Endogenous Activation-Induced Delivery of a Bioactive Photosensitizer from a Micellar Carrier to Natural DNA.

The photophysics of phenosafranin (PSF), a member of the photosensitizer phenazinium family, has been explored in nonionic Triton X-165 (TX-165) micelle, calf thymus DNA (ctDNA), and a composite environment consisting of both micelle and DNA, using diverse spectroscopic techniques of both steady-state and time-resolved natures, to divulge the binding interactions of the probe with different hosts. The vivid experimental results demonstrate that PSF binds with both micelle and DNA; however, the binding affinity of the probe is much higher toward the DNA. When micelle-carried PSF comes in proximity to ctDNA, PSF gets released from the micellar environment and intercalates with the DNA base pairs. Endogenous activation, in terms of a higher binding affinity of PSF toward ctDNA relative to that toward the micelle, is ascribed to be responsible for this transfer. Thus, this article demonstrates endogenous transfer of a bioactive molecular probe from a micellar nanocarrier to natural DNA. As the carrier micelle (TX-165) does not perturb the structure of the DNA, this work proposes that it can be used promisingly for the purpose of safe delivery of drugs. The study is expected to stimulate the generation of and/or search for advanced micelle-based carrier systems for delivery of bioactive molecular systems to biological targets like DNA.