Bio-inspired Hydroxyapatite/Gelatin Transparent Nanocomposites

Hydroxyapatite(HA)nanoparticles impart outstanding mechanical properties to organicinorganic nanocomposites in bone.Inspired by the composite structure of HA nanoparticles and collagen in bone,a high performance HA/gelatin nanocomposite was first developed.The nanocomposites have much better mechanical properties(elongation at break 29.9%,tensile strength 90.7 MPa,Young’s modulus 5.24 GPa)than pure gelatin films(elongation at break 9.3%,tensile strength 90.8 MPa,Young’s modulus 2.5 GPa).In addition,the composite films keep a high transmittance in visible wavelength range from 0%to 60%of the HA solid content.These differences in properties are attributed to the homogeneous distribution of HA nanoparticles in the gelatin polymer matrix and the strong interaction between the particle surfaces and the gelatin molecules.This protocol should be promising for HA-based nanocomposites with enhanced mechanical properties for biomedical applications.

Ionic liquid-assisted preparation of hydroxyapatite and its catalytic performance for decarboxylation of itaconic acid

The synthesis of methacrylic acid from biomass-derived itaconic acid is a green route,for it can get rid of the dependence on fossil resource.In order to solve the problems on this route such as use of a preciousmetal catalyst and a corrosive homogeneous alkali,we prepared a series of hydroxyapatite catalysts by an ionic liquid-assisted hydrothermal method and evaluated their catalytic performance.The results showed that the ionic liquid[Bmim]BF_(4) can affect the crystal growth of hydroxyapatite,provide fluoride ion for fluorination of hydroxyapatite,and adjust the surface acidity and basicity,morphology,textural properties,crystallinity,and composition of hydroxyapatite.The[Bmim]BF4 dosage and hydrothermal temperature can affect the fluoride ion concentration in the hydrothermal system,thus changing the degree of fluoridation of hydroxyapatite.High fluoride-ion concentration can lead to the formation of CaF_(2) and thus significantly decrease the catalytic performance of hydroxyapatite.The hydrothermal time mainly affects the growth of hydroxyapatite crystals on the c axis,leading to different catalytic performance.The suitable conditions for the preparation of this fluoridized hydroxyapatite are as follows:a mass ratio of[Bmim]BF4 to calcium salt=0.2:1,a hydrothermal time of 12 h,and a hydrothermal temperature of 130℃.A maximal methacrylic acid yield of 54.7%was obtained using the fluoridized hydroxyapatite under relatively mild reaction conditions(250℃ and 2 MPa of N_(2))in the absence of a precious-metal catalyst and a corrosive homogeneous alkali.

Hydroxyapatite-containing PEO-coating design for biodegradable Mg-0.8Ca alloy: Formation and corrosion behaviour

In this study, the biocompatible protective coating was formed using plasma electrolytic oxidation(PEO) on bioresorbable Mg-0.8Ca alloy. The composition of the formed coating was studied using XRD, SEM-EDX analysis, and micro-Raman spectroscopy. The uniform distribution of hydroxyapatite over the thickness of protective PEO-layer was established. Using traditional(EIS, PDP, OCP) and local scanning electrochemical methods(SVET, SIET with H^(+)-selective microelectrode), the level of protective properties of PEO-layer in a biological environment(mammalian cell culture medium, MEM) was determined. It was established that modification of Mg-0.8Ca alloy surface by PEO contributes to a significant increase in the corrosion resistance of the surface layer, making it possible to control the process of material‘s biodegradation. The maximum local electrochemical activity was recorded after 72 h of testing, while for the uncoated sample,intense corrosion degradation was recorded in the first 12 min of exposure to the cell culture medium. Formation of the PEO-coating results in a twofold decrease in the corrosion current density(2.8·10^(-6)A cm^(-2)) and an increase in the impedance modulus measured at a low frequency(1.7·10^(4)Ω cm^(2)) in comparison with the uncoated material(9.5·10^(-6)A cm^(-2);8.1·10^(3)Ω cm^(2)). The mechanism of material bioresorption was established and a model for biodegradation process of Mg-0.8Ca alloy with hydroxyapatite-containing PEO-coating in MEM was proposed. Analysis of these results and comparing with others obtained by various scientific groups indicate the prospects for application of biocompatible PEO-coating on Mg-Ca alloy in implant surgery.

Influence of Ca/P ratio on the catalytic performance of hydroxyapatite for decarboxylation of itaconic acid to methacrylic acid

Methacrylic acid,an important organic chemical,is commercially manufactured starting from fossil feedstock.The decarboxylation of itaconic acid derived for biomass is a green route to the synthesis of methacrylic acid.In view of the problems existing in the researches on this route such as use of noble metal catalyst,harsh reaction conditions and low desired-product yield,we prepared a series of hydroxyapatite catalysts with different Ca/P molar ratios and evaluated their catalytic performance.The results showed that the hydroxyapatite catalyst with a Ca/P molar ratio of 1.58 had the best catalytic activity.The highest yield of MAA up to 61.2%was achieved with basically complete conversion of itaconic acid under the suitable reaction conditions of 1 equivalent of NaOH,2 MPa of N_(2),250℃,and 2 h.On this basis,a reaction network for the decarboxylation of itaconic acid to methacrylic acid catalyzed by hydroxyapatite was established.With the aid of catalyst characterization using X-ray powder diffraction,NH3/CO2 temperature-programmed desorption,N_(2)physisorption,inductively coupled plasma optical emission spectrometry,and scanning electron microscopy,we found that the distribution of surface acid sites and basic sites,crystal growth orientation,texture properties and morphology of hydroxyapatite varied with the Ca/P molar ratio.Furthermore,the change of the crystal growth orientation and its influence on the surface acidity and alkalinity were clarified.

Corrosion behavior of composite coatings containing hydroxyapatite particles on Mg alloys by plasma electrolytic oxidation: A review

Mg and its alloys have been introduced as promising biodegradable materials for biomedical implant applications due to their excellent biocompatibility, mechanical behavior, and biodegradability. However, their susceptibility to rapid corrosion within the body poses a significant challenge and restricts their applications. To overcome this issue, various surface modification techniques have been developed to enhance the corrosion resistance and bioactivity of Mg-based implants. PEO is a potent technique for producing an oxide film on a surface that significantly minimizes the tendency to corrode. However, the inevitable defects due to discharges and poor biological activity during the coating process remain a concern. Therefore, adding suitable particles during the coating process is a suitable solution. Hydroxyapatite(HAp)has attracted much attention in the development of biomedical applications in the scientific community. HAp shows excellent biocompatibility due to its similarity in chemical composition to the mineral portion of bone. Therefore, its combination with Mg-based implants through PEO has shown significant improvements in their corrosion resistance and bioactivity. This review paper provides a comprehensive overview of the recent advances in the preparation, characterization, corrosion behavior and bioactivity applications of HAp particles on Mg-based implants by PEO.

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。

基于SPARTA框架的HAS4决赛攻击路径分析

太空网络面临的安全威胁越来越多,美国自2020年起,连续四年举办黑掉卫星(Hack-A-Sat,HAS)挑战赛,并发射真实卫星“月光者”用于HAS比赛。太空攻击研究与战术分析框架SPARTA是针对太空网络安全的对抗战术和技术知识库。借助SPARTA框架,详细分析了第四届HAS决赛中攻击使用的战术技术,对于深入理解SPARTA框架、太空网络安全具有一定借鉴意义。

Cytotoxinic Mechanism of Hydroxyapatite Nanoparticles on Human Hepatoma Cell Lines

Stable and single dispersed HAP nanoparticles were synthesized with chemical method assisted by ultrasonic treatment.HAP nanoparticles were surveyed by AFM and Zataplus.The effect on the Bel-7402 human hepatoma cell lines treated with HAP nanoparticles was investigated by the MTT methods and observation of morphology,and the mechanism was studied in changes of cell cycle and ultrastructure.The result shows that inhibition of HAP nanoparticles on the Bel 7402 human hepatoma cell lines is obviously in vitro.HAP nanoparticles the entered cancer cytoplasm,and cell proliferation is stopped at G 1 phase of cell cycle,thus,cancer cells die directly.

Hot pressing of hydroxyapatite(HA)-Ti material and stability of HA

Hot pressing of hydroxyapatite(HA) Ti system material and the stability of HA component were investigated to supply the foundation of optimizing sintering procedure of HA Ti functionally graded material(FGM). The results show that the HA powders used have excellent thermal stability and no decomposition is observed at 1 300 ℃. The existence of Ti can promote the dehydration and decomposition of HA. However, no new compounds form between HA and Ti. By selecting sintering parameters properly, ideal HA Ti material can be acquired. The relative densities of the mixtures of HA and Ti are always lower than those of pure HA or Ti, which may be caused by the decomposition of HA in the mixtures.

H5N1亚型禽流感病毒HA蛋白在水稻胚乳中的表达及其纯化

为制备H5N1亚型禽流感病毒HA蛋白并评估其免疫原性,利用水稻表达系统表达H5N1亚型禽流感病毒重组HA蛋白。首先构建了重组植物表达载体pCAMBIA1300-HA,该载体具有GT13特有启动子、信号肽SP和终止子,有利于外源基因在水稻中表达。之后将重组质粒pCAMBIA1300-HA通过电转化法导入根癌农杆菌EHA105中,筛选出阳性菌落并侵染水稻愈伤组织。经过暗培养、潮霉素筛选、分化、生根、成苗,采用CTAB法提取水稻叶片DNA,PCR鉴定结果显示,HA基因已插入到水稻基因组中,重组HA基因大小为4660 bp。将阳性植株移植到大田中,4个月后收获水稻种子,提取水稻胚乳蛋白,Western blot鉴定结果表明,HA蛋白在水稻胚乳中成功表达。重组HA蛋白通过Q阴离子层析、疏水层析和凝胶过滤层析三步分离纯化,其纯度达到90%以上。最后将纯化后的重组HA蛋白与ISA 50V佐剂混合并乳化制成疫苗,免疫小鼠,小鼠血清具有较高的特异性抗体水平,表明重组HA蛋白免疫原性较好。综上,成功构建了H5N1亚型禽流感病毒HA重组蛋白的水稻表达系统,并分离纯化获得了高纯度和免疫原性良好的重组HA蛋白。

Preparation, Characterization and Antibacterial Property of Cerium Substituted Hydroxyapatite Nanoparticles

Nanoparticles of hydroxyapatite （HAP） and cerium substituted hydroxyapatite （CeHAP） with the atomic ratio of Ce/[ Ca ＋ Ce] （xco） from 0 to 0.2 were prepared by sol-gel-supercritical fluid drying （SCFD） method. The nanoparticles were characterized by TEM, XRD, and FT-IR, and the effects of cerium on crystal structure, crystallinity, and particle shape were discussed. With the tests of bacterial inhibition zone and antibacterial ratio, the antibacterial property of HAP and CeHAP nanoparticles on Escherichia coli, Staphylococcus aureus, Lactobacillus were researched. Results showed that the nanoparticles of HAP and CeHAP could be made by sol-gel-SCFD, cerium could partially substitute for calcium and enter the structure of HAP. After substitution, the crystallinity, the IR wavenumbers of bonds in CeHAP decreased gradually with increase of cerium substitution, and the morphology of the nanoparticles changed from the short rod-shaped HAP to the needle-shaped CeHAP. The nanoparticles of HAP and CeHAP with Xco below 0.08 had antibacterial property only forcibly contacting with the test bacteria at the test concentration of 0.1 g · mi^-1, however, the Ce- HAP nanoparticles had antibacterial ability at that concentration no matter statically or dynamically contacting with the test bacteria when Xco was above 0.08, and the antibacterial ability gets better with the increase Of Xce, indicating that the antibacterial property was improved after calcium was partially substituted by cerium. The improved antibacterial effects of CeHAP nanoparticle on Lactobacillus showed its potential ability to anticaries.

HA/H2O2体系对磺胺噻唑降解的机理与效能

以盐酸羟胺/过氧化氢(HA/H2O2)作为研究体系,考察其对于磺胺噻唑(STZ)的降解效能。文章考察了HA初始浓度、H2O2初始浓度、STZ初始浓度、pH、天然有机物(NOM)、阴离子(SO2-4、Cl-和NO-3)对STZ降解的影响。结果表明:在pH值=3.0的条件下,HA/H2O2体系对STZ具有高效的降解效果,当HA的物质的量浓度由2 mmol/L增加到10 mmol/L时,对STZ的去除率从56.06%增加到85.26%;当H2O2的物质的量浓度从2 mmol/L增加到10 mmol/L时,对STZ的去除率从58.96%增加到85.26%,当STZ的物质的量浓度从2μmol/L增加到10μmol/L时,对STZ的去除率从98.72%降低到71.86%。随着pH的增大,STZ的去除率逐渐降低,在pH值>7的条件下对STZ的去除率可以忽略不计。向反应体系中分别投加5 mmol/L的SO2-4和5 mmol/L的NO-3都可以有效促进STZ的降解,而5 mmol/L的Cl-则会抑制STZ的降解。当向体系中投加小于5 mg/L的NOM则对STZ的降解的影响可以忽略不计。测定了体系中共有17种降解产物,并推测STZ通过取代反应、羟基化反应等方式逐步被降解。通过明亮发光杆菌发光值变化分析降解过程中溶液毒性的变化,测定发现STZ降解过程中急性毒性不高。实际水体试验结果表明,HA/H2O2系统对二级出水中的荧光类物质具有较好的降解效果。

Morphology and Phase Compositions of Hydroxyapatite Powder Particles Plasma-sprayed into Water

Hydroxyapatite powder particles were plasma sprayed into water, their inner structures and phase compositions were studied by using scanning electron microscope(SEM) and X-ray diffractometer. The results show that the molten HA particles have a central hollow morphology and high crystallinity. The hollow morphology was caused by sublimated P2O5 and H2O, which will have an effect on surface morphology, cohesive and adhesive strength as well as dissolution and degradation of coating. The high crystallinity is attributed to lower cooling speed in water.

Synthesis,Characterization and Antibacterial Property of Strontium Half and Totally Substituted Hydroxyapatite Nanoparticles

Nanoparticles of hydroxyapatite（HAP）, strontium half substituted hydroxyapatite （SrCaHAP） and strontium totally substituted hydroxyapatite （SrHAP） were prepared by sol-gel-supercritical fluid drying （SCFD） method. The nanoparticles were characterized by element content analysis, FT-IR, XRD and TEM, and the effects of strontium substitution on crystal structure, crystallinity, particle shape and antibacterial properties of the nanoparticles on Escherichia coli, Staphylococcus aureus, Lactobacillus were researched. Results show that strontium can half and totally substitute for calcium and enter the structure of apatite according to the initial atomic ratios of Sr/[Sr＋Ca] as 0.5, 1. The substitution decreases the IR wavenumbers of SrCaHAP and SrHAP, and changes the morphology of the nanoparticles from short rod shaped HAP to needle shaped SrCaHAP, and back to short rod shaped SrHAP. The crystallinity of HAP is higher than that of SrCaHAP, but is lower than that of SrHAP. Moreover, the antibacterial property of SrCaHAP and SrHAP are improved after the calcium is half and totally substituted by strontium.

Synthesis and Characterization of Core-shell Hydroxyapatite/chitosan Biocomposite Nanospheres

Novel core-shell hydroxyapatite/chitosan biocomposite nanospheres were synthesized in a multiple emulsion. The multiple emulsion was a w/o/w emulsion, made of diammonium phosphate solution as an inner aqueous phase, cyclohexane as an oil phase, and calcium nitrate solution and chitosan solution as an outer aqueous. The forming mechanism of core-shell spheres and the influence of temperature on the morphology of the nanospheres were investigated. The diameter of the resulting core-shell nanospheres was 100-200 nm and the thickness of the chitosan shell was about 10 nm. And it concluded that at different reaction temperature the morphologies of the products would be changed. The core-shell nanospheres have potential applications for the development of new biomedical materials.

Mechanical properties of TiO_2-hydroxyapatite nanostructured coatings on Ti-6Al-4V substrates by APS method

TiO2-hydroxyapatite （HA） nanostructured coatings were produced by atmospheric plasma spray method. The effects of starting powder composition and grain size on their mechanical properties were investigated. The microstructure and morphology were characterized by X-ray diffraction and scanning electron microscopy （SEM）. It is found that the coating with 10% HA has the best mechanical properties. Based on Rietveld refinement method, the mean grain size of the as-received powder （212 nm） extensively decreases to 66.4 nm after 20 h of high-energy ball milling. In spite of grain growth, the deposited coatings maintain their nanostructures with the mean grain size of 112 nm. SEM images show that there is a lower porosity in the coating with a higher HA content. Optical microscopy images show that uniform thickness is obtained for all the coatings.

共表达膜结合型与可溶性H9N2亚型禽流感病毒HA蛋白的重组基因Ⅶ型新城疫病毒的构建及免疫效果评价

旨在构建能高效稳定表达H9N2 AIV的HA蛋白的重组基因Ⅶ型新城疫病毒,有望开发抗新城疫和H9N2亚型禽流感病毒的二联疫苗,为控制H9N2 AIV和NDV提供新的防御思路,对NDV疫苗载体的构建和优化有重要的参考意义。利用反向遗传技术,以rDHN3-mF为骨架,在病毒基因组的P和M之间的非编码区插入全长膜结合HA和另外一个带有截短跨膜结构域的可溶性HA蛋白,获得了能高效稳定表达H9N2 AIV的HA蛋白的基因Ⅶ型NDV减毒株重组病毒rDHN3mF-HA和rDHN3mF-2HA。通过鸡胚接种、Western blot、血凝效价(HA)及平均鸡胚致死时间(MDT)等试验来检测重组病毒的稳定性以及生物学特性,将重组病毒以10~6 EID_(50·)只^(-1)剂量免疫7日龄SPF鸡并测定血凝抑制(HI)抗体,在免疫后28 d对各组进行攻毒保护试验。结果显示:重组病毒在鸡胚中连续传至十五代后HA基因无突变发生;Western blot证明重组病毒可稳定高效地表达特异性的HA蛋白;重组病毒的生长曲线说明了重组病毒与亲本毒株具有相似的复制特性和低毒力特征;重组病毒免疫组的SPF鸡均能产生针对NDV或者H9N2 AIV的特异性HI抗体;攻毒保护试验结果:重组病毒均能对攻毒后的鸡产生100%保护效果;喉、肛拭子检测结果说明重组病毒可显著减少NDV与H9N2 AIV的体外排毒;气管与肺qPCR检测结果显示攻毒后3 d, rDHN3mF-2HA较rDHN3mF-HA更显著地降低了脏器中H9N2 AIV含量。本研究成功构建了共表达膜结合型与可溶性H9N2亚型禽流感HA蛋白的基因Ⅶ型重组NDV,为H9N2 AIV和NDV的一种新型重组基因工程二联活载体疫苗的研制与应用奠定了基础。

Preparation and Characterization of Nanosized Hydroxyapatite Particles in AOT Inverse Microemulsion

Nanosized particles of hydroxyapatite (HAP) were synthesized by reacting Ca(H_2PO_4)_2·H_2O solution complex with equimolar Ca(OH)_2 saturated solution in sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/isooctane water-in-oil microemulsion.The formation of microemulsion strongly depended on water content w (w=[H_2O]/[AOT] molar ratio) and concentration of surfactant and cosurfactant (1-octanol).By the variety of conductivity with w and the partial ternary phase diagram derived from a series of demarcation points,we set the basic component of microemulsions:[AOT]=0.1M(mol/dm^3),[1-octanol]=0.1M and w=3-9.Dynamic light scattering (DLS),UV-visible absorbance,TEM analysis and X-ray diffraction were used to characterize the microemulsion,formation of particles and resulting HAP particles.At low water content(w<9),the water pool radius of the droplet in the Ca(H_2PO_4)_2·H_2O microemulsion lineally depended on w.The size of final HAP particles was strongly affected by water content w and reactant concentration.With increasing water content w from 3 to 9,the size of HAP particles increased from 10-20nm to 40-50 nm at reactant concentration [Ca(H_2PO_4)2·H_2O]=12×10^(-3) mol/dm^3.The resulting HAP particles were poorly crystallized and spherical in morphology.

Preparation and Characterization Analysis of Hydroxyapatite/ Gelatin Composite

The hydroxyapatite （ HAp ）/gelatin composite was prepared by self-assembly method. X-ray diffraction confirmed that the inorganic phase in the composite was HAp. The Fourier transform infra-red spectrum （FT-IR） indicated the presence of amide and hydroxyl groups in the composite. The organic-inorganic ratio of the composite is similar to that of the human bone, which was determined by differential thermal analysis （ DTA ） and thermogravimetric analysis （ TGA ）. Transmission Electron Microscopy （TEM） showed that the composite is composed by spindly grains and the rmdtilayer nanostructure can also be seen. Gelatin in the composite assembled orderly and orderly and directionally ; and the HAp crystals grew along the gelatin molecule at nearly the same direction. A model was established to explain the process of the interaction between gelatin and HAp.

Creep-Recovery and Relaxation Behavior of High Density Polyethylene/Hydroxyapatite Nano Particles for Bone Substitutes: Effects of Gamma Radiation

The following article has been retracted due to the fact that it cannot be accepted by the author as a journal publication. The Editorial Board takes a very strong respect to the author’s situation on this matter. This paper published in Journal of Biosciences and Medicines Vol.2 No.2, April 2014, has been removed from this site.