Threading Intercalator-Induced Nanocondensates and Role of Endogenous Metal Ions in Decondensation for DNA Delivery.

The interplay of condensation and decondensation of DNA plays a crucial role in chromosome maintenance and gene expression. The molecular architectonics governing the chromatin condensation-decondensation cycle are worth studying, as DNA performs unique and distinct roles in each state and switches between two states without the loss of structural and functional integrity. This phenomenon has been adapted and implemented in transfection studies. Effective gene delivery into the cells to achieve respectable transfection efficiency has remained a challenge and emphasizes the need for understanding the steps involved in DNA delivery and transfection. Especially, recognizing the factors that effectively regulate DNA decondensation can provide logical solutions to the hurdles affecting the transfection efficiency. We designed a set of small molecule-based threading intercalation ligands as model condensing agents to study various factors influencing the DNA condensation and decondensation process. This study revealed condensation of DNA into nanocondensate by the threading intercalator and endogenous stimuli induced effective decondensation. Further, DNA nanocondensates are tracked using the intrinsic fluorescence in the lower pH of endocytic pathway and were evaluated as nonviral vectors for in cellulo delivery of plasmids. The correlation of decondensation of DNA nanocondensate with endogenous metal ions at their physiological concentrations provided valuable insights and implications for intracellular DNA delivery.