A smart DNA nanodevice for ATP-activatable bioimaging and photodynamic therapy

Rational design of activatable photosensitizers for controlled generation of singlet oxygen remains a challenge for precise photodynamic therapy(PDT). Herein, we present an aptamer-based nanodevice for adenosine 5′-triphosphate(ATP)-activatable bioimaging and PDT. The nanodevice is constructed by modifying ATP-responsive duplex DNA units and polyethylene glycol on the surface of a gold nanoparticle(AuNP) through the thiolate-Au chemistry. The DNA units were designed by the hybridization of the ATP aptamer strand with a methylene blue(MB)-modified complementary DNA(cDNA). The close proximity of MB to the surface of AuNP results in the low photodynamic activity of MB(OFF state). Once internalized into cancer cells, the ATP-binding induced conformation switch of aptamer strand leads to the release of the MB-bearing DNA strand from AuNPs, resulting in the activatable generation of singlet oxygen under light irradiation(ON state). We demonstrate that the DNA nanodevice represents a promising platform for ATP-responsive bioimaging and specific PDT in vitro and in vivo. This work highlights a potential way for specific tumor diagnosis and therapy.