Sensitive Cu2+ detection by reversible on-off fluorescence using Eu3+ complexes in SiO2, in chitosan/polyethylene oxide nanofibers

Trace amounts of heavy metal ions in the human body are essential for maintaining health. However, heavy metal ion excess or deficiency causes toxicity or disease. This study examines the sensitivity of luminescent europium complexes for the detection of Cu 2+ . Here, Eu 3+ is complexed with1,10-phenanthroline (phen) and 4,4′,4-trimethyltriphenylamine (TTA) to form luminescent [Eu 3+ (TTA) 3 phen] complexes, encapsulated in silica (SiO 2 ) nanoparticles. The silica nanoparticles are then formed into a composite with a blend of chitosan and polyethylene oxide (PEO), to make electrospun nanofibers. The combination of Eu 3+ complexes with SiO 2 nanoparticles doped in chitosan enhances the fluorescence performance. Photophysical measurements show that when the Cu 2+ concentration is 100 μmol/L, the fluorescence of the composite chitosan nanofibers can be quickly and sensitively quenched, and that concentrations as low as 10 μmol/L Cu 2+ can be detected. Furthermore, the use of chitosan and PEO to prepare the material makes these new fluorescence-based copper sensing materials suitable for Cu 2+ detection in biological systems.