Self-associating block copolymer networks for microchip electrophoresis provide enhanced DNA separation via "inchworm" chain dynamics.
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.
Chiesl
Thomas N
TN
Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, USA.
Putz
Karl W
KW
Babu
Meena
M
Mathias
Patrick
P
Shaikh
Kashan A
KA
Goluch
Edgar D
ED
Liu
Chang
C
Barron
Annelise E
AE
D004247:DNA / Q000302:isolation & purification*; D046209:Electrophoresis, Microchip / Q000379:methods*; D011108:Polymers / Q000737:chemistry*
D011108:Polymers; D004247:DNA