Fluorescent carbon dots embedded in mesoporous silica nanospheres: A simple platform for Cr(VI) detection in environmental water

In this work, amino-functionalized mesoporous silica nanospheres (NH 2 -mSiO 2 ) anchored with carbon dots (CDs) have been designed to construct an outstanding fluorescent sensor for heavy metal detection. Uniform mSiO 2 was chosen to provide an optically transparent scaffold for immobilizing CDs. With the help of amino group modification on the surface of silica, benzene-1,4-diboronic acid (BA) was used as raw material to load CDs in the pores of mSiO 2 by one-step solvothermal method. The proposed nanohybrid can solve the problem of aggregation-induced fluorescence quenching, leading to bright blue emission at 450 nm. Meanwhile, the fluorescence of NH 2 -mSiO 2 @CDs showed high sensitivity to Cr(VI) in acetic acid buffer solution (pH = 4) with detection limit as low as 5 nM by inner filter effect (IFE) and electrostatic interaction (EI). The proposed method can also be extended to other CDs-based detection systems for chemical/biological sensors.