Functional Nucleic Acid Enzymes: Nucleic Acid-Based Catalytic Factories

Biocatalysis plays a vital role in the operations of all living organisms, which is usually thought to be mediated by protein enzymes. However, the pioneering discovery of self-splicing intron-splicing RNA ribozyme demonstrated that nucleic acids can also promote catalysis, with efficiency comparable to that of proteases. The discovery of deoxyribozyme (DNAzymes) further broadened the understanding of the catalytic function of nucleic acids. Since then, nucleic acids with various catalytic functions have been gradually discovered and significant efforts have been devoted to the applications studies of nucleic acid catalyst. Consequently, a systematically and comprehensive review is needed to summarize all the advancements in the FNAzymes field. In this review, we propose the concept of functional nucleic acid enzymes (FNAzymes). FNAzymes are nucleic acids or nucleic acid complexes with special structure and catalytic functions. Then FNAzymes are divided into four groups based on the components that make them up: ribozymes, DNAzymes, modified FNAzymes, and functional nucleic acid nanozymes (FNA nanozymes). In addition, the catalytic function, structure, and catalytic mechanism of each FNAzymes are introduced. The applications of FNAzymes in biosensing, bioimaging, and biotherapy of are summarized. Finally, future development trends and application prospects of functional nucleases are discussed.