B/F/N Co-doped carbon dots as a fluorescent probe for doxycycline and flame retardant performance

This work reported on boron-, fluorine-, and nitrogen-co-doped carbon dots (B/F/N-CDs) produced via a straightforward one-step hydrothermal process, followed by a detailed characterization of their properties. The B/F/N-CDs exhibited bright visible fluorescence, which was rapidly quenched by doxycycline (DOX) through a dynamic quenching mechanism. A fluorescent sensing platform for doxycycline was established, showing good linearity within the concentration range of 0.138–0.421 mM. Satisfactory recoveries (97.79-102.77%) and low relative standard deviations (RSD ≤ 4.45%) were achieved in spiked water samples, demonstrating reliable practical applicability. Moreover, when incorporated into poly(vinyl alcohol) (PVA) films, the B/F/N-CDs reduced the second after-flame time in vertical burning tests from 9.5 s to 5.2 s, indicating improved flame-resistant performance. The results confirm that heteroatom co-doping was a viable tactic for producing multifunctional carbon dots capable of serving dual application roles.