Sono-synthesis of AuNPs@PMo12 nanohybrids as a smart nanoprobe

We report a facile eco-friendly sonochemical synthesis of polyoxometalate-stabilized gold nanoparticles that can be used as colorimetric nanosensors to detect acetaminophen. Low frequency ultrasound sonication (20 kHz) under ambient condition in the presence of phosphomolybdic acid (H3PMo12O40, PMo12) was used to reduce Au3+ to Au0 and stabilize the resulting Au0 nanoparticles (Au NPs). The polyoxometalate self-assembly on the Au NP surface gives rise to a nanoprobe that undergoes a red-shift in its absorption spectrum (color change from red to purple) as the result of the aggregation of the Au NPs upon the addition of acetaminophen. The aggregation of the Au NPs induced by the acetaminophen was confirmed by electron microscopy and spectroscopic methods and the method was validated in the concentration range of 1–30 mg/L, where it demonstrated good linearity with a limit of detection of 0.42 mg/L.