A Fluorescent Sensor for Daunorubicin Determination Using 808 nm-excited Upconversion Nanoparticles

Daunorubicin is a common antineoplastic agent used for the treatment of lymphoma and acute leukemia. Here, we report an 808 nm-excited, citric acid coated, core–shell upconversion fluorescent sensor for daunorubicin (DAU) detection in aqueous solutions. The designed Nd3+ doped core–shell structure significantly raises the upconversion fluorescence intensity, while the presence of citric acid ligands helps to reduce the surface quenching effect exerted by water and improve the dispersibility. The upconversion fluorescence of nanoparticles is efficiently quenched in the presence of DAU via a fluorescence resonance energy transfer mechanism. The dynamic quenching constant was 1.58 × 104 M−1. The fluorescence intensity ratio showed a good linear response to DAU concentration in the range of 0.1 μM to 70 μM with a detection limit of 0.06 μM. The sensing method was simple, rapid, and low-cost and was further applied to determine the levels of DAU in urine with spike recoveries from 97.3% to 101.5%. The proposed fluorescent sensor holds great potential for in vivo imaging and detection of DAU.