SEPARATIONS OF DNA FRAGMENTS BY CAPILLARY ELECTROPHORESIS IN N-SUBSTITUTED POLYACRYLAMIDES

In spite of its high resolving capability, the use of polyacrylamide a s a sieving matrix for capillary electrophoresis (CE) is limited by se veral factors, The viscosity of polyacrylamide solutions is too high f or easy capillary filling and the matrix requires a highly pressurized system to be replaced after each run. The systems currently used to p roduce short polyacrylamide chains needed to overcome this problem, re quire a careful optimization of polymerization conditions to produce p olymers of reproducible composition. In addition, the polyacrylamide v iscosity may vary with time depending on the shear stress to which the solution is subjected, This work proposes some new matrices for PNA s eparations by CE that overcome these obstacles while maintaining the h igh resolution offered by polyacrylamide. The properties of dimethylac rylamide and y(acryloylaminoethoxy)ethyl-beta-D-glucopyranoside were i nvestigated. Both polymers were found to be more suitable than polyacr ylamide as DNA sieving media, The presence of substituents on the amid o nitrogen reduces the viscosity of the polymer solutions without chan ging separation selectivity as demonstrated by the identical profile o f the double-log curves of mobility versus DNA size obtained for the t hree polymers, In general, an increase in the monomer size leads to th e formation of a network with larger pore sizes in which DNA molecules migrate more rapidly, providing shorter analysis times and more effic ient separation. (C) 1997 Elsevier Science B.V.