title: Self-associating block copolymer networks for microchip electrophoresis provide enhanced DNA separation via "inchworm" chain dynamics.
abstract: We describe a novel class of DNA separation media for microchip electrophoresis, "physically cross-linked" block copolymer networks, which provide rapid (<4.5 min) and remarkably enhanced resolution of DNA in a size range critical for genotyping. Linear poly(acrylamide-co-dihexylacrylamide) (LPA-co-DHA) comprising as little as 0.13 mol % dihexylacrylamide yields substantially improved electrophoretic DNA separations compared to matched molar mass linear polyacrylamide. Single-molecule videomicroscopic images of DNA electrophoresis reveal novel chain dynamics in LPA-co-DHA matrixes, resembling inchworm movement, to which we attribute the increased DNA resolution. Substantial improvements in DNA peak separation are obtained, in particular, in LPA-co-DHA solutions at polymer/copolymer concentrations near the interchain entanglement threshold. Higher polymer concentrations yield enhanced separations only for small DNA molecules (<120 base pairs). Hydrophobically cross-linked networks offer advantages over conventional linear polymers based on enhanced separation performance (or speed) and over chemically cross-linked gels because hydrophobic cross-links can be reversibly broken, allowing facile microchannel loading.
authors.affiliation: Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: Thomas N
authors.initials: TN
authors.lastname: Chiesl
authors.forename: Karl W
authors.initials: KW
authors.lastname: Putz
authors.forename: Meena
authors.initials: M
authors.lastname: Babu
authors.forename: Patrick
authors.initials: P
authors.lastname: Mathias
authors.forename: Kashan A
authors.initials: KA
authors.lastname: Shaikh
authors.forename: Edgar D
authors.initials: ED
authors.lastname: Goluch
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.forename: Annelise E
authors.initials: AE
authors.lastname: Barron
mesh_terms: D004247:DNA / Q000302:isolation & purification*; D046209:Electrophoresis, Microchip / Q000379:methods*; D011108:Polymers / Q000737:chemistry*
chemical_list: D011108:Polymers; D004247:DNA