Polyethyleneimine-Coated Capillaries for the Separation of DNA by Capillary Electrophoresis

Currently, the microscopic understanding of DNA structure and function is a major problem of widespread interest. Recently, capillary electrophoresis (CE) has arisen as an effective and accessible method for the fast resolution of the microscopic constituents of complex mixtures. Molecular sieving with diluted solutions of entangled linear polymers such as polyacryamide (PAA)1−3 cellulose derivatives4−6, polyvinyl amine (PVA)7−9 or polyethylene glycol (PEG) have been developed for CE separations. Due to the advantages of shorter analysis times, easily refreshed buffer systems, and stability under high electric fields compared to gel-filled capillaries, this separation procedure has recently played an important role in DNA analysis. Applications of CE to the analysis of fragmented DNA have been achieved in bare silica capillaries, with PAA coatings introduced by Hjerten being the most commonly used modification method. However, no attempt had been made so far to separate DNA in a capillary coated with a positively charged polymer, because the opposite charge of DNA would cause adsorption on the wall. On the other hand, in the last few years, the interaction of DNA with oppositely charged polymers has attracted great interest due to the importance of such systems for gene delivery. Among the several cationic polymers used for this purpose, the ability of polyethyleneimine (PEI) to act as an efficient vector for gene and oligonucleotide transfer ∗Corresponding author