Advanced Materials Interfaces
·
2020
·Vol. 7
·期 15
·2000485
·
IF 4.948
Shihua Yuan,Xinchun Chen,Chenhui Zhang
Relative motion between artificial cartilages is too slow to form a sufficient lubricating film for hydrodynamic lubrication, and this can result in large friction and wear. Hydration lubrication is effective in reducing friction at low speeds, and the lubricity is mostly determined by surface charges, which can be assessed by isoelectric point (IEP). Therefore, by controlling the IEP of friction pairs, ultralow friction can be achieved even with weak hydrodynamic lubrication. Here, a negatively charged material is synthesized by grafting carboxylate anions into an epoxy resin matrix. Compared with pristine epoxy resin (IEP = 6.0), the modified epoxy resins (IEP = 3.8, IEP = 3.0) show better tribological properties. In particular, at low speeds (4.7 and 1.2 mm s −1 ), the friction coefficients are as low as 0.02–0.04, and the average contact pressures are ≈10 MPa, when a NaCl solutions are used as the lubricants. Furthermore, the addition of hydroxyapatite to the modified epoxy resin not only increases its bioactivity, but also reduces friction. Superlubricity can be achieved for the speeds higher than 23.5 mm s −1 . These results provide a method to design artificial cartilage with good tribological and bearing capacity.
研究领域:
生物材料学
·
生物力学
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2019
·
IF 4.784
Ranran Chang,Yaoqi Tian,Zhiwei Yu,Chunrui Sun,Zhengyu Jin
Zwitterionic polymers have attracted great attention due to their unique structure, which can be used for various applications, such as the improvement of nanoparticle stability, ion exchange, sewage treatment, and biomedicine . Here, zwitterionic functionalized starch nanoparticles (SNPs) were successfully prepared in two steps by carboxymethylation and quaternization. The structure of the modified SNPs was confirmed using Fourier transform infrared spectroscopy , nuclear magnetic resonance spectroscopy , and elemental analysis. The zwitterionic SNPs with a size of 30–100 nm were well dispersed without aggregation. The relative crystallinity of zwitterionic SNPs (35.2%) was increased compared to that of SNPs (31.7%). The zwitterionic SNPs could be used effectively to absorb dyes, and its isoelectric point was around pH 9.4. The zwitterionic SNPs may be used as nontoxic adsorption carriers that can be used in health foods or drug delivery applications.
研究领域:
材料科学
·
生物医学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ADVANCES IN COLLOID AND INTERFACE SCIENCE
·
2021
·
IF 12.984
Marek Kosmulski
Summary of the points of zero charge (PZC) and isoelectric points (IEP) of various materials published in the recent literature and of older results overlooked in the previous compilations. The roles of experimental conditions, especially of the temperature, of the nature and concentration of supporting electrolyte, and of the type of apparatus are emphasized. The newest results are compared with the zero points reported in previous reviews. Most recent studies were carried out with materials whose pH dependent surface charging is already well-documented, and the newest results are consistent with the older literature. Isoelectric points of Gd(OH) 3 , Sm(OH) 3 , and TeO 2 have been reported for the first time in the recent literature.
研究领域:
化学
·
材料科学
✓ 已验证
DOI
高影响因子
FOOD RESEARCH INTERNATIONAL
·
2022
·
IF 7.425
Qingqing Yu,Tong Shi,Zhiyu Xiong,Li Yuan,Hui Hong,Ruichang Gao,Yulong Bao
In order to study the effect of oxidation on the dye-binding behavior of myofibrillar proteins, selected dyes with different charges (positively charged Sarfarin O (SO), neutral bromophenol blue (BPB), and negatively charged Orange G (OG)) were incubated with myofibrils oxidized by the Fenton system with H 2 O 2 (10 mM). Upon oxidation, loss of free thiols, formation of carbonyls, particle size, and hydrophobicity of myofibrillar proteins (MPs) increased. The absolute value of Zeta-potential increased by 14.48 % after oxidation, the myofibrillar proteins shifted to a more acidic isoelectric point (pI) upon oxidation. Oxidation decreased net positive charges of myofibrillar protein and the binding ability of MPs towards OG in the environment with pH less than pI and the affinity of MPs towards SO in the environment with pH more than pI were thus increased. Here we propose a hypothesis that oxidation-induced change in net charges is the driving force affecting the amount of protein-bound dye. This paper aims to examine the effect of oxidation on the net charges of myofibrillar proteins and to provide insight into the mechanism of oxidation-induced changes in protein-bound dyes.
研究领域:
食品科学
·
生物化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MICROCHIMICA ACTA
·
2024
·Vol. 192
·期 1
·1-11
·
IF 5.3
Yang Kaige,Fu Wenchang,Ma Yinjie,Wu Mingyuan,Li Xinyan,Wang Yan
A straightforward capillary isoelectric focusing (cIEF) method is established with a isoelectric point (pI) range spanning from 3.5 to 7.0, exhibiting excellent linearity and repeatability, with an R 2 value of 0.9937 and migration time RSDs for all standard proteins below 0.3%. Subsequently, this method was applied to model exosomes derived from cell lines and healthy human serum, and the peak attributions of exosomes were identified using DiI labeled exosomes and lysed exosomes. The reproducibility of this method in exosome detection was also validated, as the RSDs of all pI values were less than 1%. Then, we observed a significant increase in the pI of exosomes with higher cholesterol content, irrespective of whether they originated from cell culture medium or mouse plasma. Notably, serum exosomes from healthy volunteers exhibited higher pI values compared to those from hepatocellular carcinoma patients, suggesting a potential diagnostic perspective for cancer. These findings underscore the significance of pI measurement in reflecting modifications in exosomal lipid membrane composition and their implications in biological functions mediated by exosomes. Graphical
研究领域:
分析化学
·
医学诊断
·
生物化学
✓ 已验证
DOI
PubMed
高影响因子
ANALYST
·
2013
·Vol. 138
·期 21
·6445-6453
·
IF 3.969
Xiao Lin,Yuzhi Wang,Qun Zeng,Xueqin Ding,Jing Chen
A satisfactory protocol of protein extraction and separation has been established based on the ionic liquid aqueous two-phase system (IL-ATPS) for the purification of bioactive substances. Compared with the effects of eight different ionic liquids, 1-octyl-3-methylimidazolium bromide ([omim][Br]) was selected as the suitable ionic liquid. Based on the single-factor experiment, an initial serial investigative test was used to identify the optimal conditions of the extraction. Owing to their different isoelectric points, bovine serum albumin (BSA), hemoglobin (Hb) and lysozyme (Lys) were used to determine the effect of pH value on the protein extraction. Trypsin (Try) was used to confirm the protein activity. The linearity for analyzing BSA, Hb, Try and Lys was in the concentration range of 0.05–1.00 mg ml−1, 0.025–1 mg ml−1, 0.01–1.00 mg ml−1 and 0.01–1.00 mg ml−1, respectively, with a correlation coefficient of between 0.9985 and 0.9999. Limits of detection (LODs) were 16.47–7.02 μg ml−1 and RSDs of inter-day stability were less than 2.9%. Repeatability and precision were respectively lower than 5.3% and 1.1%. Under the optimum conditions, the average recoveries of BSA, Hb, Try and Lys were 90.5%, 94.5%, 92.7% and 93.8% and the obtained RSDs were 1.19%, 1.23%, 1.34% and 1.04%, respectively. According to UV spectra, conductivity, dynamic light scattering (DLS), and transmission electron microscope (TEM) images, the cluster phenomenon originating from IL itself or combined with protein was evaluated. As the driving forces which are involved in the partitioning of protein between the IL-rich phase and the phosphate phase, the cluster phenomenon could, in principle, be applied to a variety of different samples and exhibited potential value.
研究领域:
生物化学
·
分离科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
DESIGNED MONOMERS AND POLYMERS
·
2013
·
IF 0.875
Y. Zou,Y.H. Zhang,P.X. He
Amphoteric terpolymers composed of acrylamide, 2-methylacryloylxyethyl trimethyl ammonium chloride, and 2-acrylamido-2-methyl-1-propane sulfonate were prepared via free-radical polymerization in aqueous solution of ammonium sulfate (AS), using poly(2-methylacryloylxyethyl trimethyl ammonium chloride) as stabilizer to yield terpolymers with random distributions. The particle size of the synthesized amphoteric polyacrylamide (AmPAM) ranged from 1 to 8 μm and the intrinsic viscosity ranged from 5.6 to 14.2 dL/g. The influences of aqueous solution of AS concentration, stabilizer concentration, initiator concentration, monomer concentration on the conversion of monomer, the intrinsic viscosity, and the particle size were systematically investigated. The characteristic of amphoteric polymer was also be studied. Throughout the study, we found that the isoelectric point of the amphoteric polyelectrolyte we synthesized is about 7. With the increase in sodium chloride, the reduced viscosity of AmPAM increased. Among the different type of inorganic salt, the degree of influence of anionic is I > Br > Cl.
研究领域:
高分子化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
POLYMER BULLETIN
·
2011
·Vol. 67
·期 1
·141-158
·
IF 1.215
An Huiyong,Lu Cuige,Wang Pixin,Li Wenbo,Tan Ying,Xu Kun,Liu Chang
A novel hydrophobically associating polyampholytes of poly(AM/AA/AMQC12) were synthesized by the free radical copolymerization of acrylamide (AM), acrylic acid (AA), and dimethyldodecyl(2-acrylamidoethyl)ammonium bromide (AMQC12) in water without any surfactants (named AAQ series). The structures of polymers were confirmed by 1 H NMR and 13 C NMR. The molecular weight and polydispersity were obtained using gel permeation chromatography (GPC). The hydrophobically associated properties of polymer solution were characterized by rheology, steady-state fluorescence probe, and 1 H NMR relaxation time ( T
2 ). Isoelectric points (IEPs) of polymer solution were determined by the effect of pH on viscosity below critical association concentrations (cac), and the reduced viscosities of samples at IEPs were increased in the presence of NaCl. Moreover, the steady-shear viscosity of sample at IEP was also greatly enhanced in NaCl solutions when the polymer concentration is above the cac. Meantime, the storage modulus and the loss modulus of copolymers showed that the sample behaved as gel in salt media.
研究领域:
高分子化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
ANALYTICAL SCIENCES
·
2019
·Vol. 35
·期 10
·1149-1153
·
IF 1.618
Li Na,Liu Shi Gang,He Yong Qin,Mai Xi
A resonance Rayleigh scattering (RRS) technique was utilized as a tool for isoelectric point monitoring and iron(III) cation determination. The spectral properties of some amphoteric molecules (proteins and a DNA sequence) were investigated using the RRS technique. When the pH values were kept at around their isoelectric points, especially high RRS signals could be obtained, which were much stronger than those at other pH values. By using the C30 DNA sequence as a probe, the iron(III) cation can be detected rapidly. After iron(III) was added to a C30 solution, a significantly decreased RRS signal was obtained. The sensing process can be finished within 10 min with a detection limit of 0.9 μM. Thus, a sensitive, selective, and label-free method was successfully developed for iron(III) detection.
研究领域:
分析化学
·
生物化学
·
光谱学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
LANGMUIR
·
2014
·
IF 4.384
Feng Chen,Decheng Wan,Zhihong Chang,Hongting Pu,Ming Jin
Highly efficient and charge-selective adsorption and desorption of peptides at trace level by a solid-phase adsorbent is described. The adsorbent of SiO2@PEI is synthesized by covalent immobilization of branched polyethylenimines (PEI) exclusively on the outer surface of the porous silica particles (∼300 μm). For aqueous peptides (Mw = 600–3000 Da), SiO2@PEI can capture the negatively charged ones and leave the positively charged ones intact, and by adjusting pH of the system peptides with different isoelectric points (pIs) can be well separated. Targeted peptide at low abundance (at least as low as 0.1 mol % with respect to the highest one) can be well separated. The association constants of K > 1012 M–1 at pH > pI and K < 104 M–1 at pH < pI are found; that is, selectivity > 108 is generally available. Thus, a peptide even at sub-femtomolar level can be extracted and eluted for analysis, and efficient recovery (79–92%) of the peptides is found. The extraction is mainly promoted by multisite electrostatic interaction, and the hydrophilic and cationic properties of PEI at low pH play a unique role in desorption efficiency and selectivity. The unbiased nature of this method renders the adsorbent applicable to the efficient separation of a broad spectrum of peptides, including those with similar pIs.
研究领域:
分析化学
·
生物化学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
POWDER TECHNOLOGY
·
2022
·
IF 5.64
Yu Xing,Qian Li,Xiaoyi Chen,Miao Li,Shujing Wang,Yan Li,Tianyu Wang,Xitong Sun,Xianzhen Li
A series of polymer brushes were formed on the surface of mesoporous silica microspheres by copolymerizing 1-vinyl imidazole and acrylic acid through reversible-addition fragmentation chain transfer (RAFT) polymerization, with pI-switchable property and high grafting groups content. The resulting materials (SiO 2 @poly(VI- co -AA)) were then applied for removing Ni(II) from aqueous solution with a fast adsorption rate, and the maximum adsorption capacity was 62.81 mg/g. Significantly, the removal rate of 30 mg/L of Ni(II) could reach up to 99.40%, and the adsorbent also exhibited a good reusability, with the desorption efficiency of over 99%. Furthermore, the adsorption mechanism was supposed to be electrostatic interaction and complexation characterized by Zeta potentials and XPS . It implied that the SiO 2 @poly(VI- co -AA) microspheres could be considered as a potential adsorbent for removing Ni(II) from wastewater, and was expected to expand its application to remove other heavy metals and dyes.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
FOOD CHEMISTRY
·
2020
·
IF 6.306
Dong Zhang,Hongjun Li,Zefu Wang,A.M. Emara,Ying Hu,Zhifei He
The effects of oxidation degree on the isoelectric point (pI), aggregation, and structural characteristics for pork myofibrillar protein (MP) were studied by employing extracted MP, which was incubated by using a hydroxyl radical oxidation system. The concentrations of hydrogen peroxide (H 2 O 2 ) were 0, 0.5, 1, 3, 5, 10, and 20 mM. With the increased oxidation degree, the contents of α-helix, ionic bonds, and hydrogen bonds decreased significantly ( P < 0.05). Moreover, the pI value and total amino acids showed a declining trend, and the β-sheet as well as solubility rised firstly and then declined. On the contrary, random curl, β-turn, and turbidity increased significantly ( P < 0.05). Therefore, amino acid side chain groups were modified, and the opposite effect, caused by oxidation that leads to protein cross-linking and aggregation, was greater than the promotion effect, such as net negative charge, these are the main factors that leads to the instability of protein solution systems.
研究领域:
食品科学
·
生物化学
✓ 已验证
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）