32^nd World Nano Conference

Biography

Biography: Julia Perez-Prieto

Abstract

Upconversion nanoparticles, where an inorganic matrix is doped with at least two trivalent lanthanide cations (e.g. NaYF4:Yb,Tm, Yb3+being the sensitizer and Tm3+ the activator) can be stimulated with NIR light with low-energy irradiance by using a continuous-wave laser (up to 106-fold W cm−2 less excitation power than that used for dyes). NIR-excitation of UCNPs results in highly intensive emissions with an excellent signal-to- noise ratio in the UV/visible/NIR. The intra f–f electronic transitions of the dopants in UCNPs produce a set of extraordinarily sharp emissions thereby enabling selective resonance energy transfer to fluorophores which decay in the microsecond-to-millisecond time scale, thus overcoming the problem of autofluorescence of complicated samples (biological/chemical), which occurs in the nanosecond scale. Interestingly, UCNPs are very resistant to photobleaching and photoblinking, and exhibit excellent chemical and thermal stability when their surface is covered with ligands strongly bound to their surface. However, bare- UCNPs decompose into their constituents when dispersed in aqueous solutions, which is particularly negative for their biological applications.

Design of smart photoactive upconversion nanohybrids (UCNHs) for different purposes (e.g., colocalization of different payloads, photodynamic therapy, pH-triggered release of a functional molecule located on their surface) requires key pieces for controlling their chemical stability, photoluminescence and performance.