氯丙嗪分子印迹化学发光微流控传感器芯片的研究

以氯丙嗪分子印迹聚合物为识别物质,以鲁米诺-K3Fe(CN)6化学发光体系,建立了一种新型的氯丙嗪化学发光微流控分子印迹传感器芯片的检测方法。利用二氧化碳激光在聚甲基丙烯酸甲酯材质上刻蚀出200μm宽,150μm深的微通道,8 mm长,1 mm宽,0.5 mm深的微检测池。微检测池中填充50μm粒径大小的热聚合得到的氯丙嗪分子印迹聚合物作为识别物质,在线富集氯丙嗪,富集的氯丙嗪可以增强鲁米诺和K3Fe(CN)6的化学发光强度,以化学发光强度定量氯丙嗪量。该传感器的响应值与0.02~0.4μg/mL氯丙嗪呈良好的线性关系,检出限为8 ng/mL(3σ)。该微流控传感器芯片已用于测定人尿液中的氯丙嗪。     

海水中痕量锌的流动注射在线预富集和电感耦合等离子体原子荧光检测

一种较新的螯合树脂CPPI,被用来从海水中富集痕量锌。在线预富集由流动注射分析仪控制,经富集浓缩后的锌试液亦由流动注射分析仪送往电感耦合等离子体原子荧光光谱仪检测。检出限在0.1μg/L以下。     

对巯基苯硼酸修饰石英晶体微天平传感器用于测定唾液酸

硼酸与二醇的脱水缩合反应已被广泛用于检测或富集顺式邻位多羟基化合物. 本文以对巯基苯硼酸(MPBA)自组装修饰石英晶体微天平(QCM)芯片, 基于硼酸根对唾液酸的特殊反应, 建立了检测唾液酸(SA)的新方法. 采用扫描电子显微镜表征了对巯基苯硼酸对石英晶体微天平的功能化修饰过程, 并研究了溶液pH值对芯片表面亲和力的影响. 实验结果表明, 随着pH值的降低, 修饰芯片对唾液酸的结合能力增强, 而对参照物葡萄糖的结合能力则降低. 在pH=4.0的条件下, 该传感器在0.50~5.0 mmol/L范围内对唾液酸有很好的线性响应, 相关系数为0.9950, 检出限为0.15 mmol/L. 此传感器提供了一种简易的唾液酸检测方法, 为实际样品的测定奠定了基础.     

间接抑制免疫分析法测定水溶液中痕量磺胺甲噁唑

将分子印迹技术与表面等离子体共振技术联用,建立了一种新型间接抑制免疫分析法,并用于磺胺甲唑的测定.采用管内原位聚合的方法,在长30 cm,内径0.25 mm的毛细管内制备了磺胺甲唑印迹聚合物涂层.涂层厚度由扫描电子显微镜测得为198 nm.在BIAcore 3000生物传感器上自动进行检测.涂层毛细管用于免疫检测前的在线固相萃取和预富集.磺胺甲唑单克隆抗体被富集的磺胺甲唑抑制,抑制信号与磺胺甲唑的浓度成正比.在优化的实验条件下,方法的线性范围为0.04～10.0 μg/L; 检出限为0.01 μg/L.本方法可直接用于实际样品的检测,回收率好,灵敏度高,操作简便,自动化程度高.     

基于三叉型离子交换膜的带电粒子微流控富集芯片的研究

预富集是实现痕量生化物质检测的有效手段.本研究基于离子浓差极化(ICP)原理,研制了一种用于水环境中带电粒子的富集与检测的基于三叉型离子交换膜的微流控富集芯片.此芯片采用3D打印及微纳加工技术制备,通过控制富集区和缓冲区的电势差控制电渗力与排斥力,以获得较稳定的耗尽区和富集区.在富集实验中,以带负电荷的荧光素钠作为富集...     

纳米TiO2预富集在线悬浮液氢化物发生-原子荧光法测定水样中痕量砷

建立了一种基于纳米TiO2预富集在线悬浮液氢化物发生的技术,并将其与原子荧光谱仪联用检测环境水样中痕量砷.实验优化了影响As(Ⅲ)吸附以及洗脱的相关条件.在最优条件下建立了标准曲线,其线性相关系数优于0.999,检出限为0.004 μg·L-1.相对于传统氢化物发生原子荧光法,检出限和灵敏度均有明显的改善.并成功地将该...     

微流路中利用DNA选择性固定蛋白质

报道了一种可控的通过DNA复合物在微流路中杂交固定蛋白质的方法. 微流路系统中的玻璃基底上固定寡聚核苷酸, 其中的层流提供了不同的DNA-蛋白质复合物. DNA的特异性识别可以将蛋白通过表面寻址固定在基底上. 并且在体系中引入了全内反射荧光技术来追踪整个过程. 此方法的特异性和灵敏度均较高, 且蛋白质的固定和去除可重复. 实验结果显示, 同时检测特异性和非特异性的识别, 可以有效提高生物检测的准确性. 这项技术可以提高具有微流路结构的生物传感器装置的检测质量.     

压电免疫生物传感器快速检测三唑磷农药

采用活化剂碳二亚胺(EDC)和N-羟基琥珀酰亚胺(NHS)对邻巯基苯甲酸(MBA)自组装修饰的石英晶体金电极表面进行活化,再将三唑磷单克隆抗体共价固定于电极表面,建立了一种用于快速检测农药残留的压电免疫生物传感器.采用浸入-干燥法和流动注射法检测目标农药并对实验过程进行分析.两种方法均可在40～60 min内直接检测目标农药,浸入-干燥法的检出限为0.04 mg/L,流动注射法的检出限为1.0 mg/L.使用8 mol/L尿素成功解离了抗体-抗原免疫复合物,实现了免疫传感器的再生.此传感器的选择性好,可以重复使用.     

微富集柱-FAAS联用测定铅的影响因素分析

研究了微富集柱与原子吸收光谱法联用测定铅的各种影响因素，实验利用自制的微型电化学富集性对金属离子的吸附效应进行预富集，再瞬间溶出直接进入原子吸收进行测定，极大地提高了测试灵敏度和降低了检出限，可使铅测定中的特征浓度和检出限降低1－2个数量级。     

基于场放大进样及Au纳米粒子双重富集用于大肠杆菌检测的毛细管电泳电化学免疫分析法

利用Au纳米粒子作为辣根过氧化物酶(HRP)标记抗体的载体,结合电堆积预富集技术,发展了一种基于场放大进样及Au纳米粒子双重富集的毛细管电泳电化学免疫分析技术用于大肠杆菌的检测.大肠杆菌与酶标抗体免疫反应后直接进行场放大进样预富集,免疫样品快速迁移并堆积在毛细管入口端,同时带负电荷的金纳米粒子向阳极端迁移,在样品与缓冲溶液的界面处吸附样品离子.金纳米粒子作为多酶载体使检测信号进一步放大.以标记在抗体上的HRP催化H2O2氧化邻苯二胺产生的电流信号来检测大肠杆菌.同常规电动进样毛细管电泳相比,该双重富集技术可使灵敏度提高1400倍.该方法对大肠杆菌检测的线性范围为2.0～2000.0 cfu mL-1,检出限为1.0 cfu mL-1,实现了对扇贝样品中大肠杆菌的快速、灵敏检测.     

基于低温等离子体辅助催化发光的乙烯传感器

将等离子体的高活化性能与催化发光的传感特性相结合,以成本低、合成简单的碱土金属纳米MgO为传感材料,构建了基于低温等离子体辅助的催化发光传感器,用于乙烯的快速检测.由于等离子体具有高活化性能,本方法的检测温度远低于传统的催化发光检测法的常用温度(300~500℃),无需加热装置,在室温下实现了对乙烯快速、灵敏的检测.室温(25℃)下,对乙烯的检出限为37 ng/mL (30 ppm),线性范围为112~4997 ng/mL (90~3998 ppm, R=0.97669),传感器具有良好的选择性和重现性.此传感器制备简单、稳定性高、低能耗、成本低,与传统的气体检测方法相比具有良好的实用性和普适性,为开发性能优异的新型催化发光传感器提供了策略.     

ROC-curve approach for determining the detection limit of a field chemical sensor

The detection limit of a field chemical sensor under realistic operating conditions is determined by receiver operator characteristic (ROC) curves. The chemical sensor is an ion mobility spectrometry (IMS) device used to detect a chemical marker in diesel fuel. The detection limit is the lowest concentration of the marker in diesel fuel that obtains the desired true-positive probability (TPP) and false-positive probability (FPP). A TPP of 0.90 and a FPP of 0.10 were selected as acceptable levels for the field sensor in this study. The detection limit under realistic operating conditions is found to be between 2 to 4 ppm (w/w). The upper value is the detection limit under challenging conditions. The ROC-based detection limit is very reliable because it is determined from multiple and repetitive sensor analyses under realistic circumstances. ROC curves also clearly illustrate and gauge the effects data preprocessing and sampling environments have on the sensor's detection limit.     

Ultra-sensitive detection of bacterial toxin with silicon nanowire transistor

Nanowire field effect transistors (nano-FET) were lithographically fabricated using 50 nm doped polysilicon nanowires attached to two small gold terminals separated from each other by a approximately 150 nm gap to serve as the basis for electronic detection of bacteria toxins. The device characterizations, semiconducting properties and use in a robust and sensitive bio-molecular detection sensor of bacterial toxins were reported in this work. The device characteristics were demonstrated with varying gate and drain voltages. The bio-molecular detection was demonstrated using electrochemical impedance spectroscopy (EIS), using Staphylococcus aureus Enterotoxin B (SEB) as the target molecule. The detection limit of SEB was observed in the range of 10-35 fM.     

A simple microfluidic chlorine gas sensor based on gas-liquid chemiluminescence of luminol-chlorine system

In this work, a microfluidic chlorine gas sensor based on gas-liquid interface absorption and chemiluminescence detection was described. The liquid chemiluminescence reagent-alkaline luminol solution can be stably sandwiched between two convex halves of a microchannel by surface tension. When chlorine gas was introduced into the micro device, it was dissolved into the interfacial luminol solution and transferred to ClO(-), and simultaneously luminol was excited and chemiluminescence emitted. The emitted chemiluminescence light was perpendicularly detected by a photomultiplier tube on a certain detection region. The remarkable advantage of the detection system is that both adsorption and detection were carried out at the gas-liquid interface, which avoids the appearance of bubbles. The whole analytical cycle including filling CL reagent, sample injection, CL detection and emptying the device was as short as 30 s. The linear concentration range of chlorine gas detection with direct introduction of sample method is from 0.5 to 478 ppm. The detection limit of this method is 0.2 ppm for standard chlorine gas and the relative standard deviation of five determinations of 3.19 ppm spiked chlorine sample was 5.2%.     

Magnetic nanoparticle-molecular imprinted polymer: A new impedimetric sensor for tributyltin detection

Recently, molecular imprinted polymers (MIPs) were extensively used for separation and identification of specific molecules, replacing expensive and unstable biological receptors. Nonetheless, their application in electrochemical sensors has not been sufficiently explored. Here we report the use of a MIP as a specific receptor in a new highly sensitive tributyltin (TBT) electrochemical sensor. The sensor combines the specificity, pre-concentration capability and robustness of molecular imprinted polymer attached onto magnetic nanoparticles with the quantitative outputs of impedimetric measurements. The proposed device detects TBT in a concentration range of 5 pM to 5 μM with a low limit of detection (5.37 pM), which is lower than the one recommended for TBT in sea water by the US Environmental Protection Agency (EPA). We believe that this new electrochemical sensor can play an important role in the monitoring of the quality of sea and fresh waters worldwide.     

Nonenzymatic amperometric organic peroxide sensor based on nano-cobalt phthalocyanine loaded functionalized graphene film

An enzyme-free amperometric method was established for the electrochemical reduction tert-butyl hydroperoxide (TBHP) on the utilization of nano-cobalt phthalocyanine (CoPc) loaded functionalized graphene (FGR) and to create a highly responsive organic peroxide sensor. FGR was synthesized with a simple and fast method of electrolysis with potassium hexafluorophosphate (KPF₆) solution as electrolyte under the static current of 0.2 A. In the present work, FGR was dispersed in the solution of CoPc to fabricate chemical modified electrode to detect TBHP. The electro-reduction of TBHP can be catalyzed by FGR–CoPc, which has an excellent electrocatalytical activity due to the synergistic effect of the FGR with CoPc. The sensor can be applied to the quantification of TBHP with a linear range covering from 0.0260 to 4.81 mM, a high sensitivity of 13.64 A M⁻¹, and a low detection limit of 5 μM. This proposed sensor was designed as a simple, robust, and cheap analytical device for the determination of TBHP in body lotion.     

Photochromic polyoxometalate–based enzyme-free reusable sensors for real-time colorimetric detection of alcohol in sweat and saliva

This study describes a new strategy for real-time detection of alcohol in saliva and sweat. Phosphotungstic acid (PTA) is a colorless, photoelectrochromic heteropoly acid that can be reduced by ethanol under ultraviolet (UV) radiation to produce an intense blue color. This system has useful properties in the development of a new alcohol sensor: (1) the blue color can be detected by the naked eye or mobile camera, even at low ethanol concentrations; (2) color intensity is proportional to ethanol concentration; and (3) once exposed to air, reduced PTA is subsequently oxidized and returns to its colorless state offering sensor reusability. Based on these properties, we developed a simple device consisting of a PTA-impregnated non-woven material and a low-cost UV lamp that can be used to evaluate the alcohol concentration in saliva and sweat. We further enhanced the practical applicability of this sensor by demonstrating the integration of digital image analysis, multivariate analysis, and mobile camera technology with this sensor. This device can be potentially used in vehicles as a convenient, reusable alcohol sensor for drivers.     

An electrochemical peptide-based Ara h 2 antibody sensor fabricated on a nickel(II)-nitriloacetic acid self-assembled monolayer using a His-tagged peptide

We report, for the first time, the use of a Ni(II)-nitriloacetic acid (NTA) self-assembled monolayer (SAM) in the fabrication of an electrochemical peptide-based (E-PB) sensor for detection of anti-Ara h 2 antibodies. We compared the performance of the sensor fabricated on a Ni(II)-NTA SAM using a His-tagged peptide with the sensor fabricated using the conventional approach via direct immobilization of a thiolated peptide. While both sensors responded only to the correct antibody in the presence of random antibodies, we observed differences between the sensors. Specifically, the detection limit of the His-tagged sensor was 1 pM, significantly lower than the 200 pM detection limit of the conventional thiolated sensor. More importantly, unlike our previously developed E-PB sensors, both sensors are regenerable and reusable. The thiolated sensor can be readily regenerated using guanidine hydrochloride; whereas the His-tagged sensor can be regenerated by direct displacement of the His-tagged probes using Ni(II) ions. Overall, our results show that both approaches are well-suited for E-PB sensor fabrication; more importantly, specific sensor properties such as detection limit and dynamic range can be tuned by simply using a different probe immobilization method.     

Opto-fluidic micro-ring resonator for sensitive label-free viral detection

We have demonstrated sensitive label-free virus detection using the opto-fluidic ring resonator (OFRR) sensor. The OFRR is a novel sensing platform that integrates the microfluidics and photonic sensing technology with a low detection limit and small volume. In our experiment, filamentous bacteriophage M13 was used as a safe model system. Virus samples were flowed through the OFRR whose surface was coated with M13-specific antibodies. We studied the sensor performance by monitoring in real-time the virus and antibody interaction. It is shown that OFRR can detect M13 with high specificity and sensitivity. The detection limit is approximately 2.3 x 10(3) pfu mL(-1) and the detection dynamic range spanned seven orders of magnitude. Theoretical analysis was also carried out to confirm the experimental results. Our study will lead to development of novel OFRR-based, sensitive, rapid, and low-cost micro total analysis devices for virus detection.     

Layered Black Phosphorus as a Selective Vapor Sensor

Black phosphorus is a layered material that is sensitive to the surrounding atmosphere. This is generally considered as a disadvantage, especially when compared to more stable layered compounds, such as graphite or MoS₂. This sensitivity is now turned into an advantage. A vapor sensor that is based on layered black phosphorus and uses electrochemical impedance spectroscopy as the detection method is presented; the device selectively detects methanol vapor. The impedance phase measured at a constant frequency is used as a distinctive parameter for the selective quantification of methanol, and increases with the methanol concentration. The low detection limit of 28 ppm is well below the approved exposure limit of 200 ppm. The results are highly reproducible, and the vapor sensor is shown to be very selective in the presence of other vapors and to have long‐term stability.