Highly selective colorimetric sensing of Hg2+ ions by label free AuNPs in aqueous medium across wide pH range

• Gold nanoparticles (AuNPs) based label free colorimetric sensor.
• Highly selective colorimetric detection of Hg2+ by AuNPs stabilized with any stabilizing agents.
• Selective colorimetric sensing of Hg2+ across wide pH range in aqueous medium.
• Role of ascorbic acid in selective colorimetric sensing of Hg2+ by AuNPs.

Highly selective colorimetric sensing of Hg2+ ions have been demonstrated in aqueous medium across wide pH range (2.0–10.0) using AuNPs without any specific surface functionality or size and morphological control. AuNPs stabilized with different capping agents such as PEG, PSS, T-80, PVA, SDS, PVP were synthesized using ascorbic acid reducing agent and characterized by absorption spectroscopy and high-resolution transmission electron microscope (HR-TEM). Interestingly, Hg2+ addition into AuNPs exhibited highly selective colour and absorption change. The controlled studies indicate that ascorbic acid might play a significant role by converting Hg2+ to metallic Hg that promotes amalgamation with AuNPs. The concentration dependent studies indicate that the synthesized AuNPs can detect Hg2+ ions up to ppb (10−9 M) level. Importantly, T-80- and PSS-AuNPs showed selective sensing of Hg2+ across wide pH range (2.0–10.0). The recovery and interference studies demonstrate the good selectivity of AuNPs for Hg2+ ions in presence of other metal cations.

AuNPs synthesized using ascorbic acid reducing agent exhibited highly selective colorimetric sensing of Hg2+ ions in aqueous medium across wide pH range (2.0–10.0) irrespective of stabilizing agents.Figure optionsDownload as PowerPoint slide