【作者】 李颖；

【导师】 彭晖；

【作者基本信息】 华东师范大学 ， 物理电子学， 2017， 博士

【摘要】 荧光碳点由于其良好的生物兼容性和制备方法的简便性受到了广泛的关注。本论文主要采用电化学法和水热法制备了一系列荧光碳点。研究了碳点作为能量给体用于DNA杂化的检测、反应物对碳点性能的影响、聚集效应对碳点荧光性质的影响。具体如下:1.采用碳棒作为工作电极和对电极,银/氯化银作为参比电极,通过电化学氧化的方法,制备了绿色荧光的碳点,并对其形貌和荧光性能进行了表征。将所制备的荧光碳点作为能量给体,能过带正电的聚合物聚二甲基二烯丙基氯化铵(PDADMAC)作为电荷桥梁,与Cy3荧光染料标记的单链DNA通过电荷间的作用形成"三明治"结构,构建了基于荧光共振能量转移(FRET)的DNA杂化检测平台,实现了对目标DNA的定量检测。2.以磷酰基乙酸三乙酯为原料,在磷酸的存在下通过水热法,制备了磷掺杂的、水溶性的荧光碳点。研究了磷掺杂碳点的荧光性质,发现了随着荧光碳点的浓度增大,碳点的荧光发射峰红移;降低浓度导致荧光发射峰蓝移。通过实现证实了所发现的荧光红移现象是由于碳点的聚集所导致。3.研究了反应物对所得到的氮掺杂荧光碳点性能的影响。采用柠檬酸或者葡萄糖作为碳源,4,7,10-三氧-1,13-十三烷二胺或者多巴胺作为氮源,两两组合,通过水热法制备了四种碳点。通过透射电子显微镜(TEM)和原子力显微镜(AFM)对所制备的碳纳米点进行形貌表征之后,通过对它们光学性质,电化学性质的研究,发现反应原料不仅仅影响其荧光性能,也影响了其它的理化性能,如pH敏感性、光伏性能。其中用4,7,10-三氧-1,13-十三烷二胺作为氮源制备的碳点,比多巴胺作为氮源所制备的碳点具有更高的荧光量子产率;而用多巴胺作为氮源制备得到的碳点,因为其表面含有多巴胺或者多巴胺类似物的结构,具有更高的pH敏感性。此外,用多巴胺作为氮源的所制备的两种碳点不仅具有荧光特性,同时还表现出电化学活性,为通过原料的选择制备多功能荧光碳点提供了一个新的思路。4.采用具有电化学活性的溴化乙锭(EB)作为反应物,通过水热法制备了荧光碳点,其荧光峰位于510 nm,并且不随激发波长的变化而变化。循环伏安法测试结果表明,在pH为0.54时,所得到的碳点于-0.63出现了一还原峰,并且随着pH的增大,还原峰正移。该特性可用于pH变化检测。更多还原

【Abstract】 Carbon nano dots(CNs)have attracted lots of attention these years because of their biocompatibility and convience in prereration.In this paper,electrochemical and hydrothermal preparation methods are used for preparing CNs.The effect of CNs as energy donor on DNA hybridization,reactants on CNs’ properties and aggregation on fluorescent properties of CNs were studied.Details as follows:1.Carbon electrode was used as working electrode and counter electrode and silver/silver chloride(Ag/AgCl)as a reference electrode.The CNs with green fluorescence were prepared by oxidation of carbon electrode.The CNs were characterized by transmission electron microscopy(TEM)and atomic force microscopy(AFM).The prepared CNs are used for energy donor,by connecting the Cy3 labeled single stranded DNA with a cationic polymer which is short for PDADMAC.In other words,negatively charged CNs and Cy3 labeled single stranded DNA form a sandwich structure through the electrostatic interaction in the presence of the cationic polymer,PDADMAC.A sensing platform for DNA hybridization based on FRET has been designed and demonstrated using CNs as a donor.2.Using hydrothermal method,triethyl phosphonoacetate and phophous acid as reactants to prepare phosphorous doped and water-soluble fluorescent CNs.When the concentration of fluorescent CNs increases,the peaks of fluorescence peak shifts to red.On contrast,when the concentration of fluorescent CNs decreases,the fluorescence peak shifts to blue.The observed fluorescence peak’s red shift is due to the aggregation of CNs.3.In this work,we found thst the fluorescent properties of nitrogen doped CNs can be controlled by choosing reactants.We choose citric acid or glucose as carbon source,4,7,10-trioxy-1,13-tridecylenediamine or dopamine as nitrogen source to make four different kinds of CNs.After CNs were characterized by transmission electron microscopy(TEM)and atomic force microscopy(AFM).In conclusion,apart from optical properties,the electrochemical properties of CNs can be controlled by reactants,such as sensitivity in pH and photovoltaic property.The CNs prepared in the presence of TTDDA possess much stronger photoluminescence than those prepared in the presence of dopamine.However,the CNs obtained with dopamine show better pH sensitivity due to the existence of dopamine/dopamine analogues that are electron acceptors.These results clearly demonstrate that optical and other physicochemical properties of CNs can be tuned by the use of appropriate reaction precursors and provide us a new way to control the properties of carbon dots.4.By hydrothermal method,choose ethidium bromide which has electrochemical properties as the only reactant,to prepare CNs which also have electrochemical properties.The fluorescence peak of carbon dots is at 510nm and does not vary with the excitation wavelength change.The cyclic voltammetry test results show that when the pH is 0.54,the CNs have a reduction peak at-0.63.With pH increasing,the reduction peak moves positively.We can use the change to detect pH in solutions.更多还原