Preparation And Properties Of Multifunction Integrated UP-Conversion Nanoparticles

Multifunctional integration is an important developing direction of nanomaterials. Combining heterogeneous material to reaching multifunction is mostly studied, but it has the shortcomings of complex synthesis and low reliability. Using single compound could avoid the shortcomings.Up-conversion nanomaterial has unique optical property, which makes it an ideal platform for constructing multifunctional nano-system. Small nano-particles with up-conversion, magnetism, photothermal conversion and temperature sensing could be applied to multimodal imaging, temperature probe and photothermal therapy. By now there are still remaining questions in the synthesis process. Researchers mainly focus on the optical property, few works has been done on multifunctional integration and photothermal conversion. This paper studies the effections of raw material, reaction temperature on synthesis and synthesizes core-shell nanoparticles. Then multifunctional integration, temperature sensing, optical and photothermal properties are studied.Two phases mixture of NaYF4:0.2Yb,0.02Er has been synthesized using thermal decomposition method. Substituting Y3+ by Gd3+ can help to form hexagonal phase and small size. The hexagonal pure phase NaGdF4:0.2Yb,0.02Er has merely the diameter of 6.3nm. Decreasing the NH4F amount can lead to larger size. Increasing OA/ODE ratio also results in larger size and rodlike product. Higher reaction temperature is beneficial to form hexagonal phase and enlarge size.Yb3+ can improve absorptivity of incident ray observably. Concentration quenching caused by Yb3+ and Er3+ weakens luminescent intensity and strengthens photothermal conversion. With more Gd3+ doped into matrix, the formed crystal gets a smaller size, hence raises the non-radiative transition probabilities caused by surface defects and weakens luminescent intensity, strengthen photothermal conversion. NaGdF4:0.2Yb,0.02Er coated with inert shell has lower photothermal conversion and higher luminescent intensity, but coating with active shell increasing both photothermal conversion and luminescent intensity.NaGdF4:Yb,Er smaller than 10.0nm has the properties of up-conversion luminescence, photothermal conversion, temperature sensing, paramagnetism. As single compound, it has the prospect to realize optical & magnetic imaging, temperature detection, photothermal therapy.