With the interaction between photoresponsive molecules and DNA, the reversible switching-modes of DNA hybridization and dissociation were realized by photo irradiation, which would become a new generation of DNA materials for nano-architecture and nano-actuation. We briefly review the recently developed methods to photo-regulate DNA hybridization and dissociation, their switching efficiencies, and their operation/service conditions. Compared with other intercalating and inserting functionalities, inserting wedge type azobenzene by acyclic linker into the DNA backbone is considered as the most favorite approach for potential applications. Interesting application works based on the azobenzene tethered DNA materials in nanotechnology and biotechnology are introduced. In conclusion, an outlook regarding these photo-functional DNA materials and their potential applications is given.

Contents
1 Introduction
2 Reversible photoregulation of DNA hybridization
2.1 Tethering azobenzene by acyclic scaffold
2.2 Additional photoresponsive molecules
2.3 Modification of native bases
2.4 Photoresponsive molecules on the scaffold
3 Comparison of the photoregulation approaches
3.1 Photoregulation efficiency
3.2 Photoregulation power
3.3 Thermal bistability of the photoregulation
3.4 Advices for the photoregulation
4 Azobenzene tethered DNA in nanotechnology
4.1 DNA self-assembly controlled by light-irradiation
4.2 DNA nanomachines powered by light-irradiation
4.3 Other photoresponsive DNA nanomaterials
5 Photoregulation of DNA functions in biotechnology
5.1 Photoregulation of DNAzyme activity
5.2 Photoregulation of DNA translation
5.3 Photoregulation of other DNA functions
6 Conclusion and outlook