CaF₂ nanoparticles as peroxidase mimics for rapid and sensitive detection of aldosterone

In this work, CaF₂ nanoparticles were successfully synthesized by a simple direct precipitation method and firstly used as a peroxidase mimics for rapid and high sensitive colorimetric detection of aldosterone. The CaF₂ nanoparticles were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM) and powder X-ray diffraction (XRD). The CaF₂ nanoparticles can oxidize 3,3',5,5'-tetramethylbenzidine (TMB) to produce a blue product oxidized TMB (oxTMB) in the presence of H₂O₂ and this peroxidase-like activity of CaF₂ is found out to follow Michaelis-Menten kinetics. Experiments showed that the catalytic mechanism of CaF₂ nanoparticles was attributed to that it could result in the decomposition of H₂O₂ to produce hydroxyl radicals (•OH). The absorbance change value of the reaction system was linear with the aldosterone concentration in the range of 2.0-40.0 nM, and the detection limit was 0.6 nM. Moreover, the developed method was applied to detect aldosterone in human serum samples. It provides a new platform for enzyme functional simulation and analytical sensing research.