One-step UV-induced synthesis of ultra-bright fluorescent carbonized polymer dots for rapid detection of Cr(vi)

The highly toxic and carcinogenic nature of hexavalent chromium (Cr(vi)) necessitates the development of rapid and sensitive detection platforms for environmental and clinical monitoring. However, the facile preparation of ultra-bright fluorescent probes with high specificity and ultrafast response remains a significant challenge. In this study, an innovative, one-step, room-temperature photochemical strategy is proposed for the rapid synthesis of fluorescent carbonized polymer dots (CPDs) within just 20 min under ultraviolet (UV) irradiation, utilizing Rose Bengal (RB) as a photosensitizer and 3-(2-aminoethylamino) propyldimethoxymethylsilane (DAMO) as a silicon source. The resulting CPDs exhibit excellent aqueous dispersibility and strong green fluorescence (emission at 525 nm), achieving an extraordinary near-unity absolute photoluminescence quantum yield of 99.89%. These CPDs demonstrate a highly specific fluorescence quenching response to Cr(vi), driven synergistically by the inner filter effect (IFE) and electrostatic interactions (EI). Based on this unique mechanism, the developed fluorescent sensing platform achieves an ultrafast response time of less than 5 s, an excellent linear correlation within an exceptionally wide concentration range of 10-900 µM, and a low limit of detection (LOD) of 5.68 µM. Furthermore, the practical reliability of the proposed platform was successfully validated in complex real-world matrices, including lake water, human serum, and urine, yielding highly satisfactory recovery rates ranging from 91.27% to 109.09%. Ultimately, this work provides a highly efficient methodology for constructing ultra-bright CPDs and establishes a robust tool for the specific recognition and accurate quantification of Cr(vi) in diverse practical applications.