Bheeshma P Singh
University at Buffalo, USA
Title: Highly efficient NIR to NIR up-conversion CaWO4: Tm3+, Yb3+ nanophosphors and its application in bio imaging of deep tumors
Biography
Biography: Bheeshma P Singh
Abstract
CaWO4:Tm3+, Yb3+, Li+ nano-phosphors with intense NIR to NIR (excitation by 980 nm, emission at ~800 nm) up conversion were synthesized by a facile polyol route. The nanoparticles were of the order of ~20 to 60 nm. The XRD patterns confirmed a single-phase tetragonal scheelite structure having space group I41/a, irrespective of doping of small amounts of RE3+ and alkali ions. The incorporation of Li+ ions altered the crystal field symmetry around the Tm3+ ions, which increased the f–f transition probabilities of the RE3+ ions, and thus increased the up conversion intensities. Compared with CaWO4:Tm3+, Yb3+, the NIR to NIR up conversion emission intensity of 10 mol% Li+ substituted CaWO4:Tm3+, Yb3+ nanocrystals increased by 20-fold and can be pumped by ~1mW power 980 CW laser. The brightest CaWO4:Tm3+, Yb3+, Li+ nano-phosphor was applied for non-invasively visualizing the tumors in nude mice and successfully detected deep tumors in the thigh muscles. Results were based on oxide based UCNPs used for in vivo NIR-to-NIR bio-imaging which opens the window of achieving improved features using non-fl uoride based UCNPs for bio-imaging.