Microelectrodes on a Silicon Chip for Label-Free Capacitive DNA Sensing

This paper presents the experimental characterization of two-terminal microfabricated capacitors for microarrays with an electrical sensing of label-free deoxyribonucleic acid (DNA). So far, such a concept has been demonstrated only in experimental setups featuring dimensions much larger than those typical of microfabrication. Therefore, this paper investigates: 1) the compatibility of the silicon microelectronic processes with biological functionalization procedures; 2) the effects of parasitics when electrodes have realistic dimensions; 3) measurement stability and reproducibility; and 4) the possibility of a fully integrated stand-alone device. The obtained results clearly indicate that two-terminal capacitive sensing with fully integrated electronics represents a viable technology for a DNA label-free detection/recognition.     

A Fully Electronic Label-Free DNA Sensor Chip

This paper presents a microfabricated DNA chip for fully electronic, label-free DNA recognition based on capacitance measurements. The chip has been fabricated in 0.5-mum CMOS technology and it features an array of individually addressable sensing sites consisting of pairs of gold electrodes and addressing logic. Read-out circuitry is built externally using standard components to provide increased experimental flexibility. The chip has been electrically characterized and tested with various solutions containing DNA samples. Significant capacitance variations due to DNA hybridization have been measured, thus showing that the approach represents a viable solution for a single chip DNA sensor array     

Sensitive Label-Free Immunoassay by Colorimetric Plasmonic Biosensors Using Silver Nanodome Arrays

The sensitive direct detection of biomolecules is demonstrated by a colorimetric plasmonic biosensor utilizing the surface colors of plasmonic metasurfaces named Ag nanodome arrays. The Ag nanodome arrays consist of polystyrene bead monolayers coated with Ag thin films whose surface colors are optimized by changing the size of the polystyrene beads. The bulk refractive index sensitivity of colorimetric detection evaluated using the hue angle is 590° RIU⁻¹ (RIU: refractive index unit). For selected geometry, the refractive index resolution (5.0 × 10⁻⁵ RIU) obtained by colorimetric detection surpasses that of spectroscopic detection evaluated via the dip wavelength in the reflection spectrum. The numerical simulations predict an enhanced sensing performance when the hue angle of the surface colors of the Ag nanodome arrays changes from 300° to 200°, corresponding to changes in the dip wavelength from 570 to 600 nm in the reflection spectra. Furthermore, the detection sensitivity of the biomolecules is characterized using a direct IgG immunoassay format. The detection limit of the IgG concentration is as low as 134 pM using simple colorimetric detection. The feasibility of sensitive label-free immunoassays using a colorimetric plasmonic biosensor is expected to accelerate the development of highly sensitive and reliable smartphone-based plasmonic biosensors.     

基于DNA荧光探针的T4多聚核苷酸激酶 免标记荧光检测

开发一种新型的基于DNA荧光探针的T4多聚核苷酸激酶(T4 PNK)活性检测方法。先设计了可以形成发卡结构的DNA探针(PNK-Tb),再通过引入T4 PNK、ATP和λ核酸外切水解酶(λ exo),打开发卡结构,释放发卡结构3’末端富含G的碱基序列,随后与Tb~(3+)结合形成G-四链体产生显著的荧光信号。通过反应前后荧光信号的变化实现T4 PNK的高灵敏检测。实验结果表明:成功制备了新的免标记DNA荧光探针,创新性地将Tb~(3+)应用到T4 PNK活性的检测中;本荧光法定量检测的线性范围为0~100 U/mL,检测下限为2 U/mL;该策略具有良好的特异性并且可用于评估ADP对T4 PNK活性的抑制作用。基于免淬灭标记DNA荧光探针构建的T4 PNK活性检测新策略反应快速 (不超过60 min)、成本低廉、灵敏度高,在药物开发以及生物化学研究中具有广阔的应用前景。     

Tactile Sensing Using Force Sensing Resistors and a Super-Resolution Algorithm

This paper presents a tactile sensor consisting of an array of force sensing resistors (FSRs). The tactile sensing array can be seen as a coordinated system of touch sensors. The low spatial resolution measured with the FSRs compared to other force or pressure sensors required the use of a super-resolution algorithm. Super-resolution algorithms are often used in digital image processing to enhance the resolution of images. Multiple images taken from slightly different orientations are superimposed in such a way that a single higher-resolution image is obtained. Different touch sensors are briefly discussed and the use of FSRs is motivated. Image-registration techniques are discussed and the super-resolution algorithm developed for the application is presented. Some tests performed using the tactile sensor in a neck palpation device and the results of these tests are also presented.      

In-Circuit Impedance Measurement Using Current Sensing

A novel approach to in-circuit measurement of resistors, capacitors, and inductors was evolved. This approach utilizes current sensing, making possible the measurement of in-circuit components which may be directly shunted by impedances as much as two to three orders of magnitude lower in impedance than the unknown. A minature clip-on probe was developed to facilitate measurements of components mounted on printed circuit boards. A compact impedance comparator was constructed which measured in-circuit components within approximately 2 to 4-percent accuracy over the following ranges: for resistance, 1.5 ? to 1 M?; for capacitance, 100 pF to 60 ?F; and for inductance, 400 ?H to 60 H. Impedances as low as one to three orders of magnitude smaller than the measured element impedance, depending on the probe used, shunted the unknown when the stated accuracy was measured. Much of the quoted inaccuracy is due to the ±3-percent resistance and ±0.1-percent linearity tolerances of the reference resistor which was used for all measurements.     

结合边缘特征的遥感图像融合

曲波(Curvelet)变换是一种更适合于图像处理的多尺度几何分析(MGA)方法,具有很强的方向性.结合 HSI变换将其应用于全色图像和多光谱(MS)图像融合可以更好地表示图像中的有用特征.首先对多光谱图像进行 HSI变换,得到亮度分量 I,对全色图像和 I 分量进行曲波变换得到粗尺度系数和细节尺度系数,对全色图像的粗尺度系数和细节尺度系数进行叠加,计算归一化的全色曲波系数直方图,定义边缘有效因子,利用全色图像的特征信息对融合图像的粗尺度系数进行处理,对细节尺度系数采用函数对弱边缘进行增强,对新的曲波系数设计融合规则进行融合,逆变换后得到新的亮度分量 Inew,用 Inew 替代原亮度分量 I 进行逆 HSI 变换得到最终融合结果,采用统计类指标对融合结果进行评价.实验结果表明,该方法在保持光谱信息和提高空间分辨率上都有较好的效果.     

基于HCR放大的无标记型荧光传感器的构建及H5N1 DNA检测

对于高致病性H5N1禽流感病毒,构建检测该病毒的高灵敏生物传感器,并与智能包装相结合用于实时监测,这对禽流感的防控具有重要意义。基于杂交链式反应（HCR）信号放大策略,以AgNCs作为荧光信号基团,构建了一种无标记“turn on”型荧光生物传感器用于检测代表H5N1病毒的H5N1基因序列。该传感器以H5N1 DNA作为触发剂引发HCR过程,使AgNCs产生强的荧光信号变化。研究表明,当H5N1 DNA浓度在0.2~800.0 nmol/L内,该传感器具有良好的响应信号,且在0.2~200.0 nmol/L之间的荧光强度与H5N1 DNA浓度呈线性相关,线性方程为y=10.982C+567.435（R2=0.992 73）,检测限为176 pmol/L。核酸传感体系具有通用性,通过简单调整目标序列,可实现对不同目标物的特异性灵敏检测。该研究有望为高灵敏分析禽流感病毒标志物的通用传感平台设计提供思路。     

从AFLP指纹和标记基因序列看我国养殖的四种鲍的亲缘关系

九孔鲍是我国南方主要的鲍养殖对象,皱纹盘鲍与盘鲍则在北方被广泛养殖。对于皱纹盘鲍与盘鲍,尤其是九孔鲍与杂色鲍的分类关系,迄今学术界还存在着不同看法。本文通过AFLP指纹的比较以及细胞核ITS-1和18SrRNA基因片段、线粒体16S rRNA和COI基因片段DNA序列的比较,发现九孔鲍与杂色鲍之间遗传趋异很小,只达到不同地方群体差异的水平;皱纹盘鲍与盘鲍趋异较大,可以认为是属于不同亚种。本研究结果同时表明AFLP技术是进行鲍种质鉴别和遗传多样性研究的有用手段。     

Optimal Scheduling of Casting Sequence Using Genetic Algorithms

Scheduling a casting sequence involving a number of orders with different casting weights and satisfying due dates of is an important optimization problem often encountered in foundries. In this article, we attempt to solve this complex, multi-variable, and multi-constraint optimization problem by using different implementations of genetic algorithms (GAs). In comparison with a mixed-integer linear programming solver, GAs with problem-specific operators are found to provide faster (with a subquadratic computational time complexity) and more reliable solutions to very large (more than 1 million integer variables) casting sequence optimization problems. In addition to solving the particular problem, the study demonstrates how problem-specific information can be introduced in a GA for solving complex real-world problems.     

Ultrahigh-Sensitivity Sandwiched Plasmon Ruler for Label-Free Clinical Diagnosis

Optical biosensors, especially those based on plasmonic structures, have emerged recently as a potential tool for disease diagnostics. Plasmonic biosensors have demonstrated impressive benefits for the label-free detection of trace biomarkers in human serum. However, widespread applications of these technologies are hindered because of their insufficient sensitivity, their relatively complex chemical immobilization processes, and the use of prism couplers. Accordingly, a sandwiched plasmon ruler (SW-PR) based on a Au nanohole array with ultrahigh sensitivity arising from the plasmonic coupling effect is developed. Highly confined surface charges caused by Bloch wave surface plasmon polarizations substantially increase the coupling efficiency. This platform exhibits thickness sensitivity as high as 61 nm nm⁻¹ and can detect at least 200 000-fold lower analyte concentrations than a nanowell sensing platform with the same wavelength shift. Additionally, the sandwiched plasmonic biosensor allows precise and label-free testing of clinical biomarkers, namely C-reactive protein and procalcitonin, in patient serum samples without requiring a sophisticated prism coupler, extra antibodies, or a chemical immobilization technique. This study yields new insight into the structural design of plasmon rulers and will open exciting avenues for disease diagnosis and therapy follow-up at the point-of-care.     

High‐Throughput Block Optical DNA Sequence Identification

Optical techniques for molecular diagnostics or DNA sequencing generally rely on small molecule fluorescent labels, which utilize light with a wavelength of several hundred nanometers for detection. Developing a label‐free optical DNA sequencing technique will require nanoscale focusing of light, a high‐throughput and multiplexed identification method, and a data compression technique to rapidly identify sequences and analyze genomic heterogeneity for big datasets. Such a method should identify characteristic molecular vibrations using optical spectroscopy, especially in the “fingerprinting region” from ≈400–1400 cm^?1. Here, surface‐enhanced Raman spectroscopy is used to demonstrate label‐free identification of DNA nucleobases with multiplexed 3D plasmonic nanofocusing. While nanometer‐scale mode volumes prevent identification of single nucleobases within a DNA sequence, the block optical technique can identify A, T, G, and C content in DNA k‐mers. The content of each nucleotide in a DNA block can be a unique and high‐throughput method for identifying sequences, genes, and other biomarkers as an alternative to single‐letter sequencing. Additionally, coupling two complementary vibrational spectroscopy techniques (infrared and Raman) can improve block characterization. These results pave the way for developing a novel, high‐throughput block optical sequencing method with lossy genomic data compression using k‐mer identification from multiplexed optical data acquisition.     

First Asian and Microbe-Sourced DNA Sequence Reference Materials Released

<正>The Asian-sourced DNA sequence reference materials(BW-5201)and DNA sequence reference materials of 0157 genome colibacillus(BW-5202)were released by National Institute of Metrology of China(NIM)and Shenzhen Huada Gene Research Institute on June 19,2015.This is the first time to release these reference materials in the world,providing a reference for the gene sequencing and data analysis in     

采用双树轮廓波及压缩传感的多聚焦图像融合

为了拓展压缩传感(CS)的应用潜力,提出一种结合双树轮廓波(DT-Contourlet)及CS的多聚焦图像融合方法.该方法首先采用DT-Contourlet对源图像进行分解,提取图像的多尺度信息及方向信息,克服传统轮廓波变换不具平移不变性的缺点.接着,在DT-Contourlet域,将分解系数看成包含稠密和稀疏两部分:...     

Sensing Capability of Molecularly Imprinted Self-Assembled Monolayer Using Terphenylpropanethiol

A molecularly imprinted self-assembled monolayer (SAM) was fabricated on a gold plate by forming a monolayer with both thiol compound and the template molecule, and removing the template molecules by solvent extraction. 1-Dodecanethiol (DDT), 1-hexadecanethiol (HDT), [1,1′:4′,1′′-terphenyl]-4-thiol (TPT), and [1,1′:4′,1′′-terphenyl]-4-propanethiol (TPPT) were used as the thiol compounds. Cholesterol was used as the template molecule, and cholesterol, cholic acid, and deoxycholic acid were used as the substrate molecules. Cyclic voltammograms were obtained using these imprinted gold plates as a working electrode, with Ag/AgCl reference electrode and Pt counter-electrode. Potassium ferricyanide was used as a background material for oxidation and reduction. These imprinted monolayers were capable of discriminating cholesterol that had been imprinted. The order of sensing capability of the thiol compounds was TPPT > HDT > TPT > DDT.     

Sizing of Wastewater Particles Using the Electrozone Sensing Technique

Electrozone sensing is a rapid and effective method that has been widely used for particle size analysis. This method is based on the Coulter principle, which provides a measure of the solid volume of particles. However, for wastewater particles, due to the high porosity of these particles, the measured Coulter size is significantly less than the physical dimension of these particles. To quantify this effect, the size distribution curves of the sieved wastewater particles were measured using the Coulter particle sizing method, microscopy technique, and sieving methods. A theoretical model was developed by accounting for the porosity of wastewater particles to correlate the physical size of these particles to Coulter size measurement. However, this theoretical model underestimated the size of wastewater particles smaller than 100 μm. Instead, the wastewater particles size (D) for both primary and activated sludge samples was found to be linearly related to the Coulter particle size measurement (d) according to: D = 2.14d with r² = 0.98.     

A Configurable Mixed-Signal Architecture for Label-Free Smart Biosensor Applications

The authors present a novel approach to perform the readout of a genetic sensor by using a low-frequency impedance-sensing technique based on phase-shift measurements. The proposed architecture is sufficiently simple to be fit into an off-the-shelf programmable system-on-chip (PSoC) and yet has been demonstrated to be powerful enough to measure a wide range of capacitance values (100 pF-10 muF ) with a relative error smaller than 2% compared with a high-cost laboratory instrumentation. Field measurements on real sensing structures demonstrated the functionality of the system in saline solutions characterized by different molarities. In this case, the sensor model could not be reduced to a simple capacitance, and the acquired phase shifts were fitted by exploiting a constant-phase element (CPE) model of the sensor. The worst-case relative error on the extracted capacitance for a given molar concentration is 16% for the 0.1-M solution and 11% for the 0.5-M solution. Since DNA hybridization should cause a capacitance change on the order of 25%, our conclusion is that, in principle, the proposed measurement procedure is able to discriminate between single-stranded and hybridized DNAs. The measured phase shifts as a function of frequency allowed us to extract the parameters of the CPE model with an error on the phase that is smaller than 0.4^deg .     

Sensing RF Connector Tightness Using a Grounded Plate Capacitive Structure

This paper describes a grounded plate capacitive sensing technique for monitoring mated RF connector tightness. The capacitive sensing structure and conditioning electronics are fabricated on the surface of a small polystyrene disc which is integrated into the RF connector body. A model of the electrostatic-mechanical system accurately predicts the change in capacitance as a function of the torque applied to tighten the mated connectors. Mechanical displacement in the connector (or, indirectly, axial force on the mated connector) translates to a change in the period of an oscillator drive circuit. The sensing system is measured to provide a transducer sensitivity range from 0.15 pF/N $cdot$ m at the initial connector mating force to 0.74 pF/N $cdot$ m at the high end of mating force.