Ornithine-stabilised gold nanoflowers for label-free sensitive detection of Hg²⁺ via amalgamation

A simple, eco-friendly method for the synthesis of gold nanoflowers using a non-proteinogenic amino acid is discussed in the present work. Gold nanostructure with unique morphology was synthesized, with the assistance of ornithine amino acid. Ornithine-stabilised gold nanoflowers were found to be highly sensitive towards mercury ions (Hg²⁺) due to Au–Hg amalgamate formation. Due to amalgamate formation, an evolution in morphology of ornithine-stabilised gold nanoflowers happens which can be monitored by the red shift in surface plasmon resonance. Under optimum conditions, our sensor shows a dynamic response range with a detection limit of 6 nM. This developed nanosensor can be used as Hg²⁺ ion sensor in polluted water/waste water by a one-step assay protocol.