Using a Langmuir-Blodgett film of dipalmitoylphosphatidylcholine(DPPC), a model of biomembranes, as a template, we succeed in obtaining oriented KH 2PO 4(KDP) crystals toward crystal face (100) under well-compressed D...Using a Langmuir-Blodgett film of dipalmitoylphosphatidylcholine(DPPC), a model of biomembranes, as a template, we succeed in obtaining oriented KH 2PO 4(KDP) crystals toward crystal face (100) under well-compressed DPPC monolayer. This is explicable in terms of the geometrical complementarity between KDP and the DPPC monolayer. It is found that the distances between the closest K-K (0.416 nm) fit the d(100) network spacing of DPPC monolayer(0.420 nm), which results in that the special activation energy for nucleation exists in the interface covered with DPPC monolayer. DPPC monolayer has a very strong selected catalysis on the crystallization of KDP crystal face (100), and drives KDP rapid and oriented nucleation on the monolayer/solution interface. The oriented KDP crystals show a good second harmonic generation(SHG) signal.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
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
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
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
The effects of urinary macromolecul e chondroitin sulfate A(C 4 S)and L-glutamic acid(L-Glu)on the crys-tallization of calcium oxalate were studied using Langmuir-Blodgett(LB)film of dipalmitoylphosphatidylch oline(DP...The effects of urinary macromolecul e chondroitin sulfate A(C 4 S)and L-glutamic acid(L-Glu)on the crys-tallization of calcium oxalate were studied using Langmuir-Blodgett(LB)film of dipalmitoylphosphatidylch oline(DPPC)as templet.All the calcium oxalate c rystals induced by the LB film of DPPC were calcium oxalate monohydrate(COM).However,the morphology of COM was i nfluenced by the additives of C 4 S and L-Glu.C 4 S induced thin and long hexagonal COM c rystals;L-Glu made one or two (010)crystal face of COM crystals dis-appeared.The crystallization time had no effect on the morphology of COM crystals,but the concentration of C 4 S and L-Glu changed it.As increasing the co ncentration of C 4 S,the amount of COM crystals with a hexagonal prism decreased and that with a thin hexago nal slice increased.When the concen tration of C 4 S was 0.50mg ·mL -1 ,all the calcium oxalate crystals were th in hexagonal slice COM crystals.How ever,as the concentration of L-Glu in-creased from 0.01to 0.50mmol·L -1 ,the hexagonal prism-like COM crystals gradually transformed to COM crystals with one or two (010)crystal face disappearance.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
Objective： To detect the levels of dipalmitoyl phosphatidyl choline （DPPC） in the sputum of the patients with acute cerebral injury without primary pulmonary injury after mechanical ventilation treatment. Methods...Objective： To detect the levels of dipalmitoyl phosphatidyl choline （DPPC） in the sputum of the patients with acute cerebral injury without primary pulmonary injury after mechanical ventilation treatment. Methods： DPPC levels in sputum of 35 patients with acute cerebral injury but without pulmonary injury were detected with high performance liquid chromatography at the beginning of ventilation and 16-20 days, 21-40 days, and 41-60 days after ventilation, respectively. Results： There was no significant difference of the DPPC levels between 16-20 days after ventilation （3.36±0.49） and at the beginning of ventilation （3.37 ± 0.58 ） （P〉0.05）. The mean levels of DPPC decreased significantly at 21-40 days （2.87 mg/ml ±0.26 mg/ml, P〈0.05） and 41-60 days （1.93 mg/ml ±0.21 mg/ml, P〈0.01 ） after ventilation compared with that at the beginning of ventilation. At the same period, the peak inspiratory pressure and the mean pressure of airway increased significantly, whereas the static compliance and the partial pressure of oxygen in artery decreased significantly. Among the 25 patients who received ventilation for more than 20 days, 8 （32%） had slightly-decreased partial pressure of oxygen in artery compared with that at the beginning of ventilation. Conclusions： Mechanical ventilation can decrease the DPPC levels, decrease the lung compliance and increase the airway pressure, even impair the oxygenation function in patients with acute cerebral injury. Abnormal DPPC is one of the major causes of ventilator-associated lung injury.展开更多
文摘Using a Langmuir-Blodgett film of dipalmitoylphosphatidylcholine(DPPC), a model of biomembranes, as a template, we succeed in obtaining oriented KH 2PO 4(KDP) crystals toward crystal face (100) under well-compressed DPPC monolayer. This is explicable in terms of the geometrical complementarity between KDP and the DPPC monolayer. It is found that the distances between the closest K-K (0.416 nm) fit the d(100) network spacing of DPPC monolayer(0.420 nm), which results in that the special activation energy for nucleation exists in the interface covered with DPPC monolayer. DPPC monolayer has a very strong selected catalysis on the crystallization of KDP crystal face (100), and drives KDP rapid and oriented nucleation on the monolayer/solution interface. The oriented KDP crystals show a good second harmonic generation(SHG) signal.
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.
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The effects of urinary macromolecul e chondroitin sulfate A(C 4 S)and L-glutamic acid(L-Glu)on the crys-tallization of calcium oxalate were studied using Langmuir-Blodgett(LB)film of dipalmitoylphosphatidylch oline(DPPC)as templet.All the calcium oxalate c rystals induced by the LB film of DPPC were calcium oxalate monohydrate(COM).However,the morphology of COM was i nfluenced by the additives of C 4 S and L-Glu.C 4 S induced thin and long hexagonal COM c rystals;L-Glu made one or two (010)crystal face of COM crystals dis-appeared.The crystallization time had no effect on the morphology of COM crystals,but the concentration of C 4 S and L-Glu changed it.As increasing the co ncentration of C 4 S,the amount of COM crystals with a hexagonal prism decreased and that with a thin hexago nal slice increased.When the concen tration of C 4 S was 0.50mg ·mL -1 ,all the calcium oxalate crystals were th in hexagonal slice COM crystals.How ever,as the concentration of L-Glu in-creased from 0.01to 0.50mmol·L -1 ,the hexagonal prism-like COM crystals gradually transformed to COM crystals with one or two (010)crystal face disappearance.
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.
基金This study was supported by Zhejiang Provincial Program Funds of the Science and Technology Department ( No. 2004C33048)by funds of Science and Technology Department of Hangzhou City (No. 2004C33368).
文摘Objective： To detect the levels of dipalmitoyl phosphatidyl choline （DPPC） in the sputum of the patients with acute cerebral injury without primary pulmonary injury after mechanical ventilation treatment. Methods： DPPC levels in sputum of 35 patients with acute cerebral injury but without pulmonary injury were detected with high performance liquid chromatography at the beginning of ventilation and 16-20 days, 21-40 days, and 41-60 days after ventilation, respectively. Results： There was no significant difference of the DPPC levels between 16-20 days after ventilation （3.36±0.49） and at the beginning of ventilation （3.37 ± 0.58 ） （P〉0.05）. The mean levels of DPPC decreased significantly at 21-40 days （2.87 mg/ml ±0.26 mg/ml, P〈0.05） and 41-60 days （1.93 mg/ml ±0.21 mg/ml, P〈0.01 ） after ventilation compared with that at the beginning of ventilation. At the same period, the peak inspiratory pressure and the mean pressure of airway increased significantly, whereas the static compliance and the partial pressure of oxygen in artery decreased significantly. Among the 25 patients who received ventilation for more than 20 days, 8 （32%） had slightly-decreased partial pressure of oxygen in artery compared with that at the beginning of ventilation. Conclusions： Mechanical ventilation can decrease the DPPC levels, decrease the lung compliance and increase the airway pressure, even impair the oxygenation function in patients with acute cerebral injury. Abnormal DPPC is one of the major causes of ventilator-associated lung injury.
