Restraining fluoride loss from NaYF4:Yb3+,Er3+ upconverting nanoparticles in aqueous environments using crosslinked poly(acrylic acid)/poly(allylamine hydrochloride) multilayers

The use of upconverting nanoparticles in various applications in aqueous media relies on their surface modifications as most synthesis routes yield hydrophobic particles. However, introducing upconverting nanoparticles in aqueous solutions commonly results in the quenching of their luminescence intensity and in the worst case, disintegration of the nanoparticles. We demonstrate the use of poly(acrylic acid) and poly(allylamine hydrochloride) as...