Layer-by-layer engineered nanocapsules of curcumin with improved cell activity.

Nanocarriers based on electrostatic Layer-by-layer (LbL) assembly of CaCO3 nanoparticles (CaCO3 NPs) was investigated. These inorganic nanoparticles was used as templates to construct nanocapsules made from films based on two oppositely charged polyelectrolytes, poly(diallyldimethylammonium chloride), and poly (sodium 4-styrene-sulfonate sodium salt), followed by core dissolution. The naked CaCO3 NPs, CaCO3 NPs coated with the polyelectrolytes and hollow nanocapsules were found with hexagonal shape with average sizes of 350-400 nm. A reversal of the surface charge between positive to negative zeta potential values was found, confirming the adsorption of polyelectrolytes. The loading efficiency and release of curcumin were controlled by the hydrophobic interactions between the drug and the polyelectrolyte matrix of the hollow nanocapsules. The quantity of curcumin released from hollow nanocapsules was found to increase under acidic environments, which is a desirable for anti-cancer drug delivery. The hollow nanocapsules were found to localize in the cytoplasm and nucleus compartment of Hela cancer cells after 24 h of incubation. Hollow nanocapsules were non-toxic to human fibroblast cells. Furthermore, curcumin loaded hollow nanocapsules exhibited higher in vitro cell inhibition against Hela cells than that of free curcumin, suggesting that polyelectrolyte based-hollow nanocapsules can be utilized as new carriers for drug delivery.

Loading of curcumin in polyelectrolyte multilayers.

Polyelectrolyte multilayer (PEM) thin films prepared using the layer-by-layer technique are proposed as a matrix for the immobilization of 1,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-2,5-dione (curcumin), a lipophilic model drug. The PEM assembly was based on the layer-by-layer deposition of cationic poly(diallyldimethyl-ammonium chloride) (PDADMAC) and anionic poly(4-styrene sulfonate, sodium salt) (PSS) onto a quartz slide. Curcumin was loaded by dipping the PEM film into a dilute solution of curcumin dispersed in an 80/20% v/v water/ethanol solution. Within a few minutes, the film turned bright yellow as a result of the curcumin loading. The effect of the solvent composition, curcumin concentration and film thickness on the final concentration of curcumin in the PEM films was measured by UV-vis spectroscopy. The loading of curcumin was driven by its partitioning in the PEM film, and its partitioning coefficient between the 80/20 solvent and the PEM thin film was found to have a value of 2.07 x 10(5). The extinction coefficient of curcumin loaded into PEM was calculated to 64,000 M(-1) cm(-1). Results show that the loading of curcumin into the PEM films increased with the number of deposited layers, implying that curcumin partitioned into the bulk of the thin film. The maximum curcumin dose in the PEM film was measured by exposing films of various thicknesses to a high concentration (0.01% w/v) of curcumin and recording the maximum absorbance after saturation. The films thicknesses were controlled by the number of deposited PDADMAC/PSS layers (10, 20, 30, 40, 50, and 60). Results show that increasing amounts of curcumin could be loaded into the film with an increasing number of layers and up to 8 microg/cm(2) of curcumin could be loaded into a 20-layer film. These results demonstrate that the loading of lipophilic curcumin in PEM thin films is done through a partitioning mechanism and that the PDADMAC/PSS film can be used as a loading matrix for lipophilic drugs.