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类型 基础研究 预答辩日期 2018-01-28
开始(开题)日期 2014-05-27 论文结束日期 2017-12-21
地点 生物电子学国家重点实验室三楼会议室 论文选题来源 国家自然科学基金项目     论文字数 7.64 (万字)
题目 基于量子点的化学/生物荧光传感器研究
主题词 量子点,生物/化学传感器,镉离子,pH传感,逻辑运算
摘要 量子点(QD)具有独特的物理化学性质,如高量子产率、宽带吸收、窄带发射、波长连续可调、抗光漂白性好的光学性质;具有良好的电荷和能量转移的电子性质以及易表面功能化、稳定性好的化学性质,因而被广泛的应用于构建纳米荧光传感器。本论文以金属配位作用和生物偶联两种方式,分别构建量子点-分子体系和量子点-适配体/氧化石墨烯体系的荧光传感器,并分别用于离子、pH以及生物分子传感。所构建的量子点荧光传感器具有以下优势:一是高灵敏度;二是高特异性;三是可用于逻辑检测。主要研究内容如下: 1.合成了不同结构的多色量子点:一锅法合成了巯基乙酸(TGA)包覆的水溶性CdTe QD;使用连续离子层吸附反应(SILAR)法制备了核/壳型InP/ZnS量子点。所制备的量子点具有较高的荧光量子产率和较窄的半峰宽,并且发射波长连续可调(495 nm-602 nm),为量子点荧光传感器的构建提供了良好的材料基础。 2.基于高荧光量子产率的CdTe QD,用菲啰啉(Phen)作为配体,构建了量子点-菲啰啉荧光传感器。Phen通过金属亲和力作用结合到CdTe QD表面,通过光致空穴转移过程猝灭QD荧光。当Cd2+存在时,Phen与Cd2+有更强的亲合力作用,进而从QD表面脱附,致使光致空穴转移过程被打断,QD荧光恢复,从而通过QD荧光“开”方式实现了对Cd2+的超灵敏检测。检测限达到0.01 nM,线性范围为0.02 nM到0.6 μM。并且该荧光传感器对Cd2+具有很好的选择性,能够区分同一族的Zn2+。 3.通过凝血酶素、ATP适配体分别修饰两种颜色InP/ZnS QDs(TBA-QD506、ABA-QD571),并分别与氧化石墨烯(GO)结合,制备了GO/TBA-QD506和GO/ABA-QD571 pH传感器。在凝血酶素(Thr)或ATP存在条件下,所制备的传感器依pH不同,展示出可逆的“S”形绿色或橙色荧光变化曲线,实现了pH传感。传感机制利用了适配体结构可调性;信号传导机制利用了QDs与GO之间的长程共振能量转移过程(LrRET)。在pH > 8.0时,Thr与TBA结合、ATP与ABA结合,对应适配体分别形成四链体和双链,导致TBA-QD506或ABA-QD571脱离GO表面,QD506和QD571分别处于高荧光状态;当pH < 6.0时,TBA和ABA分别从四链体、双链变为单链,进而吸附于GO表面,由于LrRET过程,QD506、QD571处于低荧光状态。利用传感器在酸性pH条件下的低荧光状态和碱性pH条件下的高荧光状态特性,同时结合量子点的pH稳定性,可用于制备高可靠性的荧光开关。 4.利用适配体标记的两种颜色InP/ZnS量子点(TBA-QD506、ABA-QD571)同时与GO共组装,构建了GO/TBA-QD506/ABA-QD571逻辑器件,实现了高重置性的半加器和半减器逻辑运算。以Thr、ATP为两个输入,可实现半加器代数运算:输入Thr,QD506荧光增强;输入ATP,QD571荧光增强;两种同时输入,QD506和QD571同时增强。以两种量子点荧光比率作为输出,构建了“异或”门;以两种量子点荧光强度同时作为输出,构建了“与”门,“异或”门和“与”门组成半加器。而将两个输入改变为Thr和DNA1(ATP适配体)、ATP和DNA2(Thr适配体)时,可实现半减器代数运算:以两种量子点荧光比率作为输出,构建了“异或”门;以其中任何一种颜色量子点的荧光强度作为输出,构建了“禁”门,“异或”门和“禁”门组成半减器。利用量子点的荧光稳定性,通过改变pH值,可实现重复多次的半加器和半减器逻辑运算。该逻辑器件可实现生物分子逻辑检测:检测Thr的线性范围为0.1-50 nM,检测限为50 pM;而检测ATP的线性范围为100 nM-30 μM,检测限为40 nM。
英文题目 Study on Chemical/Biological Fluorescent Sensors Based on Quantum Dots
英文主题词 Quantum dots,Biological/chemical sensors,Cadmium ions,pH sensing,Logic circuit
英文摘要 Quantum dots (QDs) have unique optical properties such as high quantum yield, broadband absorption, narrowband and tunable emission, good anti-photobleaching, electronic properties of charge/energy transfer, and chemical properties of easy surface functionalization and good pH stability. Owing to their unique characteristics, the QDs have been widely developed as fluorescent sensors with great sensitivity. In this thesis, the QD-molecule system and QD-aptamer/GO system were, respectively, constructed by metal coordination and bioconjugation, and used as fluorescent sensors for ion, pH and biomolecule sensing. The developed QDs-based fluorescent sensors have the advantages regarding high sensitivity, high specificity and/or logic diversity. The main contents are as follows: 1.Multi-colored and multi-structured QDs were synthesized. Water-soluble TGA-capped CdTe QDs were synthesized according to the “one pot” method with CdCl2, TGA and NaHTe as raw materials. InP/ZnS core/shell QDs were synthesized following the “successive ion layer adsorption and reaction (SILAR)” method. The as-prepared QDs exhibit high fluorescence quantum yields, narrow full-width-at-half-maximum (FWHM), and size (composition-)-tunable emission (495 nm-602 nm). 2.The “QD-molecule”-configurated fluorescent sensor was constructed with CdTe QD as the scaffold and 1, 10-phenanthroline (Phen) as the ligand, and a novel ligand displacement-induced fluorescence switch strategy was developed for highly sensitive and selective detection of Cd2+. The metal affinity-driven complexation of Phen on CdTe QD quenches the QD emission by a photoinduced hole transfer (PHT) mechanism. In the presence of Cd2+, the Phen ligands are readily detached from CdTe QD due to higher affinity toward the analyte, interrupting the PHT process. As a consequence the fluorescence of CdTe QD switches on. The limit of detection (LOD) for Cd2+ detection was estimated to be ~0.01 nM, and the linear dynamic range (LDR) was defined as 0.02 nM to 0.6 μM. Importantly, this QD-Phen sensor featured with high specificity, being able to discriminate Cd2+ with Zn2+. 3.By using dual-colored InP/ZnS QDs to label two different aptamers (one for thrombin (Thr) and another for adenosine triphosphate (ATP)) (TBA and ABA), respectively, combining with graphene oxide (GO), two “QD-aptamer/GO”-configurated fluorescent sensors (GO/TBA-QD506 and GO/ABA-QD571) were constructed, and developed for pH sensing by utilizing structural tunability of aptamers. By chaning pH, the sensors in the presence of Thr or ATP exhibited reversible “S”-shaped fluorescence titration curves with the sharp transition in the range from pH 6.0-7.5. At pH > 8.0, the QD506 or QD571 showed high fluorescence, while the low fluorescence of both QD506 and QD571 were observed at pH < 6.0. The sensing mechanism relies on long range resonance energy transfer (LrRET). At basic pH, TBA bind with Thr to form G-quadruplex, and ABA bind with ATP to form duplex, releasing TBA-QD506 and ABA-QD571, respectively, from GO and interrupting the LrRET. At acidic pH, the G-quadruplex or duplex is denatured to single strands, re-adsorbing of TBA-QD506 and ABA-QD571 on GO and quenching the QDs emission by LrRET. Furthermore, benefitting from the strong anti-photobleaching properties of QDs, reliable fluorescent switches were demonstrated by utilizing the fluorescent pH-depedence of the sensors. 4.The GO/TBA-QD506/ABA-QD571 system was constructed by silmutaneous deposition of TBA-QD506 and ABA-QD571 on GO, and developed to implement logic circuits including half-adder and half-subtractor. A half adder operation was implemented by using ATP and Thr as two inputs. In the initial state, TBA-QD506 and ABA-QD571 were adsorbed onto GO. In the presence of either input, the specific recognition interaction of TBA-Thr or ABA-ATP folded the respective aptamer to G-quadruplex or duplex, releasing TBA-QD506 and ABA-QD571 from GO, respectively. In the presence of two inputs, both of TBA-QD506 and ABA-QD571 were desorbed from GO. The adsorption/desorption of QD-labelled aptamers led to fluorescent response of the system, which fits the characteristics of half adder. The system was readily reconfigured to implement a half subtractor operation by using Thr coexisted with DNA1 (label-free ATP binding aptamer), and ATP coexisted with DNA2 (label-free Thr binding aptamer) as the two inputs. Either TBA-QD506 or ABA-QD571 was desorbed from GO in the presence of either input, owing to the specific TBA-Thr or ABA-ATP recognition interaction, not interfered by the coexisted DNA1 or DNA2. In the presence of both inputs, however, the DNA1-ATP and DNA2-Thr recognition interactions occurred in priority, inhibiting the TBA-Thr and ABA-ATP interactions, and the system remained its initial state. Accordingly, the high fluorescence of either QD506 or QD571 was observed in the presence of either input, while in the presence of none or both of the inputs, the fluorescence of both QD506 and QD571 remained low. This fluorescent response fits the characteristics of half subtractor. Furthermore, repetitious half-adder and half-subtractor arithmetic operations were achieved benefitting from fluorescence stability of the QDs. In addition, the logic system can be used as fluorescent sensors for detection of Thr and ATP. The obtained LDRs for ATP and Thr were 0.1 μM to 30 μM and 0.1 nM to 50 nM, respectively; the LODs for ATP and thrombin were estimated to be 40 nM and 50 pM, respectively.
学术讨论
主办单位时间地点报告人报告主题
生物电子学国家重点实验室 2017年9月10日 逸夫科技馆三楼会议室 胡先运 基于量子点-适配体/氧化石墨烯的半加器/半减器逻辑运算
生物电子学国家重点实验室 2016年10月30日 逸夫科技馆三楼会议室 胡先运 基于DNA的逻辑运算
生物电子学国家重点实验室 2013年7月20日 逸夫科技馆三楼会议室 胡先运 基于量子点的离子检测
生物电子学国家重点实验室 2016年4月30日 逸夫科技馆三楼会议室 孙清江 荧光纳米生物传感器技术
东南大学生物科学与医学工程学院 2014年12月12日 逸夫科技馆三楼会议室 占肖卫 有机高分子光电功能材料和器件
东南大学电子科学与工程学院 2015年7月2日 逸夫科技馆三楼会议室 孙啸 G4-DNA的基因调控作用
东南大学生物科学与医学工程学院 2014年3月12日 礼东二楼报告厅 聂书明 荧光探针用于肿瘤靶向标记
生物电子学国家重点实验室 2015年6月13日 逸夫科技馆三楼会议室 胡先运 基于适配体的荧光探针
     
学术会议
会议名称时间地点本人报告本人报告题目
2nd Asia Pacific Nanobiotechnology Summit 2017年7月29日-7月30日 新加坡 Multifunctional QD-aptamer/graphene oxide platform for the construction of a half-adder, half-subtractor and switch
International Conference on Molecular Sensors and Molecular Logic Gates 2014年11月9日-12日 中国 上海
2013年全国生物与医学纳米技术博士生论坛 2013年9月24日-26日 中国 苏州 配体交换-致使量子点荧光开关,超灵敏检测镉离子
2016年全国生物与医学纳米技术博士生论坛 2016年6月16日-19日 中国 苏州
生物电子学与生物光子学联合学术论坛 2012年11月21日-23日 中国 南京
     
代表作
论文名称
Ligand displacement-induced fluorescence switch of quantum dots for ultrasensitive detection of cad
A quantum dot-labelled aptamer/graphene oxide system for the construction of half-adder and half-sub
量子点荧光传感器设计及应用
 
答辩委员会组成信息
姓名职称导师类别工作单位是否主席备注
陆祖宏 正高 教授 博导 东南大学
练鸿振 正高 教授 博导 南京大学
钱卫平 正高 教授 博导 东南大学
贺庆国 正高 研究员 博导 中科院上海微系统所
陈永华 正高 教授 博导 南京工业大学
      
答辩秘书信息
姓名职称工作单位备注
董健 副高 副教授 东南大学