Engineering a ratiometric fluorescent sensor membrane containing carbon dots for efficient fluoride detection and removal

Fluoride anion pollution is one of the main problems that needs to be addressed in contaminated water. Herein, we have developed a novel sensing platform using a pyrene boronic acid and carbon dots (CDs) for the selective detection and removal of fluoride (F⁻) ion at environmentally relevant levels. The probe consists of pyrene-boronic acid (PyB) moieties immobilized on to the surface of water-soluble CDs. The pyrene-boronic acid-based CDs (CDs-PyB) result in a sensor whose response is linear for F⁻ concentrations over a range from 0 to 200 µM (R² = 0.996) with a detection limit of 5.9 × 10⁻⁵ M and display high selectivity for F⁻ over other anions. In addition, an amino-modified cellulose membrane containing CDs-PyB has been prepared for practical sensing and removal of F⁻. The cellulose membrane-based sensor shows great potential for the detection of F⁻ with a high sensitivity, and excellent F⁻ adsorption and removal efficiency of 90.2%. Moreover, an MTT assay for the membrane demonstrates high cell proliferation ca 400% after 5 days culture, indicating excellent cytocompatibility. Our approach offers a promising direction for the construction of other sensors by simply swapping the current probe with suitable replacements for a variety of relevant applications using biocompatible and abundant naturally based materials.