金纳米颗粒增强一次性使用葡萄糖传感器的响应性能

为了提高一次性使用葡萄糖传感器响应灵敏度,降低工作电压,研究了加入金纳米颗粒的一次性使用电化学葡萄糖传感器的响应性能。采用水溶性高分子材料聚丙烯酰胺包埋葡萄糖氧化酶(GOD)制备酶电极,研究了聚丙烯酰胺溶液浓度、纳米颗粒加入以及加入量等对电极响应的影响。结果表明引入纳米粒子可显著增强葡萄糖传感器的响应灵敏度,明显缩短传感器的响应时间(<20s),降低传感器的工作电压(<0.4V)。     

铜表面硬脂酸自组装膜的制备及耐腐蚀性能

应用自组装技术在Cu(OH)2纳米柱/CuO微花阶层结构表面制备硬脂酸自组装膜(SAM),运用电化学阻抗谱探讨了形成自组装膜的较佳浓度和自组装时间,通过极化曲线和循环伏安法考察了硬脂酸自组装膜在0.1 mol/L NaCl溶液中对铜电极的缓蚀性能.结果表明,当CuO/Cu(OH)2电极在8 mmol/L硬脂酸溶液中自组...     

MOFs仿生酶传感器构筑及对肌氨酸的高灵敏检测

目的：构筑NH₂-MIL88B(Fe)/核黄素(NM88B/Rf)作为级联纳米酶用于超灵敏的电化学方法检测肌氨酸(Sar)。方法：选择具有类过氧化物酶活性的NM88B作为载体,通过电沉积与Rf建立完整的双纳米酶体系,Rf可将Sar催化为H₂O₂,NM88B进一步将生成的H2O2转化为·OH。该体系通过缩短双酶间催化间距,提升Rf的催化Sar能力,同时利用酶级联策略实现信号放大,甲基蓝(MB)捕获·OH出现明显电信号变化,显著提高Sar检测灵敏度。结果：该电化学传感器可在1 nmol/L～10 mmol/L范围内实现Sar的高灵敏度定量检测,检出限为0.43 nmol/L,比其他生物传感器低3个数量级。     

In2O3/CdS复合物的制备及光催化性能

以氧化铟(In_2O_3)纳米球作为基体,采用水热法制备了氧化铟/硫化镉(In_2O_3/CdS)复合光催化剂,并利用XRD、SEM等对所制备复合光催化剂进行了表征。结果表明:复合光催化剂由立方相的In_2O_3纳米球和六方相CdS棒状结构组成,且In_2O_3纳米球附着于CdS棒状结构表面上。光学性能测试和光降解实验发现:所得复合光催化剂与纯In_2O_3和纯CdS相比,不仅光响应范围增加,而且光催化亚甲基蓝(MB)的活性也得到显著改善。当In_2O_3/CdS中n(In_2O_3)∶n(CdS)=1∶4时,光催化效率改善尤为明显,当复合催化剂的质量为0.05 g时,MB转化率达到96.2%;这可能是由于CdS接受In_2O_3表面上的光生电子,减少了光生电子与空穴的复合机会,因而提高了光催化降解能力。     

CoO/CdS纳米复合材料的制备及其光催化降解亚甲基蓝的研究

采用物理气相沉积法制备CoO/CdS纳米复合材料,通过扫描电子显微镜(SEM)、X射线衍射仪(XRD)、X射线能谱仪(E DS)和紫外-可见分光光度计(UV-Vis)对其形貌、结构和光吸收性质进行表征,并以亚甲基蓝溶液的光催化降解为探针反应,在可见光下考察CoO/CdS纳米复合材料的光催化性能.结果表明,CoO/CdS纳米复合材料的光催化活性显著高于CdS纳米颗粒,100 min后亚甲基蓝降解率达到92.4％.     

新型CdS/CNTs光催化材料的制备及性能研究

以硝酸镉和硫代乙酰胺为原料,在经浓硝酸处理过的碳纳米管(CNTs)表面原位生成硫化镉(CdS)纳米颗粒,制备了CdS/CNTs光催化剂。在可见光条件下比较了CdS/CNTs样品与简单混合的CdS-CNTs样品以及纯的CdS样品的光催化性能,讨论了CNTs对CdS光催化性能的增强机理。结果表明,CdS/CNTs样品对甲基橙的光催化降解性能与简单混合的CdS-CNTs样品以及纯的CdS样品相比有显著增强,说明CNTs在CdS/CNTs样品中起到了分离电子-空穴对的作用。     

光照纳米银颗粒对葡萄糖生物传感器响应电流的抑制

采用纳米银-壳聚糖复合膜固定葡萄糖氧化酶,构建葡萄糖生物传感器.利用计时电流法对不同光照时间纳米银颗粒组装的酶电极响应电流进行了表征.实验结果表明,光照纳米银颗粒可以抑制葡萄糖生物传感器的响应电流;随着光照时间的延长,纳米银颗粒的抑制作用逐渐增强,当光照时间达到120min时,葡萄糖生物传感器的响应电流最小(-3.953μA/cm2).葡萄糖生物传感器响应电流的抑制可能是由纳米银颗粒表面的Ag+离子浓度及表面性能的变化引起的.     

电化学分析方法用于面膜中氯霉素现场快速检测

开发一种基于金纳米颗粒的便携式电化学传感器用于面膜中氯霉素现场快速分析。以电沉积的方式，采用沉积电位-0.6 V、沉积时间20 s，在便携式、可抛弃的丝网印刷电极表面沉积金纳米颗粒。结果显示，构建的负载金纳米颗粒的电化学传感器对氯霉素的电催化性能明显高于裸电极。实验考察了电解质溶液的pH，在较优条件下对不同浓度的氯霉素进行测定。结果显示，氯霉素浓度在0.02～0.5 mmol/L范围时，峰电流响应与氯霉素的浓度呈线性关系，方法的检出限为0.005 mmol/L。为了进一步评价方法的可行性，以市售面膜为实际样品进行添加回收实验。结果显示，三个添加水平下，氯霉素的添加回收率为106.01%～110.59%，相对标准偏差不大于3.66%(n=3)。结合手持式电化学工作站的无线蓝牙数据传输功能，可将现场检测结果实时传输至用户手机客户端，为面膜中氯霉素的现场快速筛查提供新的研究思路。     

还原敏感胱氨酸二甲酯交联PMAA纳米水凝胶的制备

以N,N'-双(甲基丙烯酰)胱氨酸二甲酯为交联剂,采用蒸馏沉淀聚合法制备了还原敏感聚甲基丙烯酸(PMAA)纳米水凝胶。使用红外光谱仪、激光粒度仪、扫描电子显微镜对纳米水凝胶的组成、粒径及形貌进行了表征,考察了交联剂用量、单体用量、引发剂用量以及反应时间对纳米水凝胶粒径及产率的影响,结果表明,通过改变制备条件可以得到不同尺寸的纳米水凝胶,其中交联剂用量及反应时间对微球粒径的影响最显著,并通过正交实验优化出最佳工艺条件,即n(引发剂)∶n(单体)∶n(交联剂)=1.1∶96∶2.9,反应时间为15 min。此外,该纳米水凝胶在10 mmol/L二硫苏糖醇(DTT)还原性条件下能够在20 min内快速响应降解,展示出良好的还原敏感性能。     

COF/CdS复合材料的制备及其可见光催化性能研究

为开发可见光响应型共价有机框架(COF)材料,以COF材料为基底构筑异质结催化剂,达到高效利用太阳能进行催化降解有机染物。首先以三醛基间苯三酚和2,5-二氨基-1,4-苯二硫酚为构筑单体,制备一种巯基功能化COF(HS-COF)作为基底材料,并利用巯基锚定Cd²⁺,然后以硫脲为硫源,通过原位生长法,实现在基底HS-COF表面原位生长CdS纳米颗粒,并利用透射电子显微镜、傅里叶红外光谱、X-射线衍射以及X-射线光电子能谱对所制备的复合材料(COF/CdS)表面的微观形貌进行表征。实验以罗丹明B(RhB)为模型污染物,在可见光照射条件下考察COF/CdS复合材料的光催化降解性能。结果表明,CdS纳米颗粒成功固载在基底COF材料表面,其对RhB降解率高达92.5%,反应速率常数为0.014 5 min^-1,与单相COF材料、CdS纳米颗粒及物理混合COF/CdS相比,其表现出更强的可见光催化性能,这表明COF/CdS具有优异的光催化活性。此外,该异质结催化剂具有良好的稳定性,经5次循环使用后对RhB降解率仍在75%以上。     

Effects of polymerization potential on the permselectivity of poly(o-phenylenediamine) coatings deposited on Pt-Ir electrodes for biosensor applications

In attempts to improve the permselectivity of poly-o-phenylenediamine (PoPD) for biosensor applications, we investigated the influence of applied electropolymerization potential on the permeability properties of the non-conducting, non-ionic form of PoPD deposited on Pt-Ir wire electrodes in neutral media, using fixed potential amperometry and cyclic voltammetry. The analytes chosen were hydrogen peroxide (the signal transduction molecule in many oxidase-based biosensors) and ascorbic acid (AA, the archetypal interference species in biological applications of biosensors). The permselectivity (S%) of Pt/PoPD, expressed as the percentage interference by AA in hydrogen peroxide calibrations carried out at +0.7 V versus SCE, showed three distinct ranges: very poor (∼70%) for mild anodic applied polymerization potentials (<200 mV), indicating little or no PoPD coating formed on the electrode surface; moderate (∼2%) when the PoPD was generated using intermediate potentials (250-300 mV); and excellent (<0.3%) for polymerization potentials >400 mV. There was also a trend in this last S% range for further improvement with increasing polymerization potential, which reached an optimum value of 0.10 ± 0.02% (n = 19 sensors) when the PoPD electrodeposition was carried out at 700 mV versus SCE. This enhancement in S% was due to a surprising combination of increases in permeability for hydrogen peroxide and decreases in AA permeability for the higher values of applied polymerization potential. In addition, the data indicate that, for the conditions used here, electropolymerization at the fixed applied potential of 0.7 V was superior to CV in terms of permselectivity for hydrogen peroxide detection by PoPD-modified electrodes in media containing AA.     

Continuous glucose monitoring using enzyme-immobilized platinized diamond microfiber electrodes

A sensitive and stable glucose biosensor for in vivo monitoring has been developed using boron-doped diamond microfiber (BDDMF) electrodes. The electrodes were modified with platinum nano-particles to detect H₂O₂, which was enzymatically produced by glucose oxidase (GOx) immobilized on the electrode surface. The platinum-modified BDDMF (Pt-BDDMF) electrodes exhibited much higher sensitivity compared to Pt-microfiber electrodes, Pt electrodes and Pt-modified diamond thin film electrodes. Deposition conditions for Pt nano-particles on the BDDMF electrodes and immobilization of GOx were optimized. GOx/overoxidized polypyrrole (OPPy)/Pt-modified BDDMF electrodes were applied for continuous interference-free glucose monitoring. Amperometric measurements of glucose showed a linear response in the range of 1-70 mM, with an R.S.D. of 3.7% for five injections of 100 μM glucose. The electrodes exhibited good stability over 3 months with no detected anodic current for ascorbic acid (AA), which is an interfering compound.     

Prussian Blue-modified microelectrodes for selective transduction in enzyme-based amperometric microbiosensors for in vivo neurochemical monitoring

Prussian Blue-modified carbon fiber microelectrodes (CFE/PBs) are proposed as an alternative to the more conventional metal transducers used for H₂O₂-detecting biosensors in brain extracellular fluid (ECF). The main advantages of this approach are the very small dimensions (∼10 μm diameter) and the low applied potentials needed (0.0 V versus SCE). Electrocatalytic and physiochemical properties of PB deposits were studied using cyclic voltammetric (CV), amperometric and spectroscopic methods (FTIR and VIS). Optimized CFE/PB microsensors displayed a H₂O₂ current density of 1.00 ± 0.04 A M⁻¹ cm⁻² with a detection limit of 10⁻⁸ M. Furthermore, to improve stability and selectivity properties, several polymeric films were investigated: Nafion, poly(o-phenylenediamine) (PoPD), and a hybrid configuration of these two polymers. Finally, the PoPD film was selected due to its excellent anti-interference properties. The use of this permselective film also enhanced the stability of PB against solubilization at high pH, albeit at the expense of slightly lower H₂O₂ sensitivity (0.48 ± 0.02 A M⁻¹ cm⁻²) and higher detection limit (∼10⁻⁷ M). However, the use of the PoPD film significantly enhanced the selectivity against the main endogenous brain interference species (ascorbic acid, uric acid, dopamine and 3,4-dihydroxyphenylacetic acid), expressed as the ratio of the sensitivity slopes (SH₂O₂/Sinterference), which was close to 600 for all interference molecules studied. A prototype of a CFE/PB-based glucose microbiosensor design is presented, together with preliminary studies of its characteristics in vitro and its functionality in brain ECF in vivo.     

Amperometric biosensor based on 3D ordered freestanding porous Pt nanowire array electrode

A three-dimensionally (3D) ordered freestanding porous platinum (Pt) nanowire array electrode (PPNWAE) with pores of several nanometers in size and a Pt nanowire array electrode (PNWAE) without pores were facilely fabricated by metal electrodeposition and direct integration with a Pt disk electrode. The unusual PPNWAE with high active area showed excellent sensitivity (0.36 mA cm(-2) mM(-1)) and a wide detection range (4.5 μM-27.1 mM) to hydrogen peroxide (H(2)O(2)). A glucose oxidase (GOD)-based biosensor (PPNWAE/GOD) with a considerably wide detection range (4.5 μM-189.5 mM) to glucose was demonstrated. Furthermore, a lower detection limit, higher sensitivity and smaller value of Michaelis-Menten constant k(m) were recorded for PPNWAE-based biosensors compared with PNWAE-based biosensors. Particularly, the response current to glucose of PPNWAE/GOD was ca. 100% higher than that of PNWAE/GOD and the response current to H(2)O(2) of PPNWAE was ca. 50% higher than that of PNWAE, owing to the granular and rougher porous nanowire surface enabling greater bioactivity for GOD. The selectivity of PPNWAE/GOD glucose biosensor was also estimated.     

The Effect of High and Variable Glucose on the Viability of Endothelial Cells Co-Cultured with Smooth Muscle Cells

Diabetes mellitus causes endothelial dysfunction. The aim of this study was to investigate the effect of normal (5 mmol/L), high (20 mmol/L), and fluctuating (5 and 20 mmol/L changed every day) glucose concentration in the culture medium on the viability of human umbilical vein endothelial cells (HUVECs) co-cultured with human umbilical artery smooth muscle cells (HUASMCs). The cultures were conducted on semi-permeable flat polysulfone (PSU) fibronectin-coated membranes immobilized in self-made inserts. The insert contained either HUVECs on a single membrane or HUASMCs and HUVECs on two membranes close to each other. Cultures were conducted for 7 or 14 days. Apoptosis, mitochondrial potential, and the production of reactive oxygen species and lactate by HUVECs were investigated. The results indicate that fluctuations in glucose concentration have a stronger negative effect on HUVECs viability than constant high glucose concentration. High and fluctuating glucose concentrations slow down cell proliferation compared to the culture carried out in the medium with normal glucose concentration. In conclusion, HUASMCs affect the viability of HUVECs when both types of cells are co-cultured in medium with normal or variable glucose concentration.     

解偶联蛋白-2在软脂酸诱导的HepG2细胞胰岛素抵抗中的作用及其与核转录因子-κB的关系

目的探讨解偶联蛋白-2(Uncoupling protein-2,UCP-2)在软脂酸诱导的HepG2细胞胰岛素抵抗(Insulin-resistance,IR)中的作用及其与核转录因子-κB(Nuclearfactor-κB,NF-κB)的关系。方法将HepG2细胞分为正常对照组、软脂酸组(加0.25mmol/L软脂酸)、高胰岛素组(加100nmol/L胰岛素)、软脂酸+京尼平组(加0.25mmol/L软脂酸和10μmol/L京尼平),培养24h后,再用100nmol/L胰岛素刺激,分别于12h后测定培养液中葡萄糖、MDA、SOD、ALT、AST、GGT、TG的浓度;油红O染色法观察细胞的脂变情况;流式细胞术检测线粒体膜电位改变;30min后采用半定量RT-PCR及Westernblot法检测细胞IRS-2、UCP-2及NF-κB的表达水平。结果胰岛素作用12h后,细胞培养液中葡萄糖含量软脂酸组与高胰岛素组比较,差异无统计学意义(P>0.05)。培养液中葡萄糖含量、ALT、AST、MDA、GGT、TG的含量及UCP-2和NF-κB的表达水平,软脂酸组均较正常对照组和软脂酸+京尼平组显著升高(P<0.05),软脂酸+京尼平组与正常对照组比较差异无统计学意义(P>0.05)。线粒体膜电位、SOD和IRS-2的水平,软脂酸组显著低于正常对照组和软脂酸+京尼平组(P<0.05),软脂酸+京尼平组与正常对照组比较差异无统计学意义(P>0.05)。结论 UCP-2在软脂酸诱导的肝脏胰岛素抵抗中起着重要作用,其机制可能与NF-κB有关。     

反胶束法制备纳米氧化锌及其在葡萄糖生物传感器中的应用

采用琥珀酸-2-乙基己基磺酸钠/环己烷反胶束体系制备纳米ZnO,并以此ZnO为载体固定葡萄糖氧化酶,用戊二醛交联制作成葡萄糖氧化酶电极. 实验结果表明,此酶电极表现出对葡萄糖溶液浓度的优良响应,线性范围在1′10-5~3′10-3 mol/L,响应灵敏度约为6 mA/(cm2×mmol/L),表观米氏常数为2.57 mmol/L. 还研究了温度和溶液pH值对电极电流响应的影响.     

Improvement of substrate-selectivity in enzyme-linked FIA-systems by differential measurement and ‘enzyme-array’

Flow injection systems with immobilized enzymes for the parallel determination of chemically similar substances such as xylose/glucose and L -leucine/L -isoleucine/L -valine are described. The determination of xylose and glucose was performed either by differential measurement or by an ‘enzyme-array’. Because of the different linear ranges of the calibration curves for xylose and glucose quantification was only possible when there was an excess of xylose (xylose 0·1–2·5 mmol dm^?3, glucose 0·001–0·1 mmol dm^?3). The parallel quantification of the branched-chain amino acids could be realized by an array arrangement using an FIA-system with several immobilized enzymes of slightly different selectivity. The total amount of branched-chain amino acids can be up to about 1·1 mmol dm^?3.     

Ni(OH)2 versus Ni/Al layered double hydroxides as matrices to immobilize glucose oxidase

Ni hydroxide and Ni/Al layered double hydroxide (LDH) were electrochemically deposited on Pt electrodes in the presence of glucose oxidase in the electrolytic solution, in order to verify if the performances of the two biosensors were dependent on the Ni content of the inorganic matrix used to entrap the enzyme. The comparative study was conducted by recording the current response due to the oxidation of H₂O₂, produced enzymatically after glucose additions, at +0.45 V versus SCE, pH 7.0 and T = 25 °C.A higher sensitivity and a narrower linearity range were observed for nickel hydroxide based biosensor (up to 5 mM against 15 mM exhibited when LDH was the immobilizing matrix). These results suggested that the amount of the enzyme entrapped on the electrode surface was higher when the matrix was Ni(OH)₂ and they were confirmed by EQCM measurements. On the contrary, the selectivity displayed by the two biosensors in the presence of interfering compounds, such as acetaminophen, citric, uric and ascorbic acids, was almost the same.     

碳水化合物反应元件结合蛋白对L02细胞糖脂代谢的影响

目的探讨碳水化合物反应元件结合蛋白(Carbohydrate response element binding protein,ChREBP)在高糖诱导肝细胞脂变中的作用。方法分别以18和25 mmol/L葡萄糖培养L02细胞,以11 mmol/L葡萄糖培养L02细胞作为对照,甘油三酯(TG)含量测定及油红O染色观察细胞脂变程度;免疫荧光观察细胞ChREBP的核转位情况;RT-PCR检测细胞肝型丙酮酸激酶(Liver pyruvate kinase,LPK)基因mRNA的表达水平,Western blot分析细胞脂肪酸合成酶(Fatty acid synthase,FAS)蛋白的表达水平。结果与对照组比较,高糖可使L02细胞内甘油三酯和脂滴含量增加,刺激ChREBP核转位,上调LPK基因mRNA和FAS蛋白的表达水平。结论葡萄糖可能通过其代谢产物经ChREBP-LPK-FAS途径诱导肝细胞脂肪变性。