Synthesis and Design of Up conversion Nanostructures and their Luminescence properties

Abstract

Recently there have been many innovations in research on up converting nanoparticles (UCNPs) doped with Lanthanoids (mostly Er3+, Yb3+ and Tm3+, Yb3+) through several synthetic approaches. A set of total 17 chemical elements (15 Lanthanides + Scandium +Yttrium) show up conversion phenomena by exciting with NIR radiation (lower energy, longer wavelength) which finally results in UV or visible light emission (higher energy, shorter wavelength) and makes them highly suitable for various applications. It is well known that for biological studies fluorescence/luminescence -imaging is an important phenomenon. Traditionally, high-energy photons used as excitation which results in low energy emission by down conversion process. But, this phenomenon causes some difficulties like short tissue penetration depth, lower photochemical stability, lower sensitivity, cell death, DNA damage due to excitation with higher energy. In contrast, up-conversion luminescence imaging gives better tissue penetration depth, good photochemical stability, improved sensitivity and very less probability of DNA damage and cell death, as excitation is done with low energy photons and can be used in cancer therapy for destroying cancer cells with the emerging higher energy radiation. newline