电聚合茜素黄R构建辣根过氧化物酶传感器的研究

利用电聚合茜素黄R(AYR)的方法,将辣根过氧化物酶(HRP)和细胞色素c(Cyt c)固载于通过一步法电沉积的碳纳米管-金纳米粒子(MWCNTsAu NPs)复合纳米材料修饰电极表面,构筑PAYR-HRP-Cyt c/M WCNTs-Au NPs修饰电极,并利用HRP对H2O2的直接电化学催化行为对H2O2进行检测。采用扫描电镜对MWCNTs-Au NPs和PAYR-HRP-Cyt c的表面形貌进行表征。利用电化学阻抗对修饰电极的构筑过程进行了监测。采用循环伏安法和计时电流法对修饰电极的电化学行为进行了研究。探讨了p H和电位对该修饰电极测定H2O2的性能的影响。该传感器对H2O2在5.0×10-7~3.14×10-3mol/L范围内呈良好的线性响应,相关系数为0.9997,灵敏度为0.50 A·L/mol,检出限(S/N=3)为9.6×10-8mol/L。     

细胞色素c在Fe_2O_3修饰电极上的直接电化学和电催化特性

采用全氟磺酸树脂Nafion将金属氧化物Fe2O3颗粒细胞色素c(Cyt c)固定玻碳电极(GCE)表面,制备了Nafion-Cyt c-Fe2O3修饰的玻碳电极,构建了基于直接电子传递的过氧化氢生物传感器。在0.10mol/L pH7.0的磷酸盐缓冲溶液中,修饰电极的循环伏安曲线上显示出一对准可逆的氧化还原峰,式量电位为22mV。Cyt c在修饰电极表面的异相电子转移速率常数为1.21s-1。修饰后的电极对过氧化氢有良好响应,响应时间小于10s,电极的安培响应与过氧化氢浓度在2.0×10-6～3.0×10-3mol/L范围内成线性关系,检出限为1.0×10-6mol/L,米氏常数为1.35mmol/L,显示出较好的亲和力。     

碳纳米管修饰电极上沙丁胺醇电催化氧化研究

将多壁碳纳米管(MWNT)分散在疏水性表面活性剂双十六烷基磷酸(DHP)溶液中形成稳定、均相的分散液,然后制备多壁碳纳米管-DHP复合膜修饰玻碳电极(MWNT-DHP/GCE).应用方波伏安法研究了沙丁胺醇在修饰电极上的电化学行为,结果表明,碳纳米管复合膜修饰电极对沙丁胺醇的氧化有良好的电催化活性,其氧化反应为一电子一质子过程,氧化电位比裸玻碳电极负移40 mV,峰电流增加了4.5倍.在最佳测试条件下,氧化峰电流与沙丁胺醇浓度在8.3×10-7~3.3×10-6mol/L范围内呈良好线性关系,开路富集2min,检出限达1.8×10-7mol/L.该修饰电极具有良好的重现性、稳定性.     

三维有序结构的金掺杂纳米TiO_2修饰电极用于H_2O_2的测定

在ITO玻璃表面构建了三维有序多孔结构的金掺杂纳米Ti O2薄膜(3DOM GTD/ITO),同时制备了一种细胞色素c(Cyt c)酶生物传感器(Cyt c/3DOM GTD/ITO)。通过透射电镜(TEM)、扫描电镜(SEM)对修饰电极进行表征。紫外-可见光谱实验表明吸附在GTD上的Cyt c能够保持其生物活性,二级结构未被破坏。同时研究了Cyt c在3DOM GTD/ITO修饰电极表面的直接电化学及对H2O2的电催化行为。结果显示,Cyt c在3DOM GTD/ITO修饰电极上有显著的直接电化学响应,峰电流与扫描速度呈线性关系,说明该电极过程是表面电化学控制过程。Cyt c/3DOM GTD/ITO修饰电极对H2O2具有良好的催化性能,线性范围为3.0×10-7~1.70×10-5mol/L,检出限为3.6×10-8mol/L(S/N=3),响应时间为5 s,且该修饰电极具有较好的重现性和稳定性。     

细胞色素c／L-半胱氨酸修饰金电极检测亚硝酸根

采用循环伏安法、交流阻抗法研究了组装在L-半胱氨酸(L-Cys)修饰金电极上的细胞色素c(Cyt c)电化学行为;采用电化学方法以及紫外-可见光谱对电极进行表征.结果表明:通过静电吸附作用组装在L-Cys修饰金电极上的细胞色素c保持了良好的生物和电化学活性,用Cyt c/L-Cys修饰金电极检测亚硝酸根,响应电流与亚硝酸根浓度在5.0×10-6～4.5×10-4mol·L-1范围内呈线性关系,线性回归方程为Ip=0.031 c 8.165×10-6,相关系数为0.999 5,检出限(S/N=3)为1.5×10-7mol·L-1.电极用于模拟样品及咸菜样品中亚硝酸根的测定,回收率为89.0%～116.0%.     

聚吡咯／多壁碳纳米管修饰电极对多巴胺的测定

制备了聚吡咯/多壁碳纳米管(PPy/MWNT)复合膜修饰电极。研究了神经递质多巴胺(DA)在该修饰电极上的电化学行为。实验表明,PPy/MWNT复合膜修饰电极对DA的电催化作用优于PPy修饰电极。在pH=4.10的0.2mol/L醋酸-醋酸钠缓冲溶液中,DA在该修饰电极上的CV曲线于0.31V和0.28V处出现一对灵敏的氧化还原峰,峰电位差△Ep比裸玻碳电极降低58mV,比PPy修饰电极降低28mV,峰电流显著增加。氧化峰电流ipa与DA浓度在1.0×10-4~7.8×10-8mol/L范围内呈良好的线性关系,线性回归方程为ip(μA)=0.2512 1.2300C(×10-5mol/L),相关系数r=0.9992,检出限为3.9×10-8mol/L。常见物质对DA的检测无干扰,DA注射液样品检测回收率为94%~104%。     

细胞色素C在4,5-二氮芴-9-酮修饰玻碳电极上的直接电化学研究

采用循环伏安法探讨了细胞色素C(Cyt C)在4, 5-二氮芴-9-酮(dafo)修饰玻碳电极表面的电化学行为.结果表明,Cyt C在dafo修饰电极上呈现一对峰形较好且准可逆的氧化还原峰,其式电位(E0′)为13 mV,峰电流与扫描速度呈线性关系,该电极过程是表面控制过程,电化学反应效率常数(ks)为0.89/s.固定在dafo上的Cyt C能促进H2O2的催化还原,响应快速而灵敏(<10 s),峰电流与H2O2浓度在5.0×10-6～3.0×10-4 mol/L范围内呈线性关系;检出限2.5×10-6 mol/L;米氏常数为1.07 mmol/L,显示出较好的亲和力.     

掺杂多壁碳纳米管改性聚溴甲酚绿膜修饰电极的制备、表征与应用研究

研究了掺杂多壁碳纳米管(MWNT)改性聚溴甲酚绿膜(PBG),以不同修饰方法制备了4种修饰电极,用扫描电镜、交流阻抗及循环伏安法等对电极进行表征。结果表明:4种修饰电极的电活化面积均得到明显提高,其中以层层修饰制备的聚溴甲酚绿膜/多壁碳纳米管复合膜(PBG/MWNT/GC)电极最能发挥MWNT和PBG的电活性。将电极用于8-羟基喹啉(8-HQ)电化学行为的研究,结果表明:4种修饰电极的伏安响应明显提高,且8-HQ在PBG/MWNT/GC上的氧化峰电位负移最多,峰电流最大,约为裸玻碳电极的4.5倍,电催化作用显著增强。8-HQ在PBG/MWNT/GC上电极反应的电子转移数和质子数均为1,是吸附控制的不可逆电氧化过程,氧化峰电流Ip与浓度c在4.0×10-6～3.5×10-4mol/L范围内呈良好的线性关系,r=-0.997 2,检出限(S/N=3)为1.96×10-8mol/L。PBG/MWNT/GC修饰电极可实现8-HQ的快捷、简便测定。     

聚2,6-吡啶二甲酸/多壁碳纳米管修饰电极的电催化性能

研制了一种聚2,6-吡啶二甲酸/多壁碳纳米管(PPDA/MCNT)复合修饰电极。该电极以中性KC l溶液为底液,在玻碳电极上以多壁碳纳米管(MCNT)作掺杂剂,通过电聚合2,6-吡啶二甲酸(PDA)而制得。该修饰电极对多巴胺(DA)有很强的电催化氧化作用。在磷酸盐缓冲液(pH 7.2)中,与碳纳米管修饰电极相比,DA的氧化峰电位降低约30 mV。利用线性扫描伏安法(LSV)测定,DA在9.0×10-8~8.0×10-6mol/L浓度范围内,其峰高与浓度呈线性关系;检出限为5.0×10-8mol/L,并可避免AA、UA对测定产生干扰。     

咖啡酸在多壁碳纳米管修饰玻碳电极上的电化学行为及其测定

制备了多壁碳纳米管(MWNT)修饰玻碳电极,并研究了咖啡酸在该电极上的电化学行为及其测定方法,与裸玻碳电极(GCE)相比,MWNT膜修饰电极(MWNT/GCE)能显著提高咖啡酸的氧化峰电流.在pH=3.29的B-R缓冲溶液中,咖啡酸在MWNT/GCE电极上出现1对准可逆的氧化还原峰,Epa=0.47 V,Epc=0.32 V,峰电流与其浓度在5.0×10-7～2.0×10-5 mol/L范围内成线性关系,检出限为5.0×10-7mol/L.实际样品测定的相对标准偏差(RSD)为0.82％(n=5),平均回收率为100.7％.MWNT膜对咖啡酸的电化学氧化有明显的催化作用.该法是一种快捷、可靠、灵敏的检测方法,可以用于咖啡酸含量的测定.     

纳米羟基磷灰石的制备及结晶尺寸的控制

Nano particle hydroxyapatite was synthesized based on wet chemical precipitation method. The precipitated hydroxyapatite powders are characterized using Inductively Coupled Plasma Spectroscopy(ICP), FT-IR spectroscopy, X-ray diffraction(XRD), transmission electron microscopy(TEM), and electron diffraction(ED). Hydroxyapatite with different mean nano particle sizes in the range of 20～160 nm was prepared. Particle sizes were mainly determined by reaction temperature. Influences of degree of supersaturation, stirring intensity and reaction temperature were analyzed based on crystallization process analysis.     

Nucleation of Hydroxyapatite on Silica-Gel: Experiments and Thermodynamic Explanation

Silica-gels prepared from ethanol, TEOS and water, using a hydrochloric acid as catalyst, were slowly dried and heated in air up to 900°C. Plate-like pieces of heat treated silica-gel were used for hydroxyapatite nucleation experiments in a simulated body fluid (SBF) medium since sol-gel processing gives the silica an active surface. The SBF was changed every 3 days.After 9 days in the SBF, hydroxyapatite was observed by SEM on the surface of the silica-gel samples. The presence of hydroxyapatite was confirmed by FTIR. Subsequent growth of hydroxyapatite was evaluated after 12 and 21 days total soaking time in SBF. A thermodynamic analysis was made in order to explain the nucleation and growth of the hydroxyapatite on the silica-gel.     

Thermal behavior of in vitro mineralized anionic collagen matrices

In the present study porcine skin and bovine pericardium were used as a source of type I collagen. Both were submitted to an alkaline treatment and mineralized by the alternate soaking method. Thermal stability and extent of mineralization have been investigated using DSC and TG. After alkaline hydrolysis there is a decrease in thermal stability but mineralization stabilizes collagen structure. Thermogravimetric data have shown that the amount of hydroxyapatite present in bovine pericardium matrix (45%) was greater than on porcine skin matrix (20%). Presence of hydroxyapatite was confirmed by EDX.     

中空羟基磷灰石的制备方法研究进展

中空结构的羟基磷灰石因具备出色的生物相容性及生物活性、大比表面积和孔体积、小尺寸、良好的机械性、热稳定性以及表面渗透性等性能优点,让其在生物、医学、材料领域产生巨大影响,具有极大的运用价值。因此,制备具有中空结构的羟基磷灰石的方法及有关性能研究成为了热点。本文对例如模板法、水热法、溶剂热法、喷雾干燥法、微波协助法、微乳液法等一系列制备中空羟基磷灰石的方法及现状进行了总结,为空心羟基磷灰石的制备、性能优化提供科学且有益的参考。     

Fourier Transform and Multi Dimensional EPR Spectroscopy for the Characterization of Sol-Gel Derived Hydroxyapatite

Calcium hydroxyapatite powder was prepared by sol-gel method using calcium acetate and PO(OC₂H₅)₃ as initial compounds, and alcohol (methyl, ethyl, and propyl-alcohol) as solvent. Homogeneous solution and gels were prepared using a molar ratio of Ca/P=1.67. The evolution of the structure was detected by X-ray diffraction, IR, and FT-n(=1,2,3)D-EPR spectroscopy. The dried gels exhibit a signal characterized by a central line and two satellites. The 2D spectrum (ESEEM vs. field sweep) showed the same modulation for the central line. The FT-EPR spectrum vs. field sweep 2D-spectrum indicated that the satellites are due to an hfs splitting with water. The central region of this 2D spectrum is influenced by P and H in a concentration ratio of [H]/[P]=2.5. The ESEEM spectrum was simulated assuming the equation V_mod=V_mod(P)^mV_mod(H)ⁿ for two spin systems S=1/2 and I=1/2. This simulation gave form andn the values of 2 and 5, respectively. This finding suggests the structure: for the unpaired state. It appears that one ethyl group does not hydrolyse in the gelation process. The ESEEM spectra of hydroxyapatite exhibit a modulation generated by P, H and Ca atoms.     

羟基磷灰石粉末的水热合成及动力学研究

以CaHPO_4·2H_2O(DCPD)为前驱物,在0.1mol·L~(-1)NaOH溶液中,100～200℃,2～12h条件下水热合成羟基磷灰石(HA)粉末。结果表明:HA晶粒尺寸和结晶程度随反应温度的提高和时间的延长而增大。提高反应温度,有利于晶粒沿c轴方向生长;延长反应时间,有利于晶粒沿a轴方向生长。在120～160℃、2～10h条件下可以得到HA纳米棒。水热合成过程中有缺钙磷灰石(DAP,Ca_(10)～(HPO_4)_x(PO_4)_(6-x)(OH)_(2-x),0≤x≤1)形成,并经历β-TCP→DAP→HA这一转化过程。转化反应为二级反应,活化能为72.91kJ·mol~(-1),推测反应为表面控制反应。     

Cell Evaluation on Alginate/Hydroxyapatite Block for Biomedical Application

Initial cell evaluation on alginate/hydroxyapatite block was investigated. Sodium alginate with 1, 3 and 5% concentration was obtained via neutral extraction of locally obtained brown seaweed, Sargassumpolycystum. Commercially available hydroxyapatite (HAp) powder was pressed uniaxially at 3 MPa to obtain the HAp block. The HAp block was then sintered at 900̊C. The sintered HAp block was then immersed in the sodium alginate solution at different concentration for 24 hours under vacuum condition. Morphological observations show that normal cell growth was observed on alginate/HAp blockafter post treatment for day 1 and 2. However, the cell starts to show some distinct morphological changes when compared to the control cells for day 5 and 7. Cell viability assay results shows that a consistent cell growth was obtained with HAp block incorporated with 3 and 5% sodium alginate. While HAp block without the incorporation of sodium alginate and HAp block incorporated with 1% sodium alginate concentration shows inconsistent cell growth. Initial cell evaluation results suggest that alginate/HAp block shows no toxicity on cell attachment and proliferation.     

Sintering of Hydroxyapatite Ceramics,with the Aid of Optical Transmittance — Temperature Spectra

The optical transmittance — temperature spectra of well-translucent thin pellets of hydroxyapatite prepared by the high isostatic pressure consolidation of xerogel particles were measured by a newly-developed thermal analysis technique. From these spectra, it was possible to identify temperature intervals with increased or decreased levels of light transmittance, clearly associated with microstructural changes. The thermal processing of treated pellets was stopped at temperatures deliberately chosen with respect to the specific transmittance states. Samples with increased transparency were prepared when the heating of pellets was stopped at the temperatures of the locally highest light transmittance measured.This revised version was published online in November 2005 with corrections to the Cover Date.     

Synthesis and Sintering-wet Carbonation of Nano-sized Carbonated Hydroxyapatite

Synthetic carbonated apatite ceramics are considered as promising alternative to auto- and allograft materials for bone substitute. In this study, Carbonated hydroxyapatite (CHA) was synthesized by nanoemulsion method. The powder produced was B-type CHA in nano-sized and had 8.25% carbonate content. The CHA samples were made into pellets and were sintered to 800 °C. Upon cooling down to 150, 200, 250 and 300 °C, carbonation with wet CO₂ was performed on the CHA in a desiccator to re-compensate the carbonate loss due to sintering and improve densification. The aim of this study was to investigate and compare the effect of cooled down temperatures on dense CHA with two kind of wet CO₂ atmospheres: direct wet CO₂ and dry CO₂ through water. Sintered CHA carbonated by using dry CO₂ through water had overall higher amount of carbonate content as compared to carbonation from wet CO₂ directly from tank. D200, sample undergone carbonation by carbonated by dry CO₂ through water at 200 °C had the highest carbonate content (3.35%).     

等离子喷涂羟基磷灰石涂层的晶化及其结构特征

Phase compositions, function group and surface morphology of recrystallized plasma sprayed hydroxyapatite (HA) coatings were examined by means of X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), Raman spectra, scanning electron microscope (SEM) and electron probe microanalyzer (EPMA). The results show that the structural integrity of HA was almost completely restored after the heat treatment of (600～700℃)×2h. Temperatures above this value were unfavorable to the restoration of OH^- and crystallinity. The recrystallizing treatment caused amorphous and decomposed phases transform into crystalline HA with a very small amount of CaO retained in coating. Under 500℃, longer keeping time led to a gradual increase of crystallinity, however, under 600℃, the crystallinity showed no obvious changes with decreased CaO content. Meanwhile, nanometer hydrox-yapatite crystals with dot-like, polyhedral, acerous and effloresent shapes and a average size of 100nm originated in the coatings.