Preparation of DNA Ion Complex Films Using a Hot-Press Molding and Their Antibacterial Functions

DNA ion complexes of anionic DNA and two forms of cationic surfactants with a sixteen-carbon alkyl chain in their tails were utilized to prepare their films using a hot-press molding. The surfactants were hexadecyl pyridinium chloride (HDPyCl) and hexadecyltrimethylammonium bromide (HDTMABr), which had different polar head groups of pyridinium and trimethylammonium cations, respectively. The ion complex powders of DNA-HDPy (D-HPy) or DNA-HDTMA (D-HTm) were converted to their free-standing films with the hot-press treatment. Both bulk structures were investigated and compared using small angle X-ray scattering (SAXS), a gas pycnometer, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and a tensile test. Further, antibacterial activities against Staphylococcus aureus of the films were also evaluated since the surfactants are known to possess inhibition of microbial growth.