Design of lanthanide-doped carbon dots Nanochemosensor for Paper-strip based as well as in-vitro Turn-off-on detection of Fe ions and hydrogen peroxide.

Shifting emission wavelengths through different excitation methods can provide valuable insights; however, the reduced intensity of the shifted peaks often presents challenges in practical applications. In this work, we report the exceptional enhancement of optical and chemical properties of carbon dots (CDs) by simple doping of erbium ions (Er ions). Doping carbon dots (CDs) with Er ions can significantly enhance their photoluminescence properties and emission wavelengths are tunable across the entire visible region. The increase in quantum yield from 24.7 % to 30.2 % could enhance the performance of these materials in practical applications. The Er ions-doped carbon dots (Er@CDs) are designed via a single-step hydrothermal method and used as a fluorescence probe for signal turn-off-on detections of Fe ions and hydrogen peroxide (HO). The fluorescence signal of Er@CDs is turn-off by the addition of Fe ions and turn-on after addition of HO with the detection of limits are 51.7 nM & 55 µM, respectively. The fluorescence intensity of Er@CDs turn-off by Fe ions may be due to the cation exchange of Er ions with Fe ions and turn-on via Fenton's process. This sensing probe follows both dynamic and static quenching mechanism and described by fluorescence lifetime decay and zeta potentials analysis. The synthesized Er@CDs is utilized for paper-based turn-off-on detection of Fe ions and HO. Additionally, the low cytotoxicity and small particle size of the Er@CDs make them ideal for in-vitro turn-off-on detection of Fe ions and HO in Hep G2 cancer cells.