功能化纳米金增强的DNA电化学检测和序列分析

用冠以大量二茂铁的纳米金微粒 /抗生蛋白链菌素结合物为标记物 ,将其标记于生物素修饰的寡聚核苷酸片段上 ,制成了具有电化学活性和纳米金放大作用的DNA电化学生物传感器 .首先采用巯基DNA和巯基烷烃混合自组装膜制备了金修饰电极 ,将探针DNA分子固定在了电极表面 ,运用杂交原则结合靶点分子在电极表面形成了双螺旋的DNA链 ,然后借助抗生蛋白链菌素和生物素之间的强亲和作用 ,引入了功能化的纳米金 .通过伏安法测定了修饰在纳米金上的二茂铁的氧化还原电流 ,可以识别和测定溶液中互补的靶点DNA ,17 mer靶点DNA的浓度在 0 .0 0 1～ 10nmol/L范围内有线性关系 ,检测限可达 0 .75× 10 -12 mol/L .     

功能化纳米金放大的DNA电化学传感器研究

研究了DNA夹心杂交和直接杂交体系,将功能化纳米金引入到标记有生物素的杂交双链上,制成具有电化学活性和纳米金放大作用的DNA电化学传感器,采用循环伏安法测试.在夹心杂交体系中,靶点DNA浓度与阳极峰电流关系曲线的相对标准偏差为3.0%～13.0%,在浓度为6.9×10^-3～0.14nmol/L范围内得到良好的线性关系,检测限达到2.0×10^-3nmol/L,实现了对单碱基突变的高灵敏检测和序列识别.直接杂交检测限为2.5×10^-4mol/L,分别在2.5×10^-4～5.0×10^-3nmol/L和5.0×10^-3～10nmol/L范围内得到峰电量与浓度的良好线性关系.并比较这两种体系.     

巯基功能化金纳米搅拌棒的制备及其对Pb(Ⅱ)和Cd(Ⅱ)的吸附检测

为实现金纳米粒子(AuNPs)对环境水体中重金属离子的选择性吸附,以刻饰不锈钢丝为基体,采用化学沉积法在刻蚀不锈钢丝表面沉积AuNPs,再用自组装法将1,8-辛二硫醇修饰于AuNPs上,制备了一种以巯基功能化金纳米为吸附剂的金属搅拌棒(AuNPs-SH-SBSE)。采用电感耦合等离子发射光谱仪(ICPOES)为检测手段,以常见的金属离子Pb(Ⅱ)和Cd(Ⅱ)为例,评价了金属搅拌棒的萃取分离性能。考察了吸附时间、pH值、解吸溶剂等因素对Pb(Ⅱ)和Cd(Ⅱ)吸附率的影响。结果表明,当吸附平衡时间为30min、pH 8.0,6.0 mL 1.5 mol/L HNO_3作洗脱剂时,Pb(Ⅱ)和Cd(Ⅱ)的吸附率分别达98.5%和87.4%。将该方法用于实际样品中痕量Pb(Ⅱ)和Cd(Ⅱ)的吸附检测,其线性范围分别为0.1~50 mg/L和0.2~20 mg/L,方法的检出限(S/N=3)分别为24 ng/L和3.6μg/L。在低、高2个浓度水平下进行加标回收实验,回收率分别为85.4%~105.0%和74.2%~97.8%,相对标准偏差(RSD,n=3)分别为3.8%~8.2%和4.2%~10.6%。该方法简单、快速、灵敏,可应用于环境水体中Pb(Ⅱ)和Cd(Ⅱ)的分离检测。     

对巯基苯硼酸／纳米金修饰玻碳电极用于葡萄糖的识别

采用自组装技术,将对巯基苯硼酸(MPBA)自组装于带正电荷纳米金(nano-gold,NG)修饰的玻碳电极(GCE)表面,从而制得用于识别葡萄糖的无酶传感器(MPBA/NG/GCE).通过交流阻抗技术和循环伏安法考察了MPBA/NG/GCE修饰电极的表面电化学特性,同时研究了葡萄糖在该修饰电极上的电化学行为,讨论了利用该修饰电极测定葡萄糖的最佳条件.结果表明:在优化的条件下,氧化峰电流与葡萄糖浓度在1.0～150.0 mmol/L范围内呈良好的线性关系,其回归方程为ΔIp (μA)=3.37+0.342c(mmol/L),相关系数为r=0.999,检出限为3.8×10-5 mol/L (S/N=3),可用于葡萄糖分子的电化学识别.     

甲烷氧化菌素功能化纳米金可视化检测微量铜

建立了基于甲烷氧化菌素(Mb)功能化纳米金(GNPs)可视化检测微量Cu~(2+)的方法。利用Mb还原氯金酸一步合成了Mb功能化的GNPs,其在Cu~(2+)诱导下会发生聚集,聚集过程可通过紫外-可见光谱来监控。发现吸光度比A_(654)/A_(520)与Cu~(2+)浓度在1～4μmol/L呈良好的线性关系(R~2=0. 98337),检出限为0. 34μmol/L。     

基于树枝状分子及功能化金纳米粒子的电化学免疫传感器检测污泥中大肠杆菌

利用树枝状分子-金纳米粒子复合物修饰电极和金纳米粒子标记物构建电化学免疫传感器,用于污泥中大肠杆菌的检测.首先在玻碳电极表面电聚合对氨基苯甲酸,通过共价作用结合第Ⅳ代氨基末端的树枝状分子(G4-PAMAM),并在其内部载入金纳米粒子,制备修饰电极(GCE/p-ABA/PAMAM (AuNPs)),用于固定大肠杆菌.采用硫堇作为电活性物质包被金纳米粒子,用于标记二抗制备金纳米粒子标记物(Ab2-Au-Th).通过抗原-抗体之间的特异性识别作用,将一抗、金纳米粒子标记物依次修饰在电极表面,用差分脉冲伏安法测定硫堇产生的电流信号,实现对大肠杆菌的检测.在优化的实验条件下,响应电流与大肠杆菌浓度的对数在1.0×102～1.0×106 cfu/mL范围内呈线性关系,检出限为70 cfu/mL(S/N=3).利用本方法检测污水处理厂的不同污泥样品中的大肠杆菌,回收率为89.4％～ 105.8％.     

金纳米颗粒表面能量转移及巯基化合物的检测

二氧化硅稳定的金纳米颗粒(Au-SiO₂)与罗丹明B之间发生表面能量转移,使罗丹明B荧光猝灭。 金纳米颗粒对罗丹明B的Stern-Volmer猝灭常数为4.3×10³ L/mol。 当荧光猝灭的混合体系中加入巯基化合物时,巯基化合物与金纳米颗粒发生强相互作用阻断罗丹明B-金纳米颗粒之间的能量转移,罗丹明B荧光恢复。 基于罗丹明B-Au-SiO₂体系对巯基化合物的单一响应,建立了一种简单快速检测巯基化合物的方法;并且由于二氧化硅对金纳米颗粒的稳定作用,金纳米颗粒成为一种可以回收利用的检测探针。     

巯基功能化膨润土吸附Pb2+的动力学和热力学研究

研究了自制巯基功能化膨润土(TFB)对Pb2+的吸附行为,考察了溶液的pH值、离子强度、吸附时间和温度对吸附平衡的影响,并对吸附过程进行了动力学与热力学研究.结果表明,常温下,吸附时间为60min、0.1mol/L的KNO3、pH=6.0、5.0g/L TFB对200mg/L的Pb2+的吸附率达到85.4％以上,TFB对Pb2+的吸附动力学符合准二级动力学方程;TFB对Pb2+的吸附热力学符合Langmuir等温线方程和Dubinin-Radushkevich (D-R)等温线方程,表明吸附主要发生在TFB表面的活性区域,属于单分子层吸附,其吸附平均活化能E在8-16kJ/mol范围内,表明该吸附过程为化学吸附,不同温度下的吸附热力学的吉布斯自由能以及熵变和焓变表明该吸附过程为自发放热反应.     

原位制备纳米功能化金电极快速检测牛奶中的微生物

在0.1 mol/L磷酸盐缓冲溶液(PBS,pH 7.0)中,于2.0V恒电位电解10 min,即可在金电极表面原位、快速制备纳米功能化修饰膜.经原子力显微镜表征,此修饰膜具有纳米尺度的蓬松结构.此纳米金膜对细胞膜上脂质过氧化反应具有显著的催化作用,因而对细菌产生电流响应.采用传统的标准平板计数法对试样进行细菌培养计数作为校正,以计时电流法电流响应作为输出信号进行细菌的测定,响应电流和细菌数量呈线性关系,据此可对牛奶样品中细菌浓度进行快速测定.本方法的测定范围为1.1×103～2.5×107 cfu/mL,检测时间缩短至1h以内,较平板计数法有显著改善.     

巯基功能化二氧化硅吸附Hg(Ⅱ)的研究进展

简单介绍了巯基功能化二氧化硅的种类及其制备。详细综述了巯基功能化介孔二氧化硅吸附剂和巯基功能化二氧化硅凝胶吸附剂,其中由于巯基对Hg²⁺有很强的酸碱相互作用,在众多重金属离子中,巯基功能化介孔二氧化硅吸附剂和巯基功能化二氧化硅凝胶吸附剂对Hg²⁺具有更好的吸附能力。最后综述了溶液pH值、吸附温度、吸附时间以及共存离子对Hg²⁺吸附过程的影响,并探讨了巯基功能化二氧化硅的再生性能。最后展望了其在含Hg²⁺污水治理行业的实际应用以及面临的机遇与挑战。     

纳米金颗粒增强信号的电化学生物传感器用于谷胱甘肽和半胱氨酸的检测

构建了一种高灵敏检测谷胱甘肽(GSH)和半胱氨酸(Cys)的新型电化学生物传感器. 先将富含T碱基的DNA1和DNA2探针分别修饰在金电极和纳米金颗粒(AuNPs)上, 再加入Hg²⁺, 通过形成T-Hg²⁺-T结构使AuNPs结合到金电极表面. 当加入GSH(或Cys)后, GSH(或Cys)可以竞争结合T-Hg²⁺-T结构中的Hg²⁺, 使AuNPs离开电极表面. 由于AuNPs上修饰的DNA探针能够静电吸附大量电活性物质六氨合钌(RuHex), 因此该过程可引起计时电量信号的显著变化, 据此实现了GSH(或Cys)的高灵敏检测. 该传感器的检出限达10 pmol/L, 比荧光法或比色法降低了2~3个数量级. 实验结果表明, 该传感器具有较好的选择性.     

Advanced Sensing of Antibiotics with Magnetic Gold Nanocomposite: Electrochemical Detection of Chloramphenicol

The sensing and accurate determination of antibiotics in various environments represents a big challenge, mainly owing to their widespread use in medicine, veterinary practice, and other fields. Therefore, a new, simple electrochemical sensor for the detection of antibiotic chloramphenicol (CAP) has been developed in this work. The amplification strategy of the sensor is based on the application of magnetite nanostructures stabilized with carboxymethyl cellulose (Fe₃O₄‐CMC) and decorated with nanometer‐sized Au nanoparticles (NPs) (Fe₃O₄‐CMC@Au). In this case, CMC serves as a stabilizing agent, preventing the aggregation of Fe₃O₄ NPs, and hence, enabling the kinetic barrier for electron transport to be overcome, and the Au NPs serve as an electron‐conducting tunnel for better electron transport. As a proof of concept, the developed nanosensor is used for the detection of CAP in human urine samples, giving a recovery value of around 97 %, which indicates the high accuracy of the as‐prepared nanosensor.     

层层自组装纳米金与乙酰胆碱酯酶电化学生物传感器检测有机磷农药

采用层层自组装技术制备了快速检测有机磷农药的生物传感器,利用带正电荷的高分子聚电解质聚二烯丙基二甲基氯化铵(PDDA)将乙酰胆碱酯酶(AChE)和金纳米粒子(AuNPs)通过静电力逐层固定到玻碳电极(GCE)表面,并采用交流阻抗和微分脉冲伏安法研究了此生物传感器的电化学行为。由于金纳米粒子优异的电催化性能和良好的生物相容性,使固定化的乙酰胆碱酯酶对其底物具有更高的亲和力和更快的响应速度。实验结果表明:修饰金纳米粒子后,传感器的氧化电流明显增大,在4.6×10-5～5.3×10-3mol/L范围内,固定化酶的抑制率与甲基对硫磷浓度的对数成正比,检出限为7.6×10-6mol/L。该生物传感器具有制备方法简便、成本低、灵敏度高等优点,已成功用于蔬菜样品中甲基对硫磷含量的测定。     

Ring‐disc Microelectrodes towards Glutathione Electrochemical Detection

An alternative approach for space‐resolved glutathione (GSH) detection using a ring‐disc microelectrode and an appropriate electroactive probe (acetaminophen) is reported. Acetaminophen is electrochemically oxidized at one of the electrodes and a fraction of the reaction product (N‐acetyl‐p‐quinoneimine) diffuses to the other, where it is detected. The collection efficiency value is dependent on the concentration of glutathione in solution, which consumes N‐acetyl‐p‐quinoneimine during its transit from the disc to the ring. Collection efficiency values close to 100 % were obtained by confining the electroactive species in a gap (<2 μm) that resembles a thin layer cell in a SECM configuration. The proposed indirect method was used to image the transport of GSH across an impermeable membrane in a SECM experiment. The method proved to be useful as a proof of concept for space‐resolved GSH electrochemical detection and a topography independent electrochemical image was acquired.     

基于引物延伸反应进行SNP基因分型的电化学方法

引物延伸反应的高特异性使其成为单核苷酸多态性(SNP)基因分型的最常用方法. 本文利用引物延伸反应, 通过二茂铁标记的dUTP将二茂铁引入到延伸的产物中, 用一条捕获探针将延伸产物捕获到电极表面, 用差分脉冲伏安法对电极表面的二茂铁进行检测, 从而实现了SNP基因分型. 考察了延伸反应的退火温度、聚合酶用量以及DNA杂交温度等因素的影响. 应用该方法对β-地中海贫血基因密码子28位单碱基突变进行检测, 获得了满意的基因分型结果. 该方法检测限可达到0.86 fmol/L, 是一种简便、快速且灵敏的SNP分型方法.     

Colorimetric and Electrochemical Methods for the Detection of SARS-CoV-2 Main Protease by Peptide-Triggered Assembly of Gold Nanoparticles

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) main protease (Mpro) has been regarded as one of the ideal targets for the development of antiviral drugs. The currently used methods for the probing of Mpro activity and the screening of its inhibitors require the use of a double-labeled peptide substrate. In this work, we suggested that the label-free peptide substrate could induce the aggregation of AuNPs through the electrostatic interactions, and the cleavage of the peptide by the Mpro inhibited the aggregation of AuNPs. This fact allowed for the visual analysis of Mpro activity by observing the color change of the AuNPs suspension. Furthermore, the co-assembly of AuNPs and peptide was achieved on the peptide-covered electrode surface. Cleavage of the peptide substrate by the Mpro limited the formation of AuNPs/peptide assembles, thus allowing for the development of a simple and sensitive electrochemical method for Mpro detection in serum samples. The change of the electrochemical signal was easily monitored by electrochemical impedance spectroscopy (EIS). The detection limits of the colorimetric and electrochemical methods are 10 and 0.1 pM, respectively. This work should be valuable for the development of effective antiviral drugs and the design of novel optical and electrical biosensors.     

基于聚硫堇/亚甲基蓝和纳米金放大的免疫传感器检测贝类毒素大田软海绵酸

采用聚硫堇(PTH)修饰电极为传感界面提供一个生物修饰功能基质膜,借助纳米金(GNPs)的导电性、生物相容性与高比表面积特性实现抗体的有效固定,并以亚甲基蓝(MB)为电子媒介加速电极表面电化学反应的电子传递,构建了一种高灵敏的非标记电化学免疫传感器,用于贝类毒素大田软海绵酸(OA)的检测。当分子结构中含有羧基和酚基的OA与其抗体特异性结合后,生成以阴离子形式存在的抗原-抗体复合物,阻碍了传感器表面电子的传递,导致峰电流下降。利用免疫反应前后峰电流的变化,可对OA进行特异性识别和准确定量。在优化实验条件下,OA浓度的对数在0.2~100 μg/L范围内与其峰电流的变化值(ΔI)呈线性相关,线性方程为ΔI=1.721 7+1.083 6lgρ,相关系数为0.992 0,检出限为0.1 μg/L。该免疫传感器重现性好、特异性强,用于实际贝类样品的测定,回收率为85.3%~112%。     

Continuous Electrochemical Detection of Gold Nanoparticles in Flow

Nanoparticles have already found numerous applications and their global production is still increasing. Therefore, the engineered nanoobjects of uncertain toxicity become ubiquitous in the environment and a continuous monitoring of their presence is highly desirable. Here, we demonstrate a continuous electrochemical detection of gold nanoparticles (AuNPs) based on synchronous processes of their electrodissolution and electrocatalysis. This approach is realized by the injection of nanoparticles suspension into the Flow Injection Analysis (FIA) system. The modular structure of FIA system is particularly applicable for carrying out of sequential operations: AuNPs passivation, oxidation of aqueous SO₂ and gold. It enables continuous, fast and reproducible gold nanoparticles determination in a wide concentration range: 10⁻¹⁰– 10⁻⁷ mol nanoobjects L⁻¹.     

Design and Development of a Non-Enzymatic Electrochemical Biosensor for the Detection of Glutathione

Glutathione (GSH-reduced form) is a tripeptide that plays a vital role as an antioxidant to remove xenobiotics in the human body and changes in GSH levels are a marker for the progression of various diseases. In this context, a highly sensitive non-enzymatic electrochemical biosensor for the detection of GSH has been developed using reduced graphene oxide Manganese oxide (rGMnO) nanocomposite as the nano-interface. Initially, graphene oxide was synthesized by Hummer's method and then thermally reduced in the presence of MnO₂ in a blast furnace to obtain rGMnO nanocomposite. The nanocomposite was characterized to validate its structure and morphological properties via Scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman, and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry and amperometry studies showed that upon the addition of GSH, the Pt/rGMnO modified working electrode exhibited a linear response in the range of 1–100 μM at an input voltage of −0.62 V. The developed sensor was found to have a sensitivity of 0.3256 μA μM⁻¹ and LOD of 970 nM with a recovery of 92–104 % in real blood serum samples.