Rhodamine B-Coated Gold Nanoparticles as Effective “Turn-on” Fluorescent Sensors for Detection of Zinc II Ions in Water

ABSTRACT

We designed a fluorescence resonance energy transfer system consisting of fluorophore Rhodamine B and gold nanoparticles for sensing of zinc ions in aqueous solution. The electrostatic attraction between positively charged N-atoms in Rhodamine molecules and negatively charged citrate corona of gold nanoparticles led to substantial fluorescence quenching. However, the quenching is switched off in the presence of zinc ions and therefore the system can be used as an effective “turn-on” fluorescence sensor. UV-Vis absorption, fluorescence spectroscopy, and transmission electron microscopy were used for sensor evaluation. The approach of “turn-on” fluorescence has real potential for sensing metallic ions in water.

KEYWORDS:

• fluorescence
• FRET
• gold nanoparticles
• Zn²⁺ ions

ACKNOWLEDGMENTS

This work was supported by CNCSIS–UEFISCSU, project number PNII_ID_PCCE_312/2008

Notes

This paper was submitted as a contribution representing work done primarily by undergraduate researchers; Daniela Simona Tira and Sorin Ulinici as PhD students, supervised by Dr. Monica Focsan, Dr. Dana Maniu, and Prof. Simion Astilean.