Xuejun Cui

Synthesis of raspberry-like monodisperse magnetic hollow hybrid nanospheres by coating polystyrene template with Fe3O4@SiO2 particles

In this paper, we present a novel method for the preparation of raspberry-like monodisperse magnetic hollow hybrid nanospheres with γ-Fe(2)O(3)@SiO(2) particles as the outer shell. PS@Fe(3)O(4)@SiO(2) composite nanoparticles were successfully prepared on the principle of the electrostatic interaction between negatively charged silica and positively charged polystyrene, and then raspberry-like magnetic hollow hybrid nanospheres with large cavities were achieved by means of calcinations, simultaneously, the magnetite (Fe(3)O(4)) was transformed into maghemite (γ-Fe(2)O(3)). Transmission electron microscopy (TEM) demonstrated that the obtained magnetic hollow silica nanospheres with the perfect spherical profile were well monodisperse and uniform with the mean size of 253nm. The Fourier transform infrared (FTIR) spectrometry, energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) provided the sufficient evidences for the presence of Fe(3)O(4) in the silica shell. Moreover, the magnetic hollow silica nanospheres possessed a characteristic of superparamagnetic with saturation magnetization value of about 7.84emu/g by the magnetization curve measurement. In addition, the nitrogen adsorption-desorption measurement exhibited that the pore size, BET surface area, pore volume of magnetic hollow silica nanospheres were 3.5-5.5nm, 307m(2)g(-1) and 1.33cm(3)g(-1), respectively. Therefore, the magnetic hollow nanospheres possess a promising future in controlled drug delivery and targeted drug applications.

Effect of fiber alignment in electrospun scaffolds on keratocytes and corneal epithelial cells behavior

The contribution of fiber alignment of scaffold on cellular mechanisms was evaluated by a comparative study of two different cells sourced from cornea. Electrospun scaffolds with similar composition and comparable fiber size were fabricated into randomly oriented and aligned scaffolds, which bear paralleled degradation of gelatin. Tensile test of wet scaffolds indicated that fiber alignment could influence its mechanical properties. Due to the unidirectional fiber orientation, aligned scaffold exhibited higher tensile modulus, higher break strength, and lower elongation at break than randomly oriented scaffold. The effect of fiber alignment on cells behavior was evaluated by cell morphology, specific protein expression, adhesion, and proliferation. Different corneal cells responded uniquely to fiber alignment of scaffold, keratocytes interacting more favorably on alignment scaffold and corneal epithelial cells more favorably on randomly oriented scaffold. These results confirmed that fiber alignment of scaffold would be benefit for cell proliferation if its contact guidance coincided with the cell shape and cytoskeletal tension. This finding is important to envisage an advanced composite scaffold that incorporates randomly oriented and aligned fibers for the growth and control of different cell types required for the successful development of corneal grafts by tissue engineering.

Preparation of microencapsulated ammonium polyphosphate with carbon source- and blowing agent-containing shell and its flame retardance in polypropylene

In this paper, a novel and facile method was carried out to microencapsulate ammonium polyphosphate (APP) via two-step surface polymerization process, which introduces the carbon source and blowing agent into the microcapsules simultaneously. The chemical composition of microencapsulated APP (MAPP) was confirmed by fourier infrared spectra (FTIR). The surface morphology and thermal behavior of APP and MAPP were investigated by scanning electron microscope (SEM) and thermogravimetric analysis (TGA), respectively. Additionally, transmission electron microscopy (TEM) demonstrates that MAPP particles possess the obvious “core/shell-like” structure. Compared with APP, the water solubility of MAPP greatly decreases that can improve the water resistance of MAPP in polymer materials when exposed to water. Moreover, the flame retardant properties of polypropylene (PP) compositing with MAPP were systematically researched by limiting oxygen index (LOI), vertical burning tests (UL-94) and cone calorimeter. The results show the flame retardant properties of PP composites are enhanced by combining MAPP than that of APP. Besides, the water resistance of PP/MAPP is also enhanced. And the char residue of PP composites after combustion was analyzed by FTIR and X-ray photoelectron spectroscopy (XPS) spectra. Based on these facts, a possible flame retardant mechanism of MAPP in PP composites was proposed.

Multi-stimuli responsive smart chitosan-based microcapsules for targeted drug delivery and triggered drug release

In the present study, we designed a novel, multi-stimuli responsive, biocompatible and non-immunogenic smart carrier for targeted delivery and triggered release of hydrophobic drugs. The designed multi-stimuli responsive smart chitosan-based microcapsules (MSRS-CS-MCs) have been fabricated successfully from folic acid (FA) functionalized thiolated chitosan via a facile sonochemical method. Targeting moiety FA and red fluorescent dye (Rhodamine B isothiocyanate, RITC) were immobilized onto the shells of microcapsules. Meanwhile, oleic acid (OA) modified Fe3O4 magnetic nanoparticles (OA-Fe3O4MNPs) and a model hydrophobic drug, green fluorescent dye (Coumarin 6, C6), were encapsulated into the microcapsules. As drug carriers, the obtained spherical MSRS-CS-MCs with the average size of 500nm showed excellent magnetic responsive ability, favorable selectively folate-receptor-mediated targeting functionality to the HeLa cells, and attractive reduction-responsive release ability for hydrophobic drugs. The integration of magnetic and reduction dual-responsiveness, folate-receptor-mediated targeting functionality and fluorescence visualization into the versatile microcapsules make MSRS-CS-MCs promising nanocarriers for future biomedical applications.

Folic acid functionalized reduction-responsive magnetic chitosan nanocapsules for targeted delivery and triggered release of drugs

A versatile folic acid (FA)-functionalized reduction-responsive magnetic chitosan (CS) nanocapsules (FA-RMCNCs) were designed and fabricated successfully from FA-functionalized thiolated chitosan with a simple sonochemical method. The targeting molecule (FA), red fluorescent probes (Rhodamine B isothiocyanate, RITC) and thiolated Fe3O4 magnetic nanoparticles (Fe3O4-SH MNPs) were immobilized in and onto the shells of nanocapsules. The as-synthesized FA-RMCNCs had a well-defined spherical morphology with the size of 200-350nm. As the carriers, FA-RMCNCs showed an excellent magnetic responsive property. The CLSM analysis revealed that the proposed FA-RMCNCs with core-shell constructure could be internalized selectively by the HeLa cells through the folate-mediated endocytosis. Moreover, the reductant-triggered release of coumarin 6 suggested that the FA-RMCNCs possessed superior reduction-responsivity of drug release. This study reveals the potential of FA-RMCNCs as magnetic/reduction dual-responsive, folate-receptor-mediated targeting nanocarriers in targeted delivery and controlled release of hydrophobic drugs.

Effects of temperature and concentration on the structure of ethylene oxide–propylene oxide–ethylene oxide triblock copolymer (Pluronic P65) in aqueous solution: a molecular dynamics simulation study

The effects of temperature and solution concentration on the structure of triblock polymeric surfactant (ethylene oxide)19(propylene oxide)29(ethylene oxide)19 (Pluronic P65) have been investigated by fully atomistic molecular dynamics simulations. The Flory–Huggins interaction parameter χ, hydrogen bonding and molecular mobility in the aqueous solution of P65 were investigated covering a composition range of 0.1–0.73 (water weight fraction) and a temperature range of 273–373 K. The Flory–Huggins parameters indicated that propylene oxide (PO) segments became hydrophobic with the increase in temperature, whereas ethylene oxide (EO) segments remained hydrophilic, which caused the increase in repulsion between EO and PO segments. The intermolecular hydrogen bonds in P65 solution including water–water hydrogen bonds and water–P65 hydrogen bonds increased with the increase in solution concentration and decreased with the increase in temperature. The critical micellar temperature of Pluronic P65 predicted by Flory–Huggins interaction parameter χ and hydrogen bonding was in good agreement with experimental data.

Fabrication of redox and pH dual-responsive magnetic graphene oxide microcapsules via sonochemical method

In this study, the biocompatible redox and pH dual-responsive magnetic graphene oxide microcapsules (MGOMCs) were prepared by a simple sonochemical method. The disulfide bonds cross-linked the wall of MGOMCs were formed from the hydrosulfuryl on the surface of thiolated graphene oxide, which was synthesized by functionalizing graphene oxide with cysteine, showed an excellent redox-responsive property to control drugs release. Moreover, oleic acid modified Fe3O4 nanoparticles were encapsulated into the microcapsules successfully with the hydrophobic drugs dispersed in the hydroxy silicone oil. The MGOMCs possess distinguished magnetic property and pH-responsive ability. Besides, the microcapsules could be engulfed by Hela cells successfully due to the appropriate size and flexible shell. The MGOMCs could be a good carrier for hydrophobic drugs, especially the anticancer drugs.

Preparation of magnetic and pH-responsive chitosan microcapsules via sonochemical method.

Abstract Magnetic and pH-responsive chitosan microcapsules (MPRCMCs) were prepared by a simple sonochemical method. Superparamagnetic oleic acid modified Fe3O4 nanoparticles (OA-Fe3O4 NPs) and hydrophobic drugs could be directly loaded into MPRCMCs during sonication. The obtained microcapsules had a well-defined spherical morphology with the average size of 2 μm. The microcapsules showed an excellent magnetic property. In addition, the pH-responsive controlled release of coumarin 6 (C6) from MPRCMCs indicated that the developed microcapsules could be a promising candidate for drugs carriers.

In situ growth induction of the corneal stroma cells using uniaxially aligned composite fibrous scaffolds

Uniaxially aligned composite fibrous scaffolds of gelatin and poly-L-lactic acid (PLLA) were fabricated using electrospinning and the scaffolds were implanted into the corneal stroma layers of New Zealand white rabbits (NZWRs) to observe the in situ growth induction of the stroma cells. The effects on cell growth were evaluated by both apparent observation and pathological analysis. It was demonstrated that the scaffolds had a good compatibility with the corneal tissues and were nontoxic by observing the changes of the structure and the physiological activity of the corneal tissues around the scaffolds using a slit lamp and in vivo confocal images. The in vivo confocal images of the scaffolds implanted into the eyes of NZWRs show the process of the cells’ ingrowth and the tissue regeneration, which indicated that the uniaxially aligned fibers could induce the polarized ingrowth of keratocytes which may provide the basis for clinical application to the in situ repair of corneal stromata.

Synthesis and surface properties of semi-interpenetrating fluorine-containing polyacrylate and epoxy resin networks

Semi-interpenetrating polymer networks (Semi-IPNs) based on fluorine-containing polyacrylate and epoxy resin were synthesized by the simultaneous polymerization of fluorine-containing acrylate and epoxy resin. Fourier transform infrared (FTIR) spectrometry and X-ray photoelectron spectroscopy (XPS) analyses proved that the fluorine-containing groups have been introduced into Semi-IPNs successfully. In addition, XPS analysis intuitively showed that the fluorine content of the film-air interface of the interpenetrating fluorine-containing polyacrylate and epoxy resin networks (FPAER-SIPNs) film was much higher than that of the film-glass interface. It is noted that the introduction of fluorine-containing groups significantly improved the hydrophobic property of polymer networks. Moreover, when the fluorine content increased, the contact angle of water on FPAER-SIPNs film was increased obviously and the water uptake was decreased gradually. These results indicated that introducing fluorine-containing groups to SIPNs has potential advantage for improving the surface properties of epoxy resin.