Hydrogen Peroxide-Assisted Ultrasonic Synthesis of BCNO QDs for Anthrax Biomarker Detection

A facile 3% hydrogen peroxide-assisted ultrasonic synthetic strategy is demonstrated to successfully synthesize fluorescent boron carbon oxynitride quantum dots (BCNO QDs). The obtained BCNO QDs exhibit intense blue fluorescence and favorable biocompatibility and water solubility. The quantum yield of the BCNO QDs is 19.9%. Owing to the absorbance energy-transfer emission effect, an efficient ratiometric fluorescence biosensor is developed for anthrax biomarker detection based on the BCNO QD-ethylenediaminetetraacetic acid disodium salt-Eu³⁺ complex. Under optimal conditions, the detection limit of the anthrax biomarker is 0.5 nM. Furthermore, the sensitivity of the system was evaluated by Bacillus subtilis spores and with the detection limit as low as 1.95 × 10⁶ spores. On combining a smartphone with the home-made BCNO QD test paper, the lowest recorded visual detection limit of 1.0 μM anthrax biomarker was achieved using a portable UV lamp. The fast response speed, excellent sensitivity, and selectivity of the approach show potential applications in clinical analysis.