Sensitive Detection Of Telomerase Activity Related Substances Based On PH Responsive Colorimetry

The occurrence of cancer is often accompanied by abnormal expression of some proteins,nucleic acids or inorganic salts in the human body,and detection of related tumor markers is of great significance to early diagnosis and treatment of cancer.Telomerase is one of common tumor markers,and its activity is inhibited in normal somatic cells,which is highly active in more than 85%of cancer cell lines.The development of a simple,rapid,convenient,and low-cost method for detecting telomerase activity can promote the spread of early tumor screening.In this paper,inspired by the mechanism of urease catalysis hydrolysis of urea to release a large amount of ammonia,we proposed two pH-responsive colorimetric methods for sensitive detection of telomerase activity related substances through the combination of signal conversion and amplification.In chapter 1,we mainly introduced the concept of telomerase,telomerase structural composition and the relationship of telomerase with tumors.We outlined traditional detection methods for telomerase activity and relationship of telomerase activity with human telomerase RNA(hTR)and pyrophosphate ion(PPi).Moreover,we compared the types and development of current telomerase activity assays by colorimetry.Finally,we presented the research significance and design ideas of this work.In chapter 2,we developed a pH-responsive colorimetric strategy for hTR detection by incorporating controllable separation ability of magnetic beads and signal amplification based on strand displacement reaction.The strand displacement reaction was initiated by target hTR,and then recycled by target hTR and magnetic separation.As a result,abundant urease was anchored on the surface of magnetic beads.After separated by an external magnetic field,urease catalyzed hydrolysis of urea to release ammonia,and a remarkable pH signal was obtained.Therefore,quantification of hTR was achieved by measuring solution pH via a portable pH meter or visualization of the solution color with the assistance of the pH indicator phenol red.In chapter 3,based on the hydrolysis mechanism of urease,we detected telomerase activity by using a pH-responsive colorimetric sensing system consisting of urease-Cu2+-PPi.Firstly,inhibition effect of Cu2+on urease activity was investigated,and optimal concentration of Cu2+ was determined.Then,PPi,by-product of telomerase extension reaction,chelated with Cu2+when added to urease-Cu2+system,and thus urease was reactived.Finally,telomerase was visually determined with the assistance of the pH indicator phenol red according to the degree of hydrolysis of urea.In chapter 4,we summarized the strategies based on pH-responsive colorimetry for telomerase activity related substances detection and looked forward to their application prospects.