A glass nanopore electrode for single molecule detection

We have developed a simple method for fabricating robust and low noise glass nanopore electrodes with pore size 10±5 nm to detect single molecules.β-Cyclodextrin was used as model compound for characterization.In 1.0 mol/L NaCl solution,the molecules generated current pulses of 2-5 pA with noise level less than 0.8 pA.A slide mode and a plug mode were suggested for the way ofβ-cyclodextrin single molecule moving into the glass nanopores.

Theoretical study on the lasing plasmon of a split ring for label-free detection of single molecules and single nanoparticles

This paper reports the plasmonic lasing of a split ring filled with gain material in water. The lasing mode（1500 nm）is far from the pump mode（980 nm）, which can depress the detection noise from the pump light. The laser intensities of the two modes simultaneously increase by more than 10^3 in amplitude, which can intensify the absorption efficiency of the pumping light and enhance the plasmonic lasing. The plasmonic lasing is a sensitive sensor. When a single protein nanoparticle（n = 1.5, r = 1.25 nm） is trapped in the gap of the split ring, the lasing spectrum moves by 0.031 nm, which is much larger than the detection limit of 10^-5 nm. Moreover, the lasing intensity is also very sensitive to the trapped nanoparticle. It reduces to less than 1/600 when a protein nanoparticle（n = 1.5, r = 1.25 nm） is trapped in the gap.

Combination of Micro-fluidic Chip with Fluorescence Correlation Spectroscopy for Single Molecule Detection

A single molecule detection technique was developed by the combination of a single channel poly （dimethylsiloxane）/glass micro-fluidic chip and fluorescence correlation spectroscopy （FCS）. This method was successfully used to determine the proportion of two model components in the mixture containing fluorescein and the rhodamine-green succinimidyl ester.

Single-atom metal-nitrogen-carbon catalysts energize single molecule detection for biosensing

Biosensors featuring single molecule detection present huge opportunities as well as challenges in food safety inspection,disease diagnosis,and environmental monitoring.Single-molecule detection is largely lacking of high enough activity,precision molecule selectivity,and understanding in the exact operating mechanism.Single-atom catalysts(SACs),especially those metals-nitrogen-carbon that mimic the natural metalloenzyme structure,and with well-defined metal atom bond configurations,high level of molecular selectivity,and easy fabrication,endow single molecule detections with practical-use feasibilities.The recent advances in single-atom catalysts also present new pathways in the key mechanism understandings.In this short review,we will first visit the brief history and advantages of SACs that have been explored only recently for molecule-scale biosensors,where they are analogous and also differentiated from those nanozymes and natural metalloenzymes.Their applications in electrochemical,photochemical,and photoelectrochemical sensors are then discussed comprehensively by focusing on the different molecule-scale sensing modes in achieving local coordination-modulated signal amplifications.Finally,we identify new opportunities and challenges faced by these SACs-based single molecule detections in the further development of biosensors.

Determination of Gossypol in Trace Level by Flow Injection Analysis with Chemiluminescence Detection

This work reports the single-molecule detection of gossypol by flow injection analysis with chemiluminescence method. The method is based on the reaction of luminol with ferricyanid in sodium hydroxide medium sensitized by gossypol. Under the optimum conditions, the CL intensity is proportional to the concentration of gossypol over the range of 1.11×10^-17-2.78×10^-16 mol/L in acid solution and 8.00×10^-11-7.39×10^-8mol/L in neutral solution with correlation coefficients 0.9983 and 0.9905, respectively. The detection limits is 1.60×10^-18 mol/L （S/N=3）. The proposed method has been applied for the determination of the gossypol in cottonseeds and pharmaceutical formulations with satisfactory results.

Exponentially modified Gaussian relevance to the distributions of translocation events in nanopore-based single molecule detection

Nanopore technique plays an important role in single molecule detection, which illuminates the properties of an individual molecule by analyzing the blockage durations and currents. However, the traditional exponential function is lack of efficiency to describe the distributions of blockage durations in nanopore experiments. Herein, we introduced an exponentially modified Gaussian （EMG） function to fit the duration histograms of both simulated events and experimental events. In comparison with the traditional exponential function, our results demonstrated that the EMG provides a better fit while covers the entire range of the distributions. In particular, the fitted parameters of EMG could be directly used to discriminate the sequence length of the oligonucleotides at single molecule level.

Self-assembling bacterial pores as components of nanobiosensors for the detection of single peptide molecules

Nano-sized bacterial pores were inserted into a lipid membrane as a nanobiosensor for the detection of single peptide molecules. Due to the intrinsic properties of single-channel conductance, the transit of individual molecules through the pore can be studied. The analysis of both the blockage current and duration is able to provide specific structural information and allows the detection of specific peptides in bulk mixtures.

Application of TIRFM in Biomolecule Research and Clinical Medicine

With the increasing demand for imaging quality, many scientists constantly explore new imaging instruments to meet the requirements. The total internal reflection fluorescence microscopy has some incomparable superiorities, so it has become one of the research hotspots in recent years. It can show great performance in single-molecule imaging because it has unique imaging principles. This apparatus is used mainly in two fields, biomolecule research and clinical medicine. To know this instrument’s function, the summary of applications in these two parts was given in this article. Now, scientists who have been focusing on this apparatus try to make this microscope combined with other late-model precise instruments that probe some unknown interaction mechanism of action. The TIRFM will show extraordinary talents in many aspects, and it will become a powerful tool for people to explore the mysteries of life.

Single-Molecular Co-localization Detection and Analysis

This talk will discuss single-molecule detection that shows on dual-color optical imaging data, image processing and statistical analysis can reliably differentiate random

基于固态纳米孔道的单颗粒散射光谱分析

固态纳米孔道单分子分析技术因其尺寸可控、无标记、高通量等优点,在近几年得到了快速的发展,已经被广泛应用于金属离子、DNA、RNA、蛋白质等物质的研究中。本文主要聚焦基于氮化硅固态纳米孔道的单颗粒散射光谱分析技术,简要介绍了近年来的研究进展,总结了固态纳米孔道的制备方法、单分子分析原理以及光电协同应用,并对拉曼散射光谱技术在固态纳米孔道单分子检测技术进行了展望。

Optical mapping of a rice BAC clone using restriction endonuclease and imaging with fluorescent microscopy at single molecule level

A method of constructing restriction map by optical mapping and single molecule fluorescent microscopy is described. DNA molecules were aligned and adsorbed on a glass coverslip surface by a modified 'molecular combing' technique, and then the surface-immobilized DNAs were cleaved in situ with a restriction endonuclease. Individual DNA molecules digested by the endonuclease EcoR I were observable with fluorescent microscopy. Using optical mapping, a physical map of a rice bacterial artificial chro-mosome clone was constructed. This method will facilitate genomic mapping and tracing the dynamic process in real time at a single molecule level with fluorescence microscopy.

Single molecule fluorescence spectroscopy for quantitative biological applications

Single molecule techniques emerge as powerful and quantitative approaches for scientific investigations in last decades. Among them, single molecule fluorescence spectroscopy （SMFS） is able to non-invasively characterize and track samples at the molecular level. Here, applications of SMFS to fundamental biological questions have been briefly summarized in catalogues of single-molecule counting, distance measurements, force sensors, molecular tracking, and ultrafast dynamics. In these SMFS applications, statistics and physical laws are utilized to quantitatively analyze the behaviors of biomolecules in cellular signaling pathways and the mechanisms of biological functions. This not only deepens our understanding of bio-systems, but also provides a fresh angle to those fundamental questions, leading to a more quantitative thinking in life science.

大肠杆菌内毒素的固态纳米孔单分子检测

细菌内毒素又称脂多糖,是革兰氏阴性菌细胞外壁的主要成分之一。微量的内毒素就可以引起生物体发热,是炎症反应、脓毒症、败血症等疾病的主要诱发因子。本文提出了一种基于固态氮化硅纳米孔检测单分子脂多糖的技术,利用电介质击穿法制备目标孔径,通过膜片钳监测脂多糖单分子的易位信息,分析得到在不同电压、不同孔径下脂多糖的构象变化,最终得到4.5 nm的最适检测孔径。本研究可用于临床医学检测、环境生物标志物的测定等。

水汽界面二维银颗粒表面上的单分子拉曼光谱检测

We have found that the silver colloids, which usually used as SERS active substrate, are inclined to aggregation on air water interface and forming a two dimension silver particle films. The formed silver particle films exhibit much higher surface Raman enhancement factor than silver colloids, and the power used on silver particle films is only about 1% of that on silver colloids. Combining with resonance Raman enhancement technique, we realize single molecular Raman detection under the common conditions by using this silver particle films as SERS active substrate.

纳米通道单分子检测低噪音电流放大器系统的研究

研制了一种新型微电流放大器系统,用于检测α-Hemolysin生物蛋白纳米通道在单分子检测实验中所产生的微弱电流信号(<100 p A)。在1 mol/L KCl、10 mmol/L Tris-HCl,1 mmol/L EDTA的缓冲液(p H 8.0)中测定了DNA-PEG-DNA交联物与纳米通道的穿越和碰撞信号。实验中使用3 k Hz贝塞尔滤波器和100 k Hz模数转换器来对电流进行采样。结果表明,此放大器系统能够有效降低电流记录过程中的噪音,有利于分辨待测物分子与纳米通道作用所产生的较小阻断的电流信号(<10 p A)。

荧光共振能量转移技术在生命科学中的应用及研究进展

荧光共振能量转移(FRET)是指两个荧光基团间能量通过偶极-偶极耦合作用以非辐射方式从供体传递给受体的现象,可被用于测定分子间的距离。FRET荧光探针主要有荧光蛋白、有机荧光染料、镧系染料和量子点,近年来有许多新的应用;测试方法上与时间分辨、单分子检测、荧光寿命和荧光相关光谱等技术联用取得了更好的成效。

超痕量分析中的激光诱导荧光检测

本文对激光诱导荧光检测器 (LIF D)及其主要器件激光器、滤光片、透镜、光电检测器、荧光探针及扫描装置的现状和发展趋势作了综述 ,介绍了LIF在单分子检测中的应用。

荧光相关光谱及其在单分子检测中的应用进展

单分子检测在生命科学、化学、物理学等领域具有重要的意义。荧光相关光谱是单分子检测的新技术,在生命科学领域有巨大的应用潜力。综述了荧光相关光谱单分子检测的原理、实验技术以及在生物分子相互作用、活细胞、核酸、疾病诊断、高通量筛选以及与毛细管电泳联用等领域的研究,并展望了其发展前景。

荧光相关光谱单分子检测系统的研究

基于激光共焦构型,构建了一套高灵敏度和高稳定性的荧光相关光谱单分子检测系统。采用高数值孔径物镜使激光束高度聚焦,并用同一物镜收集样品的荧光,单光子计数器用于实时记录荧光信号。优化系统保持物镜焦点、针孔以及单光子计数器光敏区高度同轴。采用60×1.2(NA)的水浸物镜及直径为160μm的针孔得到的检测系统结构参数为ω0和z0分别为0.42μm和1.33μm,照射微区的体积为1.3fL。单个RhodamineGreen分子可获得13倍的信噪比。用该系统获得了小分子和生物大分子(DNA片段和蛋白质)的高质量荧光相关图谱,成功实现了单个分子的检测。

检测溶液中单分子

科学的进步不但要求对物质的整体特征进行鉴定和测定 ,同时还要求对单分子化学和物理性质进行深入探索。在单分子水平对物质进行研究 ,是一项重要的学科前沿交叉领域 ,对分子工程学、分子生物学、分子医学、纳米材料和信息科学具有非常重要的意义。本文评述近年来溶液中单分子检测研究的最新进展 ,包括激光诱导荧光检测、电化学检测及我们最近提出的化学发光检测等。