Novel fluorescent polymeric nanoparticles for highly selective recognition of copper ion and sulfide anion in water

• The FPNs sensor was prepared by miniemulsion polymerization and surface grafting.
• The sensor can selectively detect copper ion and sulfide anion in water.
• The detection limit of sensor is 340 nM for Cu2+ and 2.1 μM for S2−.
• The sensor was applicable in a relatively wide pH range (4–10).
• The sensor exhibited excellent long-term photostability for Cu2+ detection (≥40 days).

In the present study, a fluorescence resonance energy transfer (FRET)-mediated multifunctional sensor based on fluorescent polymeric nanoparticles was synthesized via a combination of a facile one-pot miniemulsion polymerization and subsequently by surface modification technology. Firstly, fluorescent polymeric nanoparticles were obtained by copolymerization of styrene, vinylbenzylchloride and the fluorescent vinylic crosslinking monomer (fluorescein-O,O-bis-propene: FBP) in oil-in-water miniemulsion stabilized with a cationic surfactant (dodecyltrimethyl ammonium bromide: DTAB). Then, 1,4,7,10-tetraazacyclododecane (Cyclen) was selected as ligand to graft onto the surface of nanoparticles. Due to the specific FRET effect between FBP and the Cu2+–Cyclen complex, the as-prepared nanoparticles display highly sensitive (detection limit: 340 nM) on-off-type fluorescence change with high selectivity toward Cu2+ among 11 metal ions (such as K+, Na+, Co2+, Ni2+, Zn2+, Hg2+, Mn2+, Ca2+, Mg2+, Fe2+ and Pb2+) in 100% aqueous solution. Moreover, it is worth to note that the in situ generated nanoparticle-Cu2+ ensemble could recover the quenched fluorescence upon addition of sulfide anion resulting in an off-on-type sensing with a detection limit of 2.1 μM in the same medium. No obvious interference was observed from other familiar anions such as Cl−, NO3−, SO42−, HCO3−, CO32−, Br−, F−, S2O32−, ClO4− and HPO42−. Furthermore, the nanoparticle-based dual-ion sensor can be reversibly switched for multi-times by alternative addition of adequate Cu2+ or S2−, was also applicable in a relatively wide pH range (pH 4–10), and exhibited excellent long-term photostability for Cu2+ detection (≥40 days) in aqueous media. Thus, this approach may reveal a new pathway for selective detection of multiplex analyst in environmental and biological applications.

Novel FRET-mediated fluorescent polymeric nanoparticles for highly sensitive (detection limit: 340 nM for Cu2+ and 2.1 μM for S2−) and selective recognition of copper ion and sulfide anion in water were prepared by a facile miniemulsion polymerization and subsequent surface grafting strategy. The nanoparticle-based dual-ion sensor can be reversibly switched for multi-times by alternative addition of adequate Cu2+ or S2−, and was also applicable in a relatively wide pH range (pH 4–10), exhibited excellent long-term photostability for Cu2+ detection (≥40 days) in aqueous media.Figure optionsDownload as PowerPoint slide