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Abstract: Block copolymerization by using isocyanates is an effective method for incorporating PHB and PEG because it can prepare copolymers with good properties, such as toughness, strength, and so on. In this study, we adopted soil suspension system to estimate the biodegradability of a series of PHB/PEG multiblock copolymers with different compositions and block lengths. In the degradation process, the changes in weight loss, molecular weight, and tensile strength were periodically measured to determine the biodegradability, and the surface morphology was also observed by SEM. In contrast to pure PHB, the weight loss of the copolymer was relatively lower. On the other hand, the tensile strength and molecular weight experienced apparent decrease, and for BHG1000-3-1, they reached 46.7% and 77.7% of the initial value, respectively. SEM observation showed that the surface was covered with numerous erosion pits. All these indicate that the degradation indeed took place and long-chain molecules have been hydrolyzed into shorter ones. The crystallization behavior was also investigated by DSC and WAXD. The results showed that both the segments, PEG and PHB, can form crystalline phases at lower PHB contents ranging from 29% to 44%, and when PHB component was more than 60%, only PHB phase can crystallize. [Copyright &y& Elsevier]

Abstract: The grafting of polymers onto the surface of zinc oxide nanoparticles and radical copolymerization of methyl methacrylate (MMA) and methacrylic acid (MAA) were investigated. The copolymer chains encapsulating nanoparticles were anchored onto the surface of nano-ZnO through reactions of carboxyl groups with ZnO. Grafting percentage and grafting efficiency of composite particles were investigated by employing thermogravimetric analysis (TGA). FT-IR and 13C NMR showed that there existed a strong interaction at the interface of nano-ZnO and copolymer, which implied that the copolymer chains were grafted onto the surface of ZnO nanoparticles. Nano-ZnO being encapsulated by copolymer was confirmed by using transmission electron microscopy (TEM). Additionally, TGA plots showed that the presence of ZnO nanoparticles improved the thermal stability of copolymer to a certain extent. Another important finding is the copolymerization and grafting reaction did not alter the crystalline structure of the ZnO nanoparticles according to the X-ray diffraction patterns. It can also be seen from scanning electron microscope (SEM) that grafted polymer chains on nanoparticles interfere with the aggregation of ZnO nanoparticles in polymer matrix and improve their compatibility with the polymeric matrix. [Copyright &y& Elsevier]

Abstract: Novel poly(3-hydroxybutyrate) and poly(ethylene glycol) (PHB/PEG) multiblock copolymers were synthesized through one-step copolymerization with hexamethylene diisocyanate (HDI) as a coupling agent by varying the block composition. Molecular structures and chemical compositions were confirmed by NMR and FTIR spectral analysis. Thermal properties and mechanical properties were investigated using differential scanning calorimetry (DSC) and stress–strain experiments, respectively. The hydrophilicity and degradability were also assessed in different media at 37°C. The results show that this kind of copolymers exhibit good toughness and moderate strength in comparison with homopolymer PHB, the degradation rate and equilibrium water content (EWC) are much higher than those of the PHB homopolymer. [Copyright &y& Elsevier]

Abstract: Titanium dioxide nanoparticles were modified by polyaniline (PANI) using ‘in situ’ chemical oxidative polymerization method in hydrochloric acid solutions. Powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectra (FT-IR), X-ray photoelectron spectroscopy spectrum (XPS) and UV–vis spectra were carried out to characterize the composites with different PANI contents. The photocatalytic degradation of phenol was chosen as a model reaction to evaluate the photocatalytic activities of the modified catalysts. Results show that TiO2 nanoparticles are deposited by PANI to mitigate TiO2 particles agglomeration. The modification does not alter the crystalline structure of the TiO2 nanoparticles according to the X-ray diffraction patterns. UV–vis spectra reveal that PANI-modified TiO2 composites show stronger absorption than neat TiO2 under the whole range of visible light. The resulting PANI-modified TiO2 composites exhibit significantly higher photocatalytic activity than that of neat TiO2 on degradation of phenol aqueous solution under visible light irradiation (λ ≥400nm). An optimum of the synergetic effect is found for an initial molar ratio of aniline to TiO2 equal to 1/100. [Copyright &y& Elsevier]

Abstract: Somatic cell-mediated transgenesis is routinely used to transfer exogenous genes to livestock genomes. However, transgene insertion events are essentially random which may lead to transgene silencing or alter animal phenotype because of insertional mutagenesis. To overcome these problems, we established a gene manipulation system in goat somatic cells based on homologous recombination and flp recombinase-mediated site-specific integration. First, we performed gene targeting to introduce an frt-docking site into the α1 (I) procollagen (ColA1) locus in goat somatic cells. Second, the targeted cell clones were rejuvenated by embryo cloning, and the vigorous cells with targeted frt were reestablished. Third, a gene-replacement system was used to introduce an EGFP reporter gene into the targeted ColA1 locus via flp mediated recombination. As a result, the transgenic somatic cell exhibited faithful expression of EGFP gene under control of the CMV promoter. Similarly, other expression vectors can be introduced into the defined site to evaluate gene functions or express valuable proteins. The gene manipulation system described here will be applicable in other livestock somatic cells, and would allow for the rapid generation of livestock with transgene targeted to the defined site. [Copyright &y& Elsevier]

Abstract: Human Lactoferrin (hLF) is an iron-binding protein with multiple physiological functions. As the availability of natural hLF is limited, alternative means of producing this biopharmaceutical protein have been extensively studied. Here we report on the dominant expression of recombinant human lactoferrin (rhLF) in transgenic cloned goats using a novel optimised construct made by fusing a 3.3kb hLF minigene to the regulatory elements of the β-casein gene. The transgenic goat produced more than 30mg/ml rhLF in its milk, and rhLF expression was stable during the entire lactation cycle. The rhLF purification efficiency from whole goat milk is approximately 70%, and its purity is above 98%. Compared with natural hLF, the rhLF from transgenic goats has similar biological characteristics including molecular mass, N-terminal sequence, isoelectric point, immunoreactivity and digestive stability. More importantly, the purified rhLF showed specific anti-tumour activity in the mouse model of melanoma experimental metastasis. Therefore, our study shows that the large-scale production of functional rhLF in transgenic goat milk could be an economical and promising source of human therapeutic use in the future. [Copyright &y& Elsevier]

Abstract: The Cre/loxP site-specific recombination system is a widely used tool for genetic engineering of mammalian genomes. Recombination of loxP-modified alleles is often induced by introduction of foreign DNA vector expressing Cre into the cells. But the introduced DNA vector has the potential to integrate into the genome of the cells and continuous expression of Cre recombinase from the foreign vector has the potential to yield cytotoxicity and genotoxicity in various cells. In this study, we investigate the possibility of overcoming this limitation by using a cell-permeable TAT-Cre recombinase. We found that TAT-Cre treatment of transgenic goat fibroblast cells did not compromise the development competency of reconstructed embryos by using these TAT-Cre-treated cells as nuclear donor in nuclear transfer. Finally, we obtained two live cloned goats where a selectable gene cassette was removed. Our work not only provided an efficient protein transduction-based system for removing selectable genes from transgenic goats, but also presented strong evidence that no severe damage was made to the host cells during the process of protein transduction. [Copyright &y& Elsevier]

Abstract: Zinc oxide nanoparticles, with an average size of about 40nm, were encapsulated by polystyrene using in situ emulsion polymerization in the presence of 3-methacryloxypropyltrimethoxysilane (MPTMS) as a coupling agent and polyoxyethylene nonylphenyl ether (OP-10) as a surfactant. Polymerization mechanism of nanocomposite latex was discussed. Transmission electron microscopy (TEM) proved the presence of ZnO nanoparticle appeared to be monodisperse in nanosize in polymer composite particles. ZnO/PS nanocomposites were characterized by Fourier transform infrared spectra (FT-IR), X-ray photoelectron spectroscopy (XPS), thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results of FT-IR and XPS revealed that the surface of ZnO particle was successfully grafted by PS through the link of the coupling agent between ZnO and polymer. TGA and DSC results indicated an enhancement of thermal stability of composite materials compared with the pure polymer. SEM (scanning electron microscope) images showed a perfect dispersion of the ZnO particles in latex film. In addition, UV–visible absorption measurements demonstrated that the ZnO/PS composite coatings display a perfect performance of absorbing UV light. [Copyright &y& Elsevier]

Abstract: Two novel chelating resins were prepared by anchoring ethylenediamine to crosslinked polystyrene via a spacer containing sulfide. Their structures were characterized by Fourier transform-infrared spectra (FTIR) and scanning electron microscopy (SEM). Porous structure parameters of the resins were measured by ASAP 2020 using BET and BJH methods. Their adsorption capacities for several heavy metal ions especially Hg2+ were investigated. The results showed that for the two resins, the more N contents did not mean the better adsorption capacity and the saturated adsorption capacity of poly(2-ethylenediamidomercaptomethylstyrene) (PSM-EDA) for Hg2+ could reach to 3.0mmol/g at room temperature. Isothermal adsorptions of the resins for Hg2+ could be described by Langmuir formula. The adsorption mechanism of the resins for Hg2+, Cu2+ and Ag+ was confirmed by X-ray photoelectron spectroscopy (XPS) and FTIR. [Copyright &y& Elsevier]

Abstract: A series of ester- and amino-terminated dendrimer-like polyamidoamine (PAMAM) grafted silica-gel (SiO2-G0–SiO2-G4.0) was prepared with a divergent method by repeating two processes: (1) Michael addition of methyl acrylate (MA) to surface amino groups; and (2) amidation of the resulting esters with ethylenediamine (EDA) from γ-aminopropyl silica gel core. Their structures were characterized by FTIR, XRD, TG, porous analysis, and SEM. FTIR method was employed to monitor amidation reaction in order to judge the optimum reaction time. The results indicated it needed at least 5, 7, 8, and 9days for SiO2-G0.5, SiO2-G1.5, SiO2-G2.5, and SiO2-G3.5 to be converted into SiO2-G1.0, SiO2-G2.0, SiO2-G3.0 and SiO2-G4.0, respectively at 25°C. The porous structure analysis showed the BET surface area, BJH desorption average pore diameter and BJH desorption cumulative volume of pores for the products decreased after the series of grafting reactions. Au3+, Pd2+, Pt4+, Ag+, Cu2+, Zn2+, Hg2+, and Cd2+ were chosen as representatives to investigate the relationship between adsorption capacities and percentage of grafting of polymer onto the surface of silica-gel. The experiments showed that both ester- and amino-terminated dendrimer-like polyamidoamine (PAMAM) grafted silica-gel exhibited better adsorption capabilities for Au3+ and Pd2+ than for base metal ions Cu2+, Zn2+, Hg2+, and Cd2+ and noble metal ions Pt4+ and Ag+. One interesting conclusion could be drawn from the above investigation, that is, a high percentage of grafting of polymer onto the surface of silica-gel did not mean a high adsorption capacity. [Copyright &y& Elsevier]

Abstract: Two novel chelating resins, polystyrene supported G1.0 diethanolamine-typed dendrimer (PS-DEA) and G2.0 diethanolamine-typed dendrimer (PS-(DEA)2), were prepared by anchoring low-generations diethanolamine-typed dendrimer into crosslinked polystyrene in this paper. Fourier transform-infrared spectra (FTIR), scanning electron microscopy (SEM) and elemental analysis were employed to character their structures. The results of adsorption for metal ions showed that the resins had good adsorption capacities for Cu2+, Ag+ and Hg2+, especially PS-DEA for Cu2+. The adsorption kinetics and adsorption isotherms of PS-DEA for Cu2+ and PS-(DEA)2 for Hg2+ were studied. The results showed that the adsorption kinetics of the two resins can be modeled by pseudo second-order rate equation wonderfully and Langmuir and Freundlich equations could well interpret the adsorption of PS-(DEA)2 for Hg2+ and PS-DEA for Cu2+, respectively. The adsorption mechanism of the resins for Cu2+ was confirmed by X-ray photoelectron spectroscopy (XPS). [Copyright &y& Elsevier]

Abstract: The sorption mechanism of sulfur-containing chelating resin, poly[4-vinylbenzyl (2-hydroxyethyl) sulfide], towards Au(III) was investigated by Fourier transform infrared spectra (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive X-ray microanalysis (EDX), and X-ray diffraction (XRD). It was showed that the sulfide bond in the resin was oxidized into sulfoxide and sulfone bond, and Au(III) was deoxidized into Au(0). [Copyright &y& Elsevier]

Abstract: A novel chelating resin containing S, N and O atoms (PSME–EDA) was synthesized by using poly(2-hydroxyethylmercaptomethylstyrene) (PSME) and diethanolamine (EDA) as materials. Its structure was characterized by elemental analysis, Fourier transform-infrared spectra (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The adsorption of the resin for Hg2+ was investigated. The saturated adsorption capacity of PSME–EDA for Hg2+ could reach to about 1.1mmol/g at 25°C when the initial Hg2+ concentration was 0.02mol/l. Some factors affecting the adsorption such as temperature, reaction time and ion concentration were also studied. The results showed that adsorption was controlled by liquid film diffusion. The increasing of temperature was beneficial to adsorption. The Langmuir model was better than the Freundlich model to describe the isothermal process. The values of ΔG, ΔH, and ΔS calculated at 25°C were −7.99kJmol−1, 22.5kJmol−1 and 34.4Jmol−1 K−1, respectively. The adsorption mechanism of PSME–EDA resin for Hg(II) was confirmed by X-ray photoelectron spectroscopy (XPS). [Copyright &y& Elsevier]

Abstract: In order to explore the reuse properties of oxidized chelating resin containing sulfur after adsorption, two kinds of novel chelating resins, poly[4-vinylbenzyl-(2-hydroxyethyl)] sulfoxide (PVBSO) and poly[4-vinylbenzyl-(2-hydroxyethyl)] sulfone (PVBSO2), were synthesized using poly[4-vinylbenzyl-(2-hydroxyethyl)] sulfide (PVBS) as material. Their structures were confirmed by FTIR and XPS. The adsorption properties and mechanism for metal ions such as Au3+, Pt4+, Pd2+, Hg2+, Cu2+, Ni2+, Fe3+, Pb2+, Cd2+, and Zn2+ were investigated. Experimental results showed that PVBSO had good adsorption and selective properties for Au3+, Pd2+ and Cu2+ when the coexisting ion was Pt4+, Ni2+, Pb2+ or Cd2+. In the aqueous system containing Cu2+ and Pb2+ or Cu2+ and Cd2+, PVBSO2 only adsorbed Cu2+. The selective coefficients of PVBSO and PVBSO2 were α Au/Pt =4.8, α Au/Pd =11.8, α Pd/Pt =10.9, α Cu/Ni =2.5, α Cu/Cd =41.2, α Cu/Pb =∞, α Cu/Ni =3.0, α Cu/Cd =∞, α Cu/Pb =∞, respectively. [Copyright &y& Elsevier]