首页> 外文OA文献 >Application of catalysts and nanomaterials in the design of an electrochemical sensor for ochratoxin A
【2h】

Application of catalysts and nanomaterials in the design of an electrochemical sensor for ochratoxin A

机译:催化剂和纳米材料在赭曲霉毒素a电化学传感器设计中的应用

代理获取
本网站仅为用户提供外文OA文献查询和代理获取服务,本网站没有原文。下单后我们将采用程序或人工为您竭诚获取高质量的原文,但由于OA文献来源多样且变更频繁,仍可能出现获取不到、文献不完整或与标题不符等情况,如果获取不到我们将提供退款服务。请知悉。

摘要

Ochratoxin A is the most potent chlorinated derivative of the ochratoxin group, consisting of a 5'-chlorinated dihydroisocoumarin moiety linked by an amide bond to l-phenylalanine. Produced as a secondary fungal metabolite by several species of Aspergillus and Penicillium, ochratoxin A has been shown to readily contaminate a large variety of commodities including cereals, groundnuts, dried fruit, spices and coffee. This has led to widespread contamination of ochratoxin in wine, beer, milk and meat products. As ochratoxin A is a potent nephrotoxin exhibiting teratogenic and carcinogenic properties, the development of a rapid screening platform for the cost effective control of ochratoxin A content in foodstuffs is therefore required. The evaluation of metallophthalocyanine and carbon nanotube electrode modification toward the development of a nanostructured biosensor capable of enhancing the electrochemical detection of ochratoxin A in complex media is presented. Cyclic voltammetry at a glassy carbon electrode allowed for the optimization of detection parameters including pH and type of supporting electrolyte. Britton-Robinson buffer was found to be the most suitable supporting electrolyte in terms of sensitivity and reproducibility obtaining a LOD of 0.28 μM as determined by differential pulse voltammetry. Subsequent analysis determined the dependence of OTA oxidation on pH in acidic media which proceeds with the transfer of two electrons to form a quinone/hydroquinone couple shown to adsorb to the electrode surface. Passivation of the electrode through adsorption of oxidation products was shown to severely limit the detection of OTA upon successive detection cycles. Comparison of various metallophthalocyanine modifiers showed an increase in sensitivity toward the detection of OTA at phthalocyanine complexes with metal based redox processes. However with the exception of NiPc and CoTCPc complexes, phthalocyanine modification was limited by the increase in deviation of current response and extent of fouling. NiPc modification showed an increase in sensitivity by two fold with fouling characteristics comparable to an unmodified electrode while low improvements in fouling was observed at CoTCPc modified electrodes with sensitivity in detection comparable to an unmodified electrode.Modification of the electrode with multi- and single walled carbon nanotubes produced a significant increase in sensitivity toward the detection of ochratoxin A. The electrocatalytic activity of nanotube modifiers was attributed to the increase in surface area and to the addition of oxygenated functional groups upon acid treatment as confirmed by Raman spectroscopy. Acid functionalization of the carbon nanotubes for a period of two hours produced the greatest increase in sensitivity obtaining a respective LOD of 0.09 μM and 0.03 μM for analysis of ochratoxin A at multi- and single walled carbon nanotube modified electrodes. Centrifugal purification of carbon nanotubes was deemed necessary to improve the electrocatalytic activity of the nanotube modifiers through the removal of carbonaceous impurities as visualized by atomic force microscopy. Furthermore, a crude lipase preparation, lipase A, was investigated as a potential biological recognition element for selective detection of ochratoxin A in complex media. Lipase A enabled the hydrolysis of ochratoxin A to the electroactive species ochratoxin α as confirmed by thin layer chromatography and voltammetric analysis. Additional isolation of a pure hydrolase from the lipase A preparation is required prior to utilization within a nanostructured biosensor platform capable of detecting ochratoxin A in complex media.
机译:ch曲霉毒素A是the曲霉毒素基团中最有效的氯化衍生物,由5'氯化二氢异香豆素部分(通过酰胺键连接至1-苯丙氨酸)组成。 several曲霉毒素A由几种曲霉菌和青霉菌作为次级真菌代谢产物生产,已显示ra曲霉毒素A容易污染包括谷物,花生,干果,香料和咖啡在内的多种商品。这导致葡萄酒,啤酒,牛奶和肉类产品中曲霉毒素的广泛污染。由于曲霉毒素A是一种具有致畸和致癌特性的强效肾毒素,因此需要开发一种快速筛选平台,以经济有效地控制食品中曲毒素A的含量。提出了对金属酞菁和碳纳米管电极修饰的评价,以开发能够增强复杂介质中曲毒素A电化学检测的纳米结构生物传感器。玻碳电极上的循环伏安法可优化检测参数,包括pH和支持电解质的类型。就灵敏度和重现性而言,发现Britton-Robinson缓冲液是最合适的支持电解质,通过差分脉冲伏安法测得的LOD为0.28μM。随后的分析确定了在酸性介质中OTA氧化对pH的依赖性,这随着两个电子的转移而形成醌/对苯二酚对,并显示吸附到电极表面。电极通过氧化产物的吸附而钝化显示,严重限制了连续检测周期中OTA的检测。各种金属酞菁改性剂的比较显示,采用金属基氧化还原工艺的酞菁配合物对OTA的检测灵敏度有所提高。但是,除了NiPc和CoTCPc配合物以外,酞菁修饰受到电流响应偏差和结垢程度的增加的限制。 NiPc修饰的灵敏度提高了两倍,具有与未修饰的电极相当的结垢特性,而在CoTCPc修饰的电极上观察到的结垢改善很小,检测灵敏度与未修饰的电极相当。纳米管对检测曲霉毒素A的敏感性显着提高。纳米管改性剂的电催化活性归因于表面积的增加和酸处理后氧化官能团的添加(如拉曼光谱法所证实)。碳纳米管经过两个小时的酸官能化处理后,灵敏度得到了最大的提高,分别获得了0.09μM和0.03μM的LOD,以便在多壁和单壁碳纳米管修饰电极上分析曲霉毒素A。碳纳米管的离心纯化被认为对于通过去除碳质杂质来改善纳米管改性剂的电催化活性是必要的,如通过原子力显微镜观察的。此外,还研究了粗脂肪酶制剂脂肪酶A作为潜在的生物识别元素,可用于在复杂培养基中选择性检测曲霉毒素A。脂肪酶A使enabled曲霉毒素A水解为电活性物质active曲霉毒素α,这已通过薄层色谱法和伏安法分析得以证实。在脂肪酶A制剂中需要另外分离纯水解酶,然后才能在能够检测复杂介质中曲毒素A的纳米结构生物传感器平台中使用。

著录项

  • 作者

    Flanagan Shane Patrick;

  • 作者单位
  • 年度 2010
  • 总页数
  • 原文格式 PDF
  • 正文语种 English
  • 中图分类

相似文献

  • 外文文献
  • 中文文献
  • 专利

客服邮箱:kefu@zhangqiaokeyan.com

京公网安备:11010802029741号 ICP备案号:京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有
  • 客服微信

  • 服务号