One-step preparation of amino-PEG modified poly(methyl methacrylate) microchips for electrophoretic separation of biomolecules

A simple method for a chemical surface modification of poly(methyl methacrylate) (PMMA) microchips with amino-poly(ethyleneglycol) (PEG–NH2) by nucleophilic addition–elimination reaction was developed to improve the separation efficiency and analytical reproducibility in a microchip electrophoresis (MCE) analysis of biomolecules such as proteins and enantiomers. In our procedure, the PEG chains were robustly immobilized only by introducing an aqueous solution of PEG–NH2 into the PMMA microchannel. The electroosmotic mobilities on the modified chips remained almost constant during 35 days with 37 runs without any recoating. The PEG–NH2 modified chip provided a fast, reproducible, efficient MCE separation of proteins with a wide variety of isoelectric points within 15 s. Furthermore, the application of the modified chip to affinity electrophoresis using bovine serum albumin gave a good chiral separation of amino acids.