A near-infrared luminescent Mn2+-doped NaYF4:Yb,Tm/Fe3+ upconversion nanoparticles redox reaction system for the detection of GSH/Cys/AA

An upconversion luminescence method was developed for the determination of glutathione (GSH), L -cysteine (Cys) or L -ascorbic acid (AA) based on redox reaction . We synthesized poly(acrylic acid) (PAA)-modified Mn 2+ -doped NaYF 4 :Yb,Tm upconversion nanoparticles (UCNPs), and the luminescence of these UCNPs was effectively quenched due to their carboxyl groups coordinating with Fe 3+ to form a UCNPs/Fe 3+ system. GSH, Cys or AA reduced Fe 3+ to Fe 2+ , which induced the luminescence recovery of the UCNPs. Under the optimized conditions, wide linear concentration ranges from 0.25-300   μM for GSH, 0.5–875   μM for Cys and 0.5–350   μM for AA were found, and the detection limits (3   S/K) were 0.2   μM, 0.5   μM and 0.2   μM, respectively. Thus, the UCNPs/Fe 3+ system was successfully applied for sensing GSH, Cys or AA.