Ratiometric fluorescence detection of doxorubicin by R-CQDs based on the inner filter effect and fluorescence resonance energy transfer

Abstract

In this work, rhodamine 6G (Rh 6G) was modified on the surface of carbon quantum dots (CQDs) synthesized by a hydrothermal method via a microwave reaction and Rh 6G-CQDs (R-CQDs) with obvious double emission peaks were obtained. UV-visible (UV-vis), fluorescence, and Fourier transform infrared (FTIR) spectra showed that Rh 6G was successfully modified on the surface of CQDs. Rh 6G modification on the surface of CQDs is more stable than simple mixing dependent on electrostatic adsorption, avoids desorption and degradation of the dye, and further improves the quantum yield of CQDs. The broader emission spectrum of R-CQDs effectively increases the overlap with the absorption spectrum, R-CQDs with ratio fluorescence properties achieve selective detection of doxorubicin (DOX) by the inner filter effect (IFE) and fluorescence resonance energy transfer (FRET), and it has a good linear response in the range of 8 × 10⁻⁷–4.28 × 10⁻⁵ M with a recovery of 93.29–109.51% and a minimum detection limit of 5.31 × 10⁻⁷ M.