It is important to finely tune the upconversion (UC) properties through controlling size and structure of upconversion nanocrystals (UCNCs) and improve their efficiency. Recently, it was reported that the UC luminescence (UCL) intensity of NaLuF4:Yb(3+), Er(3+) UCNCs could be tremendously improved compared to the most efficient NaYF4:Yb(3+), Er(3+) under 980 nm excitation. In this paper, we first studied the varied size control and phase transition properties of NaREF4:Yb(3+), Er(3+) (RE = Y, Lu) UCNCs prepared by the solvothermal method. Then, we discussed if the UCL intensity of NaLuF4:Yb(3+), Er(3+) could be universally improved over that of NaYF4:Yb(3+), Er(3+) UCNCs. Furthermore, the color tuning properties of the NaREF4:Yb(3+), Er(3+) family on crystalline phase, particle size, doping concentration and phonon energy were systemically discussed. It is very interesting to observe that in heavily doped cubic NaREF4:Yb(3+), Er(3+), the color of UCL changed from red to green with decreasing particle size, while on the contrary, in hexagonal phase the color of UCL changed from green to red. A unit model was proposed to explain the phase-dependent, size-dependent color tuning UCL behavior of NaREF4:Yb(3+), Er(3+).

The synthesis of Au@mesoporous SiO(2)/rhodamine B isothiocyanate (Au@mSiO(2)/RBITC) composite nanoparticles (NPs) is presented and their unique biofunctional properties are studied. The structure and morphology of the NPs are characterized by X-ray powder diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. These NPs can not only be functionalized for fluorescence imaging, but also possess well-defined mesopore structures for drug loading and strong infrared surface plasmon absorption for light-controlled drug release and photothermal therapy for cancer cells. In the biological experiments, one 808 nm laser is coupled to a confocal laser scanning microscopy (CLSM) system to monitor the photothermal therapy, drug release, and cell position and viability in real time by using the multichannel function of CLSM for the first time. Such novel nanomaterials offer a new chemotherapeutic route for cancer treatment by combining cell imaging and hyperthermia in a synergistic way.

In this work, we prepared polyacrylic acid (PAA) coated gold nanorods (GNRs) and then the targeting peptide modified GNRs. The biocompatibility and stability of functionalized GNRs were investigated by monitoring the surface plasmon resonance (SPR) absorption intensity. The efficacy of targeted thermal therapy can be significantly enhanced via decoration with surface-bound peptide which was obtained through phage display technology. In addition, the photothermal therapy was monitored in real time with the multi-channel function of a confocal laser scanning microscope (CLSM) coupled with an 808 nm laser. This selective photothermal therapy of GNRs is a promising candidate for phototherapeutic applications.