Nanoparticles of poly(styrene-co-maleic acid) as colloidal carriers for the anticancer drug epirubicin

This article considers the preparation and physicochemical characterization of poly(styrene-co-maleic acid) nanoparticles as colloidal carriers for the anticancer drug epirubicin. The nanoparticles were prepared by nanoprecipitation approach in a mixed (water/acetone) solvent system and the drug was loaded by sorption. It was found that the size of nanoparticles could be precisely controlled (from 100 to 320 nm in diameter) by varying the polymer concentration and the acetone/water volume ratio. All nanoparticles possessed negative zeta-potentials at physiological-like conditions. The presence of human serum albumin decreased significantly the absolute value of the zeta-potential, although still remaining negative, of both drug-free and drug-loaded nanoparticles indicating albumin adsorption onto the particle surface. The nanoparticles were stable in phosphate buffered saline within the pH interval from 4.5 to 9.3 (forming precipitates at lower pH and being disintegrated at higher pH). In vitro studies of the epirubicin release indicated a relatively strong association of the drug with the polymer and sustained release of only about 10% of the loaded drug for a period of 7 h. We hope that the results reported in this article could be helpful for improvement of the preparation procedures for poly(styrene-co-maleic acid)-based nano-formulations of anticancer drugs with desired physicochemical characteristics, which appear to be important prerequisites for their successful biomedical applications.