Nation-离子液体-碳纳米管复合膜修饰电极的制备及用于抗坏血酸、多巴胺及尿酸的同时测定

制备了一种新颖的Nation-离子液体一多壁碳纳米管复合膜修饰电极,并研究了抗坏血酸（AA）、多巴胺（DA）和尿酸（uA）在该修饰电极上的电化学行为．该修饰电极结合了多壁碳纳米管良好的导电性、离子液体优良的催化性能及Nation的高选择性等优点,对AA、DA和UA的氧化具有很好的催化和分离效果,实现了AA、DA和UA的同时测定．在三者共存体系中,AA和DA、DA和UA的氧化峰电位差分别为148和167mV．对AA、DA和UA的同时检测,线性范围分别为5-3200、1～1100和1-300gmol／L,检出限分别为1．66、0．33和0．33gmol／L．该修饰电极选择性好、稳定性高、重现性好,有望用于实际样品中AA、DA和UA的同时检测．     

Microwave-assisted One-pot Synthesis of Ag NPs/C and Its Application in H2O2 and Glucose Detection

The facile preparation of Ag NPs/C via a one-pot strategy was carried out by microwave treatment of a mixed aqueous solution of AgNO₃ and glucose at 180℃ for 20 min without the presence of extra reducing agent. The as-synthesized Ag NPs/C showed high catalytic performance toward the reduction of H₂O₂. The H₂O₂ sensor constructed with as-synthesized Ag NPs/C exhibited a short amperometric response time of less than 2 s. The linear range was approximately (0.1-50) mmol/L(r=0.997), and the detection limit was approximately 3.3 μmol/L at a signal-to-noise ratio of 3. A glucose biosensor was fabricated by immobilizing glucose oxidase onto Ag NPs/C- modified glassy carbon electrode to detect glucose. The glucose sensor had a wide linear response range of 2-22 mmol/L(r=0.999) and a detection limit of 190 μmol/L.     

Preparation of Au Nanoparticles Decorated Polyaniline Nanotube and Its Catalytic Oxidation to Ascorbic Acid

With sulfonated electrospun polystyrene fiber as a template, uniform polyaniline(PANI) nanotubes were fabricated via polymerization of aniline followed by template removal. Au nanoparticles(Au_nano) were decorated on the PANI nanotube successfully via auto-reduction of HAuCl₄ on the PANI nanotube. The morphology of the nanotubes was characterized by means of scanning electron microscopy(SEM) and transmittance electron microscopy(TEM). By varying precursor concentration and incubation time, Au_nano-PANI with different size of Au_nano was obtained conveniently. Glassy carbon electrode modified with the Au_nano decorated PANI nanotubes (Au_nano-PANI/GCE) was prepared and used seccessfully for the catalytic oxidation of ascorbic acid(AA). The results of differential pulse voltammetry indicate that there is a good linear relationship between the peak currents and the concentrations of AA in the range of 5-3000 μmol/L, with the limit of detection of 1 μmol/L(S/N>3). There is no mutual interference between AA and dopamine. The electrode has been successfully applied in the detection of AA in vitamin C tablet sample.     

电活化玻碳电极的制备及其对抗坏血酸、多巴胺、尿酸与亚硝酸盐的同时测定

在1.0 mol·L-1H_2SO_4溶液中,采用循环伏安法(CV)对玻碳电极(GCE)进行电化学处理,得到"活化"的玻碳电极(A-GCE)。在0.1 mol·L-1生理性磷酸盐缓冲溶液(PBS,p H 7.0)中,A-GCE不仅能很好地改善抗坏血酸(AA)、多巴胺(DA)、尿酸(UA)和亚硝酸根(NO_2~-)的电化学行为,而且能将四者的混合溶液在GCE上重叠的弱氧化峰分成4个灵敏的氧化峰,且相邻氧化峰(AA-DA、DA-UA、UA-NO_2~-)之间的电位差(ΔEpa)分别为0.16、0.15、0.45 V,表明A-GCE对AA、DA、UA和NO_2~-具有良好的电催化活性,可用于混合溶液中四者的同时分析。在优化的实验条件下,AA、DA、UA和NO_2~-的差分脉冲伏安(DPV)峰电流与其浓度分别在5~2 100、2~140、1~700、10~1 050μmol·L-1范围内呈良好的线性关系,相关系数分别为0.998 9、0.996 8、0.997 4和0.997 8,检出限分别为0.19、0.45、0.28、0.72μmol·L-1。将A-GCE应用于血清中AA、DA、UA和NO_2~-的同时电化学分析,结果满意。     

磁性印迹纳米粒子固定血红蛋白修饰磁性电极构建过氧化氢传感器

采用表面印迹技术,以磁性二氧化硅纳米粒子（Fe₃O₄@SiO₂ NPs）作为载体、血红蛋白（Hb）为模板分子、正硅酸乙酯（TEOS）为印迹聚合物单体,制备了Hb印迹Fe₃O₄@SiO₂的磁性印迹纳米粒子（MMIPs NPs）. MMIPs NPs具有磁性内核和血红蛋白印迹壳层的核壳结构,可以富集并固定Hb. 使用壳聚糖将MMIPs NPs固定于磁性电极表面,构建血红蛋白类酶生物传感器,研究了Hb对过氧化氢（H₂O₂）的催化活性. MMIPS NPS相比于磁性非印迹纳米粒子（MNIPS NPS）,催化电流增加了14.3%. 采用磁性电极,MMIPS NPS、Hb和O₂的顺磁性使得该类酶生物传感器对H₂O₂的催化电流增加了60.0%. 血红蛋白类酶生物传感器电流响应与H₂O₂浓度在25 ~ 200 μmol·L^-1间呈线性关系,检出限为3 μmol·L^-1（S/N=3）,表明该类酶传感器对H₂O₂具有良好的催化性能.     

Chemometric Strategies to Develop a Nanocomposite Electrode for Simultaneous Determination of Ascorbic Acid,Dopamine, and Uric Acid

A simple and sensitive method for simultaneously measuring dopamine (DA), ascorbic acid (AA), and uric acid (UA) using a poly(1‐aminoanthracene) and carbon nanotubes nanocomposite electrode is presented. The experimental parameters for composite film synthesis as well as the variables related to simultaneous determination of DA, AA, and UA were optimized at the same time using fractional factorial and Doehlert designs. The use of carbon nanotubes and poly(1‐aminoanthracene) in association with a cathodic pretreatment led to three well‐defined oxidation peaks at potentials around ?0.039, 0.180 and 0.351 V (vs. Ag/AgCl) for AA, DA, and UA, respectively. Using differential pulse voltammetry, calibration curves for AA, DA, and UA were obtained over the range of 0.16–3.12×10^?3 mol L^?1, 3.54–136×10^?6 mol L^?1, and 0.76–2.92×10^?3 mol L^?1, with detection limits of 3.95×10^?5 mol L^?1, 2.90×10^?7 mol L^?1, and 4.22×10^?5 mol L^?1, respectively. The proposed method was successfully applied to determine DA, AA, and UA in biological samples with good results.     

基于聚乙烯醇离子液体负载HRP修饰石墨烯/纳米金复合膜的过氧化氢生物传感器

以石墨烯/纳米金修饰玻碳电极为基底, 用聚乙烯醇与离子液体复合物将辣根过氧化物酶固定于电极表面, 制备了过氧化氢生物传感器. 结果表明, 在0.1 mol/L HAc-NaAc+0.1mol/L KCl(pH=6.5)中, H₂O₂的氧化峰电流与其浓度在9.55×10^-6~6.01×10^-3 mol/L间呈良好线性关系, 检出限(3S/N)为3.3×10^-7 mol/L. 用标准加入法做回收实验, 回收率在93.4%~100.5%之间. 该传感器对H₂O₂具有较高的灵敏度和较低的检测限, 稳定性和重现性良好, 使用寿命较长, 且制作成本低, 可多次重复使用.     

柠檬酸修饰电极对抗坏血酸、多巴胺和尿酸的同时检测

研究柠檬酸(CA)修饰玻碳电极(CA/GC)在抗坏血酸(AA)、多巴胺(DA)和尿酸(UA)混合体系中的循环伏安(CV)行为.结果表明,AA、DA和UA在CA/GC电极上氧化峰电流增大,且三者氧化峰电位明显分离(ΔEp(DA,AA)=170 mV,ΔEp(DA,UA)=130 mV,ΔEp(AA,UA)=300 mV).据此,可同时检测AA、DA和UA.在优化的实验条件下,AA、DA和UA的氧化峰电流与其浓度分别在2.0×10-6～1.5×10-3mol.L-1,6.0×10-7～1.0×10-3mol.L-1和6.0×10-7～1.0×10-3mol.L-1范围内呈线性关系.该电极重现性好,可用于盐酸多巴胺针剂DA、VC片剂AA及人体尿液UA的测定.     

RNA Modified Electrodes for Simultaneous Determination of Dopamine and Uric Acid in the Presence of High Amounts of Ascorbic Acid

A promising electrochemical biosensor was fabricated by electrochemical grafting of ribonucleic acid (RNA) at 1.8 V (vs. SCE) on glassy carbon electrode (GCE) (denoted as RNA/GCE), for simultaneous detection of dopamine (DA) and uric acid (UA) with coexistence of excess amount of ascorbic acid (AA). The electrode was characterized by X‐ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The RNA modified layer on GCE exhibited superior catalytic ability and anionic exclusive ability in comparison with the DNA modified electrode. Three separated anodic DPV peaks were obtained at 0.312, 0.168 and ?0.016 V for UA, DA and AA, respectively, at the RNA/GCE in pH 7.0 PBS. In the presence of 2.0 mM AA, a linear range of 0.37 to 36 μM with a detection limit of 0.2 μM for DA, and in the range of 0.74 to 73 μM with a detection limit of 0.36 μM for UA were obtained. The co‐existence of 5000 fold AA did not interfere with the detection of DA or UA. The modified electrode shows excellent selectivity, good sensitivity and good stability.     

聚乙烯亚胺功能化石墨烯修饰电极同时测定抗坏血酸、 多巴胺、尿酸和色氨酸

制备了聚乙烯亚胺(PEI)功能化的石墨烯(G)修饰电极以实现抗坏血酸(AA)、 多巴胺(DA)、 尿酸(UA)和色氨酸(Trp)的分离及同时测定. 采用红外光谱(FTIR)、 紫外-可见吸收光谱(UV-Vis)、 X射线粉末衍射仪(XRD)和透射电子显微镜(TEM)对电极修饰材料进行了表征, 并优化了该修饰电极同时测定AA, DA, UA和Trp的实验条件. 在聚乙烯亚胺功能化石墨烯修饰的玻碳电极(PEI-G/GCE)上实现了AA, DA, UA 和Trp氧化峰的分离, AA-DA, DA-UA和UA-Trp的氧化峰电位差分别为298, 130和350 mV. 该修饰电极对AA, DA, UA和Trp的检测线性范围分别为50~5800, 30~2570, 0.05~400和6~1000 μmol/L; 检出限分别为16.67, 10, 0.017和2 μmol/L.     

Electrodeposited Cu‐Au Alloy Nanoparticles for Uric Acid Electrochemical Biosensor with Quick Response

A uric acid (UA) electrochemical biosensor based on the Cu‐Au alloy nanoparticles (NPs) and uricase was developed. The electrodeposition technique of Cu‐Au alloy NPs was selected to be a convenient potentiostatic method at –0.8 V in a single solution containing both Au(III) and Cu²⁺. Cyclic voltammetry and scanning electron microscopy proved the successful deposition of Cu‐Au alloy NPs. EIS demonstrated the good conductivity of Cu‐Au alloy NPs. The enzyme was immobilized on the surface of Cu‐Au alloy NPs modified electrode by casting with chitosan solution. The ultimate biosensor showed linear amperometric response towards UA in the concentration range of 3.0 to 26.0 μM with a detection limit of 0.8 μM. The main feature of the biosensor was its short response time, which was attributed to the good conductivity of Cu‐Au alloy NPs. Furthermore, the biosensor could avoid the interference of ascorbic acid and oxygen.     

MOF derived Co3O4/N-doped carbon nanotubes hybrids as efficient catalysts for sensitive detection of H2O2 and glucose

Developing enzyme-free sensors with high sensitivity and selectivity for H2O2 and glucose is highly desirable for biological science.Especially,it is attractive to exploit noble-metal-free nanomaterials with large surface area and good conductivity as highly active and selective catalysts for molecular detection in enzyme-free sensors.Herein,we successfully fabricate hollow frameworks of Co3O4/N-doped carbon nanotubes(Co3O4/NCNTs)hybrids by the pyrolysis of metal-organic frameworks followed by calcination in the air.The as-prepared novel hollow Co3O4/NCNTs hybrids exhibit excellent electrochemical performance for H2O2 reduction in neutral solutions and glucose oxidation in alkaline solutions.As sensor electrode,the Co3O4/NCNTs show excellent non-enzymatic sensing ability towards H2O2 response with a sensitivity of 87.40μA(mmol/L)^-1 cm^-2,a linear range of 5.00μmol/L-11.00 mmol/L,and a detection limitation of 1μmol/L in H2O2 detection,and a good glucose detection performance with 5μmol/L.These excellent electrochemical performances endow the hollow Co3O4/NCNTs as promising alternative to enzymes in the biological applications.     

NiMo/Al_2O_3-USY催化剂上中低温煤焦油加氢裂化性能研究

采用等体积浸渍法制得一系列NiMo/Al_2O_3-USY催化剂,在200 mL固定床上考察了不同金属负载量对其中低煤焦油加氢裂化催化性能的影响,进一步用NH_4F溶液改性USY以提高催化剂的脱硫性能,并结合XRD、氮气吸附-脱附、XPS、HR-TEM、H_2-TPR和NH_3-TPD等手段对催化剂进行了表征分析。结果表明,NiM o/Al_2O_3-USY催化剂适宜的M oO_3负载量为15%(质量分数);当MoO_3含量超过15%后,MoS_2活性相在载体上团聚,硫化程度趋于稳定,强酸酸量和孔径减少,增加金属负载量对煤焦油加氢裂化转化率影响较小。NH_4F改性USY可增大NiM o/Al_2O_3-USY催化剂的孔径,有利于提高煤焦油加氢裂化转化率。表面强酸酸量减少后,产品中的硫含量明显增加,说明强酸酸量是影响产物硫含量的关键因素。当NH_4F浓度为0.6 mol/L时,NH_4F改性USY制得的NM 0.6催化剂上煤焦油加氢裂化的转化率为87.65%,产品汽油馏分(≤180℃)硫含量为5.96 mg/kg,柴油馏分(180-320℃)硫含量为34.98 mg/kg。     

Colorimetric Detection of Glucose Using WO3 Nanosheets as Peroxidase-mimetic Enzyme

In the present work, WO₃ nanosheets(WO₃ NSs) were prepared by a facile method at room temperature. The obtained WO₃ NSs showed peroxidase-like activity, which could catalyze 3,3',5,5'-tetramethylbenzidine(TMB) to form a blue oxidation product(ox TMB) in the presence of H₂O₂. Based on this, convenient and sensitive colorimetric methods for the detection of H₂O₂ and glucose were established. The linear ranges for detecting H₂O₂ and glucose were 1-200 μmol/L and 1-100 μmol/L, respectively. The limits of the detection of H₂O₂ and glucose were as low as 0.79 and 0.96 μmol/L, respectively. This method was also successfully applied to the detection of glucose in urine samples. The detection result was consistent with that of the value detected by the clinical method, indicating the potential in clinical diagnosis and biomedical detection.     

纳米金双巯基修饰金电极差分脉冲伏安法测定多巴胺和抗坏血酸

在裸金电极上自组装4,4-二甲基联苯硫醇(MTP)膜(MTP/AuSAMs),再电还原氯金酸溶液修饰纳米金,得纳米金双巯基修饰金电极(NG/MTP/Au).研究了多巴胺(DA)和抗坏血酸(AA)在NG/MTP/Au上的电化学行为,发现该修饰电极对DA、AA的氧化具有良好的电催化作用,多巴胺(DA)和抗坏血酸(AA)的氧化峰电位差达到155mV,可以实现对此二组分混合溶液的选择性测定.差分脉冲法测得的峰电流与DA、AA浓度分别在5.0×10-7～1×10-4mol.L-1和3.5×10-6～1.0×10-3mol.L-1范围内呈线性关系,检测限(3σ)分别为1.5×10-7mol.L-1和1.2×10-6mol.L-1,相关系数0.998.     

L-半胱氨酸改性Fe3O4纳米粒子的水热合成及其应用

以L-半胱氨酸为表面改性剂与粒径调节剂,采用水热法制备具有良好分散稳定性的磁性Fe₃O₄纳米粒子。通过透射电镜（TEM）、扫描电镜（SEM）、X射线衍射仪（XRD）、比磁饱和强度测定仪（VSM）等对产物进行表征,研究L-半胱氨酸对磁性Fe₃O₄纳米粒子的形貌、粒径分布、晶型结构、分散稳定性等的影响,理论推导了L-半胱氨酸改性后的Fe₃O₄纳米粒子（L-Fe₃O₄纳米粒子）的生成机制,将该材料作为载体吸附金种后探讨其在催化对硝基苯酚方面的应用。结果表明：沉降22 h时,调节pH值为7.0制备的Fe₃O₄纳米粒子的沉降高度大约是L-Fe₃O₄纳米粒子的6.5倍;吸附金种后的L-Fe₃O₄纳米粒子催化效率大约是未改性Fe₃O₄纳米粒子的5倍。L-半胱氨酸有效的改善了Fe₃O₄纳米粒子与分散介质之间的相容性,保护并改善了纳米粒子的分散稳定性,在污水处理等方面有潜在的应用。     

介孔Co3O4多面体的制备及电化学性能

通过水热处理Co(NO₃)₂与(NH₄)₂S₂O₈合成了CoOOH多面体, 再经高温煅烧得到具有介孔结构的Co₃O₄多面体; 利用扫描电子显微镜(SEM)、 透射电子显微镜(TEM)、 X射线衍射(XRD)和N2吸附\|脱附实验等手段对其结构和组成进行了表征; 研究了反应时间、 反应温度及(NH₄)₂S₂O₈浓度等因素对CoOOH多面体形貌的影响, 分析了CoOOH多面体的形成机理. 性能测试结果表明, 该介孔Co₃O₄多面体具有良好的葡萄糖电化学检测活性, 检测线性范围为0.05~1.8 mmol/L, 响应灵敏度为148 μA·cm^-2·mmol·L^-1, 检出限为1 μmol/L.     

Synthesis of Holey Graphitic Carbon Nitride with Highly Enhanced Photocatalytic Reduction Activity via Melamine-cyanuric Acid Precursor Route

In this work, holey graphitic carbon nitride(HCN) was prepared by one-step thermal polymerization of hydrothermal product of melamine and then loaded with Ni/MoO₂(NiMo) cocatalyst obtained by NaBH₄ reduction process. The obtained material was used for photocatalytic production of H₂ from water reduction and H₂O₂ production from O₂ reduction. The best photocatalyst(1% NiMo/HCN) exhibited a H₂ evolution rate of 8.08 μmol/h while no H₂ was detected over 1% NiMo-modifed bulk g-C₃N₄(BCN) under visible light illumination. Moreover, this rate is 1.7 times higher than that of 1% Pt-modified HCN. The 1% NiMo/HCN catalyst also exhibited the highest H₂O₂ production activity with a value of 6.13 μmol/h. Such enhancement was ascribed to the efficient charge carrier separation and migration, which were promoted by the large specific surface area and pore volume of HCN and the synergy between MoO₂ and Ni. The proposed method to obtain HCN is expected to open up new ways in development of highly-active HCN-based photocatalysts for photocatalytic reduction reactions.     

Detection of dopamine using self-assembled diazoresin/single-walled carbon nanotube modified electrodes

Ultrathin films of diazoresin(DR)/single-walled carbon nanotube(SWNT) were fabricated on thioglycollic acid(TGA) decorated gold(Au) electrodes by the self-assembly method combined with the photocrosslinlcing technique.The electrochemical behavior of dopamine(DA) at the DR/SWNT modified electrodes was studied using the cyclic voltammetry(CV) and differential pulse voltammetry(DPV) methods.Under the optimal conditions,a linear CV response to DA concentration from 1 μmol/L to 40 μmol/L was observed,and the detection limit of DA was 2.1 ×10~(-3) μmol/L via the DPV method in the presence of 10 μmol/L of uric acid(UA) or 2.5 × 10~(-3) μmol/L via the DPV method in the presence of10 μmol/L of ascorbic acid(AA).Moreover,the modified electrodes exhibited good reproducibility and sensitivity,demonstrating its feasibility for analytical purposes.     

热退火气氛对溶液法制备的Sb2S3薄膜组成、结构及光伏性能的影响

采用化学浴(CBD)法在TiO₂薄膜表面制备结晶性Sb₂S₃膜层, 获得了TiO₂/Sb₂S₃平板异质结, 并结合聚[2,6-{4,4-双-(2-乙基己基)-4H-环戊并[2,1-b;3,4-b']-二噻吩}-交替-4,7-(2,1,3-苯并噻二唑)](PCPDTBT)空穴传输层和MoO₃电极界面修饰层, 制备了FTO/TiO₂/Sb₂S₃/PCPDTBT/MoO₃/Au平板结构太阳能电池, 研究了CBD方法中热退火气氛对Sb₂S₃薄膜的组成、 结构及光伏性能的影响. 结果表明, 在N₂气氛下退火时, 所得的Sb₂S₃膜层不致密且含有Sb₂O₃杂相, 电池效率仅为0.90%; 而在N₂-S气氛下退火时, 硫会与杂相Sb₂O₃发生反应生成Sb₂S₃, 进而得到纯净、 致密、 平整的结晶Sb₂S₃膜层. 在平板结构太阳能电池中, 光生空穴对电池光电流的产生有明显的贡献; 随着Sb₂O₃杂相的消除, Sb₂S₃薄膜中载流子的复合减少且传输速率增大, 使太阳能电池器件中电子与空穴的收集效率和短路电流显著提高, 电池效率提高了1.34倍, 达到2.04%.