Network Formation and Sieving Performance of Self-Assembling Hydrogels

Self-assembling hydrogels, consisting of aqueous solutions of poly(ethylene glyco)s end-capped with perfluorocarbon groups (R _f-PEGs), were studied for their electrophoretic sieving performance. These materials form physical gels, with the end groups aggregated in hydrophobic cores. The gels display high sieving performance, expressed as a large mobility dependence on DNA size, for short double-stranded DNA fragments even at relatively low polymer concentrations (∼3 wt %). This interesting characteristic can be attributed to the dense packing of interconnected micelles that build up the hydrogel network. The physically connected micelles act as a permanent network on the time scale of DNA migration over the distance between micelle cores. A mobility plateau was observed for intermediate DNA sizes that were probably too large to sieve through the network of interconnected micelles and yet too small to reptate. This plateau was followed by a reptation regime for larger DNA sizes, that has similar resolving characteristics to that observed for entangled linear PEO solutions.