【作者】 刘倩；

【导师】 蔡健荣；

【作者基本信息】 江苏大学 ， 农产品加工及贮藏工程， 2014， 博士

【摘要】 农药残留已对生态环境和人类健康造成了极大威胁,因此发展简便快捷、灵敏可靠的农药检测方法,已成为迫在眉睫的重要研究课题。与经典的色谱法相比,电化学传感检测法因具有灵敏度高、分析速度快、成本低等优点,更适合于饮用水以及农作物中农药残留的简便快捷、灵敏可靠检测。其中电化学传感功能界面的构建,是发展电化学传感器检测法的关键步骤,而将纳米科学与电化学技术有效结合,是目前电化学传感器的发展热点和趋势。本文利用合成的具有优异物理化学性能的石墨烯基功能纳米材料,构建了几种新型传感平台,并结合光电化学(PEC)、电化学发光(ECL)和安培传感等电化学检测技术,发展了几种可用于农药残留检测的电化学传感方法,具体内容如下：(1)耦合PEC技术-酶抑制原理,研制了一种可用于有机磷农药毒死蜱的快速、灵敏检测的酶抑制型PEC传感器。研究表明,合成的Cd0.5Zn0.5S/石墨烯功能纳米材料不仅具有良好的生物相容性,有效地保持固定在电极表面的乙酰胆碱酯酶(AChE)活性,而且其优异的PEC性能还为目标分析物检测提供了良好的传感平台。在优化条件下,所研制的PEC传感器响应光电流的减小值(ΔI)与毒死蜱浓度的对数呈良好的线性关系,其线性范围为1ng mL-1～1μg mL-1,检测下限为0.3ng mL-1；同时该传感器具有较好的重现性和稳定性。(2)以原位法制备的CdS纳米晶/石墨烯量子点(CdS NCs/GQDs)为ECL传感平台,研制了一种可用于有机氯农药五氯苯酚(PCP)检测的ECL传感器。研究表明,与CdS NCs相比,CdS NCs/GQDs功能纳米材料的ECL信号不仅增强了4倍,而且ECL的起始电位降低了80mV。在优化条件下,所研制传感器的ECL信号强度与PCP浓度的对数呈良好的线性关系,其线性范围为0.01-500ng mL-1,检测下限为3pg mL-1；另外,该传感器具有较好的重现性和稳定性,可应用于实际样中PCP的痕量测定。(3)利用所制备的CdS NCs/GQDs功能纳米材料良好的PEC性能,以集成的丝网印刷电极为固定化平台,研制了一种可用于有机磷农药甲基对硫磷灵敏测定的可抛式PEC传感器。研究表明,与CdS NCs相比,制备的CdS NCs/GQDs功能纳米材料的PEC信号增强了4倍,这归因于GQDs良好的电子传导能力。在优化条件下,所研制的传感器的响应光电流与甲基对硫磷浓度的对数呈良好的线性关系,其线性范围为0.01-100ng mL-1,检测下限为3pgmL-1；同时该传感器具有装置简单、响应时间短以及稳定性好等优点。(4)以部分氧化剥离的多壁碳纳米管(MWCNTs)制得的核壳结构MWCNTs@氧化石墨烯纳米带(MWCNTs@GONRs)为信号放大材料,鲁米诺为ECL发光体,研制了一种可应用于PCP测定的ECL传感器。研究表明,修饰在电极表面的MWCNTs@GONRs有效地催化了鲁米诺的氧化还原反应,与裸电极相比,鲁米诺在MWCNTs@GONRs修饰电极上的氧化峰电流增强了约3倍；其相应的ECL强度增强了约4.4倍。在优化条件下,该传感器ECL信号强度与PCP浓度的对数呈良好的线性关系,其线性范围为2pgmL-1～10ngmL-1:检测下限为0.7pg mL-1;同时该传感器具有较理想的重现性和稳定性。(5)进一步以MWCNTs@GONRs为AChE固定化材料,研制了一种可应用于氨基甲酸酯类农药西维因的安培型电化学传感器。研究表明,MWCNTs@GONRs为AChE的固定化提供了良好的生物相容性环境,有效保持了AChE良好的电催化活性。另外,固定在MWCNTs@GONRs表面的AChE对其催化底物氯化硫代乙酰胆碱具有较高的亲和性和催化活性,其米氏常数为0.25mmol L-1。该传感器的酶抑制率与西维因浓度的对数呈良好的线性关系,其线性范围为1ng mL-1～1μg mL-1,检测下限为0.3ng mL-1;同时该传感器具有良好的稳定性和重现性。(6)以一步溶剂热法制备的Fe3O4纳米粒子功能化石墨烯纳米带(Fe3O4/GNRs)为传感平台,研制了一种可应用于多巴胺测定的安培型电化学传感器。研究表明,与Fe3O4/石墨烯相比,Fe3O4/GNRs具有更好的电催化活性。所制备传感器的安培响应与多巴胺浓度呈良好的线性关系,其线性范围为1-30μmol L-1,检测下限为0.3μmolL-1。更多还原

【Abstract】 Public concern over pesticide residues has been increasing dramatically owing to the high toxicity and bioaccumulation effects of pesticides and the serious risks that they pose to the environment and human health. The development of biosensors for pesticides has been an active research area for some years in response to the demand for rapid, simple, selective, and low-cost techniques for pesticide detection, which offer great advantages over conventional analytical techniques, including high specificity for real-time analysis in complex mixtures, high sensitivity, simple operation without the need for extensive sample pretreatment, and low cost. Driven by these needs, great efforts have been made in the design, fabrication, and applicatio n of nanomaterials for electrochemical sensing devices. By incorporation of graphene-based functionalized nanomaterials in the fabrication of electrochemical sensor for pesticide residue and based on the electrochemical techniques such as photoelectrochemical (PEC), electrochemiluminescent (ECL), amperometric methods, herein, several electrochemical sensors have been successfully constructed for pesticide residue determination, as described as follows:(1) A visible light PEC platform coupled with enzyme-inhibition for rapid and sensitive determination of dursban was constructed based on dual-functional Cd0.5Zn0.5S/graphene (Cd0.5Zn0.5S/G) nanocomposite. Due to the inherent biocompatibility and remarkable PEC property of Cdo.5Z110.5S/G nanocomposite, the acetylcholinesterase (AChE) immobilized on the modified electrode can hydrolyze acetylthiocholine chloride into thiocholine, which could increase the photocurrent of the modified enzyme electrode, and the further inhibition of dursban on the enzyme electrode could decrease the photocurrent response. Based on the notable change of dursban in PEC response of the AChE-Cd0.5Zn0.5S/G modified electrode, a simple and effective way for PEC monitoring of dursban is proposed, which showed wide liner range of1ng mL-1～1μg mL-1with a low detection limit of0.3ng mL(2) Based on the amplifying ECL behavior of graphene quantum dots/CdS nanocrystals (CdS NCs/GQDs), an ultrasensitive ECL sensor was constructed for the detection of pentachlorophenol (PCP). Due to the presence of the doped GQDs, the resulting CdS NCs/GQDs exhibited4-fold enhanced ECL intensity than pure CdS NCs with the ECL onset potential80mV positively shifted. Furthermore, based on the effective inhibition of PCP on the ECL response of CdS NCs/GQDs film, a simple method for ultrasensitive determination of PCP was constructed, which showed wide linear range of0.01～500ng mL-1and low detection limit of3pg mL-1with good stability and reproducibility.(3) A novel PEC sensor for detection of the organophosphorus (OPs) pesticide parathion-methyl using CdS NCs/GQDs coupled with a screen-printed efectrode is presented. The CdS NCs/GQDs inherited the excellent electron transport of GQDs and facilitated the spatial separation of photo-generated charge carrier, resulting in the enhanced photocurrent4-fold higher than CdS NCs under visible irradiation. Based on the inhibition of parathion-methyl on the PEC response of CdS NCs/GQDs modified electrode, a simple way for PEC detection of parathion-methyl was proposed, which show good performances with a wide linear range (0.01-100ng mL-1), low detection limit (3pg mL-1), instrument simple and portable, rapid response and good stability.(4) Based on the signal amplification of core-shell structure MWCNTs@GONRs on the ECL signal of luminol, a novel ECL sensor for PCP determination was constructed. The MWCNTs@GONRs modified on the electrode can catalyze the luminol oxidation process, compared with bare electrode, the ECL of luminol was enhanced for4.4-fold on the MWCNTs@GONRs modified electrode. And PCP is found to be able to enhance the ECL intensity, based on this, a method for PCP detection was fabricated. An acceptable linear range was obtained between the log[PCP] and ECL intensity with a limit of detection of0.7pg mL-1. Moreover, the method exhibits good stability and reproducibility, which provide new way for application of MWCNTs@GONRs in pesticide determination.(5) Based on AChE immobilized on MWCNTs@GONRs nanostructure, a rapid and sensitive organophosphates amperometric biosensor was fabricated. The MWCNTs@GONRs can provide a unique microenvironment for AChE, and the immobilized AChE on the MWCNTs@GONRs modified electrode can possess its native structure and electrocatalytic activities effectively. The as-prepared biosensor shows high affinity to acetylthiocholine with a Michaelis-Menten constant value of0.25mmol L-1. Based on the inhibition of carbaryl on the enzymatic activity of the immobilized AChE, the resulting biosensor exhibits excellent performance for carbaryl detection including good reproducibility, acceptable stability, and a reliable linear relationship between the inhibition and log[carbaryl] from1ng mL-1up to1μg mL-1with a detection limit of0.3ng mL-1.(6) Fe3O4/functionalized graphene nanoribbons (Fe3O4/GNRs) were prepared in situ by a facile one-step solvothermal process, and further, an amperometric electrochemical sensor for the determination of dopamine was fabricated based on the resulting Fe3O4/GNRs. The result indicated that the electrochemical activity of Fe3O4/GNRs was better than Fe3O4-functionalized graphene nanosheets (Fe2O4/G) for the redox of dopamine. The resulting electrochemical sensor showed a linaer range of1～30μmol L-1with a detection limit of0.3μmol L-更多还原