Short chain branching has been characterized using thermal fractionation, a stepwise isothermal crystallizationtechnique, followed by a melting analysis scan using differential scanning calorimetry. Short chain branch...Short chain branching has been characterized using thermal fractionation, a stepwise isothermal crystallizationtechnique, followed by a melting analysis scan using differential scanning calorimetry. Short chain branching distributionwas also characterized by a continuous slow cooling crystallization, followed by a melting analysis scan. Four differentpolyethylenes were studied: Ziegler-Natta gas phase, Ziegler-Natta solution, metallocene, constrained-geometry single sitecatalyzed polyethylenes. The branching distribution was calculated from a calibration of branch content with meltingtemperature. The lamellar thickness was calculated based on the thermodynamic melting temperature of each polyethyleneand the surface free energy of the crystal face. The branching distribution and lamellar thickness distribution were used tocalculate weight average branch content, mean lamellar thickness, and a branch dispersity index. The results for the branchcontent were in good agreement with the known comonomer content of the polyethylenes. A limitation was that high branchcontent polyethylenes did not reach their potential crystallization at ambient temperatures. Cooling to sub-ambient wasnecessary to equilibrate the crystallization, but melting temperature versus branch content was not applicable after cooling tobelow ambient because the calibration data were not performed in this way.展开更多
Recent clinical and epidemiological research has shown that insulin is associated with the pathological mechanisms of Alzheimer＇s disease （AD） and can protect against the oxidative stress triggered by amyloidq3 pep...Recent clinical and epidemiological research has shown that insulin is associated with the pathological mechanisms of Alzheimer＇s disease （AD） and can protect against the oxidative stress triggered by amyloidq3 peptide （Aβ3）. Herein, we present a systematic study on how the cross-fibrillation of insulin and Aβ is influenced by the surface chirality of an interface designed to mimic their aggregation on the cytomembrane. Intriguingly, the surface chirality strongly affected the aggregation kinetics, structure, morphologβ and cellular responses of the cross-aggregates of insulin and Aβ. On a D-phenylalanine- modified surface, Aβ induced insulin to co-aggregate into β-sheet-rich fibrils and cross-fibrils that showed a pronounced cellular toxicity. However, on an L-phenylalanine-modified surface, insulin and Aβ3 formed non-toxic amorphous aggregates. Our work indicates that surface chirality can influence the cross- fibrillation of Aβ and insulin as well as the cytotoxicity of their aggregates.展开更多
The aggregation of amyloid-β peptide （Aβ） is implicated in the pathology of Alzheimer＇s disease （AD）, and Aβ oligomers are considered the most toxic species. Therefore, the detection and clearance of Aβ oligo...The aggregation of amyloid-β peptide （Aβ） is implicated in the pathology of Alzheimer＇s disease （AD）, and Aβ oligomers are considered the most toxic species. Therefore, the detection and clearance of Aβ oligomers are crucial for the theranostic strategies for AD. However, effective methods for the detection of Aβ oligomers are rare, and only few of the oligomer-specific sensors have therapeutic functions as well. Recent studies have demonstrated that the toxicity of Aβ oligomers is related to the number of exposed hydrophobic residues. In this study, an oligomer-specific fluorescent probe, which was based on the hydrophobic regions that are exposed on Aβ oligomer surfaces was designed and synthesized. For improving the ability to recognize Aβ oligomers, the in situ treatment of AD symptoms and the ability to penetrate the blood-brain barrier, the probe and KLVFF peptide （an Aβ-target peptide） were modified on the surfaces of magnetic nanoparticles （MNP@NFP-pep）. This complex could detect Aβ oligomers specifically, and achieve the wireless deep magnetothermally mediated disaggregation of Aβ aggregates with an alternating magnetic field. This work provides new insights into the development of a ＂sense and treat＂ system for AD therapy.展开更多
文摘Short chain branching has been characterized using thermal fractionation, a stepwise isothermal crystallizationtechnique, followed by a melting analysis scan using differential scanning calorimetry. Short chain branching distributionwas also characterized by a continuous slow cooling crystallization, followed by a melting analysis scan. Four differentpolyethylenes were studied: Ziegler-Natta gas phase, Ziegler-Natta solution, metallocene, constrained-geometry single sitecatalyzed polyethylenes. The branching distribution was calculated from a calibration of branch content with meltingtemperature. The lamellar thickness was calculated based on the thermodynamic melting temperature of each polyethyleneand the surface free energy of the crystal face. The branching distribution and lamellar thickness distribution were used tocalculate weight average branch content, mean lamellar thickness, and a branch dispersity index. The results for the branchcontent were in good agreement with the known comonomer content of the polyethylenes. A limitation was that high branchcontent polyethylenes did not reach their potential crystallization at ambient temperatures. Cooling to sub-ambient wasnecessary to equilibrate the crystallization, but melting temperature versus branch content was not applicable after cooling tobelow ambient because the calibration data were not performed in this way.
文摘Recent clinical and epidemiological research has shown that insulin is associated with the pathological mechanisms of Alzheimer＇s disease （AD） and can protect against the oxidative stress triggered by amyloidq3 peptide （Aβ3）. Herein, we present a systematic study on how the cross-fibrillation of insulin and Aβ is influenced by the surface chirality of an interface designed to mimic their aggregation on the cytomembrane. Intriguingly, the surface chirality strongly affected the aggregation kinetics, structure, morphologβ and cellular responses of the cross-aggregates of insulin and Aβ. On a D-phenylalanine- modified surface, Aβ induced insulin to co-aggregate into β-sheet-rich fibrils and cross-fibrils that showed a pronounced cellular toxicity. However, on an L-phenylalanine-modified surface, insulin and Aβ3 formed non-toxic amorphous aggregates. Our work indicates that surface chirality can influence the cross- fibrillation of Aβ and insulin as well as the cytotoxicity of their aggregates.
基金Financial support was provided by the National Basic Research Program of China （973 Program） （No. 2012CB720602）, the Project of Science and Technology Development Plan for Jilin Province （No. 20150520004JH） and the National Natural Science Foundation of China （NSFC） （Nos. 21210002, 21431007, 21402183 and 21533008）.
文摘The aggregation of amyloid-β peptide （Aβ） is implicated in the pathology of Alzheimer＇s disease （AD）, and Aβ oligomers are considered the most toxic species. Therefore, the detection and clearance of Aβ oligomers are crucial for the theranostic strategies for AD. However, effective methods for the detection of Aβ oligomers are rare, and only few of the oligomer-specific sensors have therapeutic functions as well. Recent studies have demonstrated that the toxicity of Aβ oligomers is related to the number of exposed hydrophobic residues. In this study, an oligomer-specific fluorescent probe, which was based on the hydrophobic regions that are exposed on Aβ oligomer surfaces was designed and synthesized. For improving the ability to recognize Aβ oligomers, the in situ treatment of AD symptoms and the ability to penetrate the blood-brain barrier, the probe and KLVFF peptide （an Aβ-target peptide） were modified on the surfaces of magnetic nanoparticles （MNP@NFP-pep）. This complex could detect Aβ oligomers specifically, and achieve the wireless deep magnetothermally mediated disaggregation of Aβ aggregates with an alternating magnetic field. This work provides new insights into the development of a ＂sense and treat＂ system for AD therapy.
