关键词: Optomagnetic nanocomposite, Nanorattle, Upconversion luminescence, Iron oxide, Drug delivery

Abstract: Optomagnetic multifunctional composite based on upconversion luminescence nanomaterial is regarded as a promising strategy for bioimaging, disease diagnosis and targeted delivery of drugs. To explore a mesoporous nanostructure with excellent water dispersibility and high drug-loading capacity, a novel nanorattle-structured Fe₃O₄@SiO₂@NaYF₄:Yb,Er magnetic upconversion nanorattle (MUCNR) was successfully designed by using Fe₃O₄ as core and NaYF₄:Yb,Er nanocrystals as shell. The microstructures and crystal phase of the as-prepared MUCNRs were evaluated by transmission electron microscopy, X-ray powder diffraction and N₂ adsorption/desorption isotherms. The Kirkendall effect was adapted to explain the formation mechanism of the MUCNRs. The loading content and encapsulation efficiency of doxorubicin hydrochloride (DOX) could reach as high as 18.2% and 60.7%, respectively. Moreover, the DOX loading MUCNR (DOX-MUCNR) system showed excellent sustained drug release and strong pH-dependent performance, which was conducive to drug release at the slightly acidic microenvironment of tumor. Microcalorimetry was used to quantify the interactions between the carrier structure and drug release rate directly. The heat release rates in the heat-flow diagrams are basically consistent with the DOX release rate, thereby showing that microcalorimetry assay not only provides a unique thermodynamic explanation for the structure-activity relationship of Fe₃O₄@SiO₂@NaYF₄:Yb,Er MUCNRs but also provides powerful guidance to avoid the blind selection or design of drug carriers. Therefore, our work firmly provided a comprehensive perspective for using Fe₃O₄@SiO₂@NaYF₄:Yb,Er MUCNRs as a remarkable magnetic targeted drug carrier.

Key words: Optomagnetic nanocomposite, Nanorattle, Upconversion luminescence, Iron oxide, Drug delivery