Phase behavior of catenated-linear DNA mixtures

Understanding the phase behavior of multicomponent systems is crucial in condensed matter physics, both for practical applications and fundamental exploration. Regardless of chemical composition, topology stands out as a crucial parameter in this context. We studied herein the phase behavior of a 2D catenated network of DNA rings called a kinetoplast in the presence of linear DNA. We examine the system at a fixed kinetoplast DNA concentration and linear DNA size, while varying the concentration of linear DNA. The mixing of circular DNA with linear DNA is reported to lead to the isotropic phase of the mixtures, however, catenated DNA rings (the assembly of circular DNA) lead to the phase separation in the presence of linear DNA. This distinction highlights the profound influence of topology on the phase behavior of polymer blends. The phase-separated aggregates of kinetoplasts exhibit a fractal nature, with the fractal dimension indicating the dominance of the diffusion-limited mechanism in the aggregation process. Although the structure of these aggregates is robust, significant thermal fluctuations in size and shape occur at various length scales. The understanding of the bulk phase behavior of the catenated DNA network provides crucial insights in designing the catenated-linear polymer composites.