Preparation of Bone-Like Apatite Coating on Surface of Ti-25Nb-2Zr Alloy by Biomimetic Growth Method

A bone-like apatite layer consisting of nano-crystals of apatite phase was prepared on the surface of Ti- 25Nb-2Zr alloy by chemical biomimetic growth method. TiNbZr alloy specimens were first oxidized at 500 ℃ for 2 h in the air. Then, they were immersed in 40 ℃ saturated NazHPO4 solution for 15 h and 25 ℃ saturated Ca （OH）2 solution for 8 h in turn for pre-calcification. The pre-calcified specimens were immersed in modified simulated body fluid up to 15 d for biomimetic growth. After common oxidization, amorphous titania and anatase were detected on the specimen surface. Except for the substantial amount of calcium and phosphorus, no new phase appeared on the pre-calcified specimens. After the coating process, it was found that the （002） orientation was the preferred orientation during the growing period of hydroxyapatite. The inorganic composition and structure of the coating are very similar to those of human thigh bone, which will be advantageous for its application as biomedical material.

Strontium and Silicon Co-Doped Apatite Coating: Preparation and Function as Vehicles for Ion Delivery

New methods to improve the bone response to metallic implants are still emerging, ranging from surface modifications of the metal to coatings and drug delivery. One further development of coatings on implants is to incorporate bioactive ions in order to stimulate the bone response without the need of drug delivery. The aim of the current study is to prepare apatite coatings containing Sr and Si using a solution method, for the purpose of further optimising the bone response to metal implants. Titanium substrates were activated to induce the formation of coatings in modified PBS solutions. Soaking in PBS solutions with different concentrations of strontium and silicate at 37℃ or 60℃ produced coatings with different morphologies, thicknesses and compositions. Ion release experiments showed simultaneous release of Sr and Si from the coatings both in PBS and Tris-HCl. Analysis of the results using the Korsmeyer-Peppas model indicate that the release of ions from the coatings was a combination of Fickian diffusion and degradation of the coatings. This study shows that it is possible to coat Ti substrates with modified apatite with ion release functionality and thereby increase the possibilities for a tailored bone response in vivo.

Effect of Ta_(2)O_(5)nanoparticles on bioactivity,composition,structure,in vitro and in vivo behavior of PEO coatings on Mg-alloy

The present study investigates the physical and chemical characteristics,behavior in vitro and in vivo,and biocompatibility of coatings containing Ta_(2)O_(5),which are obtained by plasma electrolytic oxidation(PEO)on MA8 magnesium alloy.The obtained coatings demonstrate in vivo biocompatibility and in vitro bioactivity.Compared to the base PEO coating,the layers containing Ta_(2)O_(5)facilitate the development of apatite in simulated body fluid,suggesting that the inclusion of nanoparticles improves bioactivity of the coatings.It was found that incorporation of Ta_(2)O_(5)nanoparticles increases roughness and porosity of the formed layers by increasing particle concentration in electrolytes for the PEO process contributing to sufficient soft tissue ingrowth in vivo.Based on in vivo studies,these coatings also provide favorable tissue response and minimal inflammatory reaction in comparison with the bare magnesium alloy due to protection of living tissues from deleterious corrosion events of magnesium implant such as local alkalization and intense hydrogen evolution.The results obtained in the present study concluded biocompatibility,tissue integration of the PEO coatings containing Ta_(2)O_(5)nanoparticles making them a promising protective layer for biodegradable magnesium implants.

Preparation of Laminin-apatite-polymer Composites Using Metastable Calcium Phosphate Solutions

A synthetic polymer with a laminin-apatite composite layer on its surface would be useful as a percutaneous device. The preparation of such a composite was attempted in the present study using poly（ ethylene terephthalate ） （PET） and polyethylene （PE） as the synthetic polymer. PET and PE plates and those pretreated with an oxygen plasma were alternately dipped in calcium and phosphate ion solutions, and then immersed in a metastable calcium phosphate solution supplemented with laminin （ LCP solution ）. The PET and PE plates pretreated with an oxygen plasma formed a uniform and continuous layer of a laminin-apatite composite on their surfaces. In contrast, the PET and PE plates that had not been pretreated with an oxygen plasma did not form a continuous layer of a laminin-apatite composite on their surfaces. The hydrophilic functional groups on the PET and PE surfaces introduced by the plasma treatment were responsible for the successful laminin-apatite coruposite coating.

Controlling Bovine Serum Albumin Release From Biomimetic Calcium Phosphate Coatings

Biomimetic calcium phosphate (CaP) coating has been used successfully for protein delivery, but the release of protein from CaP coating is mainly dependent on the limited dissolution of the CaP coating and the passive diffusion of the protein in the CaP coating. In the present work, our aim is to improve the release behavior of protein from CaP coating and make it more controllable. By using bovine serum albumin (BSA) as a model protein, our strategy is to tailor BSA release profiles by controlling the distribution of BSA in CaP coatings. To achieve this aim, BSA was added to a modified simulated body fluid (m-SBF) at different stages of coating formation to obtain tailored BSA release profiles. Sustained BSA release was obtained when BSA was added to m-SBF at the initial stage of the coating where the BSA was incorporated into the lattice structure of the coating. In contrast, a relatively faster release was observed when BSA was added during the later stage of coating formation where BSA was mainly adsorbed to the coating surface. As a result, the BSA release efficiency could be tailored by adding BSA into m-SBF at different coating formation stages. More importantly, the coating composition was not altered with the change of BSA adding times and all the beneficial properties of the biomimetic coating were reserved. Therefore, the BSA release from CaP coatings can be tailored by adjusting its distribution in the coating to achieve a more satisfactory release profile.

In vitro study of iron doped hydroxyapatite

The effect of iron substitution on the bioactivity of hydroxyapatite (HAp) under the physiological conditions was investigated. Five samples of iron doped hydroxyapatite (FeHAp) with different iron concentrations (0, 0.05, 0.1, 0.2, and 0.3 mol%) were synthesized by wet chemical method. The formation of bone-like apatite layer on the surface of the samples was detected using X-ray diffraction (XRD), Fourier transforms infrared (FTIR) and scanning electron microscope techniques. The changes of the pH of SBF medium were measured at pre-determined time intervals using a pH meter. The dissolution of calcium, phosphorus and iron ions in SBF medium was determined by single beam scanning spectrophotometer. XRD and FTIR results exhibit the formation of carbonate apatite layer on the surface of the immersed samples, which increase with the increase of iron content. SEM results showed agglomeration of small crystals on the surface of the immersed samples. The solubility and dissolution tests revealed that iron doped HAp samples had a higher solubility and dissolution rate than pure sample, which indicated that iron increased the bioactivity of HAp in vitro.

Influence of Biomimetic Apatite Coating on the Biobehavior of TiO_(2)Scaffolds

Immersion of scaffolds in Simulated Body Fluid(10SBF)is a standardized method for evaluating their bioactivity,simulating in vivo conditions where apatite deposits can be formed on the surface of scaffold,facilitating bone integration and ensuring their suitability for bone implant purposes,ultimately contributing to long-term implant success.The effect of apatite deposition on bioactivity and cell behavior of TiO_(2)scaffolds was studied.Scaffolds were soaked in 10SBF for different durations to form HAP layer on their surface.The results proved the development of a hydroxyapatite film resembling the mineral composition of bone Extracellular Matrix(ECM)on the TiO_(2)scaffolds.The XRD test findings showed the presence of hydroxyapatite layer similar to bone at the depth of 10 nm.A decrease in the specific surface area(18.913 m^(2)g^(−1)),the total pore volume(0.045172 cm^(3)g^(−1)(at p/p0=0.990)),and the mean pore diameter(9.5537 nm),were observed by BET analysis which confirmed the formation of the apatite layer.It was found that titania scaffolds with HAP coating promoted human osteosarcoma bone cell(MG63)cell attachment and growth.It seems that immersing the scaffolds in 10SBF to form HAP coating before utilizing them for bone tissue engineering applications might be a good strategy to promote bioactivity,cell attachment,and implant fixation.

电化学沉积时间对碱预处理钛合金表面HA涂层的影响

采用碱预处理钛合金表面再电化学沉积的方法,研究了电化学沉积时间对羟基磷灰石(HA)涂层物相、形貌、生物活性及其与钛合金基体间结合强度的影响。结果表明,碱预处理钛合金表面制备的电化学沉积涂层主要由片状HA相组成,电化学沉积时间对涂层物相组成没有影响,但会影响涂层厚度;沉积时间60 min时得到的HA涂层较致密,与基体的结合强度达17.85 MPa。各沉积时间下得到的HA涂层均具有较好的生物活性,在模拟体液(SBF)中,CO_(3)^(2-)置换HA中的PO_(4)^(3-)进入磷灰石中形成类骨磷灰石CHA,呈馒头状,直径7~8μm,且在SBF中浸泡3 d,CHA可铺满HA表面。

钛和钛合金生物活化研究现状

金属钛及其合金在人体硬组织替换中具有广泛的应用。为改善其表面性能,使其具有表面生物活性,研究发展了多种生物活化方法。包括物理法、化学法和电化学法3大类。本文对钛及钛合金种植体的各种表面活化方法进行了综述。阐述了各种方法进行钛及钛合金表面活化的工艺过程及其活化机理,分别指出了各种方法的优缺点。与物理法相比,化学法具有设备和操作简单、易形成均匀涂层、结构和成分与自然骨相似等优点。对化学法,还需要进一步提高效率,提高涂层与基体之间的结合强度,并对其长期植入效果及其活化机理进行深入研究。

多孔钛的制备及磷灰石涂层的仿生沉积

作者提出了制备多孔金属材料的有效方法:利用混和金属粉末和有机粘稠剂,经双氧水发泡和烧结,可得到多孔材料,其材料的孔隙率和孔径大小能在制备过程中进行控制;采用钛珠在真空中烧结形成多孔钛结构亦可制备了多孔钛.制成多钛孔材料后,采用一种简单的沉积方法在上述两种多孔钛表面沉积磷灰石涂层,试验表明,沉积的涂层在不同的基体表面上呈现出不同的特征形貌,在光滑的活性表面,可形成晶种均匀.晶体呈片状生长的网状结构;在基体的粗糙、尖锐处,其基体表面能高,可形成更多的晶种,而晶体生长受限,仅能形成亚微米级的团聚微晶.

骨髓成骨细胞在碱热处理的磷灰石涂层钛表面的分化增殖研究(英文)

为了研究骨髓基质细胞转化的成骨细胞在碱热处理的涂层磷灰石钛表面的分化增殖,将钛片经过碱热处理后,浸泡于与类似体液的环境进行表面磷灰石涂层。应用骨髓成骨细胞作为实验工具,观察体外细胞在处理的涂层钛片上的生长,碱性磷酸酶以及降钙素的分泌。在早期,有磷灰石涂层的钛片成骨细胞黏附高于对照组;在晚期,两组之间没有明显差异;成骨细胞分化的标志——碱性磷酸酶活性和降钙素的表达,磷灰石涂层组都明显高于对照组。研究表明:碱热处理的磷灰石涂层钛能够促进成骨细胞黏附,有利于细胞向成骨分化。

碳/碳复合材料表面声电沉积磷灰石动力学研究(英文)

采用声电沉积技术,在碳/碳复合材料表面制备了生物活性磷酸钙涂层。扫描电镜、X射线衍射、红外反射以及X射线能谱分析表明所制涂层呈现网状结构,其由钙磷比为1.64、含碳酸根的羟基磷灰石组成。根据扫描电镜观察,描述了磷灰石的形成过程。羟基磷灰石的沉积过程可简化为两步——钙磷离子向碳/碳阴极表面运动和羟基磷灰石在碳/碳表面生长。基于此描述,导出了羟基磷灰石沉积动力学公式,并且发现,沉积过程受扩散控制,扩散活化能是30.3kJ/mol.

多孔钛表面梯度磷灰石涂层的简单化学法制备

通过碱液处理或碱热处理并在模拟体液(SBF)中浸泡,在多孔钛表面制备了具有梯度结构的类骨磷灰石层。结果表明,碱液处理使多孔钛表面形成了网状多孔结构,组成为钛酸钠、金红石等。热处理后磷灰石在多孔钛表面的初期沉积更均匀。涂层中钙、磷、氧以及钛元素的含量随深度而变化,形成了梯度结构。具有表面梯度磷灰石涂层的多孔钛有望用于临床矫形,以提高种植体的生物活性和骨结合强度。

利用预钙化处理提高碱热处理多孔钛的表面生物活性

采用粉末冶金方法制备多孔钛样品,孔隙率约为40%,最大孔径为240μm。经过NaOH溶液、热处理后,多孔钛再在Na2HPO4溶液和饱和Ca(OH)2溶液中分别浸泡进行预钙化处理。未经预钙化处理的样品在SBF中浸泡,形成表面磷灰石涂层约需28d的时间。经过预钙化的样品在SBF中浸泡只需4d,这说明预钙化过程大大提高了多孔钛的生物活性。其作用机理为:预钙化过程中样品表面的钛酸钠水解,形成带负电的Ti-OH基团,使Ca2+离子吸附到表面。在SBF中浸泡时,表面附近在短时间内达到钙-磷过饱和。且Ca2+离子增大表面附近的pH值,Ca2+离子和PO4离子、OH-离子的活度积增大,刺激了磷灰石成核并形成涂层。除碱热处理并预钙化的样品外,其余3-样品表面磷灰石的Ca/P原子比均小于人体自然骨的Ca/P原子比。涂层的结晶细小而薄,不破坏多孔钛的孔隙结构。

预钙化处理后的钛表面磷灰石涂层的形成

本研究采用碱液处理钛样品 ,并进行预钙化处理 ,在模拟体液 (SBF)中浸泡 ,能在较短时间内形成表面致密的磷灰石涂层。碱液处理使钛表面生成了钛酸钠及氧化钛等物质 ,在SBF中浸泡时 ,会发生水解而使表面形成带负电的Ti OH基团。预钙化处理使带负电的钛表面由静电引力而聚集了大量的Ca2 + 离子。Ca2 + 能吸引带负电的HPO2 -4到达表面 ,从而使表面附近能在较短时间内达到钙 磷过饱和。Ca2 + 离子又能使表面附近的pH值增大 ,Ca2 + 离子和HPO2 -4离子的活度积就增大 ,从而刺激了磷灰石晶体的成核与长大 。

仿生磷灰石涂层与钛基体结合强度的划痕法实验

本文采用碱热处理及SBF浸泡的方法在钛片上制备了仿生磷灰石涂层 ,并采用AES进行表面成分—深度分析 ,划痕法测定磷灰石涂层与基体的结合强度。结果显示 ,经碱热处理而制得的钛表面仿生磷灰石涂层与基体结合的界面为成分梯度界面 ,二者的结合要通过成分含量呈梯度变化的过渡层 :Ca、P元素的含量从表面到基体逐渐下降 ,Ti元素的含量逐渐上升。热处理有利于提高涂层的基体结合强度 ,其原因是热处理使SBF中形成的磷灰石的晶核细小而均匀 ,使得表面涂层与基体之间的结合更为紧密。预钙化处理后形成的磷灰石涂层与金属之间仍为成分梯度界面 ,因此对涂层的基体结合强度影响不大。

含氟羟基磷灰石涂层体外细胞相容性研究

在羟基磷灰石(HA)中掺入氟可以降低其在体内的溶解性,对提高钛合金植入体表面生物活性改性层(涂层)的长效性有着重要的意义。本研究采用溶胶-凝胶法在钛合金基板上制备了含氟羟基磷灰石(Ca10(PO4)6(OH)2-xFx)(FHA)涂层。X光衍射(XRD)和X光电子能谱(XPS)分析结果显示:本实验中获得的涂层是一个纯磷灰石晶相,含氟涂层中x为1.2。在体外成骨细胞相容性的研究中,以HA涂层为对照,通过定时细胞的计数测定了细胞生长曲线,用流式细胞仪法测定了细胞周期,用MTT比色法分析了涂层浸提液的细胞毒性。实验结果表明:在HA涂层中引入氟后,FHA涂层浸提液对细胞毒性级别为0级,该涂层不但没有对细胞产生毒性,而且会促进成骨细胞的贴壁生长,有着更好的细胞生长速度和增殖活性。

不同过饱和钙化溶液中多孔钛表面磷灰石层的形成

将减液处理过的多孔钛浸泡在含有不同离子及离子浓度的3种过饱和钙化溶液中,均制得了多孔钛表面磷灰石涂层。所有涂层的钙磷比均小于羟基磷灰石的钙磷化学计量比。在SBF和ACS中形成的涂层的钙磷比与人骨中的钙磷比比较接近。在SCS和ACS中形成的涂层还含有磷酸八钙。过饱和度的增加可以引起磷灰石更快成核与生长。较小的过饱和度和Mg^(2+)离子的结晶生长抑制作用使SBF中形成了结晶细小且比较薄的涂层,不破坏多孔钛的孔隙结构。在SCS中形成的涂层厚度约70μm,使孔隙尺寸大大减小。在ACS中形成的涂层有孔隙被堵塞的现象。