Fabrication and Characterization of Copper Nanoparticles in PVA/PAAm IPNs and Swelling of the Resulting Nanocomposites

Yan-Ling Luo,Li-Li Chen,Feng Xu,Qiang-Suo Feng 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.5

Well-dispersed copper nanoparticles were fabricated using poly(vinyl alcohol)/polyacrylamide interpenetrating polymer networks (PVA/PAAm IPNs) as a nanoreactor template. The synthesis of the IPNs hydrogels was achieved in the presence of glutaraldehyde and N,N'-methylene-bis-acrylamide. The resulting PVA/PAAm/Cu nanocomposite hydrogels were characterized, and the swelling and mechanical properties were investigated. The results indicated that the copper nanoparticles had a spherical shape with a size range from 10 to 20 nm. The complexation of PVA in PVA/PAAm IPNs with Cu 2+played an important role in avoiding the aggregation of copper nanoparticles and providing particle size and size distribution controllability and stability. Although the swelling capacity of the nanocomposite hydrogels was slightly lower than that of the control, they had better compression mechanical properties. The water uptake and mechanical properties can be easily tuned by changing the component ratios to meet the requirements of specific applications, such as drug controlled release or tissue engineering.

Synthesis, Phase Behavior, and Simulated In vitro Degradation of Novel HTPB-b-PEG Polyurethane Copolymers

Yan-Ling Luo,Yan Miao,Feng Xu 한국고분자학회 2011 Macromolecular Research Vol.19 No.12

Two types of polyurethanes with alternating and random block architectures, hydroxyl-terminated liquid polybutadiene and poly(ethylene glycol) block copolymers (HTPB-alt-PEG and HTPB-co-PEG), were synthesized using a coupling reaction route between the hydroxyl groups and the isocyanate groups. The chemical and crystal structures were characterized using Fourier transform-infrared spectroscopy (FTIR) and X-ray diffraction, while phase behavior was examined using scanning electron microscopy (SEM) and differential scanning calorimetry. The biodegradation in a simulated human body fluid was investigated through mass loss, SEM, and FTIR. The experimental results indicated that all of the polyurethane samples bore the microphase separation structure, and the separation degree depended on the sequence structure and molecular weight (MW) of PEG and further affected their in vitro degradation. The driving force was related to the restricted movement of the molecular segments, the crystallization of the soft/hard phases, and/or the hydrogen bonding interactions between the hard segments. The surface morphological change of the degraded samples further demonstrated that the degradation became serious as the PEG MW increased and that the random block copolymers decomposed more easily than the alternating copolymers. The block polymer materials are expected to be incorporated into specific applications in related biomedical fields.

Relationship between Chemical Structures and Functions of Tea Polysaccharides

Feng Jin,Ling-Yan Jia,You-Ying Tu 한국차학회 2015 한국차학회지 Vol.- No.S

The worldwide consumption of tea is second only to water. Thus any health effects of drinking tea could have a significant impact on public health. Although tea has historically been thought to promote good health, research into the possible health benefits of tea is more recent. Tea polysaccharides sources show various important biological activities together with proteins and polynucleotides, such as anti-blood coagulation, anti-radiation, antioxidant, reducing blood sugar levels, hypoglycemic activities, anti-HIV, anti-cancer, cell-cell communication, cell adhesion and molecular recognition in the immune system, which are strongly affected by their chemical structures and chain conformations. In recent years, some tea polysaccharides sources have attracted much attention in the field of biochemistry and pharmacology. Observational studies have repeatedly shown that tea polysaccharides were mostly glycoconjugates in which a protein carries one or more carbohydrate chains covalently associated with a polypeptide backbone, usually some forms of via N- or O-linkages. It is interesting and important to elucidate the relation among chemical structures, chain conformations of tea polysaccharides and their biological activities. However, tea polysaccharides are usually composed of various monosaccharides linked with different glucosidic bonds. Some tea polysaccharides have hyperbranched structures. Moreover, tea polysaccharides often have high molecular weights, and tend to form aggregates in solution that can mask the behavior of individual macromolecules. In consequence, to characterize the chemical structures and chain conformations of polysaccharides is not an easy task. To make clear the chemical structures and chain conformations of tea polysaccharides is important to understand their biological activities. This article attempts to review the current development on structural and conformational characterization of some tea polysaccharides. In this paper, the various aspects of the investigation results of tea polysaccharides chemical structures in the recent decades were summarized. The chemical structures were analyzed by FTIR, NMR (one and two dimensions), CD and AFM, and so on.

RASSF1A Suppresses Proliferation of Cervical Cancer Cells

Feng, Lei,Li, Jie,Yan, Ling-Di,Tang, Jian Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.14

Background: This study aimed to explore the effects of ras association domain family 1 A (RASSF1A) on proliferation and apoptosis of human cervical cancer cell line Hela cells. Materials and Methods: RASSF1A was cloned into the pcDNA3.1(+) vector to generate pcDNA3.1(+)-RASSF1A plasmid for transfection into Hela cells. Changes in the proliferation and apoptosis of cultured Hela cells were examined by the 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium chloride assay and flow cytometry. A protein array was used to analyze the expression of apoptotic factors. Results: Plasmid pcDNA3.1(+)-RASSF1A was generated and transfected into Hela cells to stably express RASSF1A in Hela cells. RASSF1A transfection was effective in inhibiting the proliferation of Hela cells up to 52.4%, as compared to cells transfected with an empty plasmid. RASSF1A expression also successfully induced apoptosis in human cervical cells with an apoptosis rate of 20.5%. More importantly, protein array results showed that RASSF1 A transfection induced overexpression of p21 and caspase 8, while decreasing the expression of survivin in Hela cells. Conclusions: RASSF1A expression was effective in suppressing the proliferation and increasing apoptosis of Hela cells, and may be a potential therapy for cervical cancer in clinic.

Structural Analysis of an Acidic Polysaccharide Isolated from White Tea

Feng Jin,Ling-Yan Jia,You-Ying Tu 한국식품과학회 2015 Food Science and Biotechnology Vol.24 No.5

A novel white tea polysaccharide (WTPS) was isolated from white tea. The structure and ingredients of WTPS were characterized using UV-vis, an amino acid analyzer, GC, Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance spectroscopy (NMR). WTPS was an acidic polysaccharide mainly composed of mannose (D-Man) and arabinose (L-Ara) with lesser amounts of glucose (D-Glc), rhamnose (L-Rha), and galactose (D-Gal) with molar ratios of 4.5:4.2: 2.2:1.1:1. Seventeen amino acids were confirmed as components of WTPS. The polysaccharide appeared to be homogenous with a weight average Mw of 2.9×104 Da based on gel permeation chromatography analysis. WTPS was identified as a hydrophilic polysaccharide consisting of monosaccharide and acidic heteropolysaccharid chains based on FTIR, NMR, and AFM analysis.

N-Carbamylglutamate in Combination with Vitamin C Show Synergistic Role to Anti-Heat Stress in Sows

Feng Tao,Bai Jia-hua,Xu Xiao-ling,Huang Zheng,Guo Yong,Liu Yan 한국동물생명공학회(구 한국동물번식학회) 2014 한국동물번식학회 한중일 심포지엄 Vol.2014 No.1

Synthesis, Characterization, and Micellization of pH-Responsive Poly(4-vinylpyridine)-block-Poly(methacrylic acid) Four-Armed Star-Shaped Block Copolymers

Feng Xu,Shu-Zhen Zheng,Yan-Ling Luo,Ting-Ting Chen 한국고분자학회 2013 Macromolecular Research Vol.21 No.9

pH-sensitive poly(4-vinylpyridine)-block-poly(methacrylic acid) (P4VP-b-PMAA) four-armed starshaped block copolymers were synthesized by two-step atom transfer radical polymerization (ATRP), followed by hydrolysis of P4VP-b-poly(tert-butyl methacrylate) (P4VP-b-PtBMA). The chemical structure and molecular weight of the as-synthesized block copolymers were characterized by Fourier transform infrared spectrometry (FTIR), nuclear magnetic resonance (1H and 13C NMR), and gel permeation chromatography (GPC) determinations. The solution behavior was investigated by surface tension technique, ultraviolet visible (UV-vis) transmittance,transmission electron microscopy (TEM), dynamic light scattering (DLS), and zeta potentials measurements. The experimental results indicated that the copolymers can spontaneously assemble into spherical-shaped core-shell micelle aggregates, with a critical micelle concentration (CMC) about 200 mg L-1, hydrodynamic diameters from 90to 210 nm, depending on the environmental pH values and compositional ratios. The transmittance measurements revealed that the block copolymers produce evident phase transition in aqueous solution at pH from 6.5 to 7.0. Zeta potential data revealed high micelle stability. The as-synthesized block copolymers are anticipated to find their applications in the realms of specific drug release, metal loading and heterogeneous catalysis.

Microwave-Assisted Synthesis of Flower-like and Plate-like CuO Nanopowder and Their Photocatalytic Activity for Polluted Lake Water

Ling Xu,Hai-Yan Xu,Feng Wang,Feng-Jun Zhang,Ze-Da Meng,Wei Zhao,오원춘 한국세라믹학회 2012 한국세라믹학회지 Vol.49 No.2

Flower-like and plate-like CuO nanopowder has been successfully synthesized using a facile microwave-assisted synthetic route. The morphology and size of the final products strongly depended on microwave power. The phase, structures and morphologies of the as-prepared products were investigated in detail by BET surface area analysis, X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM). In addition, the chemical oxygen demand of polluted lake water was employed for characterization of these new photocatalysts. The results showed correlations between the morphology of CuO micro-crystals and their catalytic properties.

Molecular Cloning and Function Analysis of an Anthocyanidin Synthase Gene from Ginkgo biloba, and Its Expression in Abiotic Stress Responses

Feng Xu,Hua Cheng,Rong Cai,Lin Ling Li,Jie Chang,Jun Zhu,Feng Xia Zhang,Liu Ji Chen,Yan Wang,Shu Han Cheng,Shui Yuan Cheng 한국분자세포생물학회 2008 Molecules and cells Vol.26 No.6

Anthocyanidin synthase (ANS, leucoanthocyanidin oxygenase), a 2-oxoglutarate iron-dependent oxygenase, catalyzed the penultimate step in the biosynthesis of the anthocyanin class of flavonoids, from the colorless leucoanthocyanidins to the colored anthocyanidins. The full-length cDNA and genomic DNA sequences of ANS gene (designated as GbANS) were isolated from Ginkgo biloba for the first time. The full-length cDNA of GbANS contained a 1062-bp open reading frame (ORF) encoding a 354-amino-acid protein. The genomic DNA analysis showed that GbANS gene had three exons and two introns. The deduced GbANS protein showed high identities to other plant ANSs. The conserved amino acids (H-X-D) ligating ferrous iron and residues (R-X-S) participating in 2-oxoglutarate binding were found in GbANS at the similar positions like other ANSs. Southern blot analysis indicated that GbANS belonged to a multi-gene family. The expression analysis by real-time PCR showed that GbANS expressed in a tissue-specific manner in G. biloba. GbANS was also found to be up-regulated by all of the six tested abiotic stresses, UV-B, abscisic acid, sucrose, salicylic acid, cold and ethylene, consistent with the promoter region analysis of GbANS. The recombinant protein was successfully expressed in E. coli strain with pET-28a vector. The in vitro enzyme activity assay by HPLC indicated that recombinant GbANS protein could catalyze the formation the cyanidin from leucocyanidin and conversion of dihydroquercetin to quercetin, suggesting GbANS is a bifunctional enzyme within the anthocyanidin and flavonol biosynthetic pathway.

Synthesis and Micellization of Thermosensitive PNIPAAm-b-PLA Amphiphilic Block Copolymers Based on a Bifunctional Initiator

Feng Xu,Yan-Ling Luo,Ting-Ting Yan 한국고분자학회 2011 Macromolecular Research Vol.19 No.12

The thermo-sensitive amphiphilic block copolymer poly(N-isopropylacrylamide)-block-poly(D,L-lactide)(PNIPAAm-b-PLA) was synthesized using a simple free radical copolymerization route based on a bifunctional initiator, 2,2-azobis(2-methylpropion amidine) dihydrochloride followed by the ring-opening polymerization of D,L-actide in the presence of a Sn(Oct)_2 catalyst. The chemical structure of the PNIPAAm-b-PLA copolymers was verified using Fourier transform-infrared spectrophotometry and nuclear magnetic resonance, and the molecular weight and polydispersity index were examined using gel permeation chromatography. The amphiphilic PNIPAAm-b-PLA block copolymers could self-assemble into spherically shaped micelles in an aqueous solution with a transmission electron microscopy diameter range of 40-56 nm and a dynamic laser scattering hydrodynamic diameter of 90-200 nm. This behavior depends on the environmental temperature, the hydrophobic interactions among PNIPAAm molecular chains, the intermolecular hydrogen bonding between the PNIPAAm chains and water molecules, and the intramolecular hydrogen bonding between the -CONH_2 groups. The copolymers held a critical micellization concentration of 4.93-7.21 mg·L^-1 and a low critical solution temperature of 31.15-32.62 ℃ being more or less affected by their compositions, PLA or PNIPAAm block length, and polymerization temperature. The as-prepared PNIPAAm-b-PLA block polymers are anticipated to be applied as candidate drug release carriers.