Fluorescein‐Labeled Starch Maleate Nanoparticles as Sensitive Fluorescent Sensing Probes for Metal Ions

Fluorescein 5(6)‐isothiocyanate starch maleate (FISM) nanoparticles were prepared by covalently attached fluorescein 5(6)‐isothiocyanate (FITC) with starch maleate. FISM nanoparticles with a mean particle size of 87 nm were formed via self‐assembly upon precipitation in ethanolic solution. FISM nanoparticles were strongly fluorescent with maximum emission wavelength of 518 nm. The fluorescence of FISM nanoparticles can be quenched by silver (Ag+) and lead (Pb2+) ions in a concentration dependent manner. We have demonstrated the first use of FISM nanoparticles as cheap and effective fluorescent sensing probes for Ag+ and Pb2+ ions with detection limits as low as 2.55 × 10−5 M and 3.64 × 10−5 M, respectively.