Genipin-stabilized caseinate-chitosan nanoparticles for enhanced stability and anti-cancer activity of curcumin.

Nanoparticles formed by the assembly of protein and polysaccharides are of great interest for the delivery of hydrophobic molecules. Herein, the formation of genipin-crosslinked nanoparticles from caseinate (CS) and chitosan (CH) is reported for the delivery of curcumin, a polyphenolic compound from turmeric, to cells. Genipin-crosslinked CS-CH nanoparticles (G-CCNPs) having a diameter of ∼250 nm and a low polydispersity index showed excellent stability over a wide pH range, as indicated by dynamic light scattering and transmission electron microscopic measurements. Cellular uptake of curcumin loaded into G-CCNPs by HeLa cells was improved, as measured by confocal laser scanning microscopy (CLSM) and fluorescence-activated cell-sorting analysis. Cell proliferation assays indicated that G-CCNPs were nontoxic and that curcumin's anticancer activity in vitro was also improved by G-CCNPs. Stability of curcumin at neutral pH was enhanced by G-CCNPs. CLSM study revealed that G-CCNPs were poorly internalized by HeLa cells, possibly because of strong cell membrane interactions and a negative zeta potential. Overall, our results suggested that the enhanced curcumin cytotoxicity might be associated with the enhanced stability of curcumin by G-CCNPs and free curcumin released from G-CCNPs into the cell. These biocompatible NPs might be suitable carriers for enhancing curcumin's therapeutic potential.