Eco-friendly synthesis of gold nanoparticles onto glassy carbon electrode and its application to DNA biosensor

This work studies gold nanoparticle (AuNP) nucleation and growth mechanism from deep eutectic solvent (DES)-based choline chloride and glycerol (glyceline) onto glassy carbon electrode (GCE) and its application for DNA biosensor. Investigation of the current density transients indicated that the AuNPs were formed by the simultaneous presence of Au diffusion-controlled 3D nucleation and growth and residual water reaction over the Au nuclei growing surfaces. The AuNP structure was characterized by the field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. AuNPs were used to fabricate electrochemical DNA sensor. The hybridization was monitored by cyclic voltammetry and electrochemical impedance spectroscopy measurement using potassium ferri/ferrocyanide redox probes \({\left[Fe{(CN)}_{6}\right]}^{3-/4-}\) ${\left[F,e,{(CN)}_6\right]}^{3-/4-}$ as the indicator probe. Results show that the biosensor exhibited a linear correlation to the logarithm of the target DNA concentration ranged from 1.10⁻¹⁴ M to 1.10⁻⁹ M, and the limit of detection was 1.10⁻¹⁴ M. Furthermore, the findings indicate that the prepared electrode exhibited excellent reproducibility and long-term stability when applied for determining M. tuberculosis samples.