应用功能化的金纳米通道分离阿特拉津和百草枯

将金(Ⅰ)通过化学沉积法于4℃经9h使之沉积于聚碳酸酯滤膜(孔径100nm)的内孔壁上,从而制得金纳米通道膜。经清洗并干燥后的膜在十八烷基硫醇[CH3(CH2)16CH2SH](0.1+99.9)溶液中浸泡12h,从而使金纳米通道膜被十八烷基硫醇修饰(将此膜简写作C18SH-Mem)并使其呈疏水性。试验在分离装置的样品池中加入阿特拉津和百草枯两种农药的混合溶液,并使其通过C18H37SH-Mem,经过一定时间后,在膜另一端的检测池中对上述两农药分别在222nm及257nm波长处进行检测。结果表明:在检测池中只测得疏水性的阿特拉津而未能测得百草枯,说明亲水性的百草枯不能在疏水性的经修饰的金纳米通道中迁移。据此,应用修饰后的金纳米通道可达到上述两农药的完全分离。     

金纳米通道的研究及其在分析化学中的应用

微纳尺度的研究是微纳米技术的重要组成部分。本文重点对金纳米通道的制备及其在分离分析、传感器等方面的研究和应用作了评述。展望了金纳米通道的应用前景。     

小分子阿特拉津和罂粟碱检测的免疫芯片技术研究

采用蛋白芯片竞争法对小分子半抗原的污染物进行检测。在获得特异性抗体的前提下,首先将阿特拉津半抗原进行了衍生化,然后将该衍生物和氨基罂粟碱分别与载体蛋白质卵清蛋白(OVA)进行偶联。实验证明新合成的完全抗原能够与其相应抗体发生特异性的结合。实验还对蛋白芯片检测阿特拉津进行了条件优化,其抗体固定化时间为2h,用卵清蛋白为封闭液的封闭时间为1h,样品稀释液pH值为8．0。并对阿特拉津及罂粟碱进行了定性、定量实验,结果表明：荧光信号强度随待测物浓度的降低而增强,有一定的线性趋势,阿特拉津检出限为0．001mg/L,罂粟碱检出限为0．01mg/L。     

阿特拉津在聚碳酸酯膜中的迁移性能研究

采用紫外分光光度法研究不同条件下阿特拉津在孔径为100 nm的聚碳酸酯膜上的迁移性能的差异,考察黑壤腐植酸与阿特拉津的结合情况.实验结果表明:溶液pH值范围为5.3 ～7.4时,阿特拉津吸光度相对稳定;不同浓度阿特拉津在聚碳酸酯膜上的迁移量与浓度呈线性关系,线性方程为γ=0.0792x-0.0016,R2=0.9999;溶液pH为6.4,阿特拉津与腐植酸的结合效果最好;离子强度逐渐增加对阿特拉津与腐植酸的结合有一定的抑制作用.     

羊抗人IgG在金纳米通道中的迁移

以聚碳酸酯超滤膜为基板,用化学镀的方法在超滤膜上沉积金,制得直径在45nm左右的金纳米通道阵列,利用制得的金纳米通道阵列搭建离子电流测量平台,可实现对羊抗人IgG分子的浓度检测.当羊抗人IgG分子通过直径45nm的金纳米通道时,由于物理占位及表面电荷的影响,会引起离子电流发生变化;在KCl浓度为0.15mol/L(pH7.48)溶液中,IgG分子的物理占位对离子电流有阻塞作用,会导致电流减小,IgG浓度在1.8～18ng/mL范围内,减小量与浓度成线性关系;实现了对IgG的定量检测.KCl浓度降低到0.025mol/L时,由于IgG分子扩散层内反离子对通道内离子浓度的贡献占主导地位,从而造成离子电流随着IgG浓度增大而增大.     

牛血清白蛋白在修饰氯离子金纳米通道中的迁移研究

采用化学镀的方法在聚碳酸酯模板上沉积金,制成金纳米通道膜,并对它进行Cl-修饰得到带负电荷的通道。再采用电化学方法(i-t法)对牛血清白蛋白(BSA)在修饰通道中的迁移进行研究。在pH7.4PBS中,对通道两端施加1.0V电压,溶液中离子迁移通过纳米通道时产生电流响应。当溶液中加入BSA后,电流响应减小,且响应变化量与浓度在1.50×10-10~1.35×10-9mol/L范围内呈线性关系,其线性回归方程为|Δi|(μA)=0.0069 0.125c(×10-9mol/L),相关系数为0.9980,检出限为9.46×10-11mol/L(S/N=3)。     

基于金纳米通道膜检测脱氧核糖核酸的研究

采用化学沉积的方法在聚碳酸酯膜上沉积金纳米颗粒得到金纳米通道膜,并用探针DNA对金纳米通道进行修饰。基于目标DNA与探针DNA杂交后,金纳米通道膜(孔径为30 nm左右)交流阻抗信号的变化,发展了一种无需标记的DNA的检测方法。该方法获得的线性回归方程为ΔR(Ω)=21.05 0.21C(nmol/L),线性相关系数为0.9864;线性检测范围为35~450 nmol/L,检出限为20 nmol/L。这种金纳米通道膜在DNA或RNA的检测及分离方面具有较好的应用前景。     

纳米金/聚多巴胺-还原氧化石墨烯复合膜修饰传感器的构建及对百草枯测定研究

实验利用氧化石墨烯和多巴胺分子制备了聚多巴胺-还原氧化石墨烯(PDA-rGO)复合膜,建立了高灵敏的纳米金/聚多巴胺-还原氧化石墨烯复合膜传感器(Au/PDA-rGO/GCE),用于检测百草枯并利用差分脉冲伏安法(DPV)和循环伏安法(CV)研究了百草枯在传感器上的电化学行为。首先,通过在碱性溶液中多巴胺的聚合反应来还原氧化石墨烯,以获得聚多巴胺改性的还原氧化石墨烯。其次,在电极表面滴涂10μL的聚多巴胺-还原氧化石墨烯悬浮液,在此基础上固定纳米金(GNPs)。结果表明,该传感器对百草枯有良好的电化学催化作用。实验优化了聚多巴胺-还原氧化石墨烯的制备条件和电极修饰条件。百草枯的还原峰电流在8.0×10^-8～3.0×10^-5 mol·L^-1范围内线性关系良好,检出限为2.2×10^-8 mol·L^-1。该修饰电极用于实际水和土壤样品中百草枯的测定,结果令人满意。     

加速溶剂萃取-气相色谱/质谱法测定灯盏花及其土壤中阿特拉津和二甲戊乐灵残留

建立了加速溶剂萃取(ASE)-气相色谱/质谱法(GC/MS)同时测定灯盏花及其土壤中阿特拉津和二甲戊乐灵2种除草剂的农药残留。样品采用丙酮-二氯甲烷(1∶1,V/V)加速溶剂萃取,弗罗里硅土柱层析净化,用GC/MS选择离子监测(SIM)法测定。结果表明,2种除草剂在0.05~2.00mg/L范围内线性良好,相关系数分别为0.9987~1.0000(灯盏花),0.9880~0.9980(土壤);在0.1、0.5和1.0mg/L添加水平下,2种除草剂在灯盏花及其土壤中的平均回收率分别为67.38%~104.02%和71.69%~105.58%,相对标准偏差(RSD)分别为3.21%~13.48%和2.65%~18.26%,方法的检出限(LOD)在灯盏花中为3.00~4.10ng/g,在土壤中为1.50~2.50ng/g。应用该法成功测定了云南省灯盏花及其土壤样品中2种除草剂残留。     

纳通道的物质传输特性及应用

近年来,随着材料科学、微纳加工技术和微纳尺度物质传输理论的发展,纳通道技术得到了越来越多的研究和关注。纳通道包括生物纳通道和人工纳通道,其孔径通常为1～100 nm。在这一尺度下,通道表面与通道内物质之间的作用概率大大增强,使得纳通道表现出许多与宏观体系不同的物质传输特性,例如通道表面电荷与通道内离子之间的静电作用产生了离子选择性,通道内电化学势的不对称分布产生了离子整流特性,物质传输过程中占据通道产生了阻塞脉冲特性等。纳通道中的这些物质传输特性在传感、分离、能源等领域具有广泛应用,例如通过对纳通道进行功能化修饰可以实现门控离子传输;利用亚纳米尺度的通道可以实现单分子传感;利用通道与传输物质之间的相互作用可以实现离子、分子、纳米粒子的分离;利用纳通道的离子选择性可以在通道内实现电荷分离,将不同形式的能量(如光、热、压力、盐差等)高效转化为电能。纳通道技术是化学、材料科学、纳米技术等多学科的交叉集合,在解决生物、环境、能源等基本问题方面具有良好的前景。该文综述了近10年来与纳通道物质传输理论以及纳通道技术应用相关的前沿研究,梳理了纳通道技术的发展过程,并对其在各个领域的应用进行了总结与展...     

Extraction mechanisms of charged organic dye molecules into silica-surfactant nanochannels in a porous alumina membrane

Extraction mechanisms of charged organic dye molecules are examined for an assembly of silica-surfactant nanochannels with a channel diameter of 3.4 nm, which is formed inside the pores of an anodic alumina membrane by a surfactant-template method. Experimental results confirm that the extraction mechanism depends on the sign of a charge of the dye molecules. The extraction of the cationic rhodamine 6G is predominantly caused by an ion-pair extraction process, whereas an anion-exchange process is mainly responsible for the extraction of the anionic sulforhodamine B. These extraction mechanisms are discussed by considering the microstructures of the silica-surfactant nanochannels.     

New competitive dendrimer-based and highly selective immunosensor for determination of atrazine in environmental,feed and food samples: The importance of antibody selectivity for discrimination among related triazinic metabolites

A new voltammetric competitive immunosensor selective for atrazine, based on the immobilization of a conjugate atrazine-bovine serum albumine on a nanostructured gold substrate previously functionalized with poliamidoaminic dendrimers, was realized, characterized, and validated in different real samples of environmental and food concern. Response of the sensor was reliable, highly selective and suitable for the detection and quantification of atrazine at trace levels in complex matrices such as territorial waters, corn-cultivated soils, corn-containing poultry and bovine feeds and corn flakes for human use. Selectivity studies were focused on desethylatrazine, the principal metabolite generated by long-term microbiological degradation of atrazine, terbutylazine-2-hydroxy and simazine as potential interferents. The response of the developed immunosensor for atrazine was explored over the 10⁻²–10³ ng mL⁻¹ range. Good sensitivity was proved, as limit of detection and limit of quantitation of 1.2 and 5 ng mL⁻¹, respectively, were estimated for atrazine. RSD values <5% over the entire explored range attested a good precision of the device.     

Development of an ELISA procedure to study sorption of atrazine onto a sewage sludge-amended luvisol soil

Pesticides may contaminate ground and surface waters and one of the major factors governing this property is soil sorption. Sorption can be assessed by batch equilibrium technique which produces lots of extracts with high dissolved organic carbon concentration in which the pesticide concentration has to be determined. We developed an ELISA procedure to analyse atrazine based on polyclonal antibodies (C193) for which tracer structure and dilutions of immunochemical reagents were adapted to fit the purpose. After a 1000-fold dilution (or after an SPE clean-up procedure) extracts of a sewage-sludge amended luvisol (used as an example application of the methodology developed) could be reliably analysed. The Freundlich model is able to describe adsorption for this system (r² = 0.977) delivering a distribution coefficient K_F of 1.6 ± 0.2 (mg kg⁻¹) (mg L⁻¹)^−N and an isotherm nonlinearity factor N of 0.70 ± 0.09.     

Part per trillion determination of atrazine in natural water samples by a surface plasmon resonance immunosensor

A new immunoassay for continuously monitoring atrazine in water has been developed. It uses a portable biosensor platform based on surface plasmon resonance (SPR) technology. This immunoassay is based on the binding inhibition format with purified polyclonal antibodies, with the analyte derivative covalently immobilized on a gold sensor surface. An alkanethiol self-assembled monolayer (SAM) was formed on the gold-coated sensor surface in order to obtain a reusable sensing surface. The low detection limit for the optimized assay, calculated as the concentration that produces a 10% decrease in the blank signal, is 20 ng/L. A complete assay cycle, including regeneration, is accomplished in 25 min. Additionally, a study of the matrix effects of different types of wastewater was performed. All measurements were carried out with the SPR sensor system (β-SPR) commercialised by the company Sensia, S.L. (Spain). The small size and low response time of the β-SPR platform would allow it to be used in real contaminated locations. The immunosensor was evaluated and validated by measuring the atrazine content of 26 natural samples collected from Ebro River. Solid-phase extraction followed by gas chromatography coupled to mass spectrometric detection (SPE–GC–MS) was used to validate the new immunoassay.     

Voltammetric detection of paraquat pesticide on a phthalocyanine-based pyrolitic graphite electrode

This work describes the application of an ordinary pyrolitic graphite electrode modified by metallophthalocyanine allied to square wave voltammetry for the study of the electrochemical behavior of the herbicide paraquat and the development of a method for its analytical determination in natural water samples. Preliminary experiments indicated that the best responses, considering the intensities of the current and voltammetric profile for the paraquat reduction process, were obtained when the electrode modified by cobalt phthalocyanine was employed, which had a better catalytic activity as a result of this modification compared with that for an unmodified electrode and electrodes modified by iron, manganese and the acid form of the phthalocyanines. Studies of the concentration of cobalt phthalocyanine and the adsorption time showed that 1.0 × 10⁻⁴ mol L⁻¹ cobalt phthalocyanine with an adsorption time of 10 min was sufficient to obtain reliability and stability of modification for employment in the development of the electroanalytical procedure for paraquat determination in natural water samples. The variation in pH of a 0.10 mol L⁻¹ Britton–Robinson buffer solution and the square wave parameters indicated that the best conditions to reduce paraquat were pH 7.0, a frequency of 100 s⁻¹, a scan increment of 2 mV and a square wave amplitude of 50 mV. Under such conditions, the variation of paraquat concentrations from 5.00 × 10⁻⁷ to 2.91 × 10⁻⁵ mol L⁻¹ showed a linear relation, with detection and quantification limits of 26.53 and 88.23 μg L⁻¹; those values were lower than the maximum limits for drinking water permitted by the Brazilian Environmental Council (100 μg L⁻¹), indicating that the method could be employed to analyze paraquat in drinking water samples.     

Evaluation of the potential of Potamogeton crispus and Myriophyllum spicatum on phytoremediation of atrazine

Atrazine is one of the most frequently detected pesticides and poses a great risk to humans and the environment. In this study, the effects of two submerged macrophytes, Potamogeton crispus and Myriophyllum spicatum, on phytoremediation of atrazine were evaluated. The results showed that atrazine decayed faster in the pots where these two plants were cultivated than that of the control without the plants during the 60-day course of the experiment. Metabolite analyses of atrazine indicated that atrazine was mainly converted to diaminochlorotriazine and hydroxyatrazine. Dissipation kinetics and risk assessment of atrazine showed that atrazine was degraded rather fast in maize and generally safe for human consumption at the recommended high dosage of atrazine. The maximum permissible intake (MPI) for atrazine was calculated to be 0.23 μg/person/day for a child and 0.72 μg/person/day for an adult. However, due to the large-scale application of atrazine over the years, the atrazine residue still poses a great threat to the environment. By using submerged macrophytes M. spicatum and P. crispus, atrazine could be absorbed from the sediment, hence remediating contaminated sediment and water. This study established a protocol for evaluating submerged plants in absorption or phytoremediation of pesticides.     

Conductometric tyrosinase biosensor for the detection of diuron, atrazine and its main metabolites

The determination of diuron, atrazine, desisopropylatrazine (DIA) and desethylatrazine (DEA) were investigated using conductometric tyrosinase biosensor. Tyrosinase was immobilised on the biosensor sensitive part by allowing it to mix with bovine serum albumin (BSA) and then cross-linking in saturated glutaraldehyde (GA) vapour for 30 min. The determination of pollutants in a solution was performed by comparison of the output signal (i.e percentage of the enzymatic activity) of the biosensor before and after contact with pollutants. The measurement of the enzymatic activity was performed using 4-chlorophenol, phenol and catechol substrates and response times ranging from 1 to 5 min were observed. A 4-chlorophenol substrate was used to detect pesticides. A 30 min contact time of the biosensor in the pollutant solution was used. Under the experimental conditions employed, detection limits for diuron and atrazine were about 1 ppb and dynamic range of 2.3-2330 and 2.15-2150 ppb were obtained for diuron and atrazine, respectively. A relative standard deviation (n=3) of the output signal was estimated to be 5% and a slight drift of 1.5 μS h⁻¹ was observed. The 90% of the enzyme activity was still maintained after 23 days of storage in a buffer solution at 4 °C.     

A simple method for the spectrophotometric determination of atrazine using p-aminoacetophenone and its application in environmental and biological samples

A spectrophotometric method is described for the determination of the widely used herbicide, atrazine. Atrazine reacts with pyridine and forms a quaternary halide which adds a hydroxyl group in the presence of alkali to form a carbinol base. The heterocyclic ring of the resulting carbinol breaks forming a glutaconic dialdehyde which is subsequently coupled with p-aminoacetophenone (PMP) to form a yellow orange polymethine dye. Beer's law is obeyed in the range 0.16–1.6 ppm of atrazine at 470 nm. The method is sensitive and free from the interference of most of the foreign species. The analytical parameters have been optimised and the method has been successfully applied to the determination of atrazine in various environmental and biological samples.