Nanshan District Key Laboratory for Biopolymers and Safety Evaluation

Shenzhen, China

Nanshan District Key Laboratory for Biopolymers and Safety Evaluation

Shenzhen, China
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Liu X.,Shenzhen University | Liu X.,Nanshan District Key Laboratory for Biopolymers and Safety Evaluation | Liu X.,Shenzhen Key Laboratory of Polymer Science and Technology | Liu X.,Guangdong Research Center for Interfacial Engineering of Functional Materials | And 9 more authors.
Materials Science and Engineering C | Year: 2017

A novel rapid hemostatic and mild polyurethane-urea foam (PUUF) wound dressing was prepared by the particle leaching method and vacuum freeze-drying method using 4, 4-Methylenebis(cyclohexyl isocyanate), 4,4-diaminodicyclohexylmethane and poly (ethylene glycol) as raw materials. And X-ray diffraction (XRD), tensile test, differential scanning calorimetry (DSC) and thermogravimetry (TG) were used to its crystallinity, stress and strain behavior, and thermal properties, respectively. Platelet adhesion, fibrinogen adhesion and blood clotting were performed to evaluate its hemostatic effect. And H&E staining and Masson Trichrome staining were used to its wound healing efficacy. The results revealed the pore size of PUUF is 50–130 μm, and its porosity is 71.01%. Porous PUUF exhibited good water uptake that was benefit to adsorb abundant wound exudates to build a regional moist environment beneficial for wound healing. The PUUF wound dressing exhibit better blood coagulation effect than commercial polyurethane dressing (CaduMedi). Though both PUUF and CaduMedi facilitated wound healing generating full re-epithelialization within 13 days, PUUF was milder and lead to more slight inflammatory response than CaduMedi. In addition, PUUF wound dressing exhibited lower cytotoxicity than CaduMedi against NIH3T3 cells. Overall, porous PUUF represents a novel mild wound dressing with excellent water uptake, hemostatic effect and low toxicity, and it can promote wound healing and enhance re-epithelialization. © 2016 Elsevier B.V.

Vatankhah-Varnoosfaderani M.,Shenzhen University | Vatankhah-Varnoosfaderani M.,Chonbuk National University | Vatankhah-Varnoosfaderani M.,Islamic Azad University | Vatankhah-Varnoosfaderani M.,University of North Carolina at Chapel Hill | And 8 more authors.
Macromolecular Rapid Communications | Year: 2015

Copolymers of N-isopropylacrylamide (NIPAM) and dopamine methacrylate can establish a reversible, self-healing 3D network in aprotic solvents based on hydrogen bonding. The reactivity and hydrogen bonding formation of catechol groups in copolymer chains are studied by UV-vis and 1H NMR spectroscopy, while reversibility from sol to gel and inverse as well as self-healing properties are tested rheologically. The produced reversible organogel can self-encapsulate physically interacting or chemically bonded solutes such as drugs due to thermosensitivity of the used copolymer. This system offers dual-targeted and controlled drug delivery and release - by slowing down release kinetics by supramolecular bonding of the drug and by reducing diffusion rates due to modulus increase. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Saeb M.R.,Iran Institute for Color Science and Technology | Khorasani M.M.,Iran National Petrochemical Company | Ahmadi M.,Amirkabir University of Technology | Mohammadi Y.,Iran National Petrochemical Company | And 4 more authors.
Polymer (United Kingdom) | Year: 2015

It is the dual nature of chain shuttling polymerization (CSP) that makes control of olefin block copolymer (OBC) composition difficult and difficult, but at the same time, stimulating. Although recent investigations on OBCs brought some insights to the kinetics and microstructure of block copolymers differentiating from ethylene and α-olefins, some crucial features of these systems are not uncovered because of experimental difficulties. Thus, attention is still placed upon theoretical concepts that enable deeper understanding of behavior of end-of-batch OBCs. Extending the predictability of a well-developed Monte Carlo algorithm, we present for the first time an explicit image of hard-soft segmental growth at the course of CSP process. The stochastically tailored ethylene/1-octene copolymers with diverse architectural characteristics were simulated and characterized in terms of mole fraction of soft and hard segments, block length distribution, sequence length distribution, longest ethylene sequence distribution, and the distribution of the number of blocks per growing copolymer chain to be used as unique signatures of this reaction mechanism. © 2015 Elsevier Ltd. All rights reserved.

Stadler F.J.,Shenzhen University | Stadler F.J.,Nanshan District Key Laboratory for Biopolymers and Safety Evaluation | Stadler F.J.,Shenzhen Key Laboratory of Special Functional Materials | Stadler F.J.,Shenzhen Engineering Laboratory for Advanced Technology of Ceramics | And 4 more authors.
Rheologica Acta | Year: 2015

Sparsely branched polyolefins often exhibit a thermorheological complexity, which was reported to be maskable by a modulus shift. However, the only physical background for a modulus shift is a density change, and this influence factor is only small in the relatively narrow temperature regime accessible by polyolefins. This paper deals with the question, how this modulus shift can be caused by experimental artifacts and real effects. The physical background of these two contributions to a vertical activation energy, as well as a meaningfulness of the application of a modulus shift, is found not to be given for polyolefins, when measuring only in a temperature range between 130 and 230 °C. © 2015, Springer-Verlag Berlin Heidelberg.

Hashmi S.,Shenzhen University | Hashmi S.,Chonbuk National University | Hashmi S.,NED University of Engineering and Technology | GhavamiNejad A.,Chonbuk National University | And 6 more authors.
Soft Matter | Year: 2015

In a material consisting of graphene oxide or reduced graphene oxide and poly-N-isopropylamide (PNIPAM) in an aqueous solution, a new type of rheological behaviour is found. When subjecting the material to a short and relatively small deformation pulse, the modulus, which is observed by small deformations in the linear-viscoelastic or very slightly nonlinear range, oscillates with periodicities between 100 and several 1000 seconds; however, in many cases, it also increases systematically. The periodicity depends on the filler content and the sample preparation method (in situ polymerisation vs. blending). When subjecting the material to high nonlinear deformations (γ0 = 100-300%), the resulting linear viscoelastic behaviour changes from a periodic oscillation to a quick recovery of the original data, followed by a decrease and a subsequent increase beyond the value of the modulus of the material prior to the deformation pulse. © The Royal Society of Chemistry 2015.

Ghavaminejad A.,Chonbuk National University | Sasikala A.R.K.,Chonbuk National University | Unnithan A.R.,Chonbuk National University | Thomas R.G.,Chonnam National University | And 7 more authors.
Advanced Functional Materials | Year: 2015

A method for the versatile synthesis of novel, mussel-inspired, electrospun nanofibers with catechol moieties is reported. These mussel-inspired nanofibers are used to bind iron oxide nanoparticles (IONPs) and the borate-containing anticancer drug Bortezomib (BTZ) through a catechol metal binding mechanism adapted from nature. These smart nanofibers exhibit a unique conjugation of Bortezomib to their 1, 2-benzenediol (catechol) moieties for enabling a pH-dependent drug delivery towards the cancer cells and the IONPs via strong coordination bonds for exploiting the repeated application of hyperthermia. Thus the synergistic anticancer effect of these mussel-inspired magnetic nanofibers were tested in vitro for the repeated application of hyperthermia along with the chemotherapy and found that the drug-bound catecholic magnetic nanofibers exhibited excellent therapeutic efficacy for potential anticancer treatment. Drug-loaded magnetic nanofibers are designed for a synergistic anticancer treatment that combines hyperthermia treatment and chemotherapy. A mussel-inspired binding is used to incorporate iron oxide nanoparticles (IONPs) and the drug onto the nanofibers. The smart nanofibers are capable of pH-dependent drug delivery to cancer cells, and their IONPs enable multiple cycles of hyperthermia therapy with the application of an alternating magnetic field (AMF). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Saeb M.R.,Iran Institute for Color Science and Technology | Mohammadi Y.,Iran National Petrochemical Company | Ahmadi M.,Amirkabir University of Technology | Khorasani M.M.,Iran National Petrochemical Company | And 4 more authors.
Chemical Engineering Journal | Year: 2015

A standard Monte Carlo-based program with innovative data storage structure was developed and put into practice to tailor ethylene/1-hexene copolymers through semibatch single site metallocene catalyzed copolymerization. The distribution of copolymer composition, ethylene sequence length, longest ethylene sequence length, as well as the number-average degree of polymerization, and sequential placement of 1-hexene comonomer segments along copolymer chains were monitored and evaluated applying a computerized feeding to metallocene catalyzed ethylene/1-hexene copolymerization. In particular, bivariate copolymer composition-chain length (CC-CL) distribution was compared for two feeding recipes with uncontrolled and well-controlled comonomer insertion. The advantages of controlled feeding in comparison to uncontrolled feeding were discussed in view of aforementioned architectural features. To obtain macromolecules with tailored comonomer distributions, special feeding strategies were developed by training and examining the developed model to capture crystallization analysis fractionation (CRYSTAF) of ethylene/1-hexene chains, as a unique signature of tailored copolymers with rather narrow bivariate CC-CL distribution. The simulation results appropriately highlight the critical importance of computerized feeding with respect to uncontrolled feeding. © 2015 Elsevier B.V.

Hashmi S.,Shenzhen University | Hashmi S.,Chonbuk National University | Hashmi S.,NED University of Engineering and Technology | Vatankhah-Varnoosfaderani M.,Islamic Azad University | And 13 more authors.
Rheologica Acta | Year: 2015

Thermosensitive copolymer solutions are prepared from various molar ratios of N-isopropylacrylamide (NIPAM) and the zwitterionic monomer N-(methacryloxypropyl)-N,N-dimethyl-N-(3-sulfopropyl) ammonium betaine (Zw) by free radical polymerization. In the current study, we examined the rheological properties of poly (NIPAM/sulfobetaine) copolymer solutions. We found that the rheological properties are conceptually linked with the copolymer chemical structure and chain topology. We also report the effects of bulk molar mass and zwitterions on flow curve ɳ (γ⋅$$\overset{\cdot }{\upgamma}$$). With the introduction of the charged group in the PNIPAM-chain, its viscoelastic phase behavior and lower critical solution temperature (LCST) are affected. At varying concentrations of zwitterionic copolymer, they showed a shear thinning behavior with two relaxation regimes for entanglement relaxation and zwitterionic interaction. Interestingly, the zwitterionic interactions are related to the molar concentration of zwitterionic monomer. This is eventually associated with the topology of the copolymer chain. Our results also showed that there was a linear increase in the LCST of these solutions as a function of zwitterionic moieties. © 2015, Springer-Verlag Berlin Heidelberg.

Goldansaz H.,Catholic University of Leuven | Goharpey F.,Amirkabir University of Technology | Afshar-Taromi F.,Amirkabir University of Technology | Kim I.,Pusan National University | And 8 more authors.
Macromolecules | Year: 2015

We investigated the effects of soft dendritic polyethylene (dPE) nanoparticles on the rheological properties of a linear polystyrene (PS) matrix. The viscosity of PS-dPE nanocomposites is found to exhibit nonmonotonic dependence on the dPE concentration. In particular, with the addition of 1% dPE nanoparticles, we already observe more than 1 order of magnitude reduction in viscosity. The minimum viscosity was observed at 5% nanoparticles. At dPE concentrations higher than 5%, nanocomposite viscosity increases by addition of nanoparticles, yet it remains below the viscosity of PS. Addition of nanoparticles not only influences the terminal relaxation times of the nanocomposites but also affects their whole relaxation spectra. The viscosity of PS-dPE nanocomposites at high temperature is found to reversibly evolve with time, which proves the existence of supramolecular interactions between the PS matrix and the nanoparticles. Atomic force microscopy confirms that dPE nanoparticles are well distributed in the PS matrix, though each component of the nanocomposite exhibits its own glass transition. While the origin of viscosity reduction remains unknown, it cannot be attributed to confinement, free volume effect, change of entanglement density, surface slippage, shear banding, or particle induced shear thinning. © 2015 American Chemical Society.

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