超宽范围的电化学酶生物传感器与检测技术

目前，发酵工业因缺少高效在线检测手段，生产过程中不能及时跟踪底物或产物浓度变化，导致发酵效率低，污染排放严重。电化学酶生物传感器能够实现对生化反应中特定组分浓度的快速精确检测，已广泛应用于医疗行业。然而，该传感器检测范围过窄，在真实发酵体系中，需预先对样品进行稀释处理，仅能实现离线检测。为此，提出一种超宽范围的新型电化学酶生物传感器及检测方法。传感器采用三电极丝网印刷结构，工作电极为自制的规则普鲁士蓝纳米颗粒传感膜及生物酶，检测采用流动注射分析技术。测试表明，该传感器及检测系统对葡萄糖浓度的检测范围为0.5-120g/L，测量误差在2 %以内，测量周期< 60秒，完全满足发酵工业在线检测要求。     

硫醇自组装多晶金表面AFM图像的分形研究

本文针对多晶粗糙电极表面自组装膜（SAM）体系,提出了利用原子力显微镜（AFM）相图分形维数进行表征的新方法。首先对自组装多晶金电极进行了交流阻抗测试,结果表明随着乙醇自组装液中十二烷基硫醇（C12SH）浓度增大,自组装膜中缺陷面积减少,趋向于形成完整致密的单分子层吸附膜。而对组装电极AFM图像的分形研究表明,在不同C12SH浓度条件下,电极表面高度图分形维数无明显变化,相图却呈现不同的分形特征,且体现的变化规律与交流阻抗测试结果一致,证实了AFM相图分形维数表征法研究粗糙金表面硫醇自组装膜吸附行为的可行性,为粗糙表面分子吸附行为的AFM研究提供了新思路。     

铂黑/二茂铁修饰MEMS电极的葡萄糖传感器

利用MEMS技术小批量加工了薄膜金电极。采用电化学沉积法在金电极表面修饰纳米铂黑颗粒,以有机功能性材料二茂铁作为电子媒介体,通过戊二醛-牛血清白蛋白共价交联固定葡萄糖氧化酶制得葡萄糖生物传感器。考察了不同修饰电极的电化学行为以及酶固定量和戊二醛浓度对传感器响应特性的影响。实验结果表明:该传感器响应时间仅为5s,在0.29V的低工作电压下,线性测量范围可达到0.5～22mmol/L,灵敏度为50.35μA/(cm2.mmol.L-1),相关系数为0.9925,差异系数为4.28%。     

纳米金表面修饰提高压电免疫传感器性能研究

在石英晶体微天平的金电极上通过1,6-己二硫醇交联组装纳米金颗粒修饰传感器表面,同时结合蛋白A与抗体的Fc段特异性结合的特性定向固定人IgG构建压电免疫传感器,并用于羊抗人IgG的检测.实验结果表明,与未经修饰相比,纳米金颗粒组装修饰金电极后能明显提高压电免疫传感器的检测灵敏度、重现性和再生能力等重要性能指标,修饰后的传感器也具有非常好的在线再生性能.     

基于铂黑的微针电极阵列表面修饰方法

由于微针电极阵列尖端直径小,空间分辨率高,可以记录单个神经元的放电活动,已成为神经信号记录的首选.但商用微针电极阵列的阻抗较高,降低电极阻抗有利于提高信噪比,改善记录信号质量.采用超声电镀铂黑的方法对微针电极表面进行修饰.测试结果表明铂黑修饰后的微针电极电化学性能优异,1 kHz处阻抗约为2.5 kΩ,相比裸金电极降低...     

Hybrid Circuit Technology 91年7—12期文摘

用于厚膜精确印制工艺的新技术，在焊膏制造和使用中采用“统计过程控制”技术，丝网印制技术的自动化应用研究，大功率塑封多芯片组件的热性能，表面组装应用的微型混合电路基片焊膏滴注工艺研究，厚膜混合电路生产中的丝网印制技术，聚集红外返修系统提高灵活，选择正确的照明和移动控制系统。     

蒽基磷酸衍生物自组装膜修饰的有机薄膜晶体管

本工作主要介绍一种利用新型磷酸衍生物作为分子自组装膜来修饰二氧化硅介电层,从而提升有机薄膜晶体管性能的方法。将红荧烯真空蒸镀到这种分子自组装膜修饰的基片表面制备的晶体管其空穴迁移率为0.18cm2/Vs , 比裸二氧化硅作介电层的晶体管性能有10多倍的性能提升。研究表面这种磷酸衍生物自组装膜在促进红荧烯蒸镀成膜方面有特殊作用,可以诱导其形成有序结晶膜,从而提高晶体管整体性能。     

掺杂2,7-蒽醌二磺酸钠/聚吡咯修饰电极的合成及稳定性能的研究

本实验通过电化学方法使掺杂2,7-蒽醌二磺酸钠/聚吡咯膜附着在电极表面形成修饰电极。通过对比所制备的修饰电极和裸GC电极在不同pH值中的循环伏安图,研究其氧还原的催化性能。以及在氧饱和条件下不同pH值下,扫描90圈后的稳定性做出考察。     

薄膜绝缘层对陶瓷厚膜电致发光显示器件的影响

采用丝网印刷技术，在Al2O3陶瓷板上印刷、高温烧结内电极及绝缘层制备出陶瓷厚膜基板，进而制备了新型厚膜电致发光显示器（TDEL），整个器件结构为陶瓷基板／内电极／厚膜绝缘层／发光层／薄膜绝缘层／ITO透明电极。对用不同薄膜绝缘材料制备的显示器件的特性进行测试、比较、分析，结果表明薄膜绝缘介质层对器件的阈值电压、发光亮度均有一定的影响，以复合绝缘层的性能最优。最后对器件的衰减特性进行了初步分析。     

节约丝网印刷电容器贵金属电极的探讨

丝网印刷电极早已成为被广泛采用的电子元件制作工艺之一.在许多情况下,由于工艺过程的需要,电极材料必须采用贵金属,如银、金、钯、铂等.就我厂而言,仅用于电容器的电极,白银的使用量即以吨计.根据理论分析和实践的结果表明,大幅度减少丝网印刷贵金属的使用量是可能的,对电容器的产品质量也是有益的. 一、电容器电极的极限方阻和极限膜厚电容器电极的平面电阻为: R=ρ(l/(bδ)) (1) 式中:l为电容器电极膜电阻的长度;b为电容器电极     

Nitridation and Layered Assembly of Hollow TiO2 Shells for Electrochemical Energy Storage

The nitridation of hollow TiO₂ nanoshells and their layered assembly into electrodes for electrochemical energy storage are reported. The nitridated hollow shells are prepared by annealing TiO₂ shells, produced initially using a sol–gel process, under an NH₃ environment at different temperatures ranging from 700 to 900 °C, then assembled to form a robust monolayer film on a water surface through a quick and simple assembly process without any surface modification to the samples. This approach facilitates supercapacitor cell design by simplifying the electrochemical electrode structure by removing the need to use any organic binder or carbon‐based conducting materials. The areal capacitance of the as‐prepared electrode is observed to be ≈180 times greater than that of a bare TiO₂ electrode, mainly due to the enhanced electrical conductivity of the TiN phase produced through the nitridation process. Furthermore, the electrochemical capacitance can be enhanced linearly by constructing an electrode with multilayered shell films through a repeated transfer process (0.8 to 7.1 mF cm^–2, from one monolayer to 9 layers). Additionally, the high electrical conductivity of the shell film makes it an excellent scaffold for supporting other psuedocapacitive materials (e.g., MnO₂), producing composite electrodes with a specific capacitance of 743.9 F g^–1 at a scan rate of 10 mV s^–1 (based on the mass of MnO₂) and a good cyclic stability up to 1000 cycles.     

PZT厚膜拾振器微图形化工艺研究

采用sol-gel方法制备了PZT铁电厚膜，构成了SiO2／Si／SiO2／Ti／Pt／PZT／Ti／Pt形式的拾振器敏感元结构。基于半导体光刻技术，通过干法刻蚀电极和化学湿法刻蚀PZT厚膜等技术，成功地实现了敏感元的微图形化，解决了Pt／Ti下电极刻蚀难、制作的PZT膜形貌不好和上电极容易起壳等问题，为基于PZT厚膜的高性能拾振器的研制打下了良好的基础。     

The Synergistic Effect of Prussian‐Blue‐Grafted Carbon Nanotube/Poly(4‐vinylpyridine) Composites for Amperometric Sensing

Because of its high activity and selectivity toward the reduction of hydrogen peroxide and oxygen, Prussian blue (PB) is usually considered as an “artificial enzyme peroxidase” and has been extensively used in the construction of electrochemical biosensors. In this study, we report on the construction of amperometric biosensors via grafting PB nanoparticles on the polymeric matrix of multiwalled carbon nanotubes (MWCNTs) and poly(4‐vinylpyridine) (PVP). The MWCNT/PVP/PB composite films were synthesized by casting films of MWCNTs wrapped with PVP on gold electrodes followed by electrochemical deposition of PB on the MWCNT/PVP matrix. The electrode modified with the MWCNT/PVP/PB composite film shows prominent electrocatalytic activity toward the reduction of hydrogen peroxide, which can be explained by the remarkable synergistic effect of the MWCNTs and PB. Therefore, fast amperometric response of this sensor to hydrogen peroxide was observed with a detection sensitivity of 1.3 μA μM ^–1 of H₂O₂ per square centimeter area and a detection limit of 25 nM . These results are much better than those reported for PB‐based amperometric sensors. In addition, a glucose biosensor fabricated by casting an additional glucose oxidase (GOD) containing Nafion film above the MWCNT/PVP/PB composite film shows promise for the sensitive and fast detection of glucose. The observed high stability, high sensitivity, and high reproducibility of the MWCNT/PVP/PB composite films make them promising for the reliable and durable detection of hydrogen peroxide and glucose.     

Adsorption and Direct Electron Transfer from Hemoglobin into a Three‐Dimensionally Ordered Macroporous Gold Film

Application of protein‐based, direct electron communication in bioelectronic devices, biosensors, or biofuel cells usually requires high stability and function density of the immobilized proteins or enzymes. Traditional methods have been used to increase the function density using multilayer immobilization techniques at the expense of losing stability and electron‐communication rate, that is, generally only protein molecules near the electrode surface are electroactive. In order to overcome the above problems, a three‐dimensional, ordered, macroporous gold film electrode is synthesized electrochemically by an inverted colloidal crystal template technique. The uniform, three‐dimensional macroporous gold provides superior conductivity, high stability, and large surface area. Its interconnected macroporous structure, containing gold nanoparticles, significantly enhances the amount of adsorbed hemoglobin (Hb) molecules at the monolayer level and also provides a good microenvironment for retaining the biological activity of the adsorbed protein, as confirmed by electrochemical and attenuated total reflection Fourier‐transform infrared spectroscopy. Therefore, direct electron transfer between the adsorbed Hb and the electrode is achieved. Adsorption of Hb on the macroporous gold film electrode is monitored using electrochemical impedance spectroscopy. The saturated adsorption amount, Γ, of the Hb is determined to be 6.55×10^–10 mol cm^–2 with a surface coverage of 88.1 %. The electrochemical behavior and the adsorption mechanism of Hb on the macroporous gold film electrode are discussed on the basis of the experimental results.     

Protein Rebinding to a Surface‐Confined Imprint

A novel strategy to prepare a selective ultrathin molecularly imprinted polymer (MIP) film directly on the gold‐based transducer surface for the peptide and protein detection in aqueous solution is demonstrated using a combination of epitope‐ and electrochemical surface imprinting approach. The synthetic peptide derived from the surface‐exposed C‐terminus of cytochrome c (Cyt c, residues 96–104) is selected as the template for the imprinting. It is labeled with a fluorescent dye in order to quantitatively evaluate all stages of the imprinting process in terms of changes in mean fluorescence intensity. The labeled peptide template is first chemisorbed on the gold surface as an oriented submonolayer through an additional C‐terminal cysteine. After electropolymerization, the template is stripped off electrochemically. To allow the imprinted sites to be confined to the surface, the film thickness is controlled to be comparable to the thickness of the peptide layer. This is achieved by the electropolymerization of scopoletin. Recognition capabilities of the films are characterized and the resulting MIP film is able to selectively capture the template peptide and the corresponding target protein. In case of the peptide recognition, the MIP film can discriminate even the single amino acid mismatched sequences of the target peptide.     

人体唾液葡萄糖生物传感器

通过戊二醛交联法将葡萄糖氧化酶(GOD)固定在二茂铁(Fc)修饰的薄膜金电极上,制备了一种可用于检测人体唾液中葡萄糖含量的生物传感器。研究了不同扫描速度下二茂铁的电化学行为,以及工作电压、戊二醛浓度和酶固定量对传感器响应特性的影响。结果表明,利用戊二醛交联法制备的传感器检出限低、检测范围宽。在0~2 200μmol/L的葡萄糖标准浓度范围内,传感器灵敏度为21.45nA.μmol-1.cm-2(相关系数r=0.991 2),检出限为1μmol/L,响应时间5s。该结果可实现对唾液葡萄糖的检测,进而有望实现对血糖的检测。     

Inkjet and microcontact printing of functional materials on foil for the fabrication of pixel-like capacitive vapor microsensors

The work presented demonstrates the utilization of micro-contact printing of self-assembled monolayers (SAMs) of gold nanoparticles (NPs) to pattern the porous thin metallic film composing the top electrode of an ultra-fast capacitive relative humidity sensor based on miniaturized parallel-plates electrodes. The rest of the device, which occupies an area of only 0.0314 mm², is fabricated by inkjet printing stacked individual drops of functional materials, namely gold NPs for the bottom electrode and a polymeric humidity sensing layer, on a polymeric foil. Compared to other printing methods, the use of microcontact printing to pattern the top electrode enables the additive transfer of a solvent-free metallic layer that does not interact chemically with the sensing layer, permitting the thinning of the latter without risk of short-circuits between electrodes, and broadening the range of usable sensing materials for detection of other gases. Thinning the sensing layer yields to ultra-fast response devices with high values of capacitance and sensitivity per surface area. The fabrication process is compatible with low heat-resistant polymeric substrates and scalable to large-area and large-scale fabrication, foreseeing the development of low-cost vapor sensing sheets with high space–time resolution, where every sensor would correspond to a pixel of a large array.     

High‐Performance Dopamine Sensors Based on Whole‐Graphene Solution‐Gated Transistors

Solution‐gated graphene transistors with graphene as both channel and gate electrodes are fabricated for the first time and used as dopamine sensors with the detection limit down to 1 nM, which is three orders of magnitude better than that of conventional electrochemical measurements. The sensing mechanism is attributed to the change of effective gate voltage applied on the transistors induced by the electro‐oxidation of dopamine at the graphene gate electrodes. The interference from glucose, uric acid, and ascorbic acid on the dopamine sensor is characterized. The selectivity of the dopamine sensor is dramatically improved by modifying the gate electrode with a thin Nafion film by solution process. This work paves the way for developing many other biosensors based on the solution‐gated graphene transistors by specifically functionalizing the gate electrodes. Because the devices are mainly made of graphene, they are potentially low cost and ideal for high‐density integration as multifunctional sensor arrays.     

Substrate‐Dependent Molecular and Nanostructural Orientation of Nafion Thin Films

The effects of film thickness and substrate composition on the ionomer structure in porous electrodes are critical in understanding pathways toward developing higher performance electrochemical devices, including fuel cells and batteries. Insights are gained into the molecular and nanostructural orientation dependence for thin Nafion films (12–300 nm thick) on gold, platinum, and SiO₂ model substrates. Molecular orientation is determined from the birefringence measured using spectroscopic ellipsometry, while the nanostructural orientation of the ionic domains is measured using grazing‐incidence small‐angle X‐ray scattering. Density functional theory calculations for the molecular polarizability of the Nafion backbone and side chain show complimentary contributions to the measured birefringence values for the material. Nafion films prepared on SiO₂ substrates exhibit a nearly isotropic molecular and nanostructural orientation. Films on gold and platinum display parallel backbone orientations, relative to the substrate, with decreasing film thickness. However, a birefringence transition toward molecular isotropy is observed for 30 nm thick films on Au and Pt; while the ionic nanostructured domains continuously align parallel to the substrate. This apparent isotropic molecular orientation with increasing domain orientation highlights the difference between the backbone and side chain orientation, a key finding for elucidating transport in confined films at the interfaces.     

Gold-coated microelectrode array with thiol linked self-assembled monolayers for engineering neuronal cultures

We report the use of a gold coating on microelectrode arrays (MEAs) to enable the use of the relatively reliable surface modification chemistry afforded by alkanethiol self-assembled monolayers (SAMs). The concept is simple and begins with planar MEAs, which are commercially available for neuronal cell culture and for brain slice studies. A gold film, with an intermediate adhesive layer of titanium, is deposited over the insulation of an existing MEA in a manner so as to be thin enough for transmission light microscopy as well as to avoid electrical contact to the electrodes. The alkanethiol-based linking chemistry is then applied for the desired experimental purpose. Here we show that polylysine linked to alkanethiol SAM can control the geometry of an in vitro hippocampal neuronal network grown on the MEA. Furthermore, recordings of neuronal action potentials from random and patterned networks suggest that the gold coating does not significantly alter the electrode properties. This design scheme may be useful for increasing the number of neurons located in close proximity to the electrodes. Realization of in vitro neuronal circuits on MEAs may significantly benefit basic neuroscience studies, as well as provide the insight relevant to applications such as neural prostheses or cell-based biosensors. The gold coating technique makes it possible to use the rich set of thiol-based surface modification techniques in combination with MEA recording.