Curcumin-Pluronic Nanoparticles: A Theranostic Nanoformulation for Alzheimer's Disease.

There is an increased need of drugs with multifunctional properties for visualization of β-amyloid (Aβ) plaques for early diagnosis and treatment of Alzheimer's disease (AD). Curcumin (Cur) is a potent antiamyloid, antiinflammatory, and antiapoptotic natural product that has been used to treat several neurodegenerative diseases, including AD. Curcumin can reduce amyloid burden, rescue neuronal damage, and restore normal cognitive and sensory motor functions in AD. Curcumin is a promising natural product theranostic because it fluoresces and preferentially binds to misfolded Aβ. However, poor water solubility, limited bioavailability, and inability to cross the blood-brain barrier (BBB) limit curcumin use for biological applications. In this work, ultrasmall (~ 11 nm) curcumin encapsulated Pluronic F127 nanoparticles (FCur NPs) were developed and optimized to enhance bioavailability, facilitate circulation in the bloodstream, and improve BBB penetration. We compare BBB crossing ability of FCur NPs and free curcumin using an in vitro BBB model, and we demonstrate brain accumulation following intravenous administration to healthy mice. FCur NPs display 6.5-fold stronger fluorescent intensity in the brain than those from free curcumin. In addition, in vitro comparison with Congo red, a marker for Aβ plaques, revealed that encapsulated curcumin maintains its ability to bind to Aβ plaques. FCur NPs exhibited antioxidant and antiapoptotic activity when compared to free curcumin. The combination of in vitro and in vivo results suggest potential utility of the inexpensive FCur NPs as a theranostic agent for AD.