Multifunctional Hybrid Nanomaterials from Water Dispersible CaF₂:Eu³⁺, Mn²⁺ and Fe₃O₄ for Luminescence and Hyperthermia Application

Abstract

CaF 2 nanoparticles doped with 1 at. % Eu 3+ and codoped with Mn 2+ ions (1, 2, and 3 at. %) were synthesized at 180 °C by using ethylene glycol as a capping agent and solvent medium. The emission spectra of these nanomaterials show two main peaks at 590 and 612 nm after excitation at 240 or 394 nm. Enhancement in luminescence is found upon codoping of Mn 2+ . Parts of Eu 3+ ions are substituted into Ca 2+ sites (having a symmetry environment), which is reflected in the higher probability of magnetic dipole transition over that of electric dipole transition. The polymer film of polyvinyl alcohol incorporated with CaF 2 :1Eu shows the red emission. The prepared nanomaterials are highly water dispersible. The hybrid of CaF 2 :1Eu and Fe 3 O 4 shows the heating ability up to 42 °C under an AC magnetic field. This is suitable for cancer therapy through hyperthermia. A very high specific absorption rate (SAR) of 283 W/g is observed. This can be ascribed to the increased magnetocrystalline anisotropy and Brownian relaxation. Biocompatibility of hybrid nanoparticles up to 75% in HeLa cells is observed. Also, this hybrid shows the red emission, and thus, it will be useful in tracing of magnetic nanoparticles through in vivo and in vitro optical imaging applications. Interestingly, the new exciton band at 300 nm is found in such a hybrid material.

Enhancement of Luminescence Intensity in Dy3+ Ions Doped YVO4 Nanomaterials by Ba2+ Ion Codoping and YVO4:2Dy/Fe3O4 Nanohybrid for Hyperthermia Application

“…Unlikely with excitation spectra of YVO 4 :2Dy which has the highest intensity peak at 320 nm (V-O CT); the hybrid shows the strongest peak at 300 nm which is assigned to exciton formation between YVO 4 :2Dy and Fe 3 O 4 interface. Such type of exciton formation was reported in some previous papers [8,22]. Here, we strongly believe that the peak normally observed at 320 nm is being canvassed by the strong exciton peak at 300 nm since after the formation of hybrid it is confirmed that both emission and excitation are lower than corresponding values of YVO 4 :2Dy but after the formation of hybrid peak at 300 nm is still remained as a strong peak from which it is concluded that it is generated from exciton.…”

“…Heat generation from eddy current is negligible compare to Brownian and Neel's which main component is for heat generation in the magnetic samples. The detailed studies of the heat generation during the hyperthermia had been reported elsewhere [8]. Heat generation from samples in terms of specific absorption rate (SAR) is given by the following relation.…”

“…EG is nontoxic and can be easily washed with water, methanol, ethanol, acetone, etc. Due to presence of polar functional group, NPs capped with EG are water dispersible and such water dispersibility properties makes them applicable in biolabelling through optical imaging [8].…”

Enhancement of luminescence in white emitting strontium fluoride core @ calcium fluoride shell nanoparticles

“…The solid fluoride materials have drawn attention due to their unique properties, like low-energy phonons, high ionicity, electron-acceptor behaviour, high resistivity and anionic conductivity [6–8] and also have wide range of potential optical applications in optics, biological labels and lenses [9, 10]. Fluoride base system possesses very low vibrational energy comparing oxide-base system therefore quenching of excite states of the lanthanide ions is minimal in fluoride-based system [11, 12]. …”

Quartz Tuning Fork as Humidity Sensor

“…The structural, morphological properties of QTF coated with Nanocrystalline ZnO using SILAR followed by CBD were examined by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) [8]. The XRD diffraction analysis is carried out using PANalytical (X'PERT-PRO) X-Ray diffractometer with cu Kα radiation (λ=1.54056 Ȧ).…”