Enhanced performance of Fe3+ detection via fluorescence resonance energy transfer between carbon quantum dots and Rhodamine B

Abstract

Carbon quantum dots (CQDs) were prepared by a facile hydrothermal method and emitted a broad fluorescence covering the entire blue and green light wavelength scope. Because their emission spectra overlaped with the absoprtion spectrum of Rhodamine B (RhB) molecules, fluorescent resonance energy transfer (FRET) phenomenon between CQDs as the energy donors and RhB as the energy acceptors was observed when CQDs were mixed with RhB in a solution. To obtain the optimal FRET efficiency, the concentrations of CQDs and RhB should be adjusted to 0.559 mg mL⁻¹ and 1.25 μM, respectively, at pH = 6.2. None of the metal ions except for Fe³⁺ hindered this FRET process as well as deactivated the electronic excitation energy of RhB molecules through migration, resulting in an enhancement of fluorescence quenching rates. Therefore, the developed system allowed enhancing the selectivity and sensitivity of Fe³⁺ detection via the FRET effects, and could be used for accurate measurements of time-dependent conformational changes and monitoring the corrosion processes of iron materials over an extended period.