Star polymer electrophoresis

In an extremely important paper, Heuer, et al. used photomicrography to examine electrophoresis of synthetic DNA stars in linear polyacrylamide having an estimated molecular weight of 5-6 MDa(13). Polymer concentrations covered 0.5-10 g/1, the nominal overlap concentration (estimated in several ways) being near 1.6 g/1. Stars were created via the approach of Seeman(22) four short (44 bp) synthetic oligonucleotides, whose complementary sequences cause them to self-assemble into a four-arm star, and whose arms bind X-phage DNA ends, were synthesized, leading to monodisperse star polymers. 

Saha, S., Heuer, D. M., and Archer, L. A. (2006). Electrophoretic mobility oflinear and star-branched DNA in semidilute polymer solutions. Electrophoresis 27, 3181—3194. 

In another example, a hydrophilic star block copolymer was composed of a hyperbranched PEI core, a PLL inner shell and a PEG outer shell. Insulin, as a model protein, can be rapidly and efficiently encapsulated by the synthesized polymer in aqueous phosphate buffer at physiological pH. Complexation between PEI-PLL-Z)-PEG and insulin was demonstrated using native polyacrylamide gel electrophoresis. An in vitro release study by dialysis showed sustained release of the encapsulated protein at physiological pH, and an accelerated release when the pH was decreased. The insulin released from the star block copolymer retained its chemical integrity and immu-nogenicity. Successful in vitro uptake studies of enhanced green fluorescent protein into Ad293 cells mediated by PEI-PLL-Z)-PEG were also performed. ... 

D. M. Heuer, S. Saha, and L. A. Archer. Electrophoretic dynamics of large DNA stars in polymer solutions and gels. Electrophoresis, 24 (2003), 3314-3322. 

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