Controllable Molecular Sieving by copoly(Poly(ethylene glycol) Acrylate/Poly(ethylene glycol) Diacrylate)-Based Hydrogels via Capillary Electrophoresis for DNA Fragments

This work proposes controllable molecular sieving using the cross-linked copoly(poly(ethylene glycol) acrylate/poly(ethylene glycol) diacrylate) (copoly(PEGA/PEGDA)) hydrogels as a sieving matrix for DNA in capillary electrophoresis (CE). Attempts were made to control the separation performance using different gel components, including the initiator concentration (CAPS), total concentration (Ct) of monomers, the ratio (R) of PEGA to PEGDA, and the length of the cross-linker (Lc). Results reveal that the molecular sieving effect in the copoly(PEGA/PEGDA) gel can be controlled by Ct, R, CAPS, and Lc, especially by the former two parameters. Higher Ct and lower R provided smaller average pore size, resulting in better separation of small-size DNA fragments, while lower Ct and higher R allowed better separation of large-size DNA fragments. Moreover, using a representing gel component, the repeated test showed a run-to-run precision of RSD < 0.9% (n = 10 tests), a column-to-column precision of RSD < 5.9% (n = 5 columns), and a day-to-day precision of RSD < 5.2% (n = 25 tests in 5 days) for the migration time. The results also reveal the rapid and high-resolution separation for 20–140 bp DNA fragments using the copoly(PEGA/PEGDA) gel when tuned to a lower R and lower Ct. When high Ct was used, the copoly(PEGA/PEGDA) gel capillary was found to have better repeatability and higher resolution than the authentic poly(acrylamide) gels owing to the better volume stability upon polymerization.