Simultaneous biosensing of catechol and hydroquinone via a truncated cube-shaped Au/PBA nanocomposite

A simultaneous testing of the trace catechol (CC) and hydroquinone (HQ) was achieved via an ultrasensitive phenolic biosensor constructed by the truncated cube-shaped gold/Prussian blue analogue (Au/PBA) nanocomposites. A facile charge-assembly strategy was developed to drive the successive mutual attractions for the crystallization among [Fe(CN)₆]^3-, Co²⁺, and [AuCl₄]^- reactants, benefiting the in-situ growth of Au nanoparticles on all faces of the PBA truncated nanocubes. On account of this special architecture, numerous 10 nm Au particles can rapidly gather the electrons from the enzyme reaction to a PBA crystal due to their high conductivity, and then the current signals will be significantly magnified through the reversible redox of the PBA. Using this nanomaterial, the as-prepared biosensor has shown an extreme wide linear range (CC: 0.2-550 µM, HQ: 1-550 µM) and an ultralow detection limit (CC: 0.06 ± 0.001 µM, HQ: 0.3 ± 0.007 µM) for the independent detections of CC and HQ. More importantly, when the two targets coexist, this biosensor can simultaneously exhibit the obvious and accurate responses of CC and HQ at the different potentials (0.17 V for CC and 0.07 V for HQ) with the high sensitivities and rare mutually interferences.