Application Of Y-Type-DNA-Functionalized Nano Probes In Cancer Diagnosis And Treatment

Cancer,also known as malignant tumor.It is a disease caused by abnormal mechanisms that control cell growth and proliferation.Not only do cancer cells grow out of the control of the body,but they attack healthy cells around them and can even be transported to other parts of the body through the body’s lymphatic or circulatory system.The incidence rate of cancer is increasing year by year,which seriously threatens human life and hinders the development of society.It is one of the main reasons for the decline of survival rate.Therefore,the biggest problem facing medical clinic is prevention and treatment.On the one hand,if the cancer can be diagnosed correctly in the early stage of its onset,and the right treatment plan can be adopted in time,the cure rate can be greatly improved.However,the conventional detection methods in clinical practice have low specificity and sensitivity,and it is difficult to detect the onset symptoms of the tumor at the early stage.When it is diagnosed,it has reached the middle and advanced stages,which greatly reduces the cure rate of cancer.The hope is that tumors can be detected quickly,and researchers are focusing on finding tumor markers at the cellular level to distinguish cancer cells from normal cells.On the other hand,in order to improve the cure rate of cancer,lots of research efforts have been focused on synthesizing new drugs and developing new treatments.There are many shortcomings of current chemotherapy,such as chemotherapy drugs on the human body normal tissue has strong sideeffects,the inability to distinguish between cancer cells and normal cells,and cancer cells to produce resistance,etc.Therefore,it is urgent for us to develop carriers that are easy to control drug release and deliver drug molecules to cancer cells,so as to reduce the toxicity and side effects of drugs on normal human organs and greatly improve the therapeutic effect of drugs.The first chapter of this paper introduced the telomerase and several methods to detect telomerase,gold nanoparticles,gold nanorods and their applications.It also explained the main content and novelty of this paper.The second chapter described the telomerase-induced drug release system for the detection and treatment of cancer cells.This system involved a DNA-functionalized nanogold probe centering on gold nanoparticles with dense modification of Y-type DNA molecular beacons on the surface.The Y-type DNA molecular beacon consisted of the telomerase primers,FAM-labeled single-strand DNA,and single-strand DNA of two templates.Doxorubicin,an anti-cancer drug molecule,was inserted into DNA double strands.When telomerase existed,TP was extended,Mismatch-DNA was released,leading to emition of fluorescent light from the FAM while releasing Dox.In Chapter 3,a novel enzyme-free signal amplifification-based assay for highly sensitive in situ fluorescence imaging and detection of intracellular telomerase activity was developed by using a gold nanoflflare probe-triggered mimichybridization chain reaction(mimic-HCR)coupled with a graphene oxide surface-anchored fluorescence signal readout pathway.When gold nanorods were locatedin near-infrared radiation,its photothermal effect caused the local temperature of the cells to rise rapidly,killed cancer cells.By synergizing multiple approaches for treating tumors,the survival rate of tumor cells was greatly reduced.