Highly fluorescent nitrogen and boron doped carbon quantum dots for selective and sensitive detection of Fe3+

Abstract

Due to the essential role of Fe³⁺ in physiological and pathological processes, the detection of Fe³⁺ has drawn increasing attention in the field of disease diagnosis and environmental protection. However, most existing methods require either cumbersome sample pretreatment or sophisticated and expensive test equipment. Recently, carbon quantum dots have found a wide range of applications such as nanoprobes for Fe³⁺ determination, albeit with limited sensitivity and selectivity. Herein, we report core–shell carbon quantum dots B₁N₂CQDs via a two-step hydrothermal approach using citric acid, boric acid and ethylenediamine as precursors. The obtained B₁N₂CQDs exhibit excellent water solubility and remarkable stability as well as a high fluorescence quantum yield of 15.4%. In addition, the fluorescence of B₁N₂CQDs is quenched exclusively by Fe³⁺ with minimal interference from other metal ions. A linear relationship with R² = 0.998 was observed between the fluorescence quenching capacity and the Fe³⁺ concentration in the range of 2–160 μM, with the limit of detection calculated to be 80 nM. Finally, the as-prepared B₁N₂CQDs were successfully applied as a highly efficient fluorescent probe for Fe³⁺ detection in river water samples and intracellular Fe³⁺ imaging in biological systems.