【作者】 王倩；

【导师】 赵伟伟；

【作者基本信息】 南京大学 ， 化学， 2019， 硕士

【摘要】 随着科技的进步,人们对生命健康、生态环境和高品质生活的要求越来越高,因此高灵敏度、低检测限和方便快捷的检测技术愈发重要。其中光电化学(Photoelectrochemical,PEC)传感器因为其自身的高灵敏度和简易的设备要求被广泛关注,近年来许多新型光电传感方法被报道。一般来说,构建高效的光电化学传感器主要从两方面入手:一方面是开发新型光电活性物质,光电活性物质是光电化学传感器的重要组成部分;另一方面是设计新颖的分析策略,分析策略是实现各类待测物和光电活性物质发生相互作用,实现特异性检测的重要桥梁。显然,开发新的光电活性材料和分析策略对光电化学生物分析的发展起到了至关重要的作用。目前,在光电活性物质的使用和开发方面,主要发展了无机光电活性物质、有机光电活性物质和复合材料等;常见的分析策略有直接检测法、光电活性物质做标记物、表面等离子体共振(SPR)增强、激子能量转移猝灭、空间位阻、原位产生电子供体和原位消耗氧等。本文将新型聚合物量子点(Polymer dots,Pdots)应用于光电化学生物传感界面的构建,探索了以下两个工作:1.构建有机-无机半导体量子点异质结作为新型光电化学生物分析平台本工作主要选取p型的有机聚合物半导体量子点和两种无机半导体量子点n型硫化镉量子点(CdSQDs)、p型的碲化镉量子点(CdTe QDs),首次构建了 CdS QDs/Pdots,Pdots/CdS QDs,CdTe QDs/Pdots和Pdots/CdTe QDs四种复合界面。在光照射下,四种电极呈现不同的光电化学行为,其中CdS QDs/Pdots,CdTe QDs/Pdots电极因为成功形成半导体异质结从而具有显著的光电流增强现象。我们测量了无机量子点的价带(VB)/导带(CB)及Pdots的最低未占分子轨道(LUMO)/最高占据分子轨道(HOMO)值,进而阐述电极光电流增益/损耗的原因。最后用光电效应良好的电极检测半胱氨酸,表现出了良好的选择性和灵敏度。2.构建新型基于空穴传导层的高效高分子量子点光电化学生物分析平台本工作以p-型聚合物量子点为主,有机小分子噻吩嗪(Phenothiazine,PTZ)作为空穴传导层,通过向电极表面滴加后红外灯烘干的方式构建高效的阴极光电流分析平台。利用紫外、荧光等表征方法阐述了阴极光电流的产生过程:制备的电极受到光照使Pdots产生的光生空穴,紧接着空穴转移到接受体PTZ提高了空穴传导效率,促进电极上的电子先后转移到PTZ和Pdots上,最后再转移到电解质中的电子受体溶解氧,因此大大增强了 Pdots的光电流。同时,利用电化学检测等测试证明了电极的成功构建和电极的高效性、稳定性。更多还原

【Abstract】 With the development of science technology,there are increasing demands for quality life,health and ecological environment.Therefore,innovative detection techniques with high sensitivity,low detection limit have attracted substantial interest.As a highly sensitive technique with simple instrumentation,photoelectrochemical(PEC)bioanalysis have been widely studied and a lot of works have been reported in recent years.Generally,there are two important aspects for the development of an efficient PEC bioanalysis:one is the exploration and application of novel photoactive materials,which is an important component for PEC bioanalysis;the other is the design and development of novel sensing strategy,which can bridge various analytes and photoactive materials to achieve high-performance detection.Obviously,new photoactive materials and analysis strategies are essential for the development of PEC bioanalysis.At present,in the aspect of photoactive materials,various inorganic,organic photoactive materials and composite materials have been investigated,while common sensing strategies include direct detection,photoelectric active material labeling,surface plasmon resonance enhancement,exciton energy transfer quenching,steric hindrance and in situ generation of electron donors.In this work,we explored the application of new polymer dots(Pdots)to construct PEC biosensing interface,including the following two tasks:1.Semiconducting Organic-Inorganic Nanodots Heterojunctions:Novel Platforms for General Photoelectrochemical Bioanalysis ApplicationIn this study,inorganic quantum dots(QDs)n-type CdS QDs,p-type CdTe QDs and ptype tetraphenylporphyrinv(TPP)-doped poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo{2,1’,3}-thiadazole)](PFBT)Pdots and were fabricated as CdS QDs/TPP-doped PFBT Pdots,TPP-doped PFBT Pdots/CdS QDs,CdTe QDs/TPP-doped PFBT Pdots,TPP-doped PFBT Pdots/CdTe QDs,on the transparent glass electrode.Upon light irradiation,four heterojunctions exhibited different PEC behaviors.CdS QDs/TPP-doped PFBT Pdots and CdTe QDs/TPPdoped PFBT Pdots displayed prominent photocurrent enhancement,as the heterojunction was fabricated successful.In order to explain the enhancement about photocurrent,their energy levels,i.e.,their valence band(VB)/conduction band(CB)or lowest unoccupied molecular orbital(LUMO)/highest occupied molecular orbital(HOMO)values,were also determined.With the model molecule L-cysteine(L-cys)as target,the proposed PEC sensor exhibited good performances.2.Construction of Hole Transfer Layer-Assisted Pdots-based PEC Bioanalysis PlatformIn this study,with the use of the organic small molecule(Phenothiazine,PTZ)and p-type PFBT Pdots as hole transfer material and photoactive material,respectively,we constructed the innovative hole transfer layer-assisted Pdots-based PEC bioanalysis interface.The PEC interface was developed by sequentially dropping PDDA,PTZ and Pdots onto the ITO electrode surface and the as-obtained photocathode could generate much enhanced cathodic photocurrent.In order to understand the mechanism of the cathode photocurrent,various optical characterization such as UV-vis and fluorescence was performed,which indicated that the photogenerated holes generated by Pdots were transferred to the hole acceptor PTZ and then transferred to the electrode,enhancing the electron transfer to the dissolved O2 in the electrolyte.At the same time,electrochemical detection were also used to study the performance of the electrode.更多还原