Anfal Alfahd

Engineering a water-compatible upconversion nanoink for NIR-readable covert printing and QR authentication

Lanthanide-doped upconversion nanoparticles (UCNPs) offer an innovative route to covert optical labels that become visible under near-infrared (NIR) excitation. Here, LiYF₄:Yb, Er@LiYF₄ core–shell (CS) nanoparticles were coated with poly(acrylic acid) (PAA) and used to create a p...