Buteinylated-hafnium oxide bionanoparticles for electrochemical sensing of wogonin

Hybridizing biomolecules with metal oxide nanostructures possessing inherent optical emission and electrochemical functionality is advantageous for external mediator-free analytical applications. This work demonstrates the ultrasonochemical synthesis of hafnium oxide (HfO₂) nanoparticles and their combination with butein, a chalcone type polyphenol, for the direct electrochemical detection of active herbaceuticals. The underlying hybridization chemistry between HfO₂ and butein within the bio-nano interface is comprehensively investigated using ultraviolet diffuse reflectance, X-ray diffraction, Fourier-transform infrared, and X-ray photoelectron spectroscopic techniques. Electron micrographs suggest the formation of elongated nano spherical particles of HfO₂ with the incorporation of butein (average particle size of 17.6 ± 2.9 nm). The catecholic OH group of butein existing on the surface of hybridized HfO₂ exhibits reversible redox behavior convenient for probing the selected target analyte at physiological pH. The electron diffusion kinetics, electron transfer coefficient and rate constant parameters of the prepared HfO₂-butein electrode material have been studied in detail for further application in biomolecular sensing of wogonin. The as-developed sensor platform exhibits a linear detection range of 20-100 μM with a current density of 60 μA cm^-2 and a detection limit of 0.63 μM, which is promising for herbaceutical analysis.