Fluoride-Free Synthesis of Poly(4-aminophenylboronic Acid) Nanowires on a Screen-Printed Carbon Electrode

Polyaminophenylboronic acid (PAPBA), containing versatile functional groups, has found increasing use in diverse applications due to its ability to interact with biomolecules. However, current synthesis methods that use surfactants, acids, and chemical oxidants present challenges in both synthesis and controlling morphology and distribution. This work presents an eco-friendly approach for the oxidative polymerization of aminophenylboronic acid (APBA) directly on a disposable screen-printed carbon electrode surface. This green approach, unlike existing chemical and electrochemical methods, avoids the harmful complexing agent fluoride and utilizes neutral media containing phosphate at room temperature. The mechanism for altering the electronic state of boron and the role of reducible oxygen functional groups on the electrode surface to initiate the polymerization reaction have been investigated by cyclic voltammetry, Raman spectroscopy, UV-visible spectroscopy, as well as density functional theory (DFT) calculations. The scanning electron microscopy (SEM) characterization confirmed the formation of nanowires. The presence of multiple functional moieties, such as imine, azo, and boronic acid [-NH+-, -N=N- and -B(OH)(2)], which are valuable for sensing purposes, has been observed from the X-ray photoelectron spectroscopy (XPS) analysis. Finally, the PAPBA-modified electrode's sensing capabilities toward diverse analytes like free-chlorine, nicotinamide adenine dinucleotide (NADH), fluoride ion, and fructose has been demonstrated.