Synthesis of mesoporous core-shell structured GdPO4:Eu@SiO2@mSiO2 nanorods for drug delivery and cell imaging applications

Abstract

Mesoporous GdPO4:Eu@SiO2@mSiO2 core-shell nanorods (NRs) were prepared by a facile two-step method. First, the monodispersed GdPO4:Eu NRs were obtained on a large scale via a facile precipitation method, then mesoporous silica was wrapped onto their surface through hydrolysis of tetraethylorthosilicate (TEOS). The XRD result indicates that the as-prepared GdPO4:Eu NRs core has hexagonal phase. The FTIR and the N2 adsorption/desorption isotherm analysis confirm the successful coating of mesoporous silica. The TEM images show that the obtained GdPO4:Eu@SiO2@mSiO2 NRs exhibit uniform monodisperse core-shell structure with a nanorod core (length of 200 nm; width of 20 nm), and mesoporous silica shell of 15 nm. Under excitation of 274 nm, GdPO4:Eu@SiO2@mSiO2 NRs show strong red luminescence from 5D0 →7FJ (J = 1, 2, 3 and 4) transitions of Eu3+. Furthermore, the GdPO4:Eu@SiO2@mSiO2 NRs exhibit obvious T1 enhancement effect due to paramagnetism of Gd3+. The drug loading capacity and pH-sensitive releasing behavior of the as-prepared GdPO4:Eu@SiO2@mSiO2 NRs were studied by using doxorubicin (DOX) as model drug. The excellent biocompatibility of GdPO4:Eu@SiO2@mSiO2 NRs was demonstrated by MTT assay. Taken together, the mesoporous GdPO4:Eu@SiO2@mSiO2 NRs may be potentially applied in fields of drug delivery and dual-modal imaging.