Research On The Properties Of Circular Functional Nucleic Acids And Their Applications In Analytical Chemistry For Life

Since the 21st century,with science and technology development,environmental degradation,and health problems caused by environmental degradation have gradually attracted people’s attention.Besides,people’s demands for health are also increasing day by day,and there is an urgent need to establish and improve detection methods for molecules related to life substances.Among the many analysis and detection methods involved in this requirement,the methods based on functional nucleic acids(FNAs)have also attracted researchers’ attention in recent years.FNAs refers to a kind of nucleic acid molecules with specific function beyond genetic functions.Natural FNAs have reported having analysis capabilities in life systems,which proves the feasibility of FNAs for detecting life-related substances.The double helix structure gives FNAs the capability of molecular design,which then expands the types of methods and strategies available for analysis.For more than 30 years of development,FNAs has made significant breakthroughs in its fundamental research and applied research.Simultaneously,as the industrialization of research in this field advances,problems in the practical application of FNAs cannot be ignored.For example,nucleic acid molecules are susceptible to enzymatic degradation,and its tertiary structure is also susceptible to environmental factors,then causing unstable functional expression.To better promote the development of FNAs in practical applications while expanding the scope of its applications,part of the research focus should place on solving the problems in its practical application requirements.Nucleic acid modification,nanocarriers,and other strategies are often to solve the functional and structural instability of FNAs in practical applications.However,such strategies also have disadvantages,such as cumbersome modification and high cost.Therefore,it is still to find the best solution.In recent years,as researchers have deepened their understanding of the structure of FNAs,strategies to improve the properties of FNAs from the perspective of its structures have also achieved specific results.This type of strategy achieves the performance of FNAs by introducing unique nucleic acid structures.The improvement does not require additional chemical modification and therefore has particular research value.Circular nucleic acid(CNAs),which refers to a type of closed-end nucleic acid molecule,it is also a type of nucleic acid structure in large numbers in nature.In recent years,circular RNA’s biological functionality has been gradually discovered,which has attracted more attention in this research field.Studies have also shown that CNAs bear molecular regulation in organisms.Natural CNAs have excellent biological stability against enzyme degradation,which shows that CNAs may solve the problems faced in applying FNAs.However,limited by synthesis methods and application requirements,CNAs’ application research is still in its infancy,which poses significant challenges to researchers in this field.Based on the above contents,and combined with the current research status in CNAs and the application requirements in FNAs,this thesis gives the research on circular functional nucleic acids(CFNAs)from three aspects,including synthesis,properties,and applications.Chapter 2 focuses on the question of limited synthesis methods of CFNAs,and then discuss the synthesis methods of CFNAs from the version of the enzymatic approach and chemical approach.Based on the research in Chapter 2,Chapters 3,4,and 5 synthesized three different types of CFNAs,including circular aptamers,circular G-quadruplexes,and circular deoxyribozymes,and then give the discussion the properties and applications of the above CFNAs.According to the results,the circularization of FNAs has a particular impact on its functionality.Through the optimization design,CFNAs can possess better performance in its intrinsic function than FNAs.Besides,CFNAs have better biological stability than FNAs,making the CFNAs have better application effects in practical applications.Indeed,this strategy can widely improve the properties of FNAs in the future.