Phosphorescence approach based on silica protected carbon dots for autofluorescence interference-free and highly...

Fluoride (F^-), an anion with the smallest ionic radius and highest charge density, plays an important role in biomedical and environmental processes, making the development of accurate F^- detection methods of great importance. Fluorometric methods with simplicity and sensitivity have gained considerable attention in F^- detection. However, their accuracy faces challenges due to issues like autofluorescence interference during real-time light excitation and limited selectivity. Therefore, it is important to establish a simple, real-time light excitation-free, and highly selective method for the accurate determination of F^- in complicated samples.

Herein, a novel phosphorescent approach is developed for the selective and accurate detection of F^- in complex samples. Phosphorescence emission CDs@SiO₂ is fabricated by confining CDs in a silica protective layer. This design retains the favorable water solubility of silica while benefitting from its inertness, making it resistant to most substances. Furthermore, phosphorescent analysis without real-time light excitation eliminates autofluorescence interference, significantly improving the signal-to-noise ratio (SNR) and simplifying sample pretreatment. The specific interaction between F^- and the Si-O bond can lead to the degradation of the silica protective layer, exposing the CDs to the solution, resulting in phosphorescence quenching, achieving the highly accurate and sensitive detection of F^- with a linear range of 0.001-4 mM and a limit of detection (LOD) of 1 μM.

This novel F^- phosphorescence method based on the metal-free phosphorescent nanomaterial CDs@SiO₂ integrates the benefits of no autofluorescence interference, high selectivity, and full aqueous compatibility, and its combination with a smartphone provides a simple, portable, and cost-effective detection platform for accurate and highly sensitive determination of F^- in complex samples.