Construction of an upconversion luminescence composite nanoprobe for ratiometric single particle imaging detection of hydrogen peroxide in food

Hydrogen peroxide (H 2 O 2 ) is associated with diseases and food safety. Thus, it is essential to achieve sensitive and efficient detection of H 2 O 2 . Herein, a ratiometric luminescence composite nanoprobe was designed for single particle imaging sensing of H 2 O 2 by combining NaYbF 4 :Er@NaYbF 4 :Tm@NaGdF 4 :Yb upconversion nanoparticles (UCNPs) with cyanine dye IR-628. High brightness NaYbF 4 :Er@NaYbF 4 :Tm@NaGdF 4 :Yb UCNPs with double-peak emission (665 and 812 nm) were synthesised. Cyanine dye IR-628 with an absorption peak at 628 nm was synthesised and served as a recognition unit. More importantly, on the basis of the upconversion luminescence total internal reflection imaging technique, we developed a ratiometric single particle imaging quantitative analysis for sensing H 2 O 2 with a limit of quantitation of 5 nM. This ratiometric single particle imaging method not only greatly eliminates the influence of the probe concentration and instrumental and environmental factors, but also reduces the dosage of the reagent used and improves the sensitivity of detection.