Spatiotemporal evolution of heterogeneous structures in agarose gels revealed by particle tracking.

Upon decreasing the temperature, agarose solution exhibited gelation and phase separation, forming a cloudy gel consisting of agarose-rich and agarose-poor phases. Both phenomena contribute to the formation of a heterogeneous gel structure, but the primary influence of both processes on this heterogeneity remains unclear. In this study, we defined the specific gelation and phase separation temperatures of an agarose solution and examined the resulting gel structures with and without phase separation. Microscopic observation and colloid diffusion analysis revealed that phase separation leads to inhomogeneities several micrometers in size. Furthermore, we found that the distributions of colloidal diffusion coefficients and particle displacements strongly reflected the heterogeneity primarily induced by phase separation and gelation. Our findings contribute to the physicochemical understanding of the heterogeneous structures of various (bio) polymer gels associated with the phase separation of polymers.