Xiaoliang Fei

Layer-by-Layer Assembled Fe3O4@C@CdTe Core/Shell Microspheres as Separable Luminescent Probe for Sensitive Sensing of Cu2+ Ions

A novel multifunctional microsphere with a fluorescent CdTe quantum dots (QDs) shell and a magnetic core (Fe(3)O(4)) has been successfully developed and prepared by a combination of the hydrothermal method and layer-by-layer (LBL) self-assembly technique. The resulting fluorescent Fe(3)O(4)@C@CdTe core/shell microspheres are utilized as a chemosensor for ultrasensitive Cu(2+) ion detection. The fluorescence of the obtained chemosensor could be quenched effectively by Cu(2+) ions. The quenching mechanism was studied and the results showed the existence of both static and dynamic quenching processes. However, static quenching is the more prominent of the two. The modified Stern-Volmer equation showed a good linear response (R(2) = 0.9957) in the range 1-10 μM with a quenching constant (K(sv)) of 4.9 × 10(4) M(-1). Most importantly, magnetic measurements showed that the Fe(3)O(4)@C@CdTe core/shell microspheres were superparamagnetic and they could be separated and collected easily using a commercial magnet in 10 s. These results obtained not only provide a way to solve the embarrassments in practical sensing applications of QDs, but also enable the fabrication of other multifunctional nanostructure-based hybrid nanomaterials.

Preparation of a durable superhydrophobic membrane by electrospinning poly (vinylidene fluoride) (PVDF) mixed with epoxy–siloxane modified SiO2 nanoparticles: A possible route to superhydrophobic surfaces with low water sliding angle and high water contact angle

A durable superhydrophobic surface with low water sliding angle (SA) and high water contact angle (CA) was obtained by electrospinning poly (vinylidene fluoride) (PVDF) which was mixed with epoxy-siloxane modified SiO(2) nanoparticles. To increase the roughness, modified SiO(2) nanoparticles were introduced into PVDF precursor solution. Then in the electrospinning process, nano-sized SiO(2) particles irregularly inlayed (it could also be regard as self-assembly) in the surface of the micro-sized PVDF mini-islands so as to form a dual-scale structure. This structure was responsible for the superhydrophobicity and self-cleaning property. In addition, epoxy-siloxane copolymer was used to modify the surface of SiO(2) nanoparticles so that the SiO(2) nanoparticles could stick to the surface of the micro-sized PVDF mini-islands. Through the underwater immersion test, the SiO(2) nanoparticles cannot be separated from PVDF easily so as to achieve the effect of durability. We chiefly explore the surface wettability and the relationship between the mass ratio of modified SiO(2) nanoparticles/PVDF and the CA, SA of electrospun mat. As the content of modified SiO(2) nanoparticles increased, the value of CA increased, ranging from 145.6° to 161.2°, and the water SA decreased to 2.17°, apparently indicating that the membrane we fabricated has a perfect effect of superhydrophobicity.

Preparation of fluorescent nanofibrous film as a sensing material and adsorbent for Cu2+ in aqueous solution via copolymerization and electrospinning.

Novel naphthalimide-functionalized nanofibrous film was prepared by copolymerization and electrospinning. Vinyl naphthalimide monomer was synthesized and then copolymerized with methyl methacrylate via solution polymerization. This prepared copolymer was electrospun into nanofibrous film, which is an excellent sensing material and adsorbent for Cu(2+). When the nanofibrous film was added into acetonitrile/aqueous solution, the presence of Cu(2+) induces the formation of a 1:1 metal-ligand complex, which exhibits a 48 nm blue-shifted from 487 nm to 439 nm in fluorescence spectra. The fluorescent film shows high sensitivities due to the high surface area-to-volume ratio of the nanofibrous film structures. The detection limit for Cu(2+) is 20 × 10(-6)M. Furthermore, the prepared materials could be utilized as an adsorbent to remove Cu(2+) in aqueous solution efficiently, the adsorption capacity was 10.39 mg of Cu(2+) ions per gram of nanofibrous film. All of the results in this paper show that the naphthalimide-functionalized nanofibrous film made by electrospun technique has excellent sensitivities and adsorbent properties toward Cu(2+) over other metal ions.

A novel reaction-based colorimetric and ratiometric fluorescent sensor for cyanide anion with a large emission shift and high selectivity

A hybrid carbazole-hemicyanine dye (Cac) has been developed as a novel colorimetric and ratiometric fluorescent sensor for cyanide detection. Upon treatment with cyanide, Cac displayed a remarkable fluorescence ratiometric response, with the emission wavelength displaying a very large emission shift (214 nm). The detection of cyanide was performed via the nucleophilic addition of cyanide anion to the indolium group of the sensor, which resulted in the blocking of the intramolecular charge transfer (ICT) process in the sensor, inducing a ratiometric fluorescence change and simultaneously an obvious color change. Furthermore, competitive anions did not showed any significant changes both in color and emission intensity ratio (I381/I595), indicating the high selectivity of the sensor to CN(-).

A new colorimetric fluorescent sensor for ratiometric detection of cyanide in solution, test strips, and in cells

A new high selective and sensitive fluorescent sensor for the detection of cyanide was developed based on the nucleophilic attack of CN− with a color change from purple to colourless. The chemosensor was used for fabrication of test strips that can detect cyanide in aqueous samples. The living animal fluorescence experiment demonstrated the practical value of the sensor in tracing the CN− in biological systems.

Magnetically separable iron oxide nanostructures-TiO2 nanofibers hierarchical heterostructures: controlled fabrication and photocatalytic activity

Novel hierarchical heterostructures of TiO2 nanofibers separately decorated with hematite (α-Fe2O3) or magnetite (Fe3O4) were prepared by combining the electrospinning technique and the hydrothermal method. Extensive characterizations of the resulting hierarchical heterostructures revealed that the secondary α-Fe2O3 or Fe3O4 nanostructures successfully grew on the surface of the primary TiO2 nanofibers substrates, thus integrating the magnetic and photocatalytic properties into the α-Fe2O3/TiO2 and Fe3O4/TiO2 hierarchical heterostructures. The component as well as morphology of the secondary α-Fe2O3 or Fe3O4 nanostructures could be further controlled by simply tuning the experimental parameters. Moreover, the magnetic properties and photocatalytic activities of the hierarchical heterostructures were systematically investigated. Electronic interactions between two semiconductors are the major contributing factor for the changed photoactivity. Most importantly, magnetic measurements showed that the Fe3O4/TiO2 hierarchical heterostructures were ferromagnetic and they could be separated and collected easily using a commercial magnet.

Synthesis and characterization of multifunctional CdTe/Fe2O3@SiO2 core/shell nanosensors for Hg2+ ions detection

Novel multifunctional magnetic-photoluminescent Hg2+ ion sensing nanocomposites were developed by applying SiO2 as the encapsulation agent to package Fe2O3 NRs and CdTe QDs, resulting in CdTe/Fe2O3@SiO2 core/shell nanostructures. The core/shell structural nanocomposites were confirmed by field-emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDXA), X-ray diffraction (XRD) patterns, high-resolution transmission electron microscopy (HRTEM) and selective-area electron diffraction (SAED) patterns. Photoluminescence (PL) spectroscopy and superconducting quantum interference device (SQUID) were used to investigate the optical and magnetic properties of the core/shell structural nanocomposites, respectively. The fluorescence of the obtained nanocomposites could be quenched effectively by Hg2+ ions without obvious changes of spectral widths and optical shift of PL emission. The quenching mechanism was studied and the results showed the existence of both static and dynamic quenching processes. The modified Stern–Volmer equation showed a linear response in the range of 1 to 10 μM with a quenching constant (Ksv) of 3.5 × 104 M−1. This hydrophilic, biocompatible, multifunctional, easy to separate and sensitive fluorescence nanosensor may find applications in Hg2+ ion determination in the biological and environmental areas.