Study of agarose aggregate formation through rheological and DLS analyses

Agarose is a natural polymer extracted from algae that has the property of forming physical gels in aqueous solutions when heat is removed from the system. This property holds considerable potential considering its applications in food and pharmaceutical industries, especially for DNA analysis. In this article, different concentrations of agarose in aqueous solutions were submitted to a progressive change in temperature, in order to obtain more or less organized structures of macromolecules. During this process, dynamic light scattering (DLS) and rheological measurements were performed. For scattering measurements, the Kohrausch–William–Watts (KWW) equation was adjusted to the data to obtain the average relaxation rate of the process. Mathematical adjustments were made for both techniques, aiming to study the helix–coil transition of polymeric chains during the temperature change, relating them by calculating the apparent activation energy of the process. Both approaches showed that apparent active energy tends to decrease for dilute solutions and at high temperatures. Given the results with DLS and rheology, we identify similar points of the aggregate formation through the shape of the activation energy curves. However, we also verified that the activation energy values suffer influence according to the nature of the measure.