Styrene maleic acid anhydride copolymer (SMA) for the encapsulation of sparingly water-soluble drugs in nanoparticles

Styrene maleic acid copolymer (SMA) is widely used in various industrial applications, such as adhesives and coatings, because of its good durability and low cost. In this study, we investigated the biological safety and functions of nanoparticle formulations with varying molecular weights of SMA. The toxicity of SMA, measured by hemolytic activity and body weight loss, was examined in mice. Amphotericin B (AmB) and all-trans retinoic acid (ATRA) are limited in clinical use because of their poor water solubility. We prepared AmB- and ATRA-loaded SMA nanoparticles for the first time; these are self-assembled nanoparticles with a high drug-loading capacity. The formation of monodispersed nanoparticles by self-assembly of SMA and their complex formations with drugs were studied by size-exclusion chromatography (HPSEC) and dynamic light scattering. After intravenous injection of the drug-loaded SMA nanoparticles, prolonged blood circulation of AmB and ATRA was observed.