Development of small, homogeneous pDNA particles condensed with mono-cationic detergents and encapsulated in a multifunctional envelope-type nano device

Non-viral DNA vectors are promising gene delivery systems and a variety of non-viral DNA vectors have been developed to date. Recently, we developed a novel non-viral gene delivery system--multifunctional envelope-type nano device (MEND). The MEND system has high transfection activity, similar to that of adenovirus vector, which is a potent viral vector. However, conventional MEND is relatively large and heterogeneous (approximately 300 nm), probably because they contain relatively large- and heterogeneous-pDNA particles condensed with polycations, such as poly-L-lysine. Small particle size is important for in vivo delivery, because large particles are rapidly eliminated from systemic circulation. Moreover, heterogeneous size of drug carriers is difficult to apply to clinical applications. Here, we describe construction of small homogeneous MEND. First, we screened mono-cationic detergents (MCD(s)) to obtain optimal pDNA condensed particles. We determined that benzyldimethylhexadecylammonium chloride (BDHAC) and thonzonium bromide (TB) were optimal pDNA condensers. Next, we packaged the condensed pDNA particles into a lipid bi-layer. The resulting lipid-encapsulated pDNA particles were then equipped with octaarginine to facilitate cell-uptake (R8-MEND (MCD)). The carrier showed high transfection activity in cultured HeLa cells. Furthermore, the R8-MEND (MCD) were small and homogeneous compared with conventional MEND. These results indicate that R8-MEND (MCD) has potential as a novel non-viral delivery system for clinical application.