Quantifying Tthe Effect of Cations on Triplet Excited States in G-Quadruplexes in Human Telomeric DNA

Today, G-quadruplexes are an active research area because of their potential as an anticancer method. Using fluorescence correlation spectroscopy (FCS), the aim of this research was to prove that different cations could produce different G-quadruplex structures, and this was quantified by measuring the stability of the affected G-quadruplexes through the dynamics of triplet excited states. Being an abnormal intermediate energy level, a G-quadruplex in which electrons go into the triplet state equates to the fact that these G-quadruplexes are less stable, and thus, they are less effective in protecting against mutations and cancer. In this experiment, human telomeric single-stranded DNA was tagged with carboxytetramethylrhodamine, a fluorophore, to quantify the dynamics of triplet excited states. From our data, we concluded that K+ did not affect the number of photons in triplet excited state whereas the number of photons in triplet excited states in Na+-based and Mg2+-based G-quadruplexes decreased with greater concentration. From this, it was reasonably hypothesized that different cations resulted in different loops around G-quadruplex structures. Specifically, Mg2+ would produce the most safe and stable G-quadruplex structure because it decreased the percentage of electrons in the triplet excited state by a wide margin. This experiment could be foundational in opening a new pathway for targeted cancer research, proving that the structure and shape of G-quadruplexes could be manipulated through a variety of mechanisms