Core Viewpoint - Functional nucleic acids (FNA) represent a transformative advancement in molecular biology and precision medicine, showcasing their structural diversity and functional potential in various biomedical applications [3][10]. Group 1: Characteristics and Types of FNA - FNA is characterized by unique secondary and tertiary structures formed through the complementary pairing of nucleotide bases, enabling biological functions such as specific target recognition, molecular binding, and catalytic activity [10]. - Aptamers, a type of FNA, are synthetic oligonucleotide sequences known for their high specificity and affinity towards various targets, functioning as "chemical antibodies" [10]. - DNAzymes are catalytically active DNA molecules evolved through in vitro selection, capable of executing specific biochemical reactions such as the cleavage and ligation of RNA and DNA [10]. Group 2: Production and Engineering Strategies - The production methods, structural principles, and biological functions of key FNAs, specifically aptamers and DNAzymes, are crucial for their application in biomedical fields [9][10]. - Engineering strategies to optimize FNA molecular characteristics include enhancing stability, affinity, and catalytic efficiency through rational design and chemical modifications [9][10]. Group 3: Clinical Applications and Challenges - The clinical translation of FNA is progressing, with two aptamer drugs, Macugen and Izervay, already approved for treating age-related macular degeneration, while DNAzymes are currently in clinical trials [10]. - Challenges remain in the clinical application of FNA, including issues related to nucleic acid degradation, delivery efficiency, and regulatory complexities [10].