Luminescent water dispersible core-shell-(Y/Eu/Li)VO4@APTES@Folate and (Y/Eu/Li)VO4@Fe3O4@PEG nanocomposites: Biocompatibility and induction heating within the threshold alternating magnetic field

Luminescent red-emitting water dispersible core-shell nanocomposites have been synthesized from luminescent (Y/Eu/Li)VO4 and superparamagnetic Fe3O4 nanoparticles. The conjugation of folic acid on the luminescent (Y/ Eu/Li)VO4 nanoparticles was achieved by a simpler chemistry via aminopropyl trimethoxysilane (APTES) coating followed by direct conjugation chemistry using dimethylaminopyridine as acyl transfer agent and N,Ndisuccinimidyl carbonate as the protecting group in dimethysulfoxide solvent. On the other hand, polyethyleneglycol coated magnetic-luminescent (Y/Eu/Li)VO4@Fe3O4@PEG nanocomposite was also fabricated from the luminescent (Y/Eu/Li)VO4 and superparamagnetic Fe3O4 nanoparticles. The induction heating abilities of the magnetic-luminescent (Y/Eu/Li)VO4@Fe3O4@PEG nanocomposite have been studied within the threshold alternating magnetic field. The alternating magnetic field (Hf) strengths used in the study ranges from 2.15 x 106 to 4.58 x 106 kAm-1 s-1 which are well below the clinical threshold limit of 5 x 106 kAm-1 s-1 for human body. The nanocomposites exhibited good stability of the dispersion and in vitro biocompatibility towards HeLa cell lines. The median lethal dose, LD50 values are found to be 717.90 mu g/mL and 677.00 mu g/mL for the (Y/Eu/Li) VO4@APTES@Folate and (Y/Eu/Li)VO4@Fe3O4@PEG nanocomposites respectively. The synthetic methodology may be adopted for the synthesis of functionalized upconversion phosphors in non-invasive infrared assisted bioimaging and magneto-optically guided cancer hyperthermia.