Manipulation of Fe/Au Peroxidase-Like Activity for Development of a Nanocatalytic-Based Assay

Nanoparticles have been discovered to have intrinsic peroxidase-like catalytic activity that shows beneficial applications in a biosensor. The aim of this study is to investigate the synthesised Fe/Au nanoparticles peroxidase-like activity and further evaluate them for development of a nanocatalytic-based assay specifically designed to detect 17β-estradiol in water. The peroxidase-like activity of the synthesised Fe/Au nanoparticles was optimised using the H2O2-ABTS system and was characterised using Michaelis-Menten kinetics. Then, the nanoparticles surface was functionalised with aptamers for specific conjugation with the target analyte, 17β-estradiol. The feasibility of this assay was tested at different concentration of aptamer-tagged Fe/Au nanoparticles and 17β-estradiol. Also, assessment of this assay was conducted with potentially interfering materials and spiked real tap water samples. Results obtained from absorbance data reveal that the Fe/Au-17β-estradiol complex significantly hampered the peroxidase-like catalytic activity of the nanoparticles. The absorbance intensity declined drastically after aptamer-tagged nanoparticles (Fe/Au-fl-apt) captured the targets and formed nanoparticles-analytes complexes. This assay showed good accuracy and reproducibility for detection of 17β-estradiol concentration ranging from 3 to 272 ng/L. Furthermore, the aptamers used in this study were very selective towards the target analyte and related compounds showed little to no interference. Thus, a simple, rapid and sensitive detection assay, specific for 17β-estradiol was developed using a new detection strategy by manipulation of nanoparticles peroxidase-like activity.