The interactions of lanthanoid ions with dipalmitoylphosphatidylcholine bilayer were studied by DSC and Raman spectroscopy.The results show that the addition of lanthanoid ions causes a considerable increase of the ge...The interactions of lanthanoid ions with dipalmitoylphosphatidylcholine bilayer were studied by DSC and Raman spectroscopy.The results show that the addition of lanthanoid ions causes a considerable increase of the gel to liquid crystalline transition temperature of phospholipid and a reduction of order of lateral packing and conformation of acyl chains in SUVs.展开更多
Urinary phospholipids are shown to be sensitive biomarkers for kidney injury. Many works have been reported on qualitative analysis of phospholipids and relative components in human urine while quantitative analysis i...Urinary phospholipids are shown to be sensitive biomarkers for kidney injury. Many works have been reported on qualitative analysis of phospholipids and relative components in human urine while quantitative analysis is rare. We have therefore developed a reliable and convenient quantitative method to evaluate the accuracy and specificity of dipalmitoylphosphatidylcholine （DPPC） as a biomarker for kidney injury diagnosis. Chromatographic separation was achieved using a HILIC Silica Column （2.1 ram^50 mm, 5 p.m）. Gradient elution was performed with 5 mM ammonium formate （0.1% formic acid） and acetonitrile （0.1% formic acid）, at a flow rate of 0.3 mL/min. This method was validated in a linear range of 2-200 ng/mL DPPC with inter-day precision of less than 6.5% and accuracy within 111.2% in human urine. Recovery rate, stability, dilution effect and matrix effect also met the requirements for drug evaluation and research issued by FDA. As the first HPLC-MS/MS method for quantitative determination of DPPC, it has been successfully applied to determine levels of DPPC in clinical urine samples and evaluated for potential use in the measurement of DPPC as a biomarker for kidney injury.展开更多
With the extensive applications of rare earth in agriculture, medicament etc., especially the application of Gd-DTPA as nuclear magnetic resonance image reagent in clinical practice, the study of interactive mechanism...With the extensive applications of rare earth in agriculture, medicament etc., especially the application of Gd-DTPA as nuclear magnetic resonance image reagent in clinical practice, the study of interactive mechanism of rare earth in biological body has展开更多
With the wide applications of lanthanide in both industry and agriculture, the mechanism that lanthanide ions are absorbed by organism attracts more and more attention. However, the first issue of the interaction betw...With the wide applications of lanthanide in both industry and agriculture, the mechanism that lanthanide ions are absorbed by organism attracts more and more attention. However, the first issue of the interaction between lanthanide and organism is between lanthanide ions and biological membrane. Thus the study of the interaction between lanthanide ions and biological membrane plays a fundamental role in explaining the physiological effect of lanthanide. In fact the biological membrane is too展开更多
Amphiphilic lipid molecules can form various micelles depending on not only their molecular composition but also their self-assembly pathway. In this work, coarse-grained molecular dynamics simulations have been appli...Amphiphilic lipid molecules can form various micelles depending on not only their molecular composition but also their self-assembly pathway. In this work, coarse-grained molecular dynamics simulations have been applied to study the micellization behaviors of mixed dipalmitoylphosphatidylcholine （DPPC）/hexadecylphosphocholine （HPC） droplets. By vary- ing DPPC/HPC composition and the size of lipid droplets, various micelles such as spherical and nonspherical （oblate or prolate） vesicles, disk-like micelles, double or single ring-like and worm-like micelles were observed. It is found that the lipid droplet as an initial state favors forming vesicles and ring-like micelles due to in situ micellization. Our simulation results demonstrate that using special initial conditions combined with various molecular compositions is an effective way to tune lipid micellar structure.展开更多
On the basis of energy conservation law and surface pressure isotherm, the conformation energy changes of dipalmitoylphosphatidylcholine （DPPC） and dipalmitoylphosphatidylglycerol （DPPG） in pure phospholipid rnono...On the basis of energy conservation law and surface pressure isotherm, the conformation energy changes of dipalmitoylphosphatidylcholine （DPPC） and dipalmitoylphosphatidylglycerol （DPPG） in pure phospholipid rnonolayer at the air/water interface during compression are derived. The optimized conformations of phospholipids at absolute freedom state are simulated by Gaussian 98 software. Based on following assumptions： （1） the conformation energy change is mainly caused by the rotation of one special bond; （2） the atoms of glycerol near the water surface are active; （3） the rotation is motivated by hydrogen-bond action; （4） the rotation of bond is inertial, one simplified track of conformational change is suggested and the conformations of DPPC and DPPG at different states are determined by the plots of conformation energy change vs. dihedral angle. The thickness of the simulated phospholipid monolayer is consistent with published experimental result. According to molecular areas at different states, the molecular orientations in the compressing process are also developed.展开更多
Abstract The phase behavior of twelve synthesized β- sitosteryl fatty acid esters with acyl moieties with different chain lengths （C2：0-C18：0） and different degrees of unsaturation （C18：1-C18：3） were investig...Abstract The phase behavior of twelve synthesized β- sitosteryl fatty acid esters with acyl moieties with different chain lengths （C2：0-C18：0） and different degrees of unsaturation （C18：1-C18：3） were investigated in pure and mixed Langmuir monolayers with phospholipids. The surface-pressure isotherms showed that short chain fl- sitosteryl fatty acid esters gave smaller mean molecular areas and had decreased monolayer stability and the long chain steryl esters did not produce collapsed plateaus. All the steryl esters displayed strong condensing effects, but there was a pronounced structural dependency： medium chain esters （C8 and C 10） were less efficient than short and long chain esters. Atomic force microscopy imaging demonstrated that monolayers mixed with dipalmitoyl phosphatidylcholine （DPPC） displayed both DPPC-rich and steryl lipid-rich domains. However, the height and area differences between the two phases and the roughness and morphologic patterns were very dependent on the steryl lipid concentrations as well as the length, the degree of unsaturation and the molecular conformations of the acyl segments. These findings not only provide a better understanding of the interactions between phytosteryl hydrophobic derivatives and biomembranes, but also may be of general use for the design and engineering of phytosterol structural derivations for specific food and pharmaceutical applications.展开更多
Excellent wear resistance is an important feature of orthopedic implants.However,although pure polyetheretherketone(PEEK)is outperformed by carbon fiber-reinforced PEEK(CF-PEEK)for stability and durability under labor...Excellent wear resistance is an important feature of orthopedic implants.However,although pure polyetheretherketone(PEEK)is outperformed by carbon fiber-reinforced PEEK(CF-PEEK)for stability and durability under laboratory conditions,it is not clear whether CF-PEEK should be preferred in all real-world applications.Results indicate that,under dipalmitoylphosphatidylcholine(DPPC)lubrication,the wear rates of PEEK are 35%-80%lower than the wear rates of CF-PEEK for different implant materials,speeds,loadings,and DPPC concentrations.Molecular dynamics calculations confirm that DPPC self-assembles on the PEEK surface to form an easily adsorbed continuous phospholipid lubricating film.In contrast,the carbon fibers on the CF-PEEK surface hinder the formation of the protective DPPC film and the CF-PEEK surface is thus subject to faster wear.展开更多
文摘The interactions of lanthanoid ions with dipalmitoylphosphatidylcholine bilayer were studied by DSC and Raman spectroscopy.The results show that the addition of lanthanoid ions causes a considerable increase of the gel to liquid crystalline transition temperature of phospholipid and a reduction of order of lateral packing and conformation of acyl chains in SUVs.
文摘Urinary phospholipids are shown to be sensitive biomarkers for kidney injury. Many works have been reported on qualitative analysis of phospholipids and relative components in human urine while quantitative analysis is rare. We have therefore developed a reliable and convenient quantitative method to evaluate the accuracy and specificity of dipalmitoylphosphatidylcholine （DPPC） as a biomarker for kidney injury diagnosis. Chromatographic separation was achieved using a HILIC Silica Column （2.1 ram^50 mm, 5 p.m）. Gradient elution was performed with 5 mM ammonium formate （0.1% formic acid） and acetonitrile （0.1% formic acid）, at a flow rate of 0.3 mL/min. This method was validated in a linear range of 2-200 ng/mL DPPC with inter-day precision of less than 6.5% and accuracy within 111.2% in human urine. Recovery rate, stability, dilution effect and matrix effect also met the requirements for drug evaluation and research issued by FDA. As the first HPLC-MS/MS method for quantitative determination of DPPC, it has been successfully applied to determine levels of DPPC in clinical urine samples and evaluated for potential use in the measurement of DPPC as a biomarker for kidney injury.
基金Project supported by the National Natural Science Foundation of China
文摘With the extensive applications of rare earth in agriculture, medicament etc., especially the application of Gd-DTPA as nuclear magnetic resonance image reagent in clinical practice, the study of interactive mechanism of rare earth in biological body has
文摘With the wide applications of lanthanide in both industry and agriculture, the mechanism that lanthanide ions are absorbed by organism attracts more and more attention. However, the first issue of the interaction between lanthanide and organism is between lanthanide ions and biological membrane. Thus the study of the interaction between lanthanide ions and biological membrane plays a fundamental role in explaining the physiological effect of lanthanide. In fact the biological membrane is too
基金This work was supported by the National Natural Science Foundation of China （No.20974078 and No.91127046）, Computation was carried out in High Performance Computing Center of Tianjin University.
文摘Amphiphilic lipid molecules can form various micelles depending on not only their molecular composition but also their self-assembly pathway. In this work, coarse-grained molecular dynamics simulations have been applied to study the micellization behaviors of mixed dipalmitoylphosphatidylcholine （DPPC）/hexadecylphosphocholine （HPC） droplets. By vary- ing DPPC/HPC composition and the size of lipid droplets, various micelles such as spherical and nonspherical （oblate or prolate） vesicles, disk-like micelles, double or single ring-like and worm-like micelles were observed. It is found that the lipid droplet as an initial state favors forming vesicles and ring-like micelles due to in situ micellization. Our simulation results demonstrate that using special initial conditions combined with various molecular compositions is an effective way to tune lipid micellar structure.
基金Supported by the National Natural Science Foundation of China （20876047）.
文摘On the basis of energy conservation law and surface pressure isotherm, the conformation energy changes of dipalmitoylphosphatidylcholine （DPPC） and dipalmitoylphosphatidylglycerol （DPPG） in pure phospholipid rnonolayer at the air/water interface during compression are derived. The optimized conformations of phospholipids at absolute freedom state are simulated by Gaussian 98 software. Based on following assumptions： （1） the conformation energy change is mainly caused by the rotation of one special bond; （2） the atoms of glycerol near the water surface are active; （3） the rotation is motivated by hydrogen-bond action; （4） the rotation of bond is inertial, one simplified track of conformational change is suggested and the conformations of DPPC and DPPG at different states are determined by the plots of conformation energy change vs. dihedral angle. The thickness of the simulated phospholipid monolayer is consistent with published experimental result. According to molecular areas at different states, the molecular orientations in the compressing process are also developed.
文摘Abstract The phase behavior of twelve synthesized β- sitosteryl fatty acid esters with acyl moieties with different chain lengths （C2：0-C18：0） and different degrees of unsaturation （C18：1-C18：3） were investigated in pure and mixed Langmuir monolayers with phospholipids. The surface-pressure isotherms showed that short chain fl- sitosteryl fatty acid esters gave smaller mean molecular areas and had decreased monolayer stability and the long chain steryl esters did not produce collapsed plateaus. All the steryl esters displayed strong condensing effects, but there was a pronounced structural dependency： medium chain esters （C8 and C 10） were less efficient than short and long chain esters. Atomic force microscopy imaging demonstrated that monolayers mixed with dipalmitoyl phosphatidylcholine （DPPC） displayed both DPPC-rich and steryl lipid-rich domains. However, the height and area differences between the two phases and the roughness and morphologic patterns were very dependent on the steryl lipid concentrations as well as the length, the degree of unsaturation and the molecular conformations of the acyl segments. These findings not only provide a better understanding of the interactions between phytosteryl hydrophobic derivatives and biomembranes, but also may be of general use for the design and engineering of phytosterol structural derivations for specific food and pharmaceutical applications.
基金This work was financially supported by the National Natural Science Foundation of China(Grant Nos.52175180,51805366)the Natural Science Foundation of Tianjin City(Grant No.19JCQNJC04100).
文摘Excellent wear resistance is an important feature of orthopedic implants.However,although pure polyetheretherketone(PEEK)is outperformed by carbon fiber-reinforced PEEK(CF-PEEK)for stability and durability under laboratory conditions,it is not clear whether CF-PEEK should be preferred in all real-world applications.Results indicate that,under dipalmitoylphosphatidylcholine(DPPC)lubrication,the wear rates of PEEK are 35%-80%lower than the wear rates of CF-PEEK for different implant materials,speeds,loadings,and DPPC concentrations.Molecular dynamics calculations confirm that DPPC self-assembles on the PEEK surface to form an easily adsorbed continuous phospholipid lubricating film.In contrast,the carbon fibers on the CF-PEEK surface hinder the formation of the protective DPPC film and the CF-PEEK surface is thus subject to faster wear.
