Curcumin-tannic acid-poloxamer nanoassemblies enhance curcumin's uptake and bioactivity against cancer cells in vitro

Curcumin (CUR) is a bioactive natural compound with potent antioxidant and anticancer properties. However, its poor water solubility has been a major limitation against its widespread clinical use. The aim of this study was to develop a nanoscale formulation for CUR to improve its solubility and potentially enhance its bioactivity, by leveraging the self-assembly behavior of tannic acid (TA) and amphiphilic poloxamers to form CUR-entrapped nanoassemblies. To optimize drug loading, formulation variables included the CUR: TA ratio and the type of amphiphilic polymer (Pluronic® F-127 or Pluronic® P-123). The optimal CUR nanoparticles (NPs) were around 200 nm in size with a high degree of monodispersity and 56% entrapment efficiency. Infrared spectroscopy confirmed the presence of intermolecular interactions between CUR and the NP formulation components. X-ray diffraction revealed that CUR was entrapped in the NPs in an amorphous state. The NPs maintained excellent colloidal stability under various conditions. In vitro release of CUR from the NPs showed a biphasic controlled release pattern up to 72 h. Antioxidant and antiproliferative assays against a panel of human cancer cell lines revealed significantly higher activity for CUR NPs compared to free CUR, particularly in MCF-7 and MDA-MB-231 breast cancer cells. This was attributed to greater cellular uptake of the NPs compared to the free drug as verified by confocal microscopy imaging and flow cytometry measurements. Our findings present a highly promising NP delivery platform for CUR prepared via a simple self-assembly process with the ability to potentiate its bioactivity in cancer and other diseases where oxidative stress is implicated.