Fe_3O_4 nanoparticles engineered for plasmid DNA delivery to Escherichia coli

摘要

Heat shock treatment is the most popular method for transformation of Escherichia coli.Wehave used 19-nm Fe_3O_4 nanoparticles for improving heat shock protocol. PGEM-T (3,000 bp) and pCAMBIA (8,428 bp)were used as test plasmids for transformation of competent E. coli cells (strains DH5α and Jm107) obtained fromheat shock- andCaCl_2-treated bacteria.A combination of heat shock and Fe_3O_4 nanoparticles led to a significant increase (6–10 fold) in number of transformed colonies in comparison with heat shock alone. The percent increase in transformation efficiency was higher for larger pCAMBIA plasmids compared to PGEM-T. The transformation efficiency decreased in the absence of CaCl_2 and increased by addition of glycerol to the bacterial culture.