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.

Effect of Fluoride on the Ion-association of Calcium Phosphate and Crystallization of Hydroxyapatite

Using a titration setup to accurately control the reaction conditions and in situ monitor the reaction,we showed that fluoride exhibited negligible effects on the ion association process of calcium and phosphate and the formation of ACP nanospheres in a buffer solution with constant ionic strength.However,the stability of ACP increased with increasing fluoride concentration,which was ascribed to the inhibitory effect of fluoride on the aggregation of ACP nanospheres and the nucleation of nanocrystals on the surface of ACP nanospheres.Furthermore,fluoride could inhibit the lateral growth of HAP nanosheets and promote the formation of rod-like crystals.These results further improve our understanding of the crystallization pathway of HAP crystals and the regulatory effects of fluoride.

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.

Characterization of Hydroxyapatite Extracted from Crab Shell Using the Hydrothermal Method with Varying Holding Times

Hydroxyapatite(HA)is a bio ceramic commonly utilized in bone tissue engineering due to its bioactive and osteoconductive properties.Crab shells are usually disregarded as waste material despite their significant CaCO_(3) content,and have not been widely utilized in the synthesis of HA.This study aims to synthesize and analyze HA derived from crab shells using the hydrothermal method with different durations of holding time.This study utilized precipitated calcium carbonate(PCC)derived from crab shells.With a hydrothermal reactor set at 160°C and varying holding times of 14(HA_14),16(HA_16),and 18(HA_18)h,a PCC and(NH4)2HPO4 mixture was used to synthesize HA.The synthesis results were analyzed using scanning electron microscopy(SEM),fourier transform infrared spectroscopy(FTIR),and X-ray diffraction(XRD)tests.This study has accomplished the synthesis of HA from crab shells.Nonetheless,the final product of synthesis still contained CaCO_(3) as an impurity.The prolonged hydrothermal holding time of 14 to 18 h resulted in a reduction of impurities while increasing the percentage of crystal weight and crystallite size of HA.Specimen CH_18 is the best-quality product generated in this study.This specimen produced HA with the highest percentage of crystal weight and crystallite size compared to the other specimens.Furthermore,specimen CH_18 exhibited the lowest concentration of impurities.The Ca/P ratio in this specimen was also the closest to 1.67.The Ca/P ratio,crystallite size,and crystal weight percentage of this specimen are 1.54,19.06 nm,and 99.1%,respectively.

Sintering and Mechanical Properties of Magnesium and Fluorine Co-Substituted Hydroxyapatites

Biological apatites contain several elements as traces. In this work, Magnesium and fluorine co-substituted hydroxyapatites with the general formula Ca9Mg(PO4)6(OH)2-yFy, where y = 0, 0.5, 1, 1.5 and 2 were synthesized by the hydrothermal method. After calcination at 500℃, the samples were pressureless sintered between 950℃ and 1250℃. The substitution of F- for OH- had a strong influence on the densification behavior and mechanical properties of the materials. Below 1200℃, the density steeply decreased for y = 0.5 sample. XRD analysis revealed that compared to hydroxylfluorapatite containing no magnesium, the substituted hydroxyfluorapatites decomposed, and the nature of the decomposition products is tightly dependent on the fluorine content. The hardness, elastic modulus and fracture toughness of these materials were investigated by Vickers’s hardness testing. The highest values were 622 ± 4 GPa, 181 ± 1 GPa and 1.85 ± 0.06 MPa.m1/2, respectively.

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.

Effect of Silver-Loaded Zeolite on the Susceptibility of <i>Escherichia Coli</i>Against Antibiotics

We investigated the effect of silver-loaded zeolite (Ag-Z) on antibacterial activity of some antibiotics against Es-cherichia coli against antibiotics. We treated the bacterial suspension of E. coli by Ag-Z to be the level which the decrease of viable cell count was not observed. Susceptibility test of E. coli treated with Ag-Z was carried out against four antibiotics with different mode of action. Apparent increase in susceptibility was found in the case of rifampicin, not in others. The result suggests that application of Ag-Z to ward environment might give a good outcome at the treatment with rifampicin and at the treatment for pathogenic microbe spread through the air, such as tubercle bacilli.

Investigation of the Nd-Ce-Mg-Zn/Substituted Hydroxyapatite Effect on Biological Properties and Osteosarcoma Cells

Cancerous diseases and diseases resulting from bacteria and fungi are some of the pressures that humans face.Therefore,the development of biomaterials that are resistant to cancerous diseases,bacteria,and fungi has become one of the requirements of the medical field to extend the life of the biomaterial and fight pathogens after implanting these materials inside the human body.One of the important biomaterials used in the field of orthopedics is hydroxyapatite.In this research,Nano substituted hydroxyapatite was prepared by the wet precipitation method,including replacing 5%of the calcium ions with neodymium,cerium,magnesium,and zinc ions in cationic substitution.Many tests were carried out to characterize the prepared material.The biological properties were evaluated by examining the resistance of the substituted hydroxyapatite to bacteria and fungi,in addition to testing the effect of the material on normal cells and bone cancer cells.The results showed a new structure of hydroxyapatite after the substitution process and a significant improvement in the biological properties of the prepared biomaterial compared to other researches.

Azoximer bromide and hydroxyapatite:promising immune adjuvants in cancer

Immune adjuvants are immune modulators that have been developed in the context of infectious vaccinations.There is currently a growing interest in immune adjuvants due to the development of immunotherapy against cancers.Immune adjuvant mechanisms of action are focused on the initiation and amplification of the inflammatory response leading to the innate immune response,followed by the adaptive immune response.The main activity lies in the support of antigen presentation and the maturation and functions of dendritic cells.Most immune adjuvants are associated with a vaccine or incorporated into the new generation of m RNA vaccines.Few immune adjuvants are used as drugs.Hydroxyapatite(HA)ceramics and azoximer bromide(AZB)are overlooked molecules that were used in early clinical trials,which demonstrated clinical efficacy and excellent tolerance profiles.HA combined in an autologous vaccine was previously developed in the veterinary field for use in canine spontaneous lymphomas.AZB,an original immune modulator derived from a class of heterochain aliphatic polyamines that is licensed in Russia,the Commonwealth of Independent States,and Slovakia for infectious and inflammatory diseases,is and now being developed for use in cancer with promising results.These two immune adjuvants can be combined in various immunotherapy strategies.

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.

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.

The fabrication of hydroxyapatite mineralized hydrogels for bone tissue engineering

Bone is a complex but orderly mineralized tissue with hydroxyapatite(HA)as the inorganic phase and collagen as the organic phase.Inspired by natural bone tissues,HA-mineralized hydrogels have been widely designed and used in bone tissue engineering.HA is majorly utilized for the treatment of bone defects because of its excellent osteoconduction and bone inductivity.Hydrogel is a three-dimensional hydrophilic network structure with similar properties to the extracellular matrix(ECM).The combination of HA and hydrogels produces a new hybrid material that could effectively promote osteointegration and accelerate the healing of bone defects.In this review,the structure and growth of bone and the common strategies used to prepare HA were briefly introduced.Importantly,we discussed the fabrication of HA mineralized hydrogels from simple blending to in situ mineralization.We hope this review can provide a reference for the development of bone repair hydrogels.

碱改性生物炭负载纳米羟基磷灰石的制备及对染料的吸附研究

实验制备了碱改性生物炭负载纳米羟基磷灰石复合材料(BC/N-HAP),并以罗丹明B(RB)为目标污染物,考察该材料负载量、吸附剂使用量、pH及共存离子对罗丹明B去除效果的影响,并对吸附机理进行了探讨。实验结果表明,纳米羟基磷灰石成功负载到生物炭表面,当负载率为100:1(W/W BC:N-HAP),复合材料使用量为50 mg,体系pH为10时,60 min内罗丹明B的去除率为87.8%。动力学研究表明,该吸附过程符合伪二级动力学方程(R^(2)>0.99);热力学研究表明,该过程是自发吸热反应,符合Langmuir单分子层吸附模型。静电作用是复合材料吸附RB染料的主要作用力。

羟基磷灰石-聚乙烯醇/胶原-壳聚糖-明胶复合水凝胶修复兔骨软骨缺损

背景:关节骨软骨缺损是目前骨科医生面临的难题,传统修复方法难以取得满意疗效,以羟基磷灰石-聚乙烯醇为基础的复合水凝胶材料是目前研究的一个方向。目的:制备羟基磷灰石-聚乙烯醇/胶原-壳聚糖-明胶复合水凝胶,表征其物理学特征,验证其植入体内后的组织相容性及细胞黏附增殖能力,探讨其对兔骨软骨缺损的修复效果。方法:利用3D打印技术制备圆柱状多孔聚乳酸支架(孔径分别为1.2,1.4,1.6,1.8 mm),再将聚乙烯醇及羟基磷灰石混合乳液灌入聚乳酸支架中,经过冻融及二氯甲烷溶解后制成羟基磷灰石-聚乙烯醇水凝胶。然后将胶原-壳聚糖-明胶混合液灌入羟基磷灰石-聚乙烯醇水凝胶中,利用京尼平进行交联,最后经乙醇清洗及冷冻干燥制成羟基磷灰石-聚乙烯醇/胶原-壳聚糖-明胶复合水凝胶,表征4组水凝胶的物理学特征,筛选性能最优的水凝胶进行后续实验。将羟基磷灰石-聚乙烯醇水凝胶、胶原-壳聚糖-明胶复合水凝胶分别植入SD大鼠皮下,苏木精-伊红与Masson染色观察材料表面的细胞黏附生长状况。在15只兔双侧膝关节股骨滑车制作骨软骨缺损(直径5 mm、深6 mm)模型,左侧植入复合水凝胶(实验组),右侧未植入任何材料(对照组),Micro-CT及组织学检测来评估其对骨软骨缺损的修复效果。结果与结论:①综合孔隙率、含水率、力学测试及扫描电镜结果,得出孔径1.2 mm的羟基磷灰石-聚乙烯醇/胶原-壳聚糖-明胶复合水凝胶更符合天然软骨的一般特性,用于后续实验;②苏木精-伊红与Masson三色染色显示,随着材料植入大鼠皮下时间的延长,两种材料周边黏附的细胞均明显增多,其中胶原-壳聚糖-明胶植入后的细胞增殖状况更好,可见大量细胞长入其形成的网状结构,且网状结构也逐渐降解;③在兔骨软骨缺损实验中,至术后8周时,Micro-CT检查显示实验组植入的材料和周围骨-软骨整合良好,其表面及内部均有部分骨长入,对照组软骨及软骨下层仍然存在明显的缺损,未形成有效修复;苏木精-伊红与甲苯胺蓝染色显示,实验组植入复合水凝胶4-8周后即与周围骨软骨发生整合,随着时间的延长材料表面逐渐有新生软骨形成,至12周时缺损处大部分被新生软骨覆盖,软骨下层也出现良好的骨长入;对照组至术后12周虽然深层骨缺损大部分修复、浅层的软骨及软骨下骨缺损也有一定程度修复,但主要被纤维组织及部分纤维软骨替代;④结果表明,羟基磷灰石-聚乙烯醇/胶原-壳聚糖-明胶复合水凝胶材料可仿生天然软骨的结构和功能,在动物实验中能有效修复骨软骨缺损。

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。

氧化石墨烯辅助仿生矿化原位合成羟基磷灰石

羟基磷灰石(HAp)是一种与人体骨骼成分类似的无机材料,具有良好的生物相容性。本文以氧化石墨烯(GO)为模板,通过模拟体液(SBF)仿生矿化原位合成了HAp纳米粒子。通过SEM、XRD、EDS和拉曼光谱等测试分析研究了矿化时间、SBF/GO体积比对矿化产物物相组成、形貌和结构的影响。结果表明,矿化处理后的GO表面形成了大量均匀分布的类骨HAp。随着矿化时间延长和SBF体积占比增大,矿化产物的尺寸及数量增大,GO层间距逐渐扩大。本研究验证了GO辅助合成HAp的可行性,拓展了仿生矿化法的应用领域。

羟基磷灰石的电化学制备及其除氟性

采用清洁简便的多扫循环伏安法制备出羟基磷灰石(HAP),利用X射线衍射仪与红外光谱仪分析了合成的中间产物二水磷酸氢钙(DCPD)、最终产物HAP的晶面结构与官能团。扫描电镜显示HAP的表面形貌呈现分散性较好的棒状结构。同时,以水中F^(-)为吸附对象,研究了水中条件参数如pH、温度、阴离子含量等对所合成HAP吸附F^(-)容量的影响。结果表明,在pH为3~6的范围内,HAP对F^(-)的吸附量随pH升高逐渐增大,并在pH为6时达到最大;pH在6~10的范围内,HAP对F^(-)的吸附量随pH升高逐渐下降。水中可能共存的阴离子如Cl^(-)、NO_(3)^(-)、SO_(4)^(2-)、CO_(3)^(2-),不干扰HAP对F^(-)的吸附。在15~55℃的温度范围内,温度升高,HAP吸附容量增加,并在55℃时达到8.36 mg/g的最大吸附量,高于文献中同类材料的吸附量;经过4次吸附-脱附试验,HAP对模拟废水中F^(-)的去除效果依然符合国家标准。此外,HAP对F^(-)的吸附是一熵增、吸热的自发过程,符合Langmuir-Freundlich、Dubinin-Radushkevich两种吸附等温模型,并遵循颗粒内扩散的动力学反应机制。

制备羟基磷灰石的贝壳种类优选及方法比较

本研究以CaO、煅烧后的牡蛎壳、蛤蜊壳、扇贝壳和脉红螺壳为原料,分别采用反相微乳液法和聚乙二醇(PEG)辅助微波加热法制备了纳米羟基磷灰石(HA),并从产物的物理化学特性以及形态学参数方面进行比较。利用傅里叶变换红外光谱、X射线衍射对各组产物进行了化学表征,扫描电子显微镜观察样品的表面形貌,Zeta电位仪测定样品表面的电势差。结果表明,反相微乳液法制备的HA尺寸在(104.10±1.95)nm至(207.90±3.75)nm范围内,为近球形颗粒;而PEG辅助微波加热法制备得到的HA尺寸在(61.17±3.11)nm与(182.70±1.05)nm范围内,倾向于形成椭圆及棒状的颗粒,稳定性更高,且各组样品均表现出完全的亲水性。此外,对比于CaO制备的HA,以贝壳为原料制备的HA具有更好的纳米结构,其中利用脉红螺壳制备的HA在粒径大小、稳定性以及亲水性等方面均具有优势,并且具有更接近天然骨的钙磷比。因此脉红螺壳可以作为PEG辅助微波加热法制备羟基磷灰石的主要原料。

磁性介孔碳负载羟基磷灰石的制备及对U(Ⅵ)的吸附性能

采用共沉淀法研究制备了不同质量比的磁性介孔碳(MMC)与羟基磷灰石(HAP)复合材料(MMC@HAP-x,x=1、4和6)并用于去除溶液中U(Ⅵ)。采用XRD、FT-IR、Zeta等方法表征了MMC、HAP和MMC@HAP-x的结构、功能基团及表面电位等理化性质。探讨了MMC@HAP-x吸附U(Ⅵ)的动力学、热力学及吸附机制。结果表明:MMC@HAP-x对U(Ⅵ)的吸附最佳pH均为4.0,达到吸附平衡所需时间均小于10 min,MMC@HAP-6的理论饱和吸附量可达1164.62 mg/g,且吸附过程是自发的化学吸附过程。U(Ⅵ)在MMC@HAP-x的固定是由于HAP与UO_(2)^(+2)相互作用形成了Ca(UO_(2))_(2)(PO_(4))_(2)·3H_(2)O。MMC@HAP-6是一种快速的铀吸附剂,有望用于放射性废水中铀的去除。

激光诱导羟基磷灰石夹层纸表面碳化实现无墨打印

传统的油墨打印具有方便快捷的优势,但打印过程中墨水或碳粉的大量使用对人体和环境造成了不可忽视的危害。基于激光的高能粒子特性和光热辐射热效应,利用激光欠焦和聚焦两种工作模式,可实现激光无墨打印和微区加工。本文报道了一种基于羟基磷灰石的“有机-无机-有机”三明治结构多功能纸,并利用激光的光热辐射效应使功能纸表层有机材料——纤维素纤维表面温度升高,实现表层均匀碳化,夹层无机材料——羟基磷灰石阻挡能量继续传导防止纸张烧穿,以此来达到无墨打印的效果。基于激光烧蚀的无墨打印,能够显著降低打印成本,有利于激光烧蚀打印技术的推广。此外,采用激光烧蚀打印技术作用于功能纸上的打印效果具有稳定、绿色环保等特点,在档案存储用纸、食品包装用纸和后天致盲患者阅读等方面具有广泛的应用。