A Novel Biocompatible Fluorescent Sensor for Selective Detection of Copper Ions in Cancer Cells and Aluminum Ions in Pharmaceuticals

ABSTRACT A new Schiff base sensor named FHND based on fluorescein is effectively developed and thoroughly explored through both experimental and computational studies. In the presence of copper (Cu 2+) ions, the probe showed paramagnetic fluorescence quenching, whereas the presence of aluminium (Al 3+ ) ions resulted in chelation‐enhanced fluorescence signal. The sensor's complexation process and recognition performance are also examined using spectroscopic techniques such as Ultraviolet (UV), fluorescence, and Nuclear Magnetic Resonance (NMR) spectroscopy. With minimal interference of other metal ions, the FHND sensor has shown a 1:1 stoichiometry with both Cu 2+ and Al 3+ ions, along with the limit of detection of 8.9 × 10 −8 M and 10.2 × 10 −8 M, respectively. The binding constants for FHND‐Cu 2+ and FHND‐Al 3+ are found to be 4.88 × 10 5 M −1 and 0.65 × 10 5 M −1 , respectively. Interference from other metal ions is negligible (≤14 % for Cu 2 ⁺ ions, ≤6 % enhancement for Al 3 ⁺ ions). The presence of Cu 2+ ions in the culture medium of human osteosarcoma U2OS cells could be detected by the FHND sensor, without significantly attenuating the viability of those cells. Furthermore, the sensor could be used quantitatively for detecting Al 3+ ions in two different medicine solutions. Taken together, the newly developed sensor showed potential for biomedical and pharmaceutical applications in the future.