Fluorescent Adenosine Diphosphate And Pyrophosphate Probes Via Introducing Functional Groups To Zn²⁺-DPA Complex

Due to the important roles of ADP and PPi in living systems, the development of highly selective probes for ADP and PPi is of great importance. However, there are many phosphate anions, whose structures are similar to that of ADP and PPi. In addition the hydration of ADP and PPi is significant in water. All these factors make it difficult and challenging for synthetic receptors to achieve a high selectivity and sensitivity towards ADP and PPi.In view of these challenges, in this thesis, we designed and synthesized anthracene-based Zn2+-DPA complexes as fluorescent sensors for ADP and PPi, via an approach of introducing small functional groups to the complex. The main results are as follows:1. Comparing the complex with and without introducing amino groups, we proved that introducing amino groups can significantly improve the selectivity and sensitivity of the complex for phosphate anions. The binding affinity of the complex with amino groups (2-ZnL2) towards ATP and ADP was enhanced by 1000 folds compared with sensors without amino groups (2-ZnLl); 2-ZnL2 only responded to ATP, ADP and AMP, but 2-ZnL1 responded to many anions, including ATP, ADP, PPi, AMP, inorganic phosphate and citrate.2. Through the detailed research of 3-ZnL, a dinuclear Zn2+-DPA complex by introducing four-NH2 groups, we found that it is the first Zn2+-DPA-based fluorescent probe, which showed high selectivity for ADP over both ATP and PPi. The biological application of 3-ZnL was also investigated The results clearly indicate that 3-ZnL can be used to monitor the reactiveity of creatine phosphokinase and also can be applied to fluorescent image ADP in HeLa cells.3. Through the detailed research of 4-ZnL1, a dinuclear Zn2+-DPA complex by introducing four-NHCOCH3 groups, we found that it shows high selectivity and sensitivity towards PPi. Other anions, including ATP and ADP, show little influence on the recognition of PPi. The binding affinity of 4-ZnLl towards PPi was found to be as high as 107 M-1. Fluorescent imaging of PPi by 4-ZnL1 in HeLa cells was also successfully investigated4. Through the detailed research of 5-ZnL, a dinuclear Zn2+-DPA complex by introducing four-CH2OH groups, we found that it can be specially induced by PPi to form anthracene-excimer. No other anions, including ATP, can cause this phenomenon. As fast as we know, this is the first example of PPi sensors based on anthracene-excimer formation. Meanwhile, we also found that the formation of the unique anthracene-excimer between 5-ZnL and PPi can be well controlled by factors such as concentration of 5-ZnL, temperature and ionic strength.In a word, by introducing different functional group to Zn2+-DPA complex, we have developed several effective fluorescent sensors for ADP and PPi, respectively, which may imply a simple but effective way to develop fluorescent sensors for a specifc phosphate anion.