Here, a kind of porous nanoparticles GdAlO 3 :Cr 3+ , Sm 3+ (GAO:Cr,Sm) which own magnetic resonance and long persistent luminescent properties have been synthesized. The spherical morphology and narrow size distribution would allow the GAO:Cr,Sm nanoparticles to be utilised as a drug carrier and the drug release results indicate that the GAO:Cr,Sm drug carriers have an excellent drug sustained properties. Applying the Cr 3+ and Sm 3+ coped with gadolinium aluminate as the NIR persistent luminescence center and the energy transfer resonance from Gd 3+ to Cr 3+ , these nanoparticles exhibit excellent NIR persistent luminescence at 732 nm under the UV irradiation of 254 nm and it can persist for about half an hour. In addition, they possess a longitudinal relaxivity (r 1 ) value of 4.75 mM −1 s −1 , which means that these nanoparticles could be applied for MR imaging as contrast agents. Carboxymethyl Chitosan was modified on the surface of GAO:Cr,Sm nanoparticles to make them owning excellent biocompatibility and low toxicity and these nanoparticles were successful to realize in vivo imaging. Hence, the well-defined nanoprobes of GAO:Cr,Sm exhibit great potential in biomedicine as trackable drug carriers and in vivo imaging agent due to the dual-model imaging property.
Far-red-emitting (700−740 nm) phosphors are essential for the fabrication of plant lighting phosphor-converted light-emitting diodes (pc-LEDs). However, the development of highly efficient, thermally stable, and spectrally matched far-red phosphors still remains a challenge. Herein, far-red GdAlO 3 :Cr 3+ (GAO:Cr 3+ ) phosphors were synthesized via solid-state reaction and investigated for plant lighting pc-LED applications. A low-temperature flux-assisted synthesis strategy was adopted to improve the crystalline quality, suppress the defect formation, and maintain the valence state of Cr 3+ in the phosphors, finally leading to significant luminescent enhancement (∼10 times). The GAO:Cr 3+ phosphors show the 2 E sharp-line emissions around 730 nm, which is highly matched with the far-red absorption band of plants. The optimized GAO:0.01Cr 3+ phosphor exhibits a high internal quantum efficiency of 98.3% and zero thermal quenching even up to 250°C. The fabricated pc-LED can generate an overall output power of 78.1 mW at 100 mA drive current, with a high energy conversion efficiency of 25.3%. The findings demonstrate the great potential of GAO:Cr 3+ as far-red-emitting phosphor materials for plant growth pc-LED applications.
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