Controlled growth and molecular self-assembly of Au nanoparticles to Au nanochains: application towards enhancement for the electrochemical determination of paracetamol

Abstract

In the present work a novel and facile method has been developed for the controlled growth through molecular self-assembly of Au nanoparticles to Au nanochains mediated by thiolated chitosan. The growth of the Au nanoparticles to nanochains can be easily controlled by the reaction conditions at different time intervals. The growth and self-assembly of the Au nanochains was monitored by UV-vis spectroscopy and high resolution transmission electron microscopic (HRTEM) studies. The HRTEM image shows some interesting characteristics, thiolated chitosan molecules act as mediators for the self-assembly of Au nanoparticles into nanochains via a molecular self-assembly approach in which the particles are arranged in a linear array of chain like networks with uniform particle distribution. The structural properties of Au nanochains were investigated using X-ray photoelectron spectroscopy (XPS), results in high purity Au alone and X-ray diffraction (XRD) pattern reveals cubic geometry of single phase Au only. An electrochemical sensor was developed based on the fabrication of novel Au nanochains on a MWCNTs/GC modified electrode for the determination of paracetamol. In the presence of paracetamol, the Au nanochains/MWCNTs/GC modified electrode shows a well-defined quasi-reversible peak at E_pa = +0.36 V and E_pc = +0.21 V, and exhibits better electrochemical performance in physiological conditions (pH 7.0). Under the optimized experimental conditions at low operating potential (E_pa = +0.36 V), the Au nanochains/MWCNTs/GC modified electrode exhibits a better sensitivity of 0.742 μA μM⁻¹ with a detection limit of 89 nM.