LANGMUIR
·
2018
·
IF 3.789
Shuling Li,Shuji Ye,Guangming Liu
We have investigated specific ion effects on protein thermal aggregation from dilute solutions to crowded environments. Ovalbumin and poly(ethylene glycol) have been employed as the model protein and crowding agent, respectively. Our studies demonstrate that the rate-limiting step of ovalbumin thermal aggregation is changed from the aggregation of unfolded protein molecules to the unfolding of the protein molecules, when the solution conditions are varied from a dilute solution to a crowded environment. The specific ion effects acting on the thermal aggregation of ovalbumin generated by kosmotropic and chaotropic ions are different. The thermal aggregation of ovalbumin molecules is promoted by kosmotropic anions in dilute solutions via an increase in protein hydrophobic interactions. In contrast, ovalbumin thermal aggregation is facilitated by chaotropic ions in crowded environments through accelerated unfolding of protein molecules. Therefore, there are distinct mechanisms causing the ion specificities of protein thermal aggregation between dilute solutions and crowded environments. The ion specificities are dominated by ion-specific hydrophobic interactions between protein molecules and ion-specific unfolding of protein molecules in dilute solutions and crowded environments, respectively.
研究领域:
生物化学
·
分子生物学
✓ 已验证
DOI
高影响因子
CHEMICAL RESEARCH IN CHINESE UNIVERSITIES
·
2013
·Vol. 29
·期 5
·1022-1028
·
IF 0.735
Liu Gui-hua,Qiu Xue-peng,Siddiq Mohammad,Bo Shu-qin,Ji Xiang-ling
Temperature dependence of chain conformation and local rigidity of two soluble isomerized polyimides (PIs), poly(hexafluorodianhydride/3,3′-dimethylbenzidine)[poly(6FDA/3,3′-DMB)] and poly(hexafluorodianhy-dride/2,2′-dimethylbenzidine)[poly(6FDA/2,2′-DMB)] were investigated by dilute solution viscosity, size exclusion chromatography(SEC) coupled with multi-angle laser light scattering, viscometer, and refractive index detector in dimethylformamide(DMF) with either 0.1 mol/L LiBr or 3.1 mmol/L tetrabutylammonium bromide(TBAB) in the temperature range of 30 to 50 °C. The scaling relationships of [ η ]= K
η
M
α and R
g = K
g
M
ν obtained are employed to investigate the temperature dependence of chain conformation for the two polyimides. The values of α and ν are in the range of 0.66–0.69 and 0.53–0.56, respectively, for poly(6FDA/3,3′-DMB), meanwhile they are in the range of 0.64–0.68 and 0.53–0.56, respectively, for poly(6FDA/2,2′-DMB). These results reveal that random coil conformations for both PIs are not affected visibly with increasing temperature from 30 °C to 50 °C. However, values of more exact intrinsic viscosity from dilute solution measurement indicate there is only tiny coil extension or shrinkage for both PIs with temperature rising. Parameters related to chain flexibility of polymer, including persistence length l
p , shift factor M
L
(relative molecular weight per unit contour length) and backbone diameter d are estimated from the relationship between intrinsic viscosity and molecular weight for the continuous wormlike cylinder model, which indicates that two samples are flexible chains, only the chain of poly(6FDA/3,3′-DMB) is stiffer than that of poly(6FDA/2,2′-DMB) slightly.
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
Gels
·
2022
·Vol. 8
·期 11
·714
·
IF 4.432
Yongqiang Gong,Tingting Gu,Tiantian Zhang,Songnan Li,Zhenyu Yu,Mingming Zheng,Yaqing Xiao,Yibin Zhou
An investigation was conducted into the impacts of hydroxypropyl glutinous rice starch (HPGRS) and lactate-esterified glutinous rice starch (LAEGRS) on a dilute solution and gel properties of wheat starch (WS) at different proportions (0%, 1%, 3%, 5%, and 10%). The results of dilute solution viscosity showed that hydroxypropyl treatment of glutinous rice starch (GRS) could promote the extension of GRS chains, while lactate esterification led to the hydrophobic association of GRS chains, and the starch chains curled inward. Different HPGRS: WS and LAEGRS: WS ratios,β> 0 and ∆b> 0, showed HPGRS and LAEGRS produced attractive forces with WS and formed a uniform gel structure. Compared with WS gel, HPGRS, and LAEGRS could effectively delay the short-term aging of WS gels, and LAEGRS had a more significant effect. HPGRS increased the pasting viscosity, viscoelasticity, and springiness of WS gels, reduced the free water content, and established a tighter gel network structure, while LAEGRS had an opposite trend on WS. In conclusion, HPGRS was suitable for WS-based foods with stable gel network structure and high water retention requirements, and LAEGRS was suitable for WS-based foods with low viscosity and loose gel structure.Keywords:hydroxypropyl;lactate esterified;glutinous rice starch;wheat starch;dilute solution;gel properties
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
Polymers
·
2024
·Vol. 16
·期 13
·1863
·
IF 4.7
Yan Qiu,Xinyang Zhao,Hong Li,Sijun Liu,Wei Yu
The viscosity and viscoelasticity of polyelectrolyte solutions with a single electrostatic interaction have been carefully studied experimentally and theoretically. Despite some theoretical models describe experimental results well, the influence of multiple interactions (electrostatic and hydrophobic) on rheological scaling is not yet fully resolved. Herein, we systematically study the microstructures and rheological properties of short-side-chain perfluorosulfonic acid (S-PFSA), the most promising candidate of a proton exchange membrane composed of a hydrophobic backbone with hydrophilic side-chains, in water/2-propanol. Small-angle X-ray scattering confirms that semiflexible S-PFSA colloidal particles with a length of ~38 nm and a diameter of 1–1.3 nm are formed, and the concentration dependence of the correlation length (ξ) obeys the power law ξ~c−0.5consistent with the prediction of Dobrynin et al. By combining macrorheology with diffusing wave spectroscopy microrheology, the semidilute unentangled, semidilute entangled, and concentrated regimes corresponding to the scaling relationships ηsp~c0.5, ηsp~c1.5, and ηsp~c4.1are determined. The linear viscoelasticity indicates that the entanglement concentration (ce) obtained from the dependence of ηspon the polymer concentration is underestimated owing to hydrophobic interaction. The true entanglement concentration (cte) is obtained by extrapolating the plateau modulus (Ge) to the terminal modulus (Gt). Furthermore, Geand the plateau width, τr/τe(τrand τedenote reptation time and Rouse time), scale as Ge~c2.4and τr/τe~c4.2, suggesting that S-PFSA dispersions behave like neutral polymer solutions in the concentrated regime. This work provides mechanistic insight into the rheological behavior of an S-PFSA dispersion, enabling quantitative control over the flow properties in the process of solution coating.
研究领域:
材料科学
·
物理化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHINESE JOURNAL OF CHEMICAL PHYSICS
·
2024
·Vol. 37
·期 4
·563-570
·
IF 1.2
Shi Hehang,Ye Xiaodong
Two soy protein 11S fractions with different surface sulfhydryl contents were prepared. Utilizing analytical ultracentrifugation, the effects of storage time and hydrogen peroxide at different concentrations (0.5—100 mmol/L) on the two 11S fractions were investigated. Results show that after removing 2-mercaptoethanol (2-ME) by size exclusion chromatography, the 11S fraction with high surface sulfhydryl content (2.0 mol sulfhydryl/mol 11S) progressively formed 15S and 21S in dilute solutions during storage at 4 °C for 82 days. While, the 11S fraction with low surface sulfhydryl content (0.2 mol sulfhydryl/mol 11S) was stable under the same condition. Moreover, after treating the 11S with high surface sulfhydryl content with 1 mmol/L H 2 O 2 , the weight percentage of 15S reached the maximum value of 20%. The 15S induced by air and H 2 O 2 could be totally converted to 11S with the addition of 10 mmol/L 2-ME, which could be attributed to that the disulfide bond linking two 11S molecules is on the surface of the 15S and easily accessible to the reducing agent 2-ME. This study helps us to deeply understand the formation mechanism of 15S and the stability of 11S.
研究领域:
食品科学
·
蛋白质化学
·
分析化学
✓ 已验证
DOI
高影响因子
PHYSICS OF FLUIDS
·
2022
·Vol. 34
·期 2
·
IF 4.98
Gong Yanli,Zhang Cheng,Weng Xuan,Peng Bei,Jiang Hai
Microfluidic devices have been demonstrated to be able to concentrate low-abundance analytes and to be integrated in point of care (POC) devices for the purpose of reducing equipment size and cost; however, the complications involved in the fabrication of microfluidic chips or microelectrodes can be challenging. Here, we present a simple and effective microfluidic device monolithically integrated with liquid metal-based microelectrodes for the transportation and concentration of molecules in dilute solutions. Numerical and experimental studies were combined to validate and optimize the performance of the presented co-designing microfluidic chip featured by a double T-shaped manifold microchannel, in which the electrokinetically induced pressure-driven flow and concentration process were fully characterized. The microfluidic chip was used in a fluorimetric assay based on fluorescence resonance energy transfer between the fluorophore labeled aptamer and molybdenum disulfide nanosheets for the detection of cortisol, a stress biomarker of humans. Both experimental and numerical results show that a concentration factor up to 83-fold can be achieved within 5 min. By avoiding cumbersome fabrication processes and mechanical equipment, the proposed co-designing concentrating strategy provides insights for the fabrication of compact microfluidic chips that facilitate the miniaturization of POC devices with enhanced detection limit and sensitivity.
研究领域:
微流控技术
·
生物医学工程
·
分析化学
·
即时诊断
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Polymer Materials
·
2025
·
IF 4.7
Huajian Song,Bingli Jiang,Chanming Mei,Huili Wei,Shumin Jiang,Liping Liu,Chenjie Jiang,Linmin Zou,Yongyang Gong
Nonconventional luminescent polymer materials (NLMs) hold great promise for advancing bioimaging due to their unique optical properties and biocompatibility. However, their practical applications are hindered by limitations such as nonemissive behavior in dilute solutions and difficulties in organelle-specific imaging. The cooperative effects of hydrogen bonding and n → π* interactions between amide groups could facilitate molecular clustering, thereby increasing the emission efficiency of NLMs in dilute solutions. To confirm this method, two water-soluble NLMs, P1 and P2, based on aspartic acid, were synthesized. These polymers exhibit remarkable photoluminescence quantum yields (5.42% and 3.11%) at a low concentration of 0.1 mg/mL, accompanied by concentration- and excitation wavelength-dependent emsission, and aggregation-induced emission (AIE) properties. Furthermore, both polymers demonstrate temperature-sensitive emission, excellent photostability, and low cytotoxicity, making them ideal candidates for various bioapplications. Importantly, P1 exhibits selective recognition of Al3+ ions with a low detection limit of 0.92 μM, significantly below the World Health Organization guideline of 7.4 μM. Additionally, both P1 and P2 demonstrate lysosomal targeting ability, suggesting their potential for diverse applications in cellular imaging and ion sensing.
研究领域:
生物成像
·
材料科学
·
分析化学
·
细胞生物学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）