【作者】 尉艳；

【导师】 方宾；

【作者基本信息】 安徽师范大学 ， 分析化学， 2007， 硕士

【摘要】 稀土元素由于具有特殊的电子结构使其化合物具有较高的催化活性。将稀土纳米化后,无疑能在原有特性的基础上赋予一系列新的特性,使其具有一些新的电子学、光学和物理化学等性能,尤其是催化性能大大增强。本文将稀土与纳米双重特性结合起来,运用于电极表面的修饰,制备出系列纳米铈化合物修饰电极,并就生物分子、神经递质和DNA碱基为对象开展了应用研究。首先,合成了二氧化铈纳米,利用吸附法制备出纳米二氧化铈修饰电极。采用循环伏安、示差脉冲伏安和电化学阻抗等方法研究了芦丁和尿酸的电化学行为。结果表明,纳米二氧化铈修饰金电极,对芦丁的氧化有很好的电催化效应,由此建立的电化学分析方法实现了对芦丁药片的分析测定。纳米二氧化铈修饰玻碳电极能将尿酸和抗坏血酸的重叠波分成两个良好独立的伏安峰,峰电位之差达273mV,能够实现尿酸和抗坏血酸的同时测定。该电极用于人体血清中尿酸和抗坏血酸的测定,结果令人满意。其次,将纳米材料的特性和稀土铁氰化物聚合物的分子识别能力结合起来,采用电化学方法在处理过的碳纳米管界面制备了多壁碳纳米管复合聚铁氰化铈修饰电极。用循环伏安和扫描电镜等技术对其进行了表征,还考察了此电极对色氨酸的电催化作用。研究发现,该修饰电极具有很好的化学稳定性和分子识别性。再次,制备出CeO₂纳米晶包裹碳纳米管修饰电极,并且研究了鸟嘌呤和腺嘌呤在修饰电极上的电化学行为。实验表明,该电极对鸟嘌呤和腺嘌呤有良好的电催化效应。制备成的鸟嘌呤和腺嘌呤的电化学传感器具有高的灵敏度和好的稳定性,为单链DNA片断碱基的识别以及DNA的间接测定提供了一种途径,也为稀土纳米和碳纳米管在生物传感器中的应用提供了可望前景。最后,利用碳纳米管来负载催化活性较高的杂多酸稀土盐（磷钨酸铈）,制备出负载磷钨酸铈纳米的碳纳米管修饰电极。电极明显特征是固定磷钨酸铈,细化颗粒,最大程度地提高其比表面积,使其催化活性得到充分发挥。初步探讨了此修饰电极对生物分子多巴胺的伏安特性,发现该修饰电极可以有效的排除AA的干扰,对DA进行测定。更多还原

【Abstract】 Rare earth elements usually exhibit special optical and chemical properties.In recent years,attention has been paid to rare earth nanoparticles for their preparation and applications as luminous material, catalysts,electronic ceramics,glass polisher,and etc.In this paper we present a study on rare earth nanoparticles modified electrode.It may provid a good example of applying the good catalysis of rare earth and nanoparticles to electrochemistry.First,a glassy carbon electrode modified with CeO₂ nanoparticles was constructed and was characterized by electrochemical impedance spectrum（EIS）and cyclic voltammetry（CV）.The resulting CeO₂ nanoparticles modified glassy carbon electrode was used to detect uric acid（UA）and ascorbic acid（AA）simultaneously in mixture.This modified electrode exhibited potent and persistent electron-mediating behavior followed by well-separated oxidation peaks towards UA and AA with activation overpotential.For UA and AA in mixture,one can well separate from the other with a potential difference of 273mV,which was large enough to allow the determination of one in presence of the other. The proposed method showed excellent selectivity and stability,and the determination of UA and AA simultaneously in serum was satisfactory.Secondly,the CeHCF and MWNTs were modified onto the glassy carbon electrode to fabricate the modified electrode.Electrocatalytic oxidation of tryptophan at the CeHCF/MWNT/GC electrode was studied. And it had been applied to the determination of tryptophan in pharmaceutical samples with satisfactory results.The reliability and stability of the CeHCF/MWNT/GC electrode offered a good possibility for applying the technique to routine analysis of trptophan in clinical use.Thirdly,combining the properties of multi-wall carbon nanotubes with the good catalysis of CeO₂,a CeO₂/MWNT modified glassy carbon electrode was constructed.Transmission electron microscopy and X-ray data was used to observe the nanoparticles CeO₂/MWNT.The CeO₂/MWNT/GC electrode showed potent electrocatalytic activity toward the electrochemical oxidation of guanine and adenine.The proposed method showed excellent selectivity and stability,and the determination of guanine and adenine simultaneously in ssDNA（signal strand DNA）and acid-denatures DNA was satisfactory.These results may help us to develop a new method for the simultaneously determination for guanine and adenine in DNA.And the distinguishing between ssDNA and dsDNA become easy.At last,CePW nanoparticles supported on multi-wall carbon nanotubes was prepared,and it was modified onto a glassy carbon electrode then.Cyclic voltammetry（CV）and electrochemical impedance spectroscopy（EIS）were used to characterize the electrode modifying process.The electrochemical behavior of dopamine on this modified electrode was investigated and the result shows that it also can eliminate the interference of ascorbic acid and then dopamine can be determined selectively.It was applied in the sample determination and the result is satisfied with us.更多还原