DNA具有优良的理化性质而被广泛应用于构建生物传感器。近年来，通过DNA与金属离子作用构建金属离子传感器是研究热点之一；而且通过非金属离子与DNA竞争地结合金属离子又为检测非金属离子奠定了基础。本论文设计了两种检测Hg2+和I-的光学DNA传感器，通过光学手段分析了Hg2+与DNA的作用，以及I-从T-Hg2+-T结构中捕获Hg2+的行为，实现了对Hg2+和I-高灵敏、高选择性的检测。1. 基于Hg2+、I-诱导DNA结构的变化构建了检测Hg2+和I-的化学发光传感器。具体地，采用一条富G的DNA链，没有Hg2+时，富G序列与K+作用折叠形成G-四链体结构后结合hemin形成G-四链体DNA酶，有效地催化双氧水氧化鲁米诺，产生化学发光信号。当有Hg2+时，Hg2+诱导DNA形成包含T-Hg2+-T的发夹状结构，富G序列部分杂化在发夹状DNA的茎部而不能形成G-四链体结构，体系化学发光信号较弱。利用此原理，实现了对Hg2+的高灵敏度、高选择性检测，检测限为0.1 nM。更重要的是，由于I-与Hg2+的结合能力更强，I-可以从T-Hg2+-T结构中夺取Hg2+，从而释放DNA链，并在K+和hemin作用下含有G-四链体的DNA酶，催化双氧水氧化鲁米诺，化学发光信号再次增强，从而实现了对I-的检测，检测限为12 nM。这一传感器可以进一步应用于实际湖水样品中Hg2+和I-的检测。2. 基于锌卟啉与G-四链体结构结合后荧光显著增强的性质，设计了一种简单、无标记的检测Hg2+和I-的荧光传感器。采用一条富G的发夹状DNA，富G序列包含在茎部且不能与锌卟啉结合，自由的锌卟啉荧光较弱。加入Hg2+时，Hg2+与T-T错配碱基对作用引起该发夹状DNA转变为另一种包含T-Hg2+-T的发夹状结构而释放出富G序列。该富G序列与K+作用形成G-四链体结构后与锌卟啉结合，使锌卟啉的荧光显著增强。利用此现象检测了Hg2+，检测限为2 nM。加入I-时，T-Hg2+-T结构中的Hg2+被夺取出来，DNA又转变为最初的发夹状结构，无法与锌卟啉结合，锌卟啉荧光减弱。根据荧光的减弱，实现了对I-的检测，检测限为20 nM。

DNA has been widely used to construct biosensor due to its excellent physicochemical property. It is very interesting to construct metal ion sensor based on the interaction between DNA and metal ions. Moreover, some nonmetal ions can further capture metal ion from DNA, which laid a foundation for detecting nonmetal ions. In this thesis, two kinds of optical DNA sensors for the detection of Hg2+ and I- were designed, respectively. Some spectroscopic methods were used to analyze the interaction between Hg2+ and DNA, and the capturing process of Hg2+ by I- from T-Hg2+-T complex. Then, the detection of Hg2+ and I- with high sensitivity and selectivity were achieved.1. A chemiluminescence sensor for the detection of Hg2+ and I- was constructed, based on the structure change of the DNA induced by Hg2+ and I-. Specially, a G-rich DNA was adoped, in the absence of Hg2+, the G-rich DNA could fold into G-quadruplex in the presence of K+, and further bond with hemin to form DNAzyme to effectively catalyze H2O2-mediated oxidation of luminol and produce chemiluminescence. In the presence of Hg2+, Hg2+induced the DNA transformed into a stem-loop structure containing T-Hg2+-T, the G-rich sequence was partially caged in the stem of the hairpin and could not form G-quadruplex. So the chemiluminescence was greatly decreased. Based on the facts, the highly sensitive and selective detection of Hg2+ was achieved. More importantly, based on the stronger binding ability of I- with Hg2+, I- could capture Hg2+ from T-Hg2+-T complex, making the DNA released. The DNA bond K+ and hemin to form G-quadruplex DNAzyme and catalyzed H2O2-mediated oxidation of luminol to generate chemiluminescence again. This sensor could be applied to detect I- with a detection limit of 12 nM. In addition, the assay for the detection of Hg2+ and I- were challenged in real lake water sample.2. A simple and label-free fluorescence sensor for the detection of Hg2+ and I- was designed, based on the enhanced fluorescence of ZnPPIX when binding with G-quadruplex. A G-rich hairpin DNA could not bind with ZnPPIX due to the G-rich sequence was caged in the stem. So the fluorescence of free ZnPPIX was weak. In the presence of Hg2+, Hg2+ induced the hairpin DNA transformed into another hairpin structure containing T-Hg2+-T, and the G-rich sequence was released. Then the G-rich sequence formed G-quadruplex in the presence of K+, then further bond with ZnPPIX. As a result, the fluorescence of bond ZnPPIX was enhanced. Based on the facts, the detection of Hg2+ was achieved with a detection limit of 2 nM. Subsequently, I- was added, and Hg2+ was extracted from T-Hg2+-T complex with DNA transformed into the initial hairpin structure. The fluorescence of ZnPPIX was greatly decreased. Based on the phenomenon, the I- sensor was developed with a detection limit of 20 nM.