Xuewu Ge

USTC-CityU Joint Advanced Research Center, Hong Kong, Hong Kong

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Publications (118)251.3 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Poly(ethylene terephthalate)-g-polyacrylonitrile (PET-g-PAN) composite film with a porous surface was fabricated via gamma-ray-radiation-induced graft polymerization on PET film in an aqueous solution system. The original PET film was first irradiated by gamma ray in the aqueous solution of acrylic acid. Next, the graft polymerization of acrylonitrile (AN) was induced by gamma ray on the surface of the above modified PET film in an aqueous solution of AN. The prepared PET-g-PAN composite film has a smaller static water contact angle than the original PET film. The SEM and AFM images show that the grafted PAN layer on the surface of PET-g-PAN composite film is composed of closely-arranged spherical PAN microspheres with an average diameter of 30 nm. The gaps between the PAN microspheres form fine pores (less than 30 nm) on the surface. The gas barrier property of the PET-g-PAN composite film is much better than that of the original PET film. This work provides a facile and green method to prepare PET-g-PAN composite film with a controllable porous surface morphology by taking advantage of the radiation-induced graft polymerization technique in an aqueous solution system.
    Radiation Physics and Chemistry 01/2015; 106:261–267. · 1.38 Impact Factor
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    ABSTRACT: Three-dimensionally ordered macroporous (3DOM) polytetrafluoroethylene (PTFE) has hardly been prepared due to the poor solubility in most of solvents and high melting temperature of PTFE raw material. In this work, monodispersed polystyrene (PS) microspheres and PTFE latex particles were controlled to simultaneously deposit from water. After the deposits were calcinated at 400 oC, a self-supported superhydrophobic 3DOM PTFE film with a static water contact angle of 154° was successfully fabricated. The pore size can be tunable from 1.5 μm to 3 μm, depending on the size of PS microspheres. The prepared 3DOM PTFE film were used as micro-molds and micro-reactors to prepare poly(methyl methacrylate) (PMMA) particles and TiO2 macroporous material, respectively. This work provides a facile method to fabricate 3DOM PTFE materials.
    Langmuir 09/2014; · 4.38 Impact Factor
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    ABSTRACT: Four kinds of 13C-labeled polyacrylonitrile (PAN) samples were prepared respectively by solution polymerization of acrylonitrile (AN) with selective 13C labeling of different molecular sites. The composition and structure of the residues from the thermal treatment of PAN in argon at 250 and 350 °C were quantitatively analyzed in detail by one- and two-dimensional solid-state 13C nuclear magnetic resonance (ssNMR) experiments. Compared with the NMR spectrum of each labeled carbon in AN monomer unit, nine chemical structures created during the heat treatment process have been identified accurately. On this basis, four reaction routes were proposed. It is noted that the main chemical change for PAN started from a cyclization reaction at a relatively low temperature, then experienced an aromazation reaction to form a molecular chain basically composed of isolated pyridine units, instead of the commonly reported ladder structure. This work also shows that the combination of selectively 13C-labeled technique and a high spinning speed of 20 kHz in magic-angle spinning (MAS) NMR experiment could improve the detection sensitivity to nearly 2 orders of magnitude, and provide a clear ssNMR spectra with little peak overlaps, which will be helpful to discover the complex reaction mechanism in the manufacture of carbon fibers with high performance.
    Macromolecules 06/2014; 47(12):3901–3908. · 5.93 Impact Factor
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    ABSTRACT: This work presents a synthesis of submicron-sized raspberry-like hollow microspheres loaded with corrosion inhibitor (1H-benzotriazole (BTA)) through a multi-stage emulsion polymerization. The combination of hierarchical raspberry-like surface structure and loading of BTA makes the prepared microspheres have good corrosion resistance. When BTA-loaded raspberry-like hollow microspheres are embedded in a water-borne polyurethane film, the obtained composite film can protect the copper from corrosion both in acidic and alkaline corrosive solutions.
    Surface and Coatings Technology 01/2014; 238:15–26. · 1.94 Impact Factor
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    ABSTRACT: A strand displacement reaction (SDR) system that runs solely on oligonucleotides has been developed for the amplification detection of adenosine triphosphate (ATP). It involves a target-induced SDR and an entropy-driven catalytic cycle of two SDRs with five oligonucleotides, denoted as substrate, fuel, catalyst, C-1, and C-2. Catalyst, released from the ATP aptamer–catalyst duplex by ATP molecule, catalyzes the SDRs to finally form the substrate–fuel duplex. All of the intermediates in the catalytic SDR processes have been identified by polyacrylamide gel electrophoresis (PAGE) analysis. The introduction of ATP into the SDR system will induce the ATP aptamer to form G-quadruplex conformation so as to release catalyst and trigger the SDR cycle. When the substrate and C-2 oligonucleotides were labeled with a carboxyfluorescein (FAM) fluorophore and a 4-([4-(dimethylamino)phenyl]azo)benzoic acid (DABCYL) quencher, this SDR catalytic system exhibited a “turn-on” response for ATP. The condition for detecting ATP, such as Mg2+ concentration, has been optimized to afford a detection limit of 20 nM. This work provides an enzyme-free biosensing strategy and has potential application in aptamer-based biosensing.
    Analytical Biochemistry 01/2014; 446:69–75. · 2.58 Impact Factor
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    ABSTRACT: A strand displacement reaction-based system was developed for the determination of adenosine triphosphate (ATP). It involved an entropy-driven catalytic cycle that directly employed the ATP aptamer as the catalyst. Introduction of ATP into the system induced the catalyst to form the G-quadruplex conformation and inhibited its catalytic activity. All intermediates in the catalytic cycle processes were identified by polyacrylamide gel electrophoresis analysis. When the oligonucleotides were labeled with a carboxyfluorescein fluorophore and a 4-([4-(dimethylamino)phenyl]azo)benzoic acid quencher, this strand displacement reaction-based catalytic system exhibited a “switch-on” response for ATP. Conditions for detecting ATP, such as the toehold length, concentrations of the catalyst and magnesium ion, and incubation temperature, were optimized to obtain a detection limit of 50 nM and a linear response up to 1400 nM of ATP. This target inhibited catalytic cycle provides an enzyme-free biosensing strategy and has potential application in aptamer-based biosensing.
    Analytical Letters 01/2014; 47(3). · 0.97 Impact Factor
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    ABSTRACT: In this report, we study the formation mechanism of cage-like polymer microspheres fabricated conveniently and efficiently through a swelling-osmosis process of sulfonated polystyrene (SPS) microspheres in a ternary mixed solvent (water/ethanol/heptane). The SEM and TEM observations indicated that the morphology of the final cage-like SPS microspheres is mainly controlled by the composition of the mixed solvent and the swelling temperature. Considering the solubility parameters of related reagents and the low interface tension of heptane and the aqueous solution of ethanol (only 6.9 mN/m), we confirm that the porogen procedure starts from the swelling of SPS microspheres by heptane, followed by the osmosis process of water molecules into the swollen SPS microspheres forced by the strong hydrophilicity of -SO3H group. The water molecules permeated into SPS microspheres will aggregate into water pools, which form the pores after the microspheres are dried. These prepared cage-like SPS microspheres are further served as scaffold for the in situ generated CdS nanoparticles under -ray radiation. The CdS/SPS composite microspheres show great fluorescence performance. This work shows that the cage-like SPS microspheres have a wide industrial application prospect due to their economical and efficient preparation and loading nanoparticles.
    Langmuir 11/2013; · 4.38 Impact Factor
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    ABSTRACT: In this work, we first reported that the phase separation can take place both inside and outside of a multi-hollow-structured crosslinked seed microspheres swollen by styrene monomers in water during the radiation-induced seeded emulsion polymerization. The phase separation process in these two opposite directions will determine the morphology of final latex particles. First, sulfonated crosslinked polystyrene (SCPS) seed microspheres were swollen by styrene in water. Water will permeate into the SCPS seed microspheres during the swelling process, forced by the osmotic pressure produced by the strong hydrophilicity of the sulfonic acid groups. New aqueous phases are created and stabilized by the hydrophilic -SO3H groups, resulting in a multi-hollow structure of swollen SCPS seed microspheres. When the polymerization of styrene is induced by 60Co -ray radiation, the phase separation of newly-formed polystyrene phase will occur at the seed microsphere-water interface inside and/or outside of the SCPS seed microspheres through adjusting the diameter of seed microsphere, the content of crosslink agent, and the sulfonation degree of SCPS seed microspheres. As a result, SCPS latex particles with a variety of special morphologies, such as spherical multi-hollow, plum-like, and walnut-like latex particles were obtained. The results of this study provide not only a simple and interesting way to design and synthesize multi-hollow polymer latex particles with controllable surface morphologies, but also a better understanding on phase separation mechanism during the swelling and polymerization of monomers in crosslinked amphiphilic polymer networks.
    Langmuir 11/2013; · 4.38 Impact Factor
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    ABSTRACT: The adsorption of DNAs in G-quadruplex solution onto 13nm gold nanoparticles (AuNPs) was studied through monitoring of the localized surface plasmon resonance (LSPR) absorbance of 13nm AuNPs at 520 and 650nm (A650/A520) in the solutions of three widely studied guanine-rich sequences, TBA(5'-GGTTGGTGTGGTTGG-3'), PW17(5'-GGGTAGGGCGGGTTGGG-3'), and PSO (5'-GGGTTAGGGTTAGGGTTAGGG-3'). It was found that the degree of adsorption of DNAs in Pb(2+) stabilized G-quadruplex (G-Pb(2+)) solutions is up to 93% after more than 5h of incubation. Furthermore, the lead concentrations in the solutions containing G-quadruplex and AuNP were analyzed by an inductively coupled plasma atomic emission spectrometer. The results showed that Pb(2+) had been released from the G-quadruplexes, which means the G-quadruplexes may be unfolded in the presence of AuNP. This interaction between G-quadruplexes and AuNP demonstrated that long time incubation between DNAs and AuNPs would possibly make it unable to distinguish G-quadruplex from ssDNA. Thus, a biosensing system consisting of PW17 and AuNPs was developed to detect Pb(2+). It was found that the LSPR responses at A650/A520 were sensitive to [Pb(2+)]. However, the sensitivity of the system was interfered by the potential unfolding of PW17-Pb(2+) in the presence of AuNPs. This unexpected adverse effect of AuNPs on DNA-based biosensors should be taken into consideration in the future development of biosensing systems that are based on ssDNA aptamers and unmodified AuNPs.
    Biosensors & Bioelectronics 10/2013; 53C:479-485. · 6.45 Impact Factor
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    ABSTRACT: A strand displacement reaction (SDR) system that runs solely on oligonucleotides has been developed for the amplification detection of adenosine triphosphate (ATP). It involves a target induced SDR and an entropy-driven catalytic cycle of two SDRs with five oligonucleotides, denoted respectively as "substrate", "fuel", "catalyst", "C-1" and "C-2". The "catalyst", released from ATP aptamer-"catalyst" duplex by ATP molecule, catalyzes the SDRs to form the "substrate-fuel" duplexes finally. All the intermediates in the catalytic SDR processes have been identified by PAGE analysis. Introduction of ATP into the SDR system will induce the ATP aptamer to form G-quadruplex conformation so as to release the "catalyst" and trigger the SDR cycle. When the "substrate" and "C-2" oligonucleotides were labeled with a carboxyfluorescein (FAM) fluorophore and a 4-([4-(dimethylamino)phenyl]azo)benzoic acid (DABCYL) quencher, this SDR catalytic system exhibits a "turn-on" response for ATP. Condition for detecting ATP, such as Mg(2+) concentration, has been optimized to afford a detection limit of 20 nM. This work provides an enzyme-free biosensing strategy and has the potential application in aptamer-based biosensing.
    Analytical Biochemistry 10/2013; · 2.58 Impact Factor
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    ABSTRACT: A newly designed functionalization type for gold nanoparticles (AuNP) with split aptamer has been developed for the detection of adenosine triphosphate (ATP). The ATP aptamer was split into two parts with their 5′ prime or 3′ prime modified with thiol. Both the 5′ SH and 3′ SH modified strands for each split aptamer fragment were functionalized onto the same AuNP to construct double-functionalized AuNP–DNA conjugates. Thus, the split aptamer can be reassembled into intact folded structure in the presence of ATP molecule with two potential assembly types, which induces the assembly of AuNP–DNA conjugates. In this double-functionalized system, the traditional assembly type might facilitate another assembly type, which was found to give much higher LSPR change in the presence of ATP than the traditional assembly type, and improve the sensitivity for ATP detection. Time courses of the assemble processes with different assembly types, Mg2+ concentrations, and aptamer fragments densities on AuNP were followed using the absorption ratio at 650 nm and 520 nm. ATP response with this newly designed system was investigated using absorption spectra and dynamic light scattering method.
    Talanta 10/2013; 115:506–511. · 3.50 Impact Factor
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    ABSTRACT: Novel golf-ball-like polystyrene (PS) microspheres were obtained through gamma-ray-radiation-initiated polymerization of styrene (St) monomers in a Pickering emulsion stabilized by amphiphilic snowman-like PS Janus microspheres, which were synthesized via seed emulsion polymerization of St swollen in poly(acrylic acid)-functionalized crosslinked PS (PA-CPS) seed microspheres. It was found that the stability of the Pickering emulsion and the hole size of the golf-ball-like PS microspheres depend on the geometry of the amphiphilic snowman-like PS Janus microspheres, which can be tuned by the weight ratio of the styrene monomer to PA-CPS seed microspheres (WS-CPS). This work provides a simple strategy to synthesize amphiplailic Janus microspheres and opens a new way to prepare polymer microspheres with holes on the surface.
    CHEMISTRY LETTERS. 09/2013; 42(9):963-965.
  • Liang Ma, Mozhen Wang, Xuewu Ge
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    ABSTRACT: To improve the compatibility between ethylene-methyl acrylate-glycidyl methacrylate random terpolymer (E-MA-GMA) elastomer and poly(ethylene terephthalate) (PET), thereby enhance the toughening effect of E-MA-GMA on PET, γ-radiation-induced graft copolymerization technique was used to graft methyl acrylate (MA) monomer onto PET. The produced PET-g-PMA copolymer can be used as a self-compatibilizer in PET/E-MA-GMA blend since the copolymer contains the same segments, respectively, with PET and E-MA-GMA. The impact strength of PET/E-MA-GMA blend increased nearly by 30% in the presence of less than 0.1 wt% PET-g-PMA compared with that of the neat PET/elastomer blend, without loss of the tensile strength of the blends. This work proposed a potential application of radiation-induced grafting copolymerization technique on the in-situ compatibilization of PET/elastomer blends so as to improve the integral mechanical properties of PET based engineering plastic.
    Radiation Physics and Chemistry 09/2013; · 1.38 Impact Factor
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    ABSTRACT: Colloidal crystalline microspheres with photonic band-gap properties responsive to media pH have been developed for in vivo imaging purposes. These colloidal crystalline microspheres were constructed from monodispersed core-shell nano-size particles with poly(styrene-co-acrylic acid) (PS-co-PAA) cores and poly(acrylic acid-co-N-isopropylacrylamide) (PAA-co-PNIPAM) hydrogel shells cross-linked by N,N'-methylenebisacrylamide. A significant shift in the photonic band-gap properties of these colloidal crystalline microspheres was observed in the pH range of 4-5. This was caused by the discontinuous volume phase transition of the hydrogel coating, due to the protonation/deprotonation of its acrylic acid moieties, on the core-shell nano-sized particles within the microspheres. The in vivo imaging capability of these pH-responsive photonic microspheres was demonstrated on a test organism - Japanese medaka, Oryzia latipes - in which the morphology and change in pH along their gastrointestinal (GI) tracts were revealed under an ordinary optical microscope. This work illustrates the potential of stimuli-responsive photonic band-gap materials in tissue-/organ-level in vivo bio-imaging.
    Analytica chimica acta 07/2013; 787:193-202. · 4.31 Impact Factor
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    ABSTRACT: Microspherical photonic colloidal crystalline beads that are responsive to media ionic strength of cationic electrolytes have been developed for in vivo imaging of the morphology and concentration gradient of cationic electrolytes along the gastrointestinal (GI) tract of live Japanese medaka (Oryzias latipes). These responsive photonic beads were assembled from core–shell nano-sized particles with polystyrene-co-polyacrylic acid (PS-co-PAA) cores and poly(hydroxyethyl methacrylate-co-p-styrene sulfonate) (PHEMA-co-PSS) hydrogel shells. The three-dimensional orderly packing of these nano-sized core–shell particles gave rise to the photonic properties of the resultant colloidal crystalline array of microspheres. The cationic electrolyte-induced volume phase transition of the sulfonate-laden hydrogel shells of the nano-sized particles altered the lattice spacing among those particles and brought about the photonic responses of the colloidal crystalline beads. Unambiguous changes in the diffraction colour of the colloidal crystalline beads were observable under ordinary ambient light in solution media of increasing concentration of sodium chloride up to 500 mM. These photonic colloidal crystalline beads were found to possess enough structural integrity for in vivo imaging of the GI tract of live Japanese medaka. With the use of a conventional optical microscope, the gradient in the ionic strength of cationic electrolytes along the GI tract of live Japanese medaka larvae was readily revealed, with a lower electrolyte concentration in the mid-intestine (<50 mM) compared to that of the posterior-intestine (≥50 mM). Our results demonstrated the potential of stimuli-responsive photonic materials in bio-imaging applications.
    J. Mater. Chem. B. 02/2013; 1(11):1535-1540.
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    ABSTRACT: In this work, an asymmetric swelling-dissolving process of original sub-micron sized decentered sulfonated polystyrene/silica (SPS/silica) particles in a ternary mixed solvent (water/ethanol/heptane) was first reported. Actinia-like and porous snowman-like SPS/silica composite particles are fabricated through tuning the composition of the ternary mixed solvent. Actinia-like particles, with a silica core embedded in a "blooming" SPS matrix, are obtained when the composition of the mixed solvent is 5 g/ 5 g/ 0.1 g (water /ethanol/heptane). If the amount of heptane in the mixed solvent is doubled, porous snowman-like particles are produced. The TEM and SEM images show that silica particles are exposed in these two anisotropic SPS/silica composite particles compared with the original decentered SPS/silica particles. Considering the particles morphology and the swelling and dissolving performance of SPS in different solvents, the formation of the new-shaped anisotropic SPS/silica composite particles should be attributed to an asymmetric swelling-dissolving process, i.e., the swelling-dissolving rate of SPS coating around the protruding silica part is faster than the other part of the composite particles. The anisotropic swelling-dissolving property of polymer/inorganic composite particles inspires a facile way to the fabrication of new composite particles.
    Langmuir 01/2013; · 4.38 Impact Factor
  • Yongfei Xu, Mozhen Wang, Xuewu Ge
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    ABSTRACT: The emulsion polymerization of styrene (St) and methyl methacrylate (MMA) induced by 10 MeV pulsed electron beams (PEB) was investigated. The monomer conversion of MMA and St was found to be very low so that the final prepared poly(methyl methacrylate) (P(MMA)) and polystyrene (PS) latex particles exhibit porous structures, as verified by TEM and SEM observations. The results of dynamic light scattering (DLS) and gel permeation chromatography (GPC) showed that both the particle size and the molecular weight of PS and PMMA latexes decrease with the increase of the absorbed dose. However, the molecular weights and the particle sizes of the PS and PMMA latexes change differently with the irradiation time. This work indicated that emulsion polymerization induced by high energy electron beam has an advantage over that induced by γ-ray or chemical initiators in the preparation of latex with a low molecular weight and porous structure.
    Radiation Physics and Chemistry 10/2012; 81(10):1634–1638. · 1.38 Impact Factor
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    ABSTRACT: Polystyrene (PS) microspheres coated with β-cyclodextrin (β-CD) were fabricated via γ-ray-induced emulsion polymerization in a ternary system of styrene/β-CD/water (St/β-CD/water). The solid inclusion complex of St and β-CD particles formed at the St droplets-water interface can stabilize the emulsion as the surfactant. TEM and XPS results showed that β-CD remains on the surface of PS particles. The average size of the PS particles increases from 186 to 294 nm as the weight ratio of β-CD to St rises from 5% to 12.5%. The water contact angle (CA) of PS latex film is lower than 90°, and reduces with the β-CD content even to 36°. Thus, this work provides a new and one-pot strategy to surface hydrophilic modification on hydrophobic polymer particles with cyclodextrins through radiation emulsion polymerization.
    Macromolecular Rapid Communications 08/2012; · 4.93 Impact Factor
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    ABSTRACT: A novel spongelike polymer material has been fabricated by γ-ray induced polymerization of methylmethacrylate (MMA) in an emulsion containing cross-linked sulfonated polystyrene (CSP) particles. Scanning electron microscopy (SEM) images reveal that the spongelike structure is made up of interlinked nanosized PMMA particles with micrometer-sized CSP-PMMA particles embedded inside. The nitrogen adsorption isotherm discloses that the spongelike material has a high specific surface area of 29 m(2)/g and a narrow pore size distribution of 60-120 nm. The formation mechanism is discussed in this paper, which indicates that the key steps to form the spongelike material include a Pickering emulsion stabilized by the CSP particles, followed by the swelling process of MMA into these particles. This approach offers a more convenient alternative to prepare polymeric spongelike material without any etching procedure.
    Langmuir 03/2012; 28(13):5498-502. · 4.38 Impact Factor
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    ABSTRACT: We report a facile and novel strategy on the fabrication of well-defined raspberry SiO2/polystyrene (SiO2/PS) particles via radiation miniemulsion polymerization. Starting from methacryloxypropyltrimethoxysilane (MPS)-functionalized SiO2 particles (176 nm), raspberry SiO2/PS particles (257 nm) with a submicron SiO2 core decorated by nano-sized PS latex particles (58 nm) are obtained after γ-ray induced miniemulsion polymerization of styrene (St). It is found that MPS grafted density on the surface of submicron SiO2 particles, the weight ratio of St to SiO2 particles (WSt/o-SiO2), as well as the surfactant concentration will affect the morphology and wettability of the resultant SiO2/PS hybrid particles. When the well-defined raspberry SiO2/PS particles are deposited on a blank glass substrate, a dual-size roughness surface topology was observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). This film has a static water contact angle as high as 151°. However, this film exhibits a large contact angle hysteresis (116°) and strong adhesion to water. Furthermore, this kind of superhydrophobic particulate film can be used as a “mechanical hand” for transportation of small water droplets without loss, thus it may have potential applications in industrial fields.
    Journal of Materials Chemistry 02/2012; 22(12):5784-5791. · 6.63 Impact Factor

Publication Stats

405 Citations
251.30 Total Impact Points

Institutions

  • 2013–2014
    • USTC-CityU Joint Advanced Research Center
      Hong Kong, Hong Kong
    • City University of Hong Kong
      • Department of Biology and Chemistry
      Kowloon, Hong Kong
  • 1997–2014
    • University of Science and Technology of China
      • Department of Polymer Science and Engineering
      Luchow, Anhui Sheng, China