A green synthetic approach for size tunable nanoporous gold nanoparticles and its glucose sensing application

Highlights: • Synthesis of 0-D nanoporous gold nanoparticles in an environment benign procedure. • A two-step approach employing Au-Ag alloys seeds as precursor. • Size of synthesized nanoporous particles can easily be tuned. • No involvement of any harsh chemical during the entire synthesis. • High electrocatalytic activity toward glucose sensing. A novel approach for environmentally benign green synthesis of zero-dimensional monodispersed nanoporous gold nanoparticles (npGNPs) with tunable size has been developed. It involves the use of Oryza sativa seeds (Asian rice) extract as a reducing agent for the simultaneous bio-reduction of gold (Au³⁺) and silver (Ag⁺) ions to form alloys nanoprecursor that led to the formation of npGNPs using Au (I) as an oxidative etchant in galvanic replacement reaction. In comparison to conventional methods, no harsh reaction conditions were used during the synthesis to comply with the green chemistry. The synthesized npGNPs were characterized using transmission electron microscopy (TEM), field emission-scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and UV–visible spectroscopy. Monodispersed nanoporous gold nanoparticles in the size range of 80–150 nm were obtained as confirmed by electron microscopy. The size can easily be tuned by varying the concentration of silver precursor. The synthesized nanoporous gold nanoparticles were then evaluated for their electrocatalytic activity toward non-enzymatic glucose sensing by cyclic voltammetry (CV) and linear scan voltammetry (LSV). In a comparative study with bare Au electrode and Au-Ag nanoparticles modified electrode, the resulting npGNPs modified sensor exhibited a better response toward glucose in the linear range from 1 to 50 μM with a sensitivity of 6.67 µA µM⁻¹ cm².