Catalytic Nucleic Acids for Bioanalysis.

Nucleic-acid-based bioaffinity elements, isolated from randomized oligonucleotide libraries through systematic evolution of ligands by exponential enrichment (SELEX), have found numerous applications in chemical biology, medicine, analytical chemistry, and materials science. Aptamers are artificially selected oligonucleotides with target binding abilities, whereas DNAzymes can catalyze chemical reactions in a specific manner. More recently, efforts have been taken to develop bifunctional nucleic acids by coupling catalytic DNAzymes with antibody-mimicking aptamers. Specifically, regulation gene expression and amplified intracellular biosensing have been accomplished with aptazymes by combining recognition units of aptamers and catalytic units of DNAzymes. Alternatively, nucleoapzymes were developed to enhance the catalytic activity of DNAzymes via proximity concentrating of substrates to the catalytic site by aptamers. These catalytic nucleic acids hold great promise for bioanalysis and other biomedical applications, which are summarized in this review.