RESUMO
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.
RESUMO
Herein, we feature our recent efforts toward the development and application of nanoelectrochemistry at liquid/liquid interfaces, which are also known as interfaces between two immiscible electrolyte solutions (ITIES). Nanopipets, nanopores, and nanoemulsions are developed to create the nanoscale ITIES for the quantitative electrochemical measurement of ion transfer, electron transfer, and molecular transport across the interface. The nanoscale ITIES serves as an electrochemical nanosensor to enable the selective detection of various ions and molecules as well as high-resolution chemical imaging based on scanning electrochemical microscopy. The powerful nanoelectroanalytical methods will be useful for biological and material applications as illustrated by in situ studies of solid-state nanopores, nuclear pore complexes, living bacteria, and advanced nanoemulsions. These studies provide unprecedented insights into the chemical reactivity of important biological and material systems even at the single nanostructure level.
