The latest paper from our group covers the ultra-reliable synthesis of polyethyleneimine (PEI)-coated upconversion nanoparticles (UCNPs). These UCNPs are stable in water and other biologically relevant substances, and emit red light, making them ideal for biophotonics applications. Additionally, they can act as FRET donors, meaning that they can be used for optical sensing via upconversion intensity and emission lifetime measurements. Those of you in-the-know will notice that the red-band emission is favourable for transmission through blood and tissue!

This paper is the result of a lot of work by Dr Rebecca McGonigle - well done Rebecca! Thanks for Dr Shiao Chow and Ciera Connelly for assisting with polymer assays. And thanks again to our international collaborators who have helped with the photophysics, electron microscopy, and FRET side of things!

Rebecca McGonigle, Christian Homann, Ciera Connelly, Marta Gajewska, Niko Hildebrandt, Robert Pal, Shiao Chow, Ute Resch-Genger, Lewis E. MacKenzie; Polyethyleneimine (PEI) molecular weight alters the photophysical and FRET properties of water dispersible NaYF4:Yb,Er upconversion nanoparticles. Nanoscale 2026; https://doi.org/10.1039/d6nr02308