Novel imprinted polyethyleneimine nano-fluorescent probes with controllable selectivity for recognizing and adsorbing metal ions

Abstract

Novel ion imprinted nano-fluorescent probes (IIP-fluorescein) based on polyethyleneimine (PEI) were obtained via simple imprinting and grafting with fluorescein, and used for high recognition, detection and adsorption of Cu2+, Zn2+ and Cr3+ in aqueous solution. The selectivity of PEI is adjustable through an imprinting process for Cu2+, Zn2+or Cr3+, which have a strong affinity for the amino group. Each probe reveals specific selectivity to and recognition of the relevant template metal ion over seven other common metal ions. The three probes exhibit a large linear detection range, high accuracy and strong adsorption capacity for Cu2+, Zn2+ and Cr3+. The sensitive and selective detection, as well as the removal of Cu2+, Zn2+ and Cr3+ by using IIP-fluorescein was further demonstrated in polluted tap and river water, indicating their potential application in environmental monitoring and treatment. Additionally, the sensing mechanism of IIP-fluorescein for metal ions was investigated through Gaussian 09. The synergistic effect of photo-induced electron transfer (PET) and intramolecular charge transfer (ICT) was demonstrated in the sensing process for metal ions. The design concept might propose a method for developing and studying other fluorescent probes with similar systems (containing amino groups, mercapto groups or cyano groups).