Transfecting pDNA to E. coli DH5α using bovine serum albumin nanoparticles as a delivery vehicle

We describe the formulation of bovine serum albumin nanoparticles (BSA-NPs) by the coacervation method using surfactants. Plasmids (pUC18, pUC18egfp and pBBR1MCS-2) isolated from E. coli were incorporated into the BSA matrix by incubating in albumin solution prior to formulation of NPs. Plasmid incorporation was calculated by % yield, entrapment efficiency, DNA loading capacity and release of entrapped DNA by comparing with blank NPs. BSA-DNA binding studies were carried out by using fluorescence spectroscopy and Fourier Transform Infra Red Spectroscopy (FT-IR). The surface charge distribution of the NPs loaded with plasmid was calculated using zeta potential. The photoluminescence of BSA-NPs was quenched when loaded with pDNA, confirming the interaction of DNA with BSA. Altogether, these results provide evidences for the excellent DNA carrying efficiency of BSA-NPs without loss of plasmid's integrity. The NPs were used to transfect E. coli DH5α strain lacking ampicillin resistance. They, however, showed ampicillin resistance subsequent to transfection with plasmid encoding ampicillin resistance gene. Effect of transfection was confirmed by confocal microscopy and by the isolation of the plasmid by agarose gel electrophoresis from the transfected bacterial culture. This study clearly demonstrates the efficacy of BSA-NPs as delivery vehicle for pDNA transfection.