Structures and Antibacterial Properties of DNA Ion Complex Films Consisting of Different Cationic Surfactants with the Same Carbon Number in Their Tails

Abstract

DNA ion complexes were prepared from DNA and two forms of cationic surfactants, hexadecylpyridinium chloride (HDPyCl) (also known as cetylpyridinium chloride (CPC)) and hexadecyltrimethylammonium bromide (HDTMABr) (also known as cetyltrimethylammonium bromide (CTAB)), which are antibacterial and have the same sixteen carbons in their tail alkyl chains, but different polar head groups. The anionic DNA and the cationic surfactant were sufficiently reacted and washed well to obtain DNA ion complexes with equal moles. These films were prepared using iso-propanol. The bulk and surface structure of the films were examined and compared using small angle X-ray scattering (SAXS), a gas pycnometer, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), a static water contact angle meter, and atomic force microscopy (AFM). The two different DNA ion complex films consisting of surfactants with the same carbon number were found to be different in their DNA-DNA distances, film densities, and surface chemical compositions. Both films showed antibacterial properties.