Qingbiao Yang

Preparation and characterization of a PAN nanofibre containing Ag nanoparticles via electrospinning

A polyacrylonitrile (PAN) nanofiber containing Ag nanoparticles was prepared by an electrospinning technology. To prevent the nanoparticles from coagulating in polymer solutions, an approach of in-situ preparing nanoparticles in PAN solution was used. Diameters of the nanoparticles and nanofiber as well as distribution of the former in the latter were characterized by Transmission electron microscopy. Crystal structure of the nanoparticles was given by X-ray diffraction. Absorption spectrum of the nanocomposites was measured by UV-Vis. Conductivity of the nanocomposites was compared with the pure PAN nanofiber.

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.

A convenient route to polyvinyl pyrrolidone/silver nanocomposite by electrospinning

Silver nanoparticles prepared through reduction of AgNO3 by ethanol under refluxing conditions in polyvinyl pyrrolidone (PVP) ethanol solution were dispersed into PVP nanofibre film by electrospinning. The optical properties of Ag nanoparticles in PVP ethanol solution were measured by ultraviolet–visible (UV–vis) spectroscopy. The presence of face-centred cubic (fcc) crystalline silver embedded in PVP nanofibre film was indicated by the x-ray diffractometer (XRD) pattern. The morphology and distribution of silver nanoparticles in PVP nanofibres were observed by transmission electron microscopy (TEM). The interaction between PVP and Ag nanoparticles was confirmed by the x-ray photoelectron spectrum (XPS). In addition, Ag/PVP nanocomposite film was characterized by the surface enhanced Raman scattering (SERS) spectrum.

Porphyrin-functionalized Fe3O4@SiO2 core/shell magnetic colorimetric material for detection, adsorption and removal of Hg2+ in aqueous solution

A fluorimetric/colorimetric mercury(II) sensor based on porphyrin-functionalized Fe3O4@SiO2 core/shell magnetic microspheres has been developed and demonstrated by sol–gel grafting reaction. These multifunctional microspheres show excellent fluorescence sensitivity and selectivity towards Hg2+ over other metal ions (K+, Na+, Ba2+, Mn2+, Ca2+, Co2+, Cu2+, Ag+, Mn2+, Ni2+ and Pb2+). Upon addition of Hg2+, the color of porphyrin-functionalized Fe3O4@SiO2 microspheres changes from red to green within 1 min and the fluorescence of microspheres becomes obviously weak. Conversely, no significant changes in fluorescence emission or color are observed in the parallel experiment with other metal ions. Regarding the reversibility of the microspheres, the color and fluorescence of the porphyrin-functionalized Fe3O4@SiO2 microspheres in the presence of Hg2+ ion are found to be almost reversible when the microspheres are treated with EDTA solution. Furthermore, the used microspheres can efficiently remove Hg2+ ions in aqueous solution and easily separated from the mixture by adding an external magnetic field. Theses results suggest that functionalized Fe3O4@SiO2 core/shell magnetic microspheres are potentially useful materials for simultaneously detecting and removing environmental pollutants.

A new fluorescent and colorimetric sensor for hydrazine and its application in biological systems

Hydrazine is a very important industrial chemical and exhibits high toxicity to human beings. Here we have constructed a novel ICT-based fluorescence sensor with a high selectivity and sensitivity, rapid detection, and huge color-change. We used the sensor for hydrazine determination in live cells and also in live fish, and manufactured dipsticks using our sensor. The sensing mechanism is well rationalized with the aid of TD-DFT (time-dependent density functional theory) calculations.

Electrospun novel bifunctional magnetic–photoluminescent nanofibers based on Fe2O3 nanoparticles and europium complex

Novel bifunctional magnetic-photoluminescent nanofibers based on Fe(2)O(3) nanoparticles and europium complex Eu(DBM)(3)(Bath) (DBM=dibenzoylmethanate, Bath=bathophenanthroline) have been prepared by electrospinning. Extensive characterizations of the resulting bifunctional nanofibers have been performed using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM). The influence on photoluminescence properties of bifunctional nanofibers of the addition of Fe(2)O(3) nanoparticles has also been studied. The results indicate that due to decreased symmetry in the composite nanofibers the excitation bands of the composite nanofibers are split into two different components. Furthermore, the existence of the Fe(2)O(3) and polymer hybrid matrixes can improve the thermal and photo stability of the europium complex and elongate the fluorescence lifetime of the europium complex.

Synthesis of magnetic and fluorescent multifunctional hollow silica nanocomposites for live cell imaging

In this paper, we report a synthesis of multifunctional core/shell silica nanocomposites in mixed water-ethanol solvents at room temperature. Water-soluble CTAB-stabilized nanoparticles (Fe(3)O(4) and quantum dots) are used as templates and tetraethoxysilane (TEOS) is used as a precursor to fabricate multifunctional hollow silica nanocomposites. Owing to the high abundance of folate receptors in many cancer cells, folic acid is used as the targeting ligand. By coupling with folic acids, the multifunctional silica nanocomposites conjugates are successfully used for tumor cell imaging. In vitro cellular uptakes of such SiO(2) nanocomposites are investigated with fluorescence microscope, which demonstrate much higher internalization of the folate-decorated SiO(2) nanocomposites by Hela cancer cells which are of over-expression of folate receptors than the cellular uptake by NIH 3T3 fibroblast cells which are of low expression of folate receptors. Magnetic manipulation, fluorescence imaging, hollow structure, and cell targeting are simultaneously possible using a multifunctional silica nanocomposite. Our results demonstrate a robust hydrophobic nanoparticles-based approach for preparing multifunctional and biocompatible hollow silica composites, which could be also suitable for silica coating of other kinds of nanoparticles.

A novel multinozzle electrospinning process for preparing superhydrophobic PS films with controllable bead-on-string/microfiber morphology

Superhydrophobic polystyrene (PS) surfaces with mechanical integrity were manufactured by electrospinning in this work. We first report a novel strategy here to combine bead-on-string fibers from 4% PS solution and micro-sized fibers from 20% PS solution homogeneously in one electrospinning step by multinozzle electrospinning. The superhydrophobicity of electrospun sheet can be achieved by the presence of bead-on-string fibers, while micro-sized PS fibers are responsible for the improvement of mechanical property of electrospun mat due to their elastic and flexible behavior. The distinctive design of our multinozzle electrospinning setup places two nozzles in separate electrical fields which guarantee that fibers with different structures are mixed homogeneously. We investigate the relationship between the mass ratio of fibers from two types of solutions and the CA of electrospun mat, the effect of mass ratio to the mechanical property of electrospun mat can also be observed. The result shows that CA value of PS surface merely comprised of bead-on-string fibers could reach up to 154.65°. As the content of microfibers increased, the value of CA decreased, ranging from 153.66° to 145.94°, but the tensile strength of composite mat was enhanced from 0.50 MPa to 1.22 MPa correspondingly which is beneficial to put the mats into practice.

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.