Exclusion of spheres by agarose gels during agarose gel electrophoresis: Dependence on the sphere's radius and the gel's concentration

Agarose gel electrophoresis of spheres (radius = R) has been used to determine the effective radius (P_E) of the pores of an agarose gel (percentage of agarose in a gel = A). The value of P_E at a given A was taken to be the R of the largest sphere that enters the gel. When log P_E is plotted as a function of log A, the results can be represented by: P_E = 118A^-0.74 for 0.2 ≤ A ≤ 4.0 (P_E in nm). However, the data suggest significant nonlinearity in this plot, the magnitude of the exponent of the P_E vs A relationship increasing by about 20% as A increases from 0.2 to 4.0. From these data, P_E's as big as 1500 nm and as small as 36 nm can be achieved with agarose gels formed with unmodified, unadulterated agarose and usable for electrophoresis.