title: A facile approach for cupric ion detection in aqueous media using polyethyleneimine/PMMA core-shell fluorescent nanoparticles.
abstract: A facile approach was developed to produce a dye-doped core-shell nanoparticle chemosensor for detecting Cu(2+) in aqueous media. The core-shell nanoparticle sensor was prepared by a one-step emulsifier-free polymerization, followed by the doping of the fluorescent dye Nile red (9-diethylamino- 5H-benzo[alpha] phenoxazine-5-one, NR) into the particles. For the nanoparticles, the hydrophilic polyethyleneimine (PEI) chain segments serve as the shell and the hydrophobic polymethyl methacrylate (PMMA) constitutes the core of the nanoparticles. The non-toxic and biocompatible PEI chain segments on the nanoparticle surface exhibit a high affinity for Cu(2+) ions in aqueous media, and the quenching of the NR fluorescence is observed upon binding of Cu(2+) ions. This makes the core-shell nanoparticle system a water-dispersible chemosensor for Cu(2+) ion detection. The quenching of fluorescence arises through intraparticle energy transfer (FRET) from the dye in the hydrophobic PMMA core to the Cu(2+)/PEI complexes on the nanoparticle surface. The energy transfer efficiency for PEI/PMMA particles with different diameters was determined, and it is found that the smaller nanoparticle sample exhibits higher quenching efficiency, and the limit for Cu(2+) detection is 1 microM for a nanoparticle sample with a diameter of approximately 30 nm. The response of the fluorescent nanoparticle towards different metal ions was investigated and the nanoparticle chemosensor displays high selectivity and antidisturbance for the Cu(2+) ion among the metal ions examined (Na(+), K(+), Mg(2+), Ca(2+), Zn(2+), Hg(2+), Mn(2+), Fe(2+), Ni(2+), Co(2+) and Pb(2+)). This emulsifier-free, biocompatible and sensitive fluorescent nanoparticle sensor may find applications in cupric ion detection in the biological and environmental areas.
authors.affiliation: College of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, People's Republic of China.
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
authors.forename: Fang
authors.initials: F
authors.lastname: Zeng
authors.forename: Shuizhu
authors.initials: S
authors.lastname: Wu
authors.forename: Junhua
authors.initials: J
authors.lastname: Su
authors.forename: Jianqing
authors.initials: J
authors.lastname: Zhao
authors.forename: Zhen
authors.initials: Z
authors.lastname: Tong
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry; D002412:Cations / Q000032:analysis; D003300:Copper / Q000032:analysis* / Q000737:chemistry; D031541:Fluorescence Resonance Energy Transfer; D005456:Fluorescent Dyes / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D053758:Nanoparticles / Q000737:chemistry*; D010078:Oxazines / Q000737:chemistry*; D011094:Polyethyleneimine / Q000737:chemistry*; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D014867:Water / Q000737:chemistry
chemical_list: D001672:Biocompatible Materials; D002412:Cations; D005456:Fluorescent Dyes; D010078:Oxazines; D014867:Water; D003300:Copper; D011094:Polyethyleneimine; D019904:Polymethyl Methacrylate; C044808:nile red