An ultra-low detection limit gold(III) probe based on rhodamine-covalent hydrogel sensor

ABSTRACT

A highly sensitive and selective optical chemosensor (Arg-Rhoen) for determination of Au³⁺ was prepared by covalent immobilization of rhodamine ethylenediamine on agarose gel. Spectrophotometric studies of complex formation, chemical structures and purity of the hydrogel sensor were carried out using TGA, NMR, TEM, and IR. The complexation study results indicated that this probe can selectively detect Au³⁺ via a metal ion chelation-induced ring-opening reaction, and then caused a remarkable colour change from colourless to pink and a strong fluorescence enhancement. Theoretical DFT calculation results suggested that the hydrogel sensor Arg-Rhoen formed stable complexes with Au³⁺ through a large number of cation–dipole interactions. Reusability has been established by repeatedly dipping and rinsing the hydrogel in aqueous Au³⁺ and EDTA in basic solutions. We believe that this approach may provide an easily measurable and inherently sensitive method for Au³⁺ detection in environmental and biological applications.

GRAPHICAL ABSTRACT

KEYWORDS:

• Agarose hydrogel
• sensor
• rhodamine
• gold
• DFT

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research project was financially supported by the Mahasarakham University and Center of Excellence for Innovation in Chemistry (PERCH-CIC), Office of the Higher Education Commission, Ministry of Education.