Reversible photoregulation in biological systems via introduction of azobenzene into nucleic acid

As photoisomerization mechanism and characteristic of azobenzene was deeper and deeper, reversible photoregulation of related processes via introduction of azobenzene into nucleic acids has received a lot of attention. Azobenzene, as a photoresponsive unit, was not only used to synthesize artificial intelligent materials or molecular machines, but also infiltrating rapidly into analysis and modulation of chemical biological systems. In view of information diversity provided by nucleic acid molecules, the modular introduction of these switchable units into nucleic acids has allowed diverse applications ranging from reversible formation of duplex, photoswitchable RNA silencing, reversible control of gene expression, reversible aptamer recognition, to reversible photocontrol of DNAzymes, as well as obtaining structural information and intermolecular interaction using the introduced azobenzene as an internal probe. Thus, the combination of functional azobenzene group with nucleic acids to apply in biological systems will be a hot topic in the field of nucleic acid chemistry. Here, the design principles and characteristics of four different combining ways between azobenzene and nucleic acids were mainly elaborated, and reversible regulation of structure and function of nucleic acid in biological systems was reviewed due to photo-isomerization properties of azobenzene photosensitizers by screening some representative examples. Finally, the problems that may exist in the biosystems, and looks into the future and trends of the research were also depicted.