Improved loading of hydrophobic molecules in polyelectrolyte multilayers thin films using the layer-by-layer surface modification

Abstract

Polyelectrolyte multilayers (PEM) thin films fabricated using the Layer-by- Layer (LbL) technique can provide nanostructure coating for improve the loading of hydrophobic molecules. In this work, the films prepared by alternative layers of cationic poly (diallydimethylammonium chloride) (PDADMAC) and anionic poly (sodium 4-styrene-sulfonate) (PSS) were loaded with l,7-bis-(4-hydroxy-3- methoxy-3-methoxyphenyl)-l,6-heptadiene-2,5-dione (curcumin, CUR) which is beneficial compound in medical applications and used here as a hydrophobic drug. The effects of temperature and water/ethanol composition on the loading of CUR into PEM films were characterized by Atomic force microscopy (AFM) and Ellipsometry although the amount of CUR in the films was measured by UV-visible spectroscopy. Then modified the films by using cetrimethylammonium bromide (CTAB) or sodium dodecyl sulphate (SDS) surfactants to improve the solubility and stability of CUR. The results show that the loading of CUR in PEM films can be controlled by solvent composition driven by solid-liquid partitioning mechanism. The loading was decreased with increasing temperature owing to the rising solubility of CUR. Furthermore, the surfactants modification of PEM film was found to increase the final loading of CUR in the film.