【作者】 张淑平；

【导师】 施利毅；

【作者基本信息】 上海大学 ， 材料学， 2008， 博士

【摘要】 有机磷和氨基甲酸酯类农药是目前使用最广泛的农药和杀虫剂。作为神经毒剂,这两类农药会抑制人及动物体内乙酰胆碱酯酶活性。农药残留常用的检测方法为色谱法、质谱法以及波谱法等,通常耗时长、成本高,难以满足现场快速检测的需要。而免疫分析法、生物传感器检测法及酶抑制法等具有高效快速检测等特点。近几年来,相对而言,利用酶抑制原理的生物传感器检测法为有机磷和氨基甲酸酯类农药的检测提供一条快速、简便的途径,且酶传感器法无需大型的仪器设备,适于现场检测及大量样品筛选。鉴于此,本论文着重研究了农残速测的酶传感器法,研究了电流型胆碱酯酶生物传感器的制备,并将碳纳米管这一纳米新材料用作电极修饰和酶直接固定化的载体,得到灵敏度高、稳定性好的传感器。研究内容及结果如下:1、采用用三电极电化学分析系统,对工作电极一玻碳电极进行了有效的预处理及电化学氧化法活化,之后在1.7V的工作电压下,在玻碳电极表面进行2h的MWNTs电沉积,得到带有大量负电荷MWNTs“前驱层”,为硫代胆碱（TCh）检测提供良好前提,该前处理技术尚未见文献报道。2、由于电流型生物传感器对农药残留的检测实际上是对酶促反应产物TCh浓度的检测。因此,本文对TCh的性质及检测过程中的电化学行为进行了全面系统的研究,将Ellman法及电化学法对TCh浓度的检测进行了对照,确定了电化学检测方法的可靠性与准确性。3、根据TCh的性质及电化学行为,选择多壁碳纳米管（MWNTs）修饰玻碳电极。首先对MWNTs进行化学改性,使之具备更好的分散性、生物兼容性、富集抗污染及电化学催化性能。分别用滴涂法和层层自组装法（LBL）修饰玻碳电极。其中,在“前驱层”基础上,以带正电荷的聚电解质（PDDA）溶液和带负电的MWNTs分散液,实现了MWNTs的静电吸附自组装修饰过程。“前驱层”更有利于LBL自组装的进行,所得到的修饰电极对5.000×10^-3mol·L^-1TCh的检测与裸电极相比,峰电流提高一倍,氧化峰电位则由0.65V降低到0.35V,峰电流值与TCh的浓度呈现更好的线性关系,而且检测稳定性和重复性大大提高。此外,电流-时间法（i-t法）对TCh进行检测,更加灵敏,工作电位可以降低到0.30V,对TCh的检测限可降为7.500×10^-7mol·L^-1。4、基于碳纳米管在TCh检测方面的优良的性能,进一步研究乙酰胆碱酯酶（AChE）在碳纳米管上的直接固定化技术,并与酶片法对照。碳纳米管修饰电极表面直接固定化酶活力为0.010U,重复性好,而且酶活力稳定。所制备的酶生物传感器,其酶活力受农药抑制后,电流的变化响应与酶的抑制率具有良好的线性关系,认为该生物传感器在农药检测中具有很好的实用性与可行性。5、分别对氨基甲酸酯类农药甲萘威和克百威,有机磷农药甲胺磷和敌敌畏四种农药进行了检测。实验确定,浓度在10^-10—10^-7g·L^-1范围内,酶的抑制率与四种农药浓度的负对数值均呈良好线性关系。其中,在对浓度为10^-8g·L^-1的甲萘威、克百威、甲胺磷、敌敌畏农药水样的检测中,分别得到了108%、124%、130%、112%的平均回收率。因此,该酶生物传感器对农药的检测有着良好的使用效果和前景。更多还原

【Abstract】 Organophosphorus compounds（OPs） and carbamate are widely used as pesticides, insecticides and chemical warfare agents.These compounds affect the nervous system by inhibiting acetylcholinesterase（AChE） function of regulating the neurotransmitter acetylcholine.Traditionally,the widely used methods for determination of organophosphorus pesticides are liquid/gas chromatography,mass chromatography and Spectroscopy,these methods are sensitive and allow discrimination among different organophosphorus compounds but they are expensive and require a long time not to satisfy the need of fast detection.Meanwhile,immunoassay and biosensor are sensitive and fast.As a comparison,biosensor based on enzyme inhibition technique provided a promising way to detect organophosphorus pesticides which was both rapid and simple. With this method a mass of samples could be detected quickly and no expensive instruments.So we placed emphasis on studying of biosensor based on carbon nanotubes（CNTS） and enzyme,the carbon nanotubes is as a directly immobolilization material of AChE.So the biosensor have good stability and sensitivity.1.A three-electrode analysis system linked to CHI800 electrochemical analyzer was used as a detection system,before pretreating and electrochemical activation process, CNTS pioneer layer was electroposited at 1.70V for 2h,the modified electrode showed a good character in detection of[Fe（CN）₆]^3-/[Fe（CN）₆]^4-,which paved the way of the detection of thiocholine（TCh） and seldom provided in references.2.Because the detection of pesticides residue was based on the detection of TCh, electrochemical properties of thiocholine were studied carefully,the concentration of TCh was determined by Ellman method and electrochemical technique and the same results was given,and the peak current has good linearity with concentration of TCh.So this results tell us the electrochemical technique is reliable and intensive. 3.According to the electrochemical properties of Tch,modification technique of multi-walled carbon nanotubes（MWNTs） towards glass carbon electrode（GCE） was studied,firstly,MWNTs was functionized to be good dispersion,biocompatible, anti-fouling and good electroactalatical.Then drop method and a controllable layer-by-layer（LBL） self-assembly modification technique of multi-walled carbon nanotubes（MWNTs） towards glass carbon electrode（GCE） was studied,by LBL, the bilayer membranes of PDDA and MWNTs,which were fabricated by alternate immersion of GCE in 1.0%poly（diallyldimethylammonium chloride）（PDDA） solution and 1mg·L^-1MWNTs dispersed in pH 9.18 borate buffer solution for 15 minutes either,were self-assembled to GCE after two hours’ electro-deposition of MWNTs at the voltage of 1.70 V.The modified GCE with five self-assembled {PDDA/MWNTs}n bilayers showed good sensitivity,stability,and high reproducibility towards the detection of 5×10^-3mol·L^-1 TCh.In comparison with bare GCE,the obtained oxidative potential decreased from 0.65V to 0.35V,and the peak current value increased by almost 100 percent,the peak current also has good linearity with concentration of TCh.Meanwhile,the modified GCE showed a low even lower oxidative potential of 0.30 V,the detection limit of less than 7.500×10^-7 mol·L^-1 with current-time techniques.4.Direct immobilization methods of AChE to MWNTs were also studied and make a comparasion to enzyme immobilization to membrane,the direct immobilization of AChE to modified electrode was finished by LBL self-assembly technique in PDDA solution and AChE solution,the activity of AChE was 0.010U,it is stable and repeatable,the changes of current response in the obstained biosensor has good linearity with enzyme inhibition rates,so pesticides residue can be detected by this biosensor practically and intensively.5.There is a good linearity of enzyme inhibition rate and -lg value of concentration of both the organophosphorus compounds（methamidophos and dichlorvos） and carbamates pesticides（carbaryl and carbofuran） in the range of 10^-10-10^-7g·L^-1.In the detection of water samples with pesticides concentration of 10^-8g·L^-1 of carbaryl, carbofuran,methamidophos and dichlorvos,the average recoveries are 108%,124%, 130%and 112%separately.So the enzyme sensor may have a good use in the rapid detection of organophosphorus and carbamates pesticides.更多还原