Aptamer Functionalized Poly-G-Quadruplexes Probe For Diagnosis And Treatment Of Cancer

Cancer is the top public health problem all over the world.In the United States,the mortality rate caused by malignant tumors is the second place,second only to cardiovascular diseases.In China,malignant tumors have surpassed cerebrovascular diseases and heart diseases,ranking the first in the curr ent mortality ranking.It is well known that early cancer patients are much easier to treat than late cancer patients.Therefore,the early detection and diagnosis of cancer is of great significance.It can not only reduce the mortality of cancer patients,but also save a lot of manpower,material and financial resources.Cancer cells contain a unique set of cell surface receptors that provide potential targets for tumor theranostics.Here,we have constructed an aptamer functionalized poly-G-quadruplexes probe for the diagnosis and treatment of cancer cells.This designed probe combined particular sequence for the c-Met on the cell surface and poly-G-quadruplexes structures that allow a rapid and efficient fluorescent readout upon the binding of ThT.The poly-G-quadruplexes also function as a carrier for photosensitizers TMPyP4 to commit cells to death.This unique c-Met targeting aptamer enabled simultaneous monitoring of c-Met on the cell surface with ThT and photodynamic killing of these lung cancer cells with TMPyP4.This strategy is expected to enhance the development of tumor-targeted diagnosis and therapy,the details are summarized as follows:1.Construction and characterization of the aptamer functionalized poly-G-quadruplexes probe.In this chapter,the aptamer functionalized poly-G-quadruplexes probe were obtained by employing a polymerase terminal deoxynucleotidyl transferase(TdT).We used a three-part substrate DNA strand: an aptamer SL1 sequence,a poly-T linker sequence,and a primer sequence,and it can be extended by TdT to produce a long rich-G DNA.We firstly investigated the products of TdT polymerization under G-rich dNTP pool.We found that the G-rich poly-G-quadruplexes can enhance the fluorescence intensity of G-quadruplex-specific dye ThT.Meanwhile,the poly-G-quadruplexes function as a carrier for photosensitizers such as TMPyP4.This method requires not only one step reaction,but also simple operation and no complicated separation step.2.The application of the aptamer functionalized poly-G-quadruplexes probe in bioimaging.Based on the previous chapter research of the TdT generated poly-Gquadruplexes,we explored a simple,rapid response,high efficiency,easy to operate bioimaging platform is mainly based on the combination of the aptamer functionalized poly-G-quadruplexes probe and ThT can enhance the ThT fluorescence,it is targeted to cancer cells A549 through aptamer sequence,thus realizing the cancer cell "turn-on" detection and imaging.The method has the advantages of non-washing,low background signal,high sensitivity and selectivity.3.The application of the aptamer functionalized poly-G-quadruplexes probe in PDT.Based on the previous chapter,we developed a simple and efficient platform for killing cancer cell by employing TdT producing poly-G-quadruplexes under an appropriate ratio of dNTP can combine with TMPyP4,it is targeted to cancer cells A549 through aptamer sequence,and then quickly produces reactive oxygen species under ultraviolet light,thus killing cancer cells.Compared with the single G-quadruplex structure,the amount of the designed probe load TMPyP4 is greatly improved.