, different biological solutions were developed in bone‐guided regeneration. However, due to the limitations with the existing biological grafts, a lot of researches have been devoted toward biomaterials including metals, ceramics, and polymers. On the basis of the interface reactions between the implant and the surrounding tissues, these biomaterials may be classified as “nearly inert” or bioactive. Interestingly, the bioactive materials exhibit a specific biological response, leading to the formation of a natural bonding junction between the bone and the implant during bone regeneration. Recently, a special attention has been paid to a new generation of bioactive materials, i.e. (nano)structured biomaterials composed of a bioresorbable polymer matrix reinforced with bioactive inorganic compounds. While (bio)ceramic component provides the bioactivity, these materials can be readily engineered in such a way that their resorption rate in the body match the formation rate of the new tissue. This review hence reports the different biological and non‐biological solutions developed in bone‐guided regeneration, with a special emphasis on polymer‐based materials, and our recent results obtained in osseointegration The bone physiology, and its natural regeneration are also described. Copyright © 2011 John Wiley & Sons, Ltd.     

Degradation behaviors of electrospun fibrous composites of hydroxyapatite and chemically modified poly(dl-lactide)

It is essential to individually tailor the biodegradability of electrospun fibers and their composites to meet the requirements of specific application. Electrospun poly(dl-lactide) (PDLLA) fibers grafted with functional groups were obtained to induce in situ mineralization of hydroxyapatite (HA), and HA/PDLLA composites were fabricated through hot-pressing of mineralized fibers after layer-by-layer deposition. The degradation behaviors during up to 1 year incubation were clarified for functionalized PDLLA fibers, mineralized HA/PDLLA fibers and hot-pressed composites. The carboxyl and amino groups of electrospun fibers indicated enhancement and alleviation of the autocatalysis effect on the polyester hydrolysis, respectively. The distribution of HA within fiber matrices led quick and strong water absorption, and caused neutralization of the weak acid environment and alleviation of the autocatalysis effect. Due to the location of mineralized HA on the surface of functionalized fibers, significant HA loss and preferential removal of amorphous and low-crystalline apatitic phase were determined during the degradation process. The hot-pressed composites indicated dense structure, small pore size and fusion on the fiber surface, leading significantly lower degradation rate than electrospun fibers and mineralized fibers. Higher degradation rate of matrix polymers and HA loss were shown for hot-pressed composites from mineralized fibers than those from blend electrospun HA/PDLLA fibers. The obtained results should provide solid basis for further applications of functionalized PDLLA fibers, mineralized fibers and fibrous composites in biomedical areas.     

Marine derived polysaccharides for biomedical applications: chemical modification approaches

Polysaccharide-based biomaterials are an emerging class in several biomedical fields such as tissue regeneration, particularly for cartilage, drug delivery devices and gelentrapment systems for the immobilization of cells. Important properties of the polysaccharides include controllable biological activity, biodegradability, and their ability to form hydrogels. Most of the polysaccharides used derive from natural sources; particularly, alginate and chitin, two polysaccharides which have an extensive history of use in medicine, pharmacy and basic sciences, and can be easily extracted from marine plants (algae kelp) and crab shells, respectively. The recent rediscovery of poly-saccharidebased materials is also attributable to new synthetic routes for their chemical modification, with the aim of promoting new biological activities and/or to modify the final properties of the biomaterials for specific purposes. These synthetic strategies also involve the combination of polysaccharides with other polymers. A review of the more recent research in the field of chemical modification of alginate, chitin and its derivative chitosan is presented. Moreover, we report as case studies the results of our recent work concerning various different approaches and applications of polysaccharide-based biomaterials, such as the realization of novel composites based on calcium sulphate blended with alginate and with a chemically modified chitosan, the synthesis of novel alginate-poly(ethylene glycol) copolymers and the development of a family of materials based on alginate and acrylic polymers of potential interest as drug delivery systems.     

Phospholipid bilayer formation on hydroxyapatite sol-gel synthesized films

Lipid bilayers supported by porous biomaterials are being explored as models for cell membranes. Hydroxyapatite is a relevant material currently being used extensively for biomedical applications. In this study, hydroxyapatite films produced via a sol-gel chemistry route have been characterized and explored as a scaffolding material for lipid membranes. The hydroxyapatite has been characterized using XRD, SEM, and AFM, followed by vesicle-fusion of lipids characterized by fluorescence microscopy and fluorescence recovery after photobleaching (FRAP) to determine the diffusion coefficient of this system. The HA films produced in this work were found to produce slow lateral diffusion and, in the two-phase lipid systems, some domains were observed. The low lateral diffusion coefficients were believed to be a result of the large undulations present on the hydroxyapatite film surface.     

电纺丝法制备聚乳酸/多壁碳纳米管/羟基磷灰石杂化纳米纤维的研究

电纺丝是一种利用聚合物溶液或熔体在强电场中进行喷射纺丝的加工技术,所制得的纤维、直径一般在数十纳米至几微米之间,比传统方法制得的纤维直径小几个数量级,是获得纳米尺寸长纤维的有效方法之一．     

Preparation of chitosan/hydroxyapatite guided membrane used for periodontal tissue regeneration

<正>In an effort to develop biomaterials to meet guided tissue regeneration(GTR) standards for periodontal tissue recovery,a homogeneous and transparent chitosan(CS)/hydroxyapatite(HA) membrane with potential applications as GTR barrier in periodontal therapy has been prepared via in situ compositing.The membrane has been designed to have a smoothrough asymmetric structure that meets the demand for GTR.Component and morphology of the membrane are characterized by XRD and SEM.It can be indicated that HA was in situ synthesized uniformly in the CS membrane.Mechanical experiments of the membranes with various HA contents show that their tensile strengths are adequate for periodontal therapy.Biological properties of the membrane have been performed by cell toxicity assays,hemolysis tests and animal experiments.Results indicate that the membrane has good biocompatibility and inductive effect for cell growth.Therefore this membrane can be potentially applied as GTR barrier membrane for periodontal tissue regeneration.     

Application of carbon fibers to biomaterials: a new era of nano-level control of carbon fibers after 30-years of development

Carbon fibers are state-of-the-art materials with properties that include being light weight, high strength, and chemically stable, and are applied in various fields including aeronautical science and space science. Investigation of applications of carbon fibers to biomaterials was started 30 or more years ago, and various products have been developed. Because the latest technological progress has realized nano-level control of carbon fibers, applications to biomaterials have also progressed to the age of nano-size. Carbon fibers with diameters in the nano-scale (carbon nanofibers) dramatically improve the functions of conventional biomaterials and make the development of new composite materials possible. Carbon nanofibers also open possibilities for new applications in regenerative medicine and cancer treatment. The first three-dimensional constructions with carbon nanofibers have been realized, and it has been found that the materials could be used as excellent scaffolding for bone tissue regeneration. In this critical review, we summarize the history of carbon fiber application to the biomaterials and describe future perspectives in the new age of nano-level control of carbon fibers (122 references).     

Associates of thioalkyl derivatives of 2-arylaminopyrimidine with hydroxyapatite-based nanocomposites

Co-precipitation and ultrasonic treatment methods have been used for the in situ formation of the composites of hydroxyapatite (HA) covered with nanoparticles of magnetite as well as compositions of magnetite, gold and silver. The thioalkyl-substituted derivatives of 2-arylaminopyrimidine, structural analogs of antitumor drug Imatinib containing one or two SH groups and capable to chemisorption on hydroxyapatite and its nanocomposites, have been synthesized. Two-component Fe₃O₄(HA) and three-component Fe₃O₄(HA)Au and Fe₃O₄(HA)Ag composites have been found the most promising as nanocarriers of bioactive compounds.     

Viscoelastic properties of poly(ε‐caprolactone) – hydroxyapatite micro‐ and nano‐composites

Various composites have been proposed in the literature for the fabrication of bioscaffolds for bone tissue engineering. These materials include poly(ε‐caprolactone) (PCL) with hydroxyapatite (HA). Since the biomaterial acts as the medium that transfers mechanical signals from the body to the cells, the fundamental properties of the biomaterials should be characterized. Furthermore, in order to control the processing of these materials into scaffolds, the characterization of the fundamental properties is also necessary. In this study, the physical, thermal, mechanical, and viscoelastic properties of the PCL‐HA micro‐ and nano‐composites were characterized. Although the addition of filler particles increased the compressive modulus by up to 450%, the thermal and viscoelastic properties were unaffected. Furthermore, although the presence of water plasticized the polymer, the viscoelastic behavior was only minimally affected. Testing the composites under various conditions showed that the addition of HA can strengthen PCL without changing its viscoelastic response. The results found in this study can be used to further understand and approximate the time‐dependent behavior of scaffolds for bone tissue engineering. Copyright © 2012 John Wiley & Sons, Ltd.     

Study of the gamma irradiation effects on the PMMA/HA and PMMA/SW

The behavior of the poly(methyl methacrylate) (PMMA) under the action of gamma radiation has been sufficiently studied. In this work, we present results from melt flow index (MFI), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and electron paramagnetic resonance (EPR) of PMMA composites with hydroxyapatite (HA) and seaweed residues (SW) irradiated with gamma rays at 1.08 kGy/h. Composites of PMMA/HA and PMMA/SW with 10%, 20% and 30% of the filler were prepared. The results show an increase in the MFI values with the integral dose of radiation, being consistent with chain-scission reactions. No EPR signal was observed in pure PMMA, while in the composites, the typical EPR signal of the PMMA radicals was observed, which increased with the amount of HA or SW. When comparing the relative intensities of the EPR signals for both types of composites, a slight increase in the concentration of free radicals generated in the sample with SW respect to that of PMMA/HA composite was obtained. A decay of the total free radical concentration was observed as time elapsed.     

Characterization of hdpe/ha Composites Treated with Titanate and Zirconate Coupling Agents

The development of new materials for bone substitution has been of great interest for the scientific community in the last years. High-density polyethylene (HDPE) and hydroxyapatite (HA) composites have been used in biomedical applications without any inflammatory response. However, the differences in nature of both materials have motivated the use of coupling agents to improve their interfacial interactions. In this work, the effects of adding three different commercial coupling agents (NZ12, Lica01, Lica12) to high-density polyethylene (HDPE)/hydroxyapatite (HA) composites were studied. Composites containing 20 parts per hundred (phr) of HA previously treated with the already mentioned coupling agents were characterized by mechanical tests and their morphologies were analyzed afterwards. Composites with 0.3 and 0.5 wt% of NZ12 unfolded an increase in their Young's modulus and tensile strength, as a consequence of an improved dispersion of the filler into the polymeric matrix. Analysis of the samples by XPS showed that the zirconate coupling agent interacted more with the HA, as reflected in the lower binding energies of the corresponding oxygen atoms, which agrees with their better performance from the mechanical point of view.     

Hierarchical Hollow Hydroxyapatite Microspheres: Microwave‐Assisted Rapid Synthesis by Using Pyridoxal‐5′‐Phosphate as a Phosphorus Source and Application in Drug Delivery

Three‐dimensional (3D) hydroxyapatite (HAP) hierarchical nanostructures, in particular hollow nanostructures, have attracted much attention owing to their potential applications in many biomedical fields. Herein, we report a rapid microwave‐assisted hydrothermal synthesis of a variety of hydroxyapatite hierarchical nanostructures that are constructed by the self‐assembly of nanorods or nanosheets as the building blocks, including HAP nanorod‐assembled hierarchical hollow microspheres (HA‐NRHMs), HAP nanorod‐assembled hierarchical microspheres (HA‐NRMs), and HAP nanosheet‐assembled hierarchical microspheres (HA‐NSMs) by using biocompatible biomolecule pyridoxal‐5′‐phosphate (PLP) as a new organic phosphorus source. The PLP molecules hydrolyze to produce phosphate ions under microwave‐hydrothermal conditions, and the phosphate ions react with calcium ions to form HAP nanorods or nanosheets; then, these nanorods or nanosheets self‐assemble to form 3D HAP hierarchical nanostructures. The preparation method reported herein is time‐saving, with microwave heating times as short as 5 min. The HA‐NRHMs consist of HAP nanorods as the building units, with an average diameter of about 50 nm. The effects of the experimental conditions on the morphology and crystal phase of the products are investigated. The hydrolysis of PLP under microwave‐hydrothermal conditions and the important role of PLP in the formation of 3D HAP hierarchical nanostructures are investigated and a possible formation mechanism is proposed. The products are explored for potential applications in protein adsorption and drug delivery. Our experimental results indicate that the HA‐NRHMs have high drug/protein‐loading capacity and sustained drug‐release behavior. Thus, the as‐prepared HA‐NRHMs are promising for applications in drug delivery and protein adsorption.     

生物降解高分子/羟基磷灰石复合材料研究进展

由于高分子/HA复合材料兼具HA优良的生物性能和高分子材料良好的力学性能而受到了广泛的重视.本文综述了近年来生物降解高分子/羟基磷灰石复合材料的研究进展,介绍了胶原及其衍生物、聚酯、甲壳素及其衍生物、淀粉等可降解高分子材料与羟基磷灰石复合作为骨修复材料的研究进展,并对此类材料存在的问题和发展前景进行了讨论.