利用分子印迹传感器选择性测定绿麦隆

以绿麦隆为模板分子,邻氨基酚为功能单体,在金电极表面电聚合制得具有特异性识别孔穴的绿麦隆分子印迹膜。采用循环伏安、差分脉冲伏安法研究了印迹膜的性能、结构、分子印迹效应和模板分析物,并比较了传感器对其它结构相似化合物的选择性响应,发现该传感器对绿麦隆检测具有良好的选择性。绿麦隆浓度在3.0×10-7~1.5×10-6mol/L范围内与峰电流呈线性关系,检出限为1.0×10-7mol/L,在干扰物质共存情况下的回收率为105%~116%。     

“门控制”效应分子印迹传感器测定绿麦隆

在氧化铂电极表面采用化学聚合法制得绿麦隆分子印迹膜传感器。利用"门控制"中"门"的数量变化控制催化性能的强弱,结合氧化铂对过氧化氢的催化放大效应,有效的提高了传感器的灵敏度并建立了对环境中绿麦隆残留的检测方法。研究了氧化铂电极对过氧化氢的催化效果,并对分子印迹膜聚合配比、过氧化氢浓度、洗脱时间、重吸附时间进行优化。在优化条件下,绿麦隆浓度在1.0×10^-88.0×10^-6mol/L范围内与氧化铂电极对过氧化氢的催化电流呈负相关性,检出限为5.4×10^-9moL/L。该传感器成功应用于农田水样的检测,其回收率为98.5%¹02.0%。     

基于多壁碳纳米管增敏材料的辣根过氧化物酶分子印迹电化学传感器的制备及对H2O2的检测

以辣根过氧化物酶(HRP)为蛋白质模板分子, 邻苯二胺(o-PD)为聚合单体, 首先将预先羧基化的多壁碳纳米管(MWCNTs)通过阶跃电位法电沉积在玻碳电极上作为增敏材料, 然后在该电极上电聚合含HRP的邻苯二胺电沉积液形成一层聚合膜, 去除模板化合物后, 制得对HRP具有特异性识别能力的分子印迹聚合物(MIPs)膜; 利用聚邻苯二胺(POPD)的自探针效应构建了分子印迹电化学传感器. 该传感器的响应电流与HRP浓度在1.0×10 ^-10~1.0×10 ^-5 mg/mL范围内有良好的线性关系, 相关系数为0.991, 检出限为1.5×10 ^-11 mg/mL(S/N=3); 该传感器的响应电流与H₂O₂浓度在4.0×10 ^-7~1.4×10 ^-5 mol/L范围内有良好的线性响应, 相关系数为0.992, 检出限为2.6×10 ^-7 mol/L(S/N=3), 将该传感器用于实际样品H₂O₂的检测, 回收率在91.2%~97.1%之间. 建立了基于MIPs膜的HRP和H₂O₂双分析物传感器的制备方法, 该方法可应用于酶及其酶促底物双分析物传感器.     

基于巯基乙酸与离子液体共修饰的过氧化氢生物传感器的研究

采用静电组装技术,将离子液体[Bmim]PF6与辣根过氧化物酶(HRP)交替固定在巯基乙酸修饰的金电极表面,制备了(HRP/[Bmim]PF6)n多层组装膜,并通过电化学阻抗谱(EIS)和傅立叶红外反射光谱(ATR-FTIR)对制备的组装膜进行了表征.以对苯二酚为电子媒介体,过氧化氢在(HRP/[Bmim]PF6)2双层组装膜传感器上的线性范围为1.6×10-6 ～2.5×10-3 mol/L,检出限为5.7×10-7 mol/L(S/N=3),达到95%稳态电流用时少于5 s,Kappm值为0.048 mmol/L,表明所固定的酶具有较高的生物活性.     

基于层层静电吸附天青Ⅰ和纳米金固定过氧化物酶生物传感器的研究

在玻碳电极(GCE)上,构造了一种以对氨基苯磺酸电聚合膜(PABSA)为基底,利用层层静电自组装技术固定多层天青Ⅰ(AI)和纳米金(nano-Au)制备的复合薄膜(nano-Au/AI)n,然后通过静电吸附辣根过氧化物酶(HRP)制得过氧化氢生物传感器[HRP/(nano-Au/AI)n/PABSA/GCE].采用循环伏安法和计时电流法考察了该传感器的电化学性质,并且研究了该修饰电极对H2O2的催化还原作用.在优化的实验条件下,该传感器的响应电流与其浓度在3.5×10-6～3.6×10-3 mol/L范围内呈现良好的线性关系,检出限为1.2×10-6 mol/L.该传感器的米氏常数为1.5 mmol/L,表明所固定的酶具有较高的生物活性.     

基于聚亚甲基蓝和碳纳米管/辣根过氧化物酶的有机过氧化物传感器

本文结合层层组装法和电化学聚合法,制备了电子介体聚亚甲基蓝(PMB)修饰的碳纳米管(CNTs)/辣根过氧化物酶(HRP)多层膜有机过氧化物传感器。利用电化学阻抗表征了(CNTs/HRP)n的层层组装过程,探讨了不同HRP层数对传感器响应的影响,并研究了传感器对有机过氧化物过氧化氢叔丁基、过氧化氢异丙基苯的电催化还原性能。该传感器对过氧化氢叔丁基的线性检测范围为1.75×10-5～7.25×10-3mol/L,检测限为1.36×10-6 mol/L;对过氧化氢异丙基苯的线性检测范围为3.87×10-6～1.47×10-3 mol/L,检测限为6.48×10-7 mol/L。     

基于门控制电催化效应的分子印迹传感器

以绿麦隆为模板分子,在镍电极表面聚合制得绿麦隆分子印迹膜。洗脱后的分子印迹膜重新吸附不同浓度绿麦隆分子,在印迹膜上形成不同量的印迹孔穴,H2O2通过印迹孔穴在镍电极表面产生电催化氧化,从而形成门控制电催化效应,以此对绿麦隆进行定量分析。研究表明,镍电极对H2O2有较好的催化效果,分子印迹聚合膜中模板分子、功能单体和交联剂的摩尔配比为1∶12∶30,重吸附时间为10 min,测试缓冲液pH=7.2。H2O2的催化电流值与绿麦隆浓度在1.0×10-4～4.0×10-7 mol/L范围内呈良好的线性关系;检出限为2.9×10-8 mol/L。将传感器应用于农田水样的检测,其回收率在97%～103%之间。     

一种基于碳纳米管的安培型过氧化氢生物传感器

利用硫堇(th ion ine,Th i)作为介体结合多壁碳纳米管(MWNTs)、壳聚糖(ch itosan,CH IT)、辣根过氧化酶(HRP)的混合包埋物制作过氧化氢(H2O2)生物传感器。研究结果表明所得传感器对H2O2具有明显的增敏效应,线性范围为0.03~5.5 mmol/L,相关系数为0.9995;检出限为19μmol/L(S/N=3),具有良好的稳定性及工作寿命。     

四羧基酞菁钴(Ⅲ)/Fe3O4/金胶共固定修饰免疫传感器检测尿样中核基质蛋白22

同时固定四羧基酞菁钴Ⅲ(CoPc)和HRP标记核基质蛋白22抗体(HRP-Ab-NMP22)于自组装在金电极表面的Fe3O4/Au胶上,构建了一种快速测定膀胱肿瘤患者尿液中NMP22抗原(NMP22)含量的安培免疫传感器。CoPc可被用作电极表面HRP的电子传递媒介体。当该传感器在含NMP22尿样的溶液中温育后,NMP22与HRP-Ab-NMP22免疫结合导致HRP的活性中心与CoPc之间的电子传递部分阻碍,使HRP对H2O2电催化还原电流Io降低。ΔIo与NMP22浓度在1.2~200μg/L呈线性关系;检出限为0.5μg/L。该传感器对NMP22响应灵敏,较ELISA法提高了检测速度,有望用于膀胱肿瘤的体外诊断。     

基于丝网印刷工艺的安培型酶免疫传感器的研究

研究了一种一次性安培型免疫传感器,检测辣根过氧化物酶(HRP)。用丝网印刷工艺制备三电极结构的传感器,工作电极是碳电极,银电极是伪参比电极。采用电荷传递系数、评估厚膜电极的一致性。通过戊二醛交联法,把抗HRP酶抗体固定在电极表面。加入底物H2O2和电子介体邻苯二胺,分别用安培法和比色法进行检测和比较分析。安培法测定HRP的测量范围10μg/L~10 mg/L,检出限10μg/L;比色法测定范围为2~40 mg/L,检出限2 mg/L。同时分析了湿度对传感器寿命的影响。     

苯基脲类除草剂分子印迹聚合物的合成和识别性能研究

以N-(4-异丙基苯基)-N′-亚丁基脲为模板, 甲基丙烯酸为功能单体, 乙二醇二甲基丙烯酸酯为交联剂制备了分子印迹聚合物(MIP). 研究了MIP对苯基脲类除草剂的亲和性和选择性. 在二氯甲烷流动相中制备的MIP对异丙隆(IP)、 非草隆(FN)、 甲氧隆(MX)、 敌草隆(DU)、 绿麦隆(CT)、 枯莠隆(DF)、 灭草隆(MN)、 草不隆(NB)、 播土隆(BT)和伏草隆(FU)等除草剂呈现出较高的亲和性, 而非印迹聚合物(NIP)对文中所用的14种苯基脲类除草剂均表现出非常低的保留或几乎没有保留. 实验及Mulliken电荷计算的结果显示， 苯基脲除草剂分子中的N′原子是主要的识别位点.     

Phenylurea herbicides-selective polymer prepared by molecular imprinting using N-(4-isopropylphenyl)-N′-butyleneurea as dummy template

A phenylurea herbicides-selective molecularly imprinted polymer (MIP) was prepared using N-(4-isopropylphenyl)-N′-butyleneurea as a dummy template and toluene as a porogen. The experimental results showed that the optimum molar ratio of template, functional monomer (MAA) and cross-linker (EDMA) was 1:8:20. Scatchard analysis showed that two classes of binding sites were formed in the imprinted polymer with dissociation constants of 26.81 μmol l⁻¹ and 1.428 mmol l⁻¹. The affinity and selectivity of MIP for phenylurea herbicides were studied. Among the 14 phenylurea herbicides tested, the MIP prepared showed obviously high affinity and selectivity for 10 chemicals (monuron, diuron, isoproturon, fenuron, chlortoluron, difenoxuron, metoxuron, neburon, buturon and fluometuron) with dichloromethane containing 10% hexane as mobile phase while non-imprinted polymer showed very low affinity for all the phenylurea herbicides tested. The experimental and calculated results also indicated that the size and property of the group at the N′ position of phenylurea molecules have great influence on the affinity of MIP for them and the recognition site is mainly located at the N′ position of phenylurea herbicides.     

表面增强拉曼光谱法对水中残留绿麦隆的检测

利用银镜反应原理在玻璃片上镀一层具有表面增强拉曼散射(SERS)效应的表面粗糙的银膜,通过测定农药绿麦隆在银镜表面上的表面增强拉曼光谱,探讨了绿麦隆在银镜表面的吸附取向。结果表明,在银镜表面,当绿麦隆浓度小到10-10mol L时,仍然能得到明确的光谱信息,且吸附饱和时间仅为2h,这为探索水体中微量污染物的检测方法提供了一个很好的途径。     

An electrochemical sensor for rapid determination of ractopamine based on a molecularly imprinted electrosynthesized o-aminothiophenol film

A simple electrochemical sensor based on a molecularly imprinted polymer film as the recognition element was developed for ractopamine (RAC) detection. This is the first report of a RAC-imprinted film on a gold electrode surface, synthesized through an electrochemical method using o-aminothiophenol as the functional monomer. The imprinting mechanism and experimental parameters affecting the capability of the imprinted film are discussed here. The sensor was successfully applied with constant potential amperometry for RAC detection in an indirect process with potassium ferricyanide as an electrochemical probe. The sensor had a rapid equilibrium time (120?s), high binding affinity and selectivity towards RAC, and with good reproducibility and stability. Under the experimental conditions applied, a linear relationship between the relative amperometric response and RAC ranged from 2.0?×?10(-7) to 1.4?×?10(-6)?mol?L(-1), with a lower limit of detection (LOD) of 2.38?×?10(-8)?mol?L(-1) (signal to noise ratio?=?3). The sensor was tested with feed samples spiked with trace amounts of RAC, with good recoveries between 87.4 and 90.5?%.     

Monitoring of phenylurea and propanil herbicides in river water by solid-phase-extraction high performance liquid chromatography with photoinduced-fluorimetric detection

The separation and determination of five herbicides, including propanil and the phenylureas diuron, isoproturon, linuron and neburon, has been performed by an HPLC method, using photochemically-induced fluorescence detection. The non-fluorescent herbicides were transformed into fluorescent compounds by post-column photochemical reaction. A 60:40 (v/v) acetonitrile-buffer solution of potassium phosphate dibasic (pH 7, 0.01 M) was used for the chromatographic elution to separate propanil, linuron and neburon. The overlapping of isoproturon and diuron peaks, in the selected conditions, was resolved by changing the initial movil phase composition to 50:50 (v/v) methanol-buffer solution of potassium phosphate dibasic (pH 7, 0.01 M). The procedure was applied with satisfactory results to the analysis of these herbicides in Guadiana river water samples (Badajoz, Spain), allowing the detection of herbicide residues in the order of mug l(-1), by using a solid-phase extraction (SPE) pre-concentration step.     

Gas chromatographic behaviour of urea herbicides

Summary Gas chromatographic conditions for determining eight phenylurea (chlortoluron, diuron, fluometuron, isoproturon, linuron, metabenzthiazuron, metobromuron and monuron) and one sulfonylurea (chlorsulfuron) herbicides were assessed. Degradation products of the herbicides formed in the injector were used for identification. Most phenylureas formed their respective carbamic acid methyl esters, metabenzthiazuron formed an aminobenzothiazol and chlorsulfuron formed an aminotriazine plus a phenylsulfonamide. On-column injection of standards using a BP10 capillary column was evaluated to identify the chromatographic behaviour. Detection limits ranged from 0.05 ng for chlorsulfuron to 3 ng for monuron with the NPD and, from 0.01 ng for chlorsulfuron to 5 ng for metabenzthiazuron with the ECD. The RSDs (n=4) were lower than 4% at the 12–25 ng level. The method was applied to the analysis of surface waters extracted with C18 Empore disks with recoveries higher than 85%. Each herbicide could be determined in water down to 0.1 μg·L⁻¹. Chlortoluron was found (11.4 μg·L⁻¹) in a water sample and its presence was confimed by gas chromatography-mass spectrometry.     

Use of on-line liquid chromatography-nuclear magnetic resonance spectroscopy for the rapid investigation of flavonoids from Sorocea bomplandii

A HPLC method, using photochemically-induced fluorescence detection, is described for the separation and determination of four phenylurea herbicides including diuron, isoproturon, linuron and neburon. A post-column photoreactor, consisting of a reactor knitted around a 4 W xenon lamp, has been included between the column and the detector, in order to transform the non-fluorescent herbicides into fluorophors. The influence of mobile phase composition, flow-rate, pH, and buffer concentration has been studied. An acetonitrile–buffer solution of potassium phosphate dibasic of pH 7 and 0.01 M concentration (60:40, v/v), was selected as optimum. For the fluorimetric detection, optimal excitation/emission wavelengths 324/403, 301/433, 335/411 and 326/385 nm were selected for the determination of diuron, isoproturon, linuron and neburon, respectively. The detection limits ranged between 0.07 and 0.46 μg/ml, according to the compound.     

Application of a novel electrosynthesized polydopamine-imprinted film to the capacitive sensing of nicotine

The application of novel electrosynthesized polydopamine (PDA)-imprinted film as a recognition element for the capacitive sensing of nicotine is reported. The PDA-imprinted film was electropolymerized directly on the gold electrode surface in the presence of nicotine without an additional self-assembled thiol sublayer. The compact PDA film has various functional groups that aid the imprinting procedure. Furthermore, the film shows good capacitive response since it is insulating in nature and ultrathin. The sensor’s linear response range for nicotine was between 1–25 μmol L⁻¹, with a detection limit of 0.5 μmol L⁻¹. The proposed molecularly imprinted polymer capacitive (MIPC) sensor exhibited good selectivity for nicotine. The reproducibility and repeatability of the MIPC senor were all found to be satisfactory. The results from sample analysis confirmed the applicability of the MIPC sensor to quantitative analysis.