A novel strategy for the aqueous synthesis of down-/up-conversion nanocomposites for dual-modal cell imaging and drug delivery

Abstract

A highly efficient multifunctional nanoplatform for dual-modal luminescence imaging and pH-responsive drug delivery has been developed on the basis of a facile and novel strategy by covalently binding up-conversion (UC) luminescent NaYF₄:Yb,Er nanoparticles with down-conversion (DC) fluorescent AgInS₂–ZnS quantum dots. Due to the enriched carboxylic groups in the polymer shell of UC nanoparticles, the as-prepared nanocomposites (NCs) are water-soluble, functionalizable and able to load anti-cancer drug molecules, doxorubicin (DOX), by simple physical adsorption. The release of DOX from NCs was controlled by varying the pH, with an increased drug dissociation rate in an acidic environment, favorable for controlled drug release. Moreover, the endocytosis and the efficient drug release properties of the system were confirmed by luminescence microscopy. Hence, this approach provides a valuable method for fabricating a NC system with highly integrated functionalities for dual-modal luminescence cell imaging and targeted cancer therapy.