Morphological tuning of Eu₂O₂S nanoparticles, manifestation of peroxidase-like activity and glucose assay use

Abstract

Eu₂O₂S nanoparticles have been synthesized by solvothermal decomposition of the precursor complex [NHEt₃]⁺[Eu(acda)₄]⁻, wherein acda⁻ is the anion of 2-aminocyclopentene-1-dithiocarboxylic acid. Oleylamine alone or in combination with surface active agents, such as trioctylphosphine or oleic acid, at 280 °C produced nanoparticles of three different morphologies, namely, ultrathin nanoplates, nanospheres and short rods. The optical band energy of the nanoparticles has been found to be 4.57(8) eV. Eu₂O₂S particles exhibit strong photoluminescence at room temperature with a quantum yield of about 4% upon excitation at 285 nm. All three forms display peroxidase-like activity towards the oxidation of 3,3′,5,5′-tetramethylbenzidine in the presence of H₂O₂ and follow a Michaelis–Menten enzymatic pathway. The mechanistic investigation reveals that the Eu³⁺/Eu²⁺ redox couple plays a crucial role behind this catalytic process. Catalytic efficiency of the nanoparticles decreases in the order plates > spheres > rod-like particles. Based on peroxidase activity, selective detection and estimation of glucose in the presence of related carbohydrates has been carried out.