Poria cocos-derived carbon dots for parallel detection of Cr⁶⁺/Fe³⁺ in complex environments with superior sensitivity

Multifunctional sensor capable of parallel sensing is of great importance thanks to their wide applications and great practicality. In this report, Poria cocos-derived carbon dots (CDs) were adopted for the development of multifunctional sensor for the parallel detection of Cr⁶⁺ and Fe³⁺ with superior sensitivity and applicability. Specifically, extremely low limit of detection (LOD) of 1.07 × 10^-3 nM and 1.98 × 10^-3 nM were achieved for Cr⁶⁺ and Fe³⁺, respectively. Systematic mechanism explorations revealed that the highly sensitive detection of Cr⁶⁺ was attributed to an efficient inner filter effect (IFE), while the sensing of Fe³⁺ was realized due to a strong static quenching process. Furthermore, the assay was found to be extremely versatile, achieving the reliable detection of Cr⁶⁺ and Fe³⁺ in multiple natural water environments and even biological environment. Utilizing the different reactions of Cr⁶⁺ and Fe³⁺ towards masking reagents, a logic gate that could effectively eliminate the mutual interference of Cr⁶⁺ and Fe³⁺ was successfully designed.