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

Mesoporous GdPO4:Eu@SiO2@mSiO(2) 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 N-2 adsorption/desorption isotherm analysis confirm the successful coating of mesoporous silica. The TEM images show that the obtained GdPO4:Eu@SiO2@mSiO(2) 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@mSiO(2) NRs show strong red luminescence from D-5(0) -> F-7(J) (J = 1, 2, 3 and 4) transitions of Eu3+. Furthermore, the GdPO4:Eu@SiO2@mSiO(2) NRs exhibit obvious T-1 enhancement effect due to paramagnetism of Gd3+. The drug loading capacity and pH-sensitive releasing behavior of the as-prepared GdPO4:Eu@SiO2@mSiO(2) NRs were studied by using doxorubicin (DOX) as model drug. The excellent biocompatibility of GdPO4:Eu@SiO2@mSiO(2) NRs was demonstrated by MTT assay. Taken together, the mesoporous GdPO4:Eu@SiO2@mSiO(2) NRs may be potentially applied in fields of drug delivery and dual-modal imaging. (C) 2020 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights reserved.