Retracted: <i>In vitro</i> transfection of plasmid DNA by different-cationized gelatin with or without ultrasound irradiation

Abstract

In vitro transfection of a plasmid DNA encoding luciferase by cationized gelatin was investigated with or without ultrasound (US) irradiation. Cationized gelatins with various introduction percentages of amino residues could be prepared by changing the introduction condition of ethylenediamine (ED) to the carboxyl groups of gelatin. The zeta potential of cationized gelatin became larger as the percent introduced increased, whereas a big change in the apparent molecular size of gelatin was not observed. An electrophoresis experiment revealed that the cationized gelatin was mixed with the plasmid DNA with the increased gelatin/DNA ratio to form cationized gelatin-plasmid DNA complexes. When the amount of amine residues introduced was 47.8% or higher, the complex obtained was about 200nm in diameter with a positive charge. The rat gastric mucosal (RGM-1) cells incubated with the cationized gelatin-plasmid DNA complex exhibited a luciferase activity and the activity was further enhanced by US irradiation. The amount of plasmid DNA internalized was increased not only by the complexation but also by an increase in the cationization of gelatin. The viability of cells decreased by their incubation with complexes, irrespective of the gelatin type and US irradiation. We conclude that it is necessary for US-enhanced gene expression to use cationized gelatin with the percent aminization of 47.8% or higher as the vector of plasmid DNA.