Polymers
·
2021
·Vol. 13
·期 23
·4074
·
IF 4.329
Duanwei Zhang,Fusheng Liu,Sheng Wang,Mengxi Yan,Xin Hu,Mengying Xu
This article proposes a method of increasing thermal conductivity (λ) by improving the λ value of a matrix and reducing the interfacial thermal resistance between such matrix and its thermally conductive fillers. D-GQDs (graphene quantum dots modified by polyetheramine D400) with a π–π-conjugated system in the center of their molecules, and polyether branched chains that are rich in amino groups at their edges, are designed and synthesized. AlN/DG-ER (AlN/D-GQDs-Epoxy resin) thermally conductive composites are obtained using AlN as a thermally conductive and insulating filler, using D-GQDs-modified epoxy resin as a matrix. All of the thermal conductivity, electrically insulating and physical–mechanical properties of AlN/DG-ER are investigated in detail. The results show that D-GQDs linked to an epoxy resin by chemical bonds can increase the value of λ of the epoxy–resin matrix and reduce the interfacial thermal resistance between AlN and DG-ER (D-GQDs–epoxy resin). The prepared AlN/DG-ER is shown to be a good thermally conductive and insulating packaging material.Keywords:thermal conductivity;graphene quantum dots;AlN;epoxy resin;thermally conductive composites
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高影响因子
ACS Applied Bio Materials
·
2020
·
IF 0
Ji Shen,Juan Qiao,Li Qi
Tuning the efficiency of enzymolysis in different environments is a challenge with important implications for the use of immobilized enzymes in biochemistry, pharmacology, and life science. Here, we demonstrate the use of a thermoresponsive porous polymer membrane for the construction of switchable enzyme reactors, which exhibited membrane surface property changes in diverse temperature environments. The enzyme reactor consisted of block copolymers, poly(styrene−maleic anhydride−oligo methacrylate−methoxyethoxy ethyl methacrylate) [P(St–MAn–OE–ME)], magnetic nanoparticles, and covalently bonded d-amino acid oxidase (DAAO). By varying the temperature between 25 and 39 °C, the self-assembly properties of the enzyme reactor could be controlled. Using d,l-Met as the substrate, the enzymolysis efficiency of the thermoresponsive porous polymer membrane enzyme reactor (t-PPMER) was evaluated by the chiral capillary electrophoresis technique. At higher temperatures, DAAO was embedded in the curled P(OE–ME) chains, resulting in improved enzymolysis efficiency owing to the confinement effect. At lower temperatures, inefficient enzymolysis occurred because of the stretching of the P(OE–ME) chains, which weakened the confinement effect. Remarkably, the enzymolysis rate of t-PPMER at 37 °C (3.1 mM·min–1) was 45 times higher than that at 25 °C (0.066 mM·min–1). The proposed protocol was successfully applied to the DAAO inhibitor screening. This approach capitalizes on the advantageous characteristics of the t-PPMER and provides inspirations for the construction of switchable enzyme reactors and the screening of enzyme inhibitors as potential drugs.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2020
·
IF 5.162
Jie Hao,Fangxia Wu,Rong Tang,Yuanyuan Sun,Dehua Liu,Zhenqing Zhang
Oxidized starch (oxStarch) is a major derivative of starch. In present study, 4-acetamide-TEMPO system was firstly applied to prepare specifically oxidized starch, homogeneous 1,4-linked α-D-glucuronan. The impact of oxidant amount, 4-acetamide-TEMPO amount and reaction temperature on the properties of products were investigated. The product structures were characterized with 1 H NMR for degree of oxidation (DO), SEC-MALS for MW, MS for analysis of oxidized oligosaccharides , and in-source fragmented MS for analysis of oxidized polysaccharides . The results showed that the DO of oxStarches increased, but their MWs decreased with the raise of oxidant amount; higher 4-acetamide-TEMPO amount provided higher efficiency of specific oxidation of starch, in which the product has higher DO and MW; no significant difference have been observed between the oxStarches oxidized at 4 and 25 °C, but significant degradation was observed at 50 °C. In each product, having a MW distribution, the portion with smaller size has higher DO. While some unspecific oxidation was still observed observed on the second hydroxyl groups of sugar ring in the following order of priority, position 3 > 2 > 1 > 0.
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JOURNAL OF CELLULAR AND MOLECULAR MEDICINE
·
2020
·Vol. 24
·期 5
·3022-3033
·
IF 4.486
Zheng Li,Haihua Feng,Lu Han,Lu Ding,Bingyu Shen,Ye Tian,Lilei Zhao,Meiyu Jin,Qi Wang,Haiyan Qin,Jiaqi Cheng,Guowen Liu
Chicoric acid is polyphenol of natural plant and has a variety of bioactivity. Caused by various kinds of stimulating factors, acute liver injury has high fatality rate. The effect of chicoric acid in acute liver injury induced by Lipopolysaccharide (LPS) and d -galactosamine ( d -GalN) was investigated in this study. The results showed that CA decreased the aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in serum and reduced the mortality induced by LPS/ d -GalN. CA can restrain mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-κB) to alleviate inflammation. Meanwhile, the results indicated CA can active nuclear factor-erythroid 2-related factor 2 (Nrf2) pathway with increasing the level of AMP-activated protein kinase (AMPK). And with the treatment of CA, protein levels of autophagy genes were obvious improved. The results of experiments indicate that CA has protective effect in liver injury, and the activation of AMPK and autophagy may make sense.
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TALANTA
·
2020
·
IF 5.339
Haixia Yu,Yang Chong,Penghao Zhang,Jiaming Ma,Dachao Li
Fiber-based techniques make it possible to implant a miniaturized and flexible surface plasmon resonance (SPR) sensor into the human body for glucose detection. However, the miniaturization of fiber SPR sensors results in low sensitivity compared with traditional prism-type SPR sensors due to limited sensing area. In this paper, we proposed a D-shaped fiber SPR sensor with a composite nanostructure of molybdenum disulfide (MoS 2 )-graphene to improve the sensor sensitivity. Compared with the traditional cylindrical fiber, the planar sensing area on the side-polished fiber makes it easier to modify two-dimensional materials. Chemical vapor deposition (CVD) graphene and CVD MoS 2 were modified on the sensor surface to obtain the MoS 2 -graphene composite nanostructure. π-π stacking interactions were used to modify pyrene-1-boronic acid (PBA) on the graphene. The excellent photoelectric properties of the MoS 2 -graphene composite nanostructure and the ability of PBA to specifically bind glucose molecules improved the glucose detection performance of the SPR sensor. The results show that specific detection of glucose was realized and that the highest sensitivity was achieved with three-layer MoS 2 and monolayer graphene.
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CHEMICAL RESEARCH IN CHINESE UNIVERSITIES
·
2023
·Vol. 39
·期 6
·1092-1099
·
IF 3.1
Tian Lin,Cheng Cheng,Zhao Zhenwen,Liu Wei,Qi Li
T he construct of artificial nanocatalyts by simulating natural enzymes and thereby bringing new properties for practical applications is still a challenging task to date. In this study, chiral tetrapeptide ( L -phenylalanine- L -phenylalanine- L -cysteine- L -histidine)-engineered copper nanoparticles (FFCH@CuNPs) were fabricated as an artificial peroxidase (POD). More interestingly, the nano-catalysts exhibited chiral identification function. In comparison with other nanocatalysts like L -cysteine-, L -histidine-, chiral dipeptide ( L -cysteine- L -histidine)-, or chiral tripeptide phenylalanine- L -cysteine- L -histidine)-modified CuNPs, FFCH@CuNPs demonstrated a higher POD-mimetic catalytic activity in the 3,3′,5,5′-tetramethylbenzidine (TMB)-H 2 O 2 system and stronger enantioselectivity in the recognition of 3,4-dihydroxy- D , L -phenylalanine ( D , L -DOPA) enantiomers. Considering the strength difference between the intermolecular hydrogen bonding and the π - π interactions, the principle behind the chiral discrimination of D , L -DOPA was explored. Furthermore, contents levels of surface Cu 2+ ions and hydroxyl radicals were found in the FFCH@CuNPs-D-DOPA-TMB-H 2 O 2 system than in the FFCH@CuNPs-L-DOPA-TMB-H 2 O 2 system. Based on these results, a protocol for distinguishing between D , L -DOPA enantiomers through colorimetric recognition was established. This study provides a new insight into design and fabrication of oligopeptides@CuNPs-based chiral nanozymes with improved catalytic performance and features additional to those of natural enzymes.
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Journal of Functional Foods
·
2018
·
IF 3.47
Cuicui Duan,Yujuan Zhao,Cheng Huang,Zijian Zhao,Lei Gao,Chunhua Niu,Chao Wang,Xiaoxiao Liu,Chuan Zhang,Shengyu Li
Acute liver failure (ALF) is a life-threatening clinical condition resulting from massive apoptosis of hepatocytes. This study aims to examine the protective effects of Lactobacillus plantarum C88 on LPS/D-GalN-induced ALF and elucidate its underlying molecular mechanisms in mice. The results showed that L. plantarum C88 pretreatment significantly reduced the levels of plasma ALT and AST in mice with LPS/D-GalN–induced liver injury. L. plantarum C88 pretreatment decreased the secretion of inflammatory cytokines. In addition, L. plantarum C88 remarkably increased the expression levels and nuclear translocations of Nrf2 mRNA in liver tissues, but inhibited NF-κB nuclear translocations and P65, P38 phosphorylation levels. Moreover, L. plantarum C88 enhanced the intestinal mucosal barrier by upregulating the expressions of tight junction proteins as well as HIF-1α. These results suggest that L. plantarum C88 protects against ALF associated with Nrf2 and the MAPK/NF-κB signaling pathways.
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JOURNAL OF ELECTROANALYTICAL CHEMISTRY
·
2019
·
IF 3.218
Huan Ling,Xiaowen Wu,Ke Li,Fengyu Su,Yanqing Tian,Dan Luo,Yan Jun Liu,Xiao Wei Sun
Electrochromic (EC) devices with reversible transmittance switching have promising prospects in the applications of photoelectric displays. Herein, a novel air-stable and high contrast solution-phase electrochromic device based on new viologen derivative (DPB) with A-D-A structure (A: acceptor; D: donor) was demonstrated. Devices possessed simple configuration of ITO/EC solution/ITO. Ferrocene and polycarbonate (PC) were selected as the complementary material and solvent, respectively. All of the fabrications and performance testing work were conducted in normal air condition. The DPB-based device showed deep magenta color in colored state and exhibited high optical contrast of ΔT of 72.2% (517 nm) and good coloration efficiency of 102.2 cm 2 /C at 1.8 V. The device appeared only slight degradation of ΔT (ΔT = 69.6% or retained 96.7% of its initial ΔT after 5000 s constant switching) under the normal air atmosphere, which was even better than some reported well-packaged viologen-based solution ECDs. Additionally, the UV–vis reflective spectra were also conducted to assess the reflectance property of the devices. The reflectance peak (ΔR = 2.6%) and absorption peak matched accurately, which indicated that the new viologen derivative possesses the potential application in reflective electrochromic devices.
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Journal of the Mechanical Behavior of Biomedical Materials
·
2017
·
IF 3.11
Guangmei Huang,Zhiyun Du,Zuoying Yuan,Lihua Gu,Qing Cai,Xiaoping Yang
Biodegradable organic-inorganic composites composed of polylactide (PLA) and hydroxyapatite (HA) are important bone repairing materials, while the dispersibility of nanoscaled HA in PLA and the interfacial adhesion between HA and PLA remained unsatisfactory. In this study, poly(D-lactide) (PDLA) oligomers with different molecular weights were grafted onto HA nanorods (HA-PDLA), and the HA-PDLA hybrids were mixed with poly(L-lactide) (PLLA). Dispersibility of HA-PDLA hybrids in PLLA matrix was investigated, and the formation of PDLA/PLLA stereocomplex at the interface of HA-PDLA and PLLA was studied by characterizations including crystallization, mechanical and thermal properties, taking PLLA grafted HA (HA-PLLA) and unmodified HA as comparisons. Surface grafting of PLLA or PDLA oligomers both significantly improved the dispersibility of HA nanorods in PLLA matrix. Benefiting from PDLA/PLLA stereocomplexation, HA-PDLA could increase the tensile strength and the elongation of resulting PLLA/HA nanocomposites more significantly than HA-PLLA. The interfacial interaction between HA-PDLA and PLLA matrix could be further strengthened by increasing the molecular weights of those grafted PDLA chains on HA, which was verified by changes in crystallization and glass transition behaviors. To sum up, the concept of using PDLA/PLLA stereocomplexation was feasible and effective in preparing PLA-based organic-inorganic nanocomposites targeting bone repairing.
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高影响因子
JOURNAL OF SEPARATION SCIENCE
·
2017
·Vol. 40
·期 23
·4653-4660
·
IF 2.557
Haoran Fan,Jinpeng Wang,Qingran Meng,Yaoqi Tian,Xueming Xu,Zhengyu Jin
Photoirradiation surface molecularly imprinted polymers for the separation of 6- O -α- d -maltosyl-β-cyclodextrin were synthesized using functionalized silica as a matrix, 4-(phenyldiazenyl)phenol as a light-sensitive monomer, and 6- O -α- d -maltosyl-β-cyclodextrin as a template. Fourier transform infrared spectroscopy results indicated that 4-(phenyldiazenyl)phenol was grafted onto the surface of functionalized silica. The obtained imprinted polymers exhibited specific recognition toward 6- O -α- d -maltosyl-β-cyclodextrin. Equilibrium binding experiments showed that the photoirradiation surface molecularly imprinted polymers obtained the maximum adsorption amount of 6- O -α- d -maltosyl-β-cyclodextrin at 20.5 mg/g. In binding kinetic experiments, the adsorption reached saturation within 2 h with binding capacity of 72.8%. The experimental results showed that the adsorption capacity and selectivity of imprinted polymers were effective for the separation of 6- O -α- d -maltosyl-β-cyclodextrin, indicating that imprinted polymers could be used to isolate 6- O -α- d -maltosyl-β-cyclodextrin from a conversion mixture containing β-cyclodextrin and maltose. The results showed that the imprinted polymers prepared by this method were very promising for the selective separation of 6- O -α- d -maltosyl-β-cyclodextrin.
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TALANTA
·
2016
·
IF 4.035
Jun Fang Jiang,Juan Qiao,Xiao Yu Mu,Myeong Hee Moon,Li Qi
In this work, a unique D-amino acid oxidase reactor for enhanced enzymolysis efficiency is presented. A kind of magnetic polymer matrices, composed of iron oxide nanoparticles and porous polymer membrane (poly styrene-co-maleic anhydride), was prepared. With covalent bonding D-Amino acid oxidase on the surface of the matrices and characterization of scanning electron microscope and vibrating sample magnetometer, it demonstrated that the membrane enzyme reactor was successfully constructed. The enzymolysis efficiency of the enzyme reactor was evaluated and the apparent Michaelis-Menten constants of D-Amino acid oxidase were determined ( K m was 1.10 mM, V max was 23.8 mM min −1 ) by a chiral ligand exchange capillary electrophoresis protocol with methionine as the substrate. The results indicated that the enzyme reactor could exhibit good stability and excellent reusability. Importantly, because the enzyme and the substrate could be confined into the pores of the matrices, the enzyme reactor displayed the improved enzymolysis efficiency due to the confinement effect. Further, the prepared enzyme reactor was applied for D-Amino acid oxidase inhibitors screening. It has displayed that the proposed protocol could pave a new way for fabrication of novel porous polymer membrane based enzyme reactors to screen enzyme inhibitors .
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Soft Matter
·
2015
·Vol. 11
·期 31
·6266-6274
·
IF 4.029
Chen Chen,Yue-Cheng Qian,Chuan-bin Sun,Xiao-Jun Huang
The amphiphilic random copolymer poly(β-D-glucose-co-1-octyl)phosphazene (PGOP) can undergo continuous morphological transitions in DMF–water mixed solvents. In this study, the ratio of glucose moieties to octyl moieties was controlled via a two-step thiol–ene reaction. As a result, polyphosphazenes with glycosyl functionalization degrees of 58.1% (PGOP-1), 74.1% (PGOP-2) and 87.0% (PGOP-3) were obtained. These amphiphilic polyphosphazenes self-assemble in both water and water–DMF mixtures. Several self-assembled morphologies including spheres, rods and vesicles were formed though careful control of the water content (WC) in the DMF solvent as well as of the hydrophilicity or hydrophobicity of the copolymers. We also found that an increase in the hydrophobic proportion led to faster morphological transitions at a constant WC. The thermodynamics of micellization were also studied by Isothermal Titration Calorimetry (ITC), and the strong hydrophobic interactions in PGOP-1 were demonstrated by their highly exothermic nature. These self-assemblies have potential applications in biosensing, lectin adsorption and drug loading with controlled release.
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