Chemically/Magnetically Dual-Responsive Nanoparticles for Multipurpose Colorimetric Sensor

Abstract

Magnetically responsive colloidal photonic crystals can change their structural color according to the external magnetic field, which has been widely studied in recent years. However, due to lack of recognition ability towards non-magnetic analytes, these photonic crystals can be applied to constructing a sensor only when an additional stimuli responsive unit is involved. To address this problem, we used a functional protein to modify the magnetically responsive colloidal particles to construct chemically/magnetically dualresponsive nanoparticles. For a proof of concept research in this manuscript, we modified the colloidal particles with streptavidin, and the as obtained nanoparticles were used to detect biotinylated protein via a binding and assembling strategy, which is impossible for conventional photonic crystal sensors. Not only qualitative and quantitative detections were achieved, but also the average diameters of the biotinylated protein were correctly estimated. These results have demonstrated a multipurpose detection feature of our proposed colorimetric sensor.