The influence of PEG molecular weight on apparent hydrogel microsphere size as measured by the Coulter Principle

investigating hydrogel microparticles for use in biomedical applications. Often, these investigations use the Coulter principle to evaluate the size distribution of their microparticles.1-3 Since this method uses the displacement of electrolyte to determine particle size, the electrolyte contained within the swelled hydrogel microparticles results in an underestimate of actual particle diameters. Using polyethylene glycol diacrylate (PEGDA) hydrogel microspheres, we attempted to determine a relation between polymer molecular weight and apparent Coulter diameter that would provide a correction for the underestimated diameters provided. Methods: Five polymer precursor solutions were create