Optical Materials and Bio-imaging Research Laboratory, Department of Applied Physics, Indian School of Mines, Dhanbad 826004, India.
Methods Appl Fluoresc. 2016 Oct 11;4(4):044005. doi: 10.1088/2050-6120/4/4/044005.
The upconversion (UC) process in lanthanide-doped nanophosphors has attracted great research interest for its extensive application potential in biological in vitro and in vivo imaging due to the high tissue penetration depth of near-infrared excitation and low autofluorescence background. In this article, the authors report the synthesis of oxide nanophosphor of size ⩽50 nm, which forms stable aqueous dispersion. The photoluminescence study is made on the nanophosphor upon 808 and 980 nm diode laser excitations. The 808 nm excitation resulted in strong emission at 795 nm due to the K → I transition along with other emissions from the Nd ion. The 980 nm excitation has resulted in it turning green in the 525-560 nm range and is assigned to the S → I transition of the Er ion, which is supposed to be present in a trace amount in the sample. The observation of strong UC emission indicates that the sample can be used for UC-based bio-imaging applications.
上转换（UC）过程在镧系掺杂纳米荧光粉中引起了极大的研究兴趣，因为近红外激发具有较高的组织穿透深度和较低的自发荧光背景，因此在生物体外和体内成像中有广泛的应用潜力。在本文中，作者报道了尺寸 ⩽50nm 的氧化物纳米荧光粉的合成，其形成稳定的水相分散体。在 808nm 和 980nm 激光二极管激发下对纳米荧光粉进行了光致发光研究。808nm 激发导致 795nm 处的强发射，这归因于 Nd 离子的 K ⁇ → I 跃迁以及其他发射。980nm 激发导致其在 525-560nm 范围内变为绿色，这归因于 Er 离子的 S ⁇ → I 跃迁，据推测该跃迁在样品中以痕量存在。强 UC 发射的观察表明，该样品可用于基于 UC 的生物成像应用。
