Two birds with one stone: one-step preparation of fluorine-doped CDs with sensitive sensing of copper and visualization of latent fingerprints.

Fluorine-doped carbon dots (F-CDs) are prepared through a one-pot hydrothermal method starting from ciprofloxacin, exhibiting a bright blue emission at 453 nm under the optical wavelength of 358 nm. The sensitive sensor for detecting Cu is established based on the fluorescence quenching of F-CDs, which is attributed to the static quenching caused by the formation of non-luminescent complexes between them. The limit of detection (LOD) is 46.2 nM. Meanwhile, a portable fluorescence sensor based on a lateral flow test strip (LFTS) has been developed for practical applications, which allows real-time monitoring of Cu with a satisfactory limit of detection (LOD) of 69.7 nM in a good linear range of 0.0697-50 μM. In addition, the identification of latent fingerprints (LFPs) based on F-CDs has been developed with the assistance of MATLAB, realizing high-performance fingerprint visualization and recognition. The results serve to underscore that the synthesized F-CDs not only provide a new tool for Cu detection in real samples, but also show great potential for LFPs visualization and information identification.