Synthesis of NaYF4:Yb,Er upconversion nanoparticle-based optomagnetic multifunctional composite for drug delivery system

Abstract

Optomagnetic multifunctional composite has attracted much attention in recent years because of its promising application prospect in bioimaging, analysis, detection, disease diagnosis, and targeted drug delivery. To explore a dual-targeted therapy for cancer, a novel class of optomagnetic multifunctional composite (UCNP-Fe3O4@MSNs-FA) was successfully synthesized by using upconversion nanoparticles (UCNPs) as nucleus, embedding Fe3O4 nanoparticles into the SiO2 coating layer, and modifying the surface with folic acid (FA) to strengthen its tumor targeting performance. The properties of the composite were extensively studied. The obtained composite possesses excellent upconversion fluorescence, good dispersion, high specific surface area (229.347 m2/g), and saturation magnetization value (10.9 A·m2/g). Its drug loading content and encapsulation efficiency can reach as high as 14.2% and 47.3%, respectively, using doxorubicin hydrochloride (DOX) as model drug. The DOX-UCNP-Fe3O4@MSNs-FA system shows excellent sustained drug release and strong pH-dependent performance, in which the drug release would be accelerated at the slightly acidic microenvironment in the tumor; thus, the system can realize the targeted treatment of cancers. The viability of L929 cells demonstrates the good biocompatibility of the composite. Furthermore, DOX-UCNP-Fe3O4@MSNs-FA exhibits specific cytotoxicity to folate receptor (FR) positive tumor cells, whereas DOX has weak toxicity to FR-negative cells. Therefore, the as-prepared UCNP-Fe3O4@MSNs-FA can potentially be used as an anti-cancer targeted drug delivery system and enhance the therapeutic efficacy against FR-positive tumor cells.