Surface charge tuning of functionalized silica cross-linked micellar nanoparticles encapsulating a donor–acceptor dye for Fe( iii ) sensing

In this study, a water-soluble Fe super(3+) ratiometric fluorescent sensor was designed and synthesized by encapsulating a donor-acceptor (D-A) dye 4-formacyl-triphenylamine (FTA) into silica cross-linked micellar nanoparticles (SCMNPs). The quenching of FTA-encapsulated SCMNPs (FTA-SCMNPs) on Fe super(3+) sensing was confirmed using the fluorescence titration method. FTA-encapsulated functionalized SCMNPs (FTA-NH sub(2)-SCMNPs and FTA-SO sub(3)H-SCMNPs) were synthesized to demonstrate the surface charge effect of nanoparticles on Fe super(3+) fluorescence sensing. The sensing ability of Fe super(3+) followed in this order: FTA-SO sub(3)H-SCMNPs > FTA-SCMNPs > FTA-NH sub(2)-SCMNPs, which indicates that particles with stronger negative charge have better sensing abilities. Moreover, linear correlation between the quenching intensity and lower concentration of Fe super(3+) was in accordance with the Stern-Volmer equation in FTA-SCMNPs and FTA-SO sub(3)H-SCMNPs. FTA-SO sub(3)H-SCMNPs showed good selectivity for Fe super(3+) detection. Because of the charge effect of functionalized SCMNPs on a dye-doped Fe super(3+) sensing system, these kinds of nanoparticles offered possibilities to construct sensing ability-enhanced fluorescence-quenching sensors by tuning the surface charge.