The Experts below are selected from a list of 19929 Experts worldwide ranked by ideXlab platform

Zhongying Jiang - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Osmotic Stress on Membrane Fusion on Solid Substrate
    Langmuir, 2013
    Co-Authors: Zhongying Jiang, El Mi Ra Nurlybaeva, Jie Sheng, Yu-qiang Ma
    Abstract:

    There is currently a lack of comprehensive understanding of osmotic effect on Lipid Vesicle fusion on solid oxide surface. The question has both biological and biomedical implications. We studied the effect by quartz crystal microbalance with dissipation monitoring using NaCl, sucrose as osmolytes, and two different osmotic stress imposition methods, which allowed us to separate the osmotic effects from the solute impacts. Osmotic stress was found to have limited influence on the fusion kinetics, independently of the direction of the gradient. Further atomic force microscopy experiments and energy consideration implied that osmotic stress spends the majority of chemical potential energy associated in directed transport of water across membrane. Its contribution to Vesicle deformation and fusion on substrate is therefore small compared to that of adhesion.

  • effect of calcium cation on Lipid Vesicle deposition on silicon dioxide surface under various thermal conditions
    Colloids and Surfaces B: Biointerfaces, 2012
    Co-Authors: Fan Xu, Bing Yuan, Zhongying Jiang
    Abstract:

    Abstract Calcium cation (Ca2+) is a key element to the cell membrane functions. Its effects on liquid crystal Vesicle deposition have already been learnt. In this study, it is found that Ca2+ can also influence the gel Vesicle deposition by controlling the Vesicle rupture and fusion on SiO2 at temperatures lower than the main transition temperature. Particular analyses were given to the Vesicle–SiO2 and inter-Vesicle attractions that are originated from the Ca2+ bridging effect. It is concluded that the aggregate condition of Vesicles should be taken into consideration when dealing with Vesicle deposition on a solid substrate.

Christine D. Keating - One of the best experts on this subject based on the ideXlab platform.

  • Lipid Vesicle coated complex coacervates
    Langmuir, 2019
    Co-Authors: Fatma Pir Cakmak, Alex T. Grigas, Christine D. Keating
    Abstract:

    Compartmentalization by complex coacervation is important across a range of different fields including subcellular and prebiotic organization, biomedicine, food science, and personal care products. Often, Lipid self-assemblies such as Vesicles are also present intracellularly or in commercial formulations. A systematic understanding of how phosphoLipid Vesicles interact with different complex coacervates could provide insight and improve control over these systems. In this manuscript, anionic phosphoLipid Vesicles were added to a series of different complex coacervate samples in which coacervates were formed by mixing one of five polycations with one of three (poly)anions that varied in chemical structure and length. Vesicles were found to assemble at the coacervate/continuous phase interface and/or form aggregates. We report how factors such as the charge density of polyelectrolytes and the charge ratio of cationic to anionic moieties impacts Vesicle distribution in coacervate samples. Our findings empha...

  • Lipid Vesicle coated complex coacervates
    Langmuir, 2019
    Co-Authors: Fatma Pir Cakmak, Alex T. Grigas, Christine D. Keating
    Abstract:

    Compartmentalization by complex coacervation is important across a range of different fields including subcellular and prebiotic organization, biomedicine, food science, and personal care products. Often, Lipid self-assemblies such as Vesicles are also present intracellularly or in commercial formulations. A systematic understanding of how phosphoLipid Vesicles interact with different complex coacervates could provide insight and improve control over these systems. In this manuscript, anionic phosphoLipid Vesicles were added to a series of different complex coacervate samples in which coacervates were formed by mixing one of five polycations with one of three (poly)anions that varied in chemical structure and length. Vesicles were found to assemble at the coacervate/continuous phase interface and/or form aggregates. We report how factors such as the charge density of polyelectrolytes and the charge ratio of cationic-to-anionic moieties impact the Vesicle distribution in coacervate samples. Our findings em...

  • Lipid Vesicle-Coated Complex Coacervates
    2019
    Co-Authors: Fatma Pir Cakmak, Alex T. Grigas, Christine D. Keating
    Abstract:

    Compartmentalization by complex coacervation is important across a range of different fields including subcellular and prebiotic organization, biomedicine, food science, and personal care products. Often, Lipid self-assemblies such as Vesicles are also present intracellularly or in commercial formulations. A systematic understanding of how phosphoLipid Vesicles interact with different complex coacervates could provide insight and improve control over these systems. In this manuscript, anionic phosphoLipid Vesicles were added to a series of different complex coacervate samples in which coacervates were formed by mixing one of five polycations with one of three (poly)­anions that varied in chemical structure and length. Vesicles were found to assemble at the coacervate/continuous phase interface and/or form aggregates. We report how factors such as the charge density of polyelectrolytes and the charge ratio of cationic-to-anionic moieties impact the Vesicle distribution in coacervate samples. Our findings emphasize the importance of interactions between Vesicles and polycations in the dilute supernatant phase for determining whether the Vesicles aggregate prior to assembly at the liquid–liquid interface. The uptake of an RNA oligonucleotide (A15) was also investigated to understand the effect of these liposome coatings on diffusion into coacervate droplets. Systems in which uniform Vesicle coronas assemble around coacervate droplets without restricting the entry of biomolecules such as RNAs could be of interest as bioreactors

Shinji Iijima - One of the best experts on this subject based on the ideXlab platform.

  • Protamine-modified DDAB Lipid Vesicles promote gene transfer in the presence of serum
    Journal of biochemistry, 2001
    Co-Authors: Shinji Mizuarai, Jun You, Masamichi Kamihira, Kenichiro Ono, Shinji Iijima
    Abstract:

    Cationic Lipid Vesicle-mediated gene transfer has become common for in vitro gene delivery. However, the transfection efficiency is often impaired by serum. DDAB (dimethyldioctadecyl ammonium bromide) Lipid Vesicle-mediated gene transfer, which we previously reported, has the same problem. To overcome this obstacle, we here report a novel transfection vehicle using protamine-modified DDAB Lipid Vesicles. While free protamine was simply added to the DNA/Lipid complex in the previous study, in the present method the protamine is chemically conjugated to stearic acid and incorporated into DDAB Lipid Vesicles. Gene transfer was not significantly inhibited in 10% serum-containing medium by this method for the transfection of cultured cells. Protamine-modified DDAB Lipid Vesicles also enhanced virus transduction efficiency in the presence of serum using a replication-defective retroviral vector. Furthermore, the Vesicles allowed efficient gene transfer for avian embryos in vivo. These results indicate that the method is useful for the production of transgenic animals and gene therapy.

  • Enhancement of transfection efficiency by protamine in DDAB Lipid Vesicle-mediated gene transfer.
    Journal of biochemistry, 1999
    Co-Authors: Jun You, Masamichi Kamihira, Shinji Iijima
    Abstract:

    We have previously developed a simple gene transfection procedure mediated by cationic Lipid Vesicles for animal cells, in which a commercially available cationic surfactant, dimethyldioctadecyl ammonium bromide (DDAB), was used for making Lipid Vesicles. In the present study, we examined enhancement of transfection efficiency for this method by adding protamine to plasmid DNA solution before the formation of DNA/Lipid Vesicle complexes. Both free-base protamine and protamine sulfate provided enhanced transfection efficiency and expression level, but the optimal amount of the two protamines was different. The enhancement in transfection efficiency and expression level by protamines was observed in all the cell lines (COS-7, Hela, NIH3T3, MDCK, and BHK-21C13) and all the plasmids (pCMVbeta, pmiwZ, and pCH110) tested. The enhancement in both transfection efficiency and expression level was at most 20-fold compared with that using only DDAB Lipid Vesicles. Protamines seemed to protect DNA from degradation by DNase and promote DNA delivery into a nucleus.

  • Enhancement of transfection efficiency using ligand-modified Lipid Vesicles
    Journal of Fermentation and Bioengineering, 1998
    Co-Authors: Jun You, Masamichi Kamihira, Shinji Iijima
    Abstract:

    We have developed a simple gene transfection procedure mediated by cationic Lipid Vesicles for mammalian cells, in which a commercially available synthetic cationic surfactant, dimethyldioctadecyl ammonium bromide (DDAB), was used for making Lipid Vesicles. The Lipid Vesicles were modified with insulin or galactose residue for receptor mediated gene transfer to enhance transfection efficiency. The insulin-modified Lipid Vesicle solution mixed with plasmid DNA (pCMVβ) was added to Hela, MDCK, NIH3T3 or HepG2 cells. In all the cell lines tested, the transfection efficiencies were increased 3-4 folds. However, excessive free insulin addition to the medium resulted in decreased transfection efficiency, suggesting that the specific interaction between insulin and its receptor gave increased efficiency. The galactose-modified Lipid Vesicles and the plasmid DNA solution was added to HepG2 or HuH-6 cells expressing asialoglycoprotein receptors, and the transfection efficiencies were also increased 3-4 folds with these cell lines.

Fredrik Hook - One of the best experts on this subject based on the ideXlab platform.

  • single Lipid Vesicle assay for characterizing single enzyme kinetics of phosphoLipid hydrolysis in a complex biological fluid
    Journal of the American Chemical Society, 2013
    Co-Authors: Seyed R Tabaei, Vladimir P Zhdanov, Michael Rabe, Henrik Zetterberg, Fredrik Hook
    Abstract:

    Imaging of individual Lipid Vesicles is used to track single-enzyme kinetics of phosphoLipid hydrolysis. The method is employed to quantify the catalytic activity of phospholipase A2 (PLA2) in both pure and complex biological fluids. The measurements are demonstrated to offer a subpicomolar limit of detection (LOD) of human secretory PLA2 (sPLA2) in up to 1000-fold-diluted cerebrospinal fluid (CSF). An additional new feature provided by the single-enzyme sensitivity is that information about both relative concentration variations of active sPLA2 in CSF and the specific enzymatic activity can be simultaneously obtained. When CSF samples from healthy controls and individuals diagnosed with Alzheimer's disease (AD) are analyzed, the specific enzymatic activity is found to be preserved within 7% in the different CSF samples whereas the enzyme concentration differs by up to 56%. This suggests that the previously reported difference in PLA2 activity in CSF samples from healthy and AD individuals originates from differences in the PLA2 expression level rather than from the enzyme activity. Conventional ensemble averaging methods used to probe sPLA2 activity do not allow one to obtain such information. Together with an improvement in the LOD of at least 1 order of magnitude compared to that of conventional assays, this suggests that the method will become useful in furthering our understanding of the role of PLA2 in health and disease and in detecting the pharmacodynamic effects of PLA2-targeting drug candidates.

Asgar Ali - One of the best experts on this subject based on the ideXlab platform.

  • formulation by design based risperidone nano soft Lipid Vesicle as a new strategy for enhanced transdermal drug delivery in vitro characterization and in vivo appraisal
    Materials Science and Engineering: C, 2017
    Co-Authors: Syed Sarim Imam, Abdul Ahad, Mohammed Aqil, Mohd Akhtar, Yasmin Sultana, Asgar Ali
    Abstract:

    The present study was designed to formulate and optimize transdermal risperidone soft Lipid Vesicles. The formulation optimized with phosphoLipid, safranal and ethanol were incorporated as permeation and absorption enhancers. The optimized risperidone soft Lipid Vesicle was further evaluated for skin irritation study, in-vivo pharmacokinetic study and locomotor activity. Three factor three level Box-Behnken design (BBD) was used to statistically optimize soft Lipid Vesicle using safranal (A), ethanol (B)and phosphoLipid (C) as independent variable, while their effect was observed for Vesicle size (Y1), entrapment efficiency (Y2) and flux (Y3). The optimized risperidone soft Lipid Vesicle (Ris-opt) showed nanometric Vesicle size, high entrapment efficiency and marked enhancement in transdermal flux. The extent of absorption from Ris-opt was greater when compared to oral suspension with relative bioavailability of 177%. The histopathological evaluation revealed developed formulation did not showed skin irritation compared to standard irritant. The significant findings presented here encourage further studies with risperidone soft Lipid Vesicles for treatment of schizophrenia.