Development of amperometric glucose biosensor through immobilizing enzyme in a Pt nanoparticles/mesoporous carbon matrix

Pt nanoparticles were deposited on mesoporous carbon material CMK-3. Glucose oxidase (GOx) was immobilized in the resulting Pt nanoparticles/mesoporous carbon (Pt/CMK-3) matrix, and then the mixture was cast on a glassy carbon electrode (GCE) using gelatin as a binder. The glucose biosensor exhibited excellent current response to glucose after cross-linking with glutaraldehyde. At 0.6V (vs. SCE) the response current was linear to glucose concentration in the range of 0.04-12.2mM. The response time (time for achieving 95% of the maximum current) was 15s and the detection limit (S/N=3) was 1 microM. The Michaelis-Menten constant (K(m)(app)) and the maximum current density (i(max)) were 10.8 mM and 908 microAcm(-2), respectively. The activation energy of the enzymatic reaction was estimated to be 22.54 kJ mol(-1). The biosensor showed good stability. It achieved the maximum response current at about 52 degrees C and retained 95.1% of its initial response current after being stored for 30 days. In addition, some fabrication and operation parameters for the biosensor were optimized in this work. The biosensor was used to monitor the glucose levels of serum samples after being covered with an extra Nafion film to improve its anti-interferent ability and satisfied results were obtained.     

碳螺旋纤维/MnO2复合材料的电化学性能

利用电泳沉积法(EPD)制备碳螺旋纤维基MnO_2@CMC复合材料,采用电子扫描电镜、拉曼光谱(Raman)、X射线光电子能谱(XPS)对其形貌和结构进行表征并测试其电容性能,结果显示:当电位差扫描速率为5 m V·s-1时,充放电容量较高,可达115F·g-1,在0.2 A·g-1的扫描电流下,循环200圈后电容量为96.7 F·g-1,为起始电容量的89.5%,表现出良好的电容保持率和循环稳定性。     

Biotinylated alginate immobilization matrix in the construction of an amperometric biosensor: application for the determination of glucose

The use of biotinylated alginate as an immobilization matrix of enzymes on the surface of the amperometric transducer is described herein. The model used is that of the well-established glucose detection. Several types of immobilization protocols were tested. In the exception of one protocol, biotin labeled glucose oxidase was shown to first require conjugation with avidin, before its immobilization onto a biotin-alginate gel matrix. The response of the biosensors to incremental additions of glucose, was measured by potentiostating the modified electrodes at 0.6 V/SCE. The permeability of the modified electrodes was thereafter measured by using rotating disk electrode (RDE) voltammetry with ferrocenemonocarboxylic acid as the electroactive probe.     

MnO2 /聚苯胺复合材料的制备和性能

以δ-MnO₂为前驱体,通过酸处理后引入苯胺并聚合,得到了MnO₂ /聚苯胺复合材料。经XRD分析表明,在本研究条件下,经酸处理后的δ-MnO₂晶型由δ型转变为α型,而在随后的苯胺引入及其聚合步骤中MnO₂晶型均不再改变。以200 mA·g^-1的电流进行恒电流充放电性能测试,结果显示,MnO₂ /聚苯胺复合材料的充放电容量达到160.2 mA·g^-1,与     

NiO/MnO_2分级纳米片阵列复合材料的制备与超电容性能

通过化学浴沉积和水热法在泡沫镍上制备了NiO/MnO_2分级纳米片阵列复合材料,XRD和SEM测试表明NiO纳米片垂直生长在泡沫镍上,交叉形成网状阵列结构;MnO_2纳米介孔泡沫进一步生长在NiO纳米片两侧,与NiO形成了壳核式的复合结构。循环伏安和恒流充放电测试发现,NiO/MnO_2分级纳米片阵列复合材料的电化学性能相比复合前得到明显改善,在1 A·g~(-1)的电流密度下,比电容提高至1 297 F·g~(-1);2 A·g~(-1)下循环1 000次,比电容保持率高达97%,比电容和循环性能的改善是由于分级纳米片阵列复合结构方便了电解液传质,扩大了活性材料与电解液的接触,促进了赝电容反应,提高了NiO和MnO_2的结构稳定性。     

NiO/MnO2分级纳米片阵列复合材料的制备与超电容性能

通过化学浴沉积和水热法在泡沫镍上制备了NiO/MnO₂分级纳米片阵列复合材料,XRD和SEM测试表明NiO纳米片垂直生长在泡沫镍上,交叉形成网状阵列结构;MnO₂纳米介孔泡沫进一步生长在NiO纳米片两侧,与NiO形成了壳核式的复合结构。循环伏安和恒流充放电测试发现,NiO/MnO₂分级纳米片阵列复合材料的电化学性能相比复合前得到明显改善,在1 A·g^-1的电流密度下,比电容提高至1 297 F·g^-1;2 A·g^-1下循环1 000次,比电容保持率高达97%,比电容和循环性能的改善是由于分级纳米片阵列复合结构方便了电解液传质,扩大了活性材料与电解液的接触,促进了赝电容反应,提高了NiO和MnO₂的结构稳定性。     

含氧空位的氟掺杂二氧化锰助力稳定锌离子电池

将无机盐NH₄F加入到MnO₂的前驱体溶液中,通过高效、简单的一步水热法制备了具有氧缺陷的F掺杂α-MnO₂纳米棒(记为F-MnO₂)。氧空位和F掺杂对提高F-MnO₂的导电性、促进离子扩散、提高倍率性能起着至关重要的作用。另外,由于F掺杂,形成了F—Mn键,这可以有效地抑制放电产物中Mn³⁺的Jahn-Teller畸变,从而提高结构的稳定性。得益于这些协同效应,组装的Zn||F-MnO₂全电池在0.5 A·g^-1下,首圈放电比容量高达274 mAh·g^-1,且具有较长的循环寿命和优异的倍率性能。同时,通过循环伏安(CV)和恒流充放电(GCD)曲线证明了F-MnO₂的储能机制为H⁺和Zn²⁺的共嵌入/脱出过程。     

A novel nonenzymatic hydrogen peroxide sensor based on MnO2/graphene oxide nanocomposite

A new electrocatalyst, MnO₂/graphene oxide hybrid nanostructure was successfully synthesized for the nonenzymatic detection of H₂O₂. The morphological characterization was examined by scanning electron microscopy and transmission electron microscopy. The MnO₂/graphene oxide based electrodes showed high electrochemical activity for the detection of H₂O₂ in alkaline medium. The nonenzymatic biosensors displayed good performance along with low working potential, high sensitivity, low detection limit, and long-term stability, which could be attributed to the high surface area of graphene oxide providing for the deposition of MnO₂ nanoparticles. These results demonstrate that this new nanocomposite with the high surface area and electrocatalytic activity offers great promise for new class of nanostructured electrode for nonenzymatic biosensor and energy conversion applications.     

Size dependence of SiO2 particles enhanced glucose biosensor

A wide size range of SiO₂ particles were synthesized and were used as enzyme immobilization carriers to fabricate glucose biosensors. The size of the particles was in the range of 17-520 nm. These biosensors could be operated under physiological conditions (0.1 M phosphate buffer, pH 7.2). Particle size could affect the performance of SiO₂ modified glucose biosensors drastically. The smaller particles had higher performance. The smallest SiO₂ modified biosensor could work well in the glucose concentration range of 0.02-10 mM with a correlation coefficient of 0.9993. Its sensitivity was 2.08 μA/mM and the detection limit was 1.5 μM glucose.     

空心海胆状二氧化锰的制备及其在超级电容器中的应用

采用简单的一步水热法制备了空心海胆状二氧化锰,无需任何模板剂和表面活性剂。该材料具有3D的纳米结构,结构稳定,并由单个的二氧化锰空心管自组装而成。该纳米材料的特殊结构为其提供了高的比电容。在1mol·L-1硫酸钠电解液中,扫速为1mV·s-1的条件下,该材料的比电容值为254.6F·g-1。在电流密度为1.0A·g-1的条件下,充放电循环1000次后比电容值仍保持为初始值的97.5%。表明该材料具有良好的电容性能和稳定性,其具备用作高性能超级电容器的电极材料的潜能。     

MnO_2/NiCo_2O_4的静电自组装合成及其电化学性能

通过带负电荷的MnO2纳米片与带正电荷的Co-Ni层状双氢氧化物(LDHs)纳米片的静电自组装外加后续热处理合成了异质层状结构的MnO2/NiCo2O4复合物.采用X射线衍射(XRD)、傅里叶变换红外(FTIR)光谱、拉曼光谱、原子吸收光谱(AAS)、场发射扫描电镜(FESEM)和透射电子显微镜(TEM)对其结构和形貌进行了表征.用循环伏安(CV)、恒流充放电和电化学交流阻抗技术对其电化学性能进行了测试.研究结果表明,该方法制得的异质复合物具有多孔层状堆垛结构,这种特殊的结构不仅增大了电解液离子的接触面积,而且还为其嵌入-脱出提供了有效途径.该复合物在1 A·g-1电流密度时,-0.6-0.45 V电位窗口内的比电容达482 F·g-1,优于纯组分MnO2和NiCo2O4的电容性能.     

Immobilization of glucose oxidase on rod-like and vesicle-like mesoporous silica for enhancing current responses of glucose biosensors

The use of rod-like and vesicle-like mesoporous SiO₂ particles for fabricating high performance glucose biosensors is reported. The distinctively high surface areas of mesoporous structures of SiO₂ rendered the adsorption of glucose oxidase (GOx) feasible. Both morphologies of SiO₂ enhanced the sensitivities of glucose biosensors, but by a factor of 36 for vesicle-like SiO₂ and 18 for rod-like SiO₂, respectively. The greater enhancement of vesicle-like SiO₂ can be accounted for by its higher specific surface area (509 m² g⁻¹) and larger total pore volume (1.49 cm³ g⁻¹). Interestingly, the current responses of GOx immobilized in interior channels of the mesoporous SiO₂ were enhanced much more than those of simple mixtures of GOx and the mesoporous SiO₂. This suggests that the enhancement of current responses arise not only from the high surface area of SiO₂ for high enzyme loading, but also from the improved enzyme activity upon its adsorption on mesoporous SiO₂. Also compared were the performances of glucose biosensors with GOx immobilized on mesoporous SiO₂ by physical adsorption and by covalent binding to 3-aminopropyltrimethoxysilane (APTMS) modified SiO₂ using glutaraldehyde as the cross-linker. The covalent binding approach resulted in higher enzyme loading but lower current sensitivity than with the physical adsorption.     

CoTiO3纳米粉体的合成及其对MnO2电极材料的改性作用

采用溶胶-凝胶法制得钙钛矿型CoTiO₃纳米粉体，借助XRD、TEM以及循环伏安测试对其性质进行了表征。不同量的所制样品用于MnO₂电极的物理掺杂，进行了深度恒流放电、循环伏安和充放电测试。结果表明在40%KOH电解质溶液中，样品掺杂量为5%时改性效果较好。纳米CoTiO₃参与了电极反应，抑制了电化学惰性物质Mn₃O₄的生成，从而有效地改善MnO₂的放电性能，放电容量较I.C     

Ascorbic acid sensor based on ion-sensitive field-effect transistor modified with MnO2 nanoparticles

An ascorbic acid (AA) sensor based on an ion-sensitive field-effect transistor (ISFET) was prepared by modifying the sensitive area of the transducer with MnO₂ nanoparticles. An additional Nafion membrane coated on top of the sensor was used to immobilize the MnO₂ nanoparticles and restrict the amount of ascorbic acid entering the membrane. The reaction of the MnO₂ nanoparticles with ascorbic acid produced a local pH change, which was correlated with the ascorbic acid concentration and could be monitored by the ISFET. The linear range of the ascorbic acid sensor was 0.02-1.27 mM, and the detection limit was 0.01 mM. The effects of buffer concentration, pH, and ionic strength on the sensor performance were also examined. In addition, the sensor has good stability and reproducibility, and the construction and renewal of the sensor are simple and inexpensive.     

空心海胆状二氧化锰的制备及其在超级电容器中的应用

采用简单的一步水热法制备了空心海胆状二氧化锰,无需任何模板剂和表面活性剂。该材料具有3D的纳米结构,结构稳定,并由单个的二氧化锰空心管自组装而成。该纳米材料的特殊结构为其提供了高的比电容。在1mol·L^-1硫酸钠电解液中,扫速为1mV·s^-1的条件下,该材料的比电容值为254.6F·g^-1。在电流密度为1.0A·g^-1的条件下,充放电循环1000次后比电容值仍保持为初始值的97.5%。表明该材料具有良好的电容性能和稳定性,其具备用作高性能超级电容器的电极材料的潜能。     

Magtrieve™ (CrO2) and MnO2 mediated oxidation of aldoximes: studying the reaction course

Magtrieve™ (CrO₂) and MnO₂ mediated oxidation of aldoximes to nitrile oxides were studied in details. In presence of external radical source, TEMPO, these reagents did not furnish nitrile oxides, instead favoured deoximation to aldehydes. A common trend of deoximation was established from electronically tuned aldoximes, which is: aliphatic>aromatic>aldoximes with strong electron-withdrawing group, though the extent of deoximation was less in case of CrO₂. Above effects were not observed with chloramine-T and diacetoxyiodobenzene, reagents known to produce nitrile oxides via hydroximoyl halide or equivalent ionic intermediates. A putative reaction mechanism is proposed for MO₂ (M=Cr, Mn) mediated oxidation of aldoximes through formation of a nitroso-oxime tautomeric pair. Formation of nitrile oxide is possibly occurred from the oxime tautomer via a σ-type iminoxy radical intermediate. The deoximation process, dominating in presence of external radical environment, is explained following decomposition of the nitroso tautomer.     

新生态二氧化锰的性质及pH值影响除砷效果的研究

Fresh MnO₂ was prepared by oxide reduction using KMnO₄ and MnSO₄. The structure and property of the products were characterized by TEM, SEM, XRD and BET, and the effect of pH value was studied on the removal of both As(Ⅴ) and As(Ⅲ). The results show that δ-MnO₂ is spherical, its specific surface is 325 m²·g^-1 with lots of hydroxyl on the surface. Adsorption of fresh MnO₂ of As(Ⅲ) was a corporate action of both oxide reaction and electrostatic adsorption, but the adsorption of As(Ⅴ) was due to electrostatic and anion exchange adsorption.     

Ordered mesoporous polyaniline film as a new matrix for enzyme immobilization and biosensor construction

Ordered mesoporous polyaniline film has been fabricated by electrodepositing from the hexagonal lyotropic liquid crystalline (LCC). Horseradish peroxidase (HRP), as a symbol biomolecule, was successfully immobilized on the film to construct a new kind of hydrogen peroxide biosensor. The biosensor combined the advantages of the good conductivity of polyaniline and the higher surface area of the ordered mesoporous film. Polyaniline could be served as a wire to relay electron between HRP and the electrode. The high surface area of the film supplied more sites for HRP immobilization, therefore increased the catalytic activity of the biosensor. The ordered mesoporous character of the film increased the rate of mass transport, which resulted in the improvement of sensor response and linearity. The biosensor displayed excellent electrocatalytic response to the detection of H₂O₂ in a concentration range from 1.0 μM to 2.0 mM with a detection limit of 0.63 μM. Good reproducibility, stability, high precision, wide linearity and low detection limit were assessed for the biosensor.     

N掺杂MnO2/碳布复合材料的制备及储锂性能

采用碳布（CC）为柔性基底,通过水热法制备了MnO₂/CC及N掺杂MnO₂/CC无黏结剂负极材料,借助X射线衍射（XRD）、扫描电镜（SEM）、X射线光电子能谱（XPS）、比表面积测试和恒电流充放电对材料进行了结构表征及电化学性能测试。结果表明N掺杂MnO₂/CC具有良好的倍率性能和循环稳定性。在0.1 A·g^-1的电流密度下,其首次充电比容量为948.8 mAh·g^-1,经过不同倍率测试后电流密度恢复至0.1 A·g^-1时仍然保持有907.9 mAh·g^-1的可逆比容量,容量保持率为95.7%。在1 A·g^-1的大电流密度下,其首次充电比容量为640.3 mAh·g^-1,循环100次后仍然保持有529.9 mAh·g^-1的可逆比容量,容量保持率为82.8%,可逆比容量远高于商用MnO₂。     

Amperometric glucose biosensor based on a gold nanorods/cellulose acetate composite film as immobilization matrix

We report on the utilization of gold nanorods to create a highly responsive glucose biosensor. The feasibility of an amperometric glucose biosensor based on immobilization of glucose oxidase (GOx) in gold nanorod is investigated. GOx is simply mixed with gold nanorods and cross-linked with a cellulose acetate (CA) medium by glutaraldehyde. The adsorption of GOx on the gold nanorods is confirmed by X-ray photoelectron spectroscopy (XPS) measurements. Circular dichroism (CD) and UV-spectrum results show that the activity of GOx was preserved after conjugating with gold nanorods. The current response of modified electrode is 10 times higher than that of without gold nanorods. Under optimal conditions, the biosensor shows high sensitivity (8.4 μA cm⁻² mM⁻¹), low detection limit (2 × 10⁻⁵ M), good storage stability and high affinity to glucose (). A linear calibration plot is obtained in the wide concentration range from 3 × 10⁻⁵ to 2.2 × 10⁻³ M.