scholarly journals Molecular Shape of the Cationic Lipid Controls the Structure of Cationic Lipid/Dioleylphosphatidylethanolamine-DNA Complexes and the Efficiency of Gene Delivery

2001 ◽  
Vol 276 (50) ◽  
pp. 47615-47622 ◽  
Author(s):  
Jarmila S̆misterová ◽  
Anno Wagenaar ◽  
Marc C. A. Stuart ◽  
Evgeny Polushkin ◽  
Gerrit ten Brinke ◽  
...  
Keyword(s):  
Transfection Efficiency ◽  
Cationic Lipid ◽  
Molecular Shape ◽  
Hexagonal Structure ◽  
Structure Stability ◽  
Dna Complexes ◽  
Cross Sectional ◽  
X Ray Scattering ◽  
Lipid Control ◽  
The Stability

Pyridinium amphiphiles, abbreviated as SAINT, are highly efficient vectors for delivery of DNA into cells. Within a group of structurally related compounds that differ in transfection capacity, we have investigated the role of the shape and structure of the pyridinium molecule on the stability of bilayers formed from a given SAINT and dioleoylphosphatidylethanolamine (DOPE) and on the polymorphism of SAINT/DOPE-DNA complexes. Using electron microscopy and small angle x-ray scattering, a relationship was established between the structure, stability, and morphology of the lipoplexes and their transfection efficiency. The structure with the lowest ratio of the cross-sectional area occupied by polar over hydrophobic domains (SAINT-2) formed the most unstable bilayers when mixed with DOPE and tended to convert into the hexagonal structure. In SAINT-2-containing lipoplexes, a hexagonal topology was apparent, provided that DOPE was present and complex assembly occurred in 150 mmNaCl. If not, a lamellar phase was obtained, as for lipoplexes prepared from geometrically more balanced SAINT structures. The hexagonal topology strongly promotes transfection efficiency, whereas a strongly reduced activity is seen for complexes displaying the lamellar topology. We conclude that in the DOPE-containing complexes the molecular shape and the nonbilayer preferences of the cationic lipid control the topology of the lipoplex and thereby the transfection efficiency.

scholarly journals Transfection efficiency and toxicity following delivery of naked plasmid DNA and cationic lipid–DNA complexes to ovine lung segments

2003 ◽  
Vol 8 (4) ◽  
pp. 646-653 ◽  
Author(s):  
Michael Emerson ◽  
Louise Renwick ◽  
Stephen Tate ◽  
Susan Rhind ◽  
Elspeth Milne ◽  
...  
Keyword(s):  
Plasmid Dna ◽  
Transfection Efficiency ◽  
Cationic Lipid ◽  
Dna Complexes ◽  
Naked Plasmid ◽  
Naked Plasmid Dna

Chitosan Derivatives as Gene Carriers

2005 ◽  
Vol 288-289 ◽  
pp. 97-100 ◽  
Author(s):  
Tae Hee Kim ◽  
In Kyu Park ◽  
Su Il Kim ◽  
Hwan Jeong Jeong ◽  
Hee Seung Bom ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Chemical Modification ◽  
Review Paper ◽  
Transfection Efficiency ◽  
Gene Delivery System ◽  
Dna Complexes ◽  
Gene Carriers ◽  
Toxic Material ◽  
Cell Specificity ◽  
The Stability

Chitosan has been considered to be a good candidate for gene delivery system, since it is already known as a biocompatible, biodegradable, and low toxic material with high cationic potential. However, low specificity and low transfection efficiency of chitosan need to be overcome prior to clinical trial. In this review paper, chemical modification of chitosan for enhancement of cell specificity and transfection efficiency was explained. Also, chemical modification of chitosan for the stability of chitosan/DNA complexes was reviewed.

scholarly journals pH-Sensitive Pegylated Cationic Lipid-DNA Complexes for Gene Delivery: Transfection Efficiency and Live Cell Imaging Studies

2012 ◽  
Vol 102 (3) ◽  
pp. 501a-502a ◽  
Author(s):  
Chia-Ling Chan ◽  
Ramsey Majzoub ◽  
Rahau S. Shirazi ◽  
Keng-San Liang ◽  
Kai K. Ewert ◽  
...  
Keyword(s):  
Gene Delivery ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Transfection Efficiency ◽  
Cationic Lipid ◽  
Ph Sensitive ◽  
Live Cell ◽  
Imaging Studies ◽  
Dna Complexes

New Structure of CTAB Templated Silica Films as revealed by GISAXS coupled to HRTEM

2000 ◽  
Vol 628 ◽  
Author(s):  
Sophie Besson ◽  
Catherine Jacquiod ◽  
Thierry Gacoin ◽  
André Naudon ◽  
Christian Ricolleau ◽  
...  
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Grazing Incidence ◽  
Hexagonal Structure ◽  
X Ray Diffraction ◽  
Electronic Microscopy ◽  
Silica Films ◽  
X Ray ◽  
X Ray Scattering ◽  
Hexagonal Arrangement ◽  
Spherical Micelles

ABSTRACTA microstructural study on surfactant templated silica films is performed by coupling traditional X-Ray Diffraction (XRD) and Transmission Electronic Microscopy (TEM) to Grazing Incidence Small Angle X-Ray Scattering (GISAXS). By this method it is shown that spin-coating of silicate solutions with cationic surfactant cetyltrimethylammonium bromide (CTAB) as a templating agent provides 3D hexagonal structure (space group P63/mmc) that is no longer compatible with the often described hexagonal arrangement of tubular micelles but rather with an hexagonal arrangement of spherical micelles. The extent of the hexagonal ordering and the texture can be optimized in films by varying the composition of the solution.

Structure, Stability and Water Adsorption on Ultra-Thin TiO2 Supported on TiN

2019 ◽  
Author(s):  
Jose Julio Gutierrez Moreno ◽  
Marco Fronzi ◽  
Pierre Lovera ◽  
alan O'Riordan ◽  
Mike J Ford ◽  
...  
Keyword(s):  
Density Functional ◽  
Water Adsorption ◽  
Chemical Potential ◽  
Energy Gap ◽  
Molecular Water ◽  
Structure Stability ◽  
Ambient Conditions ◽  
Rutile Structure ◽  
The Stability ◽  
The One

<p></p><p>Interfacial metal-oxide systems with ultrathin oxide layers are of high interest for their use in catalysis. In this study, we present a density functional theory (DFT) investigation of the structure of ultrathin rutile layers (one and two TiO<sub>2</sub> layers) supported on TiN and the stability of water on these interfacial structures. The rutile layers are stabilized on the TiN surface through the formation of interfacial Ti–O bonds. Charge transfer from the TiN substrate leads to the formation of reduced Ti<sup>3+</sup> cations in TiO<sub>2.</sub> The structure of the one-layer oxide slab is strongly distorted at the interface, while the thicker TiO<sub>2</sub> layer preserves the rutile structure. The energy cost for the formation of a single O vacancy in the one-layer oxide slab is only 0.5 eV with respect to the ideal interface. For the two-layer oxide slab, the introduction of several vacancies in an already non-stoichiometric system becomes progressively more favourable, which indicates the stability of the highly non-stoichiometric interfaces. Isolated water molecules dissociate when adsorbed at the TiO<sub>2</sub> layers. At higher coverages the preference is for molecular water adsorption. Our ab initio thermodynamics calculations show the fully water covered stoichiometric models as the most stable structure at typical ambient conditions. Interfacial models with multiple vacancies are most stable at low (reducing) oxygen chemical potential values. A water monolayer adsorbs dissociatively on the highly distorted 2-layer TiO<sub>1.75</sub>-TiN interface, where the Ti<sup>3+</sup> states lying above the top of the valence band contribute to a significant reduction of the energy gap compared to the stoichiometric TiO<sub>2</sub>-TiN model. Our results provide a guide for the design of novel interfacial systems containing ultrathin TiO<sub>2</sub> with potential application as photocatalytic water splitting devices.</p><p></p>

scholarly journals Nanocarriers, Progenitor Cells, Combinational Approaches, and New Insights on the Retinal Therapy

2021 ◽  
Vol 22 (4) ◽  
pp. 1776
Author(s):  
Elham Pishavar ◽  
Hongrong Luo ◽  
Johanna Bolander ◽  
Antony Atala ◽  
Seeram Ramakrishna
Keyword(s):  
Drug Delivery ◽  
Progenitor Cells ◽  
Transfection Efficiency ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Age Related Macular Degeneration ◽  
Therapeutic Approaches ◽  
Age Related ◽  
Nanofibrous Scaffolds ◽  
The Stability

Progenitor cells derived from the retinal pigment epithelium (RPECs) have shown promise as therapeutic approaches to degenerative retinal disorders including diabetic retinopathy, age-related macular degeneration and Stargardt disease. However, the degeneration of Bruch’s membrane (BM), the natural substrate for the RPE, has been identified as one of the major limitations for utilizing RPECs. This degeneration leads to decreased support, survival and integration of the transplanted RPECs. It has been proposed that the generation of organized structures of nanofibers, in an attempt to mimic the natural retinal extracellular matrix (ECM) and its unique characteristics, could be utilized to overcome these limitations. Furthermore, nanoparticles could be incorporated to provide a platform for improved drug delivery and sustained release of molecules over several months to years. In addition, the incorporation of tissue-specific genes and stem cells into the nanostructures increased the stability and enhanced transfection efficiency of gene/drug to the posterior segment of the eye. This review discusses available drug delivery systems and combination therapies together with challenges associated with each approach. As the last step, we discuss the application of nanofibrous scaffolds for the implantation of RPE progenitor cells with the aim to enhance cell adhesion and support a functionally polarized RPE monolayer.

Modeling of Cationic Lipid-DNA Complexes

2004 ◽  
Vol 11 (2) ◽  
pp. 151-167 ◽  
Author(s):  
S. May ◽  
A. Ben-Shaul
Keyword(s):  
Cationic Lipid ◽  
Dna Complexes

Measurement of cross-sectional profile for sub-15nm hp LS patterns in nanoimprint templates using small-angle x-ray scattering

2020 ◽  
Author(s):  
Kazuki Hagihara ◽  
Eiji Yamanaka ◽  
Yoshiyasu Ito ◽  
Kiyoshi Ogata ◽  
Kazuhiko Omote ◽  
...  
Keyword(s):  
Small Angle ◽  
Cross Sectional ◽  
X Ray ◽  
X Ray Scattering ◽  
Cross Sectional Profile ◽  
Sectional Profile ◽  
Ray Scattering

scholarly journals Low back pain in physiotherapy students: Prevalence and the association with neuromuscular findings

2013 ◽  
Vol 69 (4) ◽  
Author(s):  
E. Burger ◽  
H. Myezwa ◽  
V. Naidoo ◽  
B. Olivier ◽  
A. Rothberg
Keyword(s):  
Low Back Pain ◽  
Back Pain ◽  
Cross Sectional Study ◽  
Transversus Abdominis ◽  
Low Back ◽  
Cross Sectional ◽  
Active Involvement ◽  
Optimal Function ◽  
The Stability ◽  
Physiotherapy Students

Background: Physiotherapy students are prone to low back pain (LBP) due to studying and their active involvement in clinical treatment of patients. As a result of pathology, muscle activity is influenced, affecting optimal function of the spine. Method: Physiotherapy students enrolled for 2010 at the University of the Witwatersrand participated in a cross-sectional study. A questionnaire and physical assessment were completed. Results: The study revealed that the lifetime LBP prevalence was 36% among physiotherapy students. Associations with LBP were hours of practical exposure, posterior-anterior mobilisations on L4 (p=0.003) and L5 (p≤0.001) centrally and unilaterally, left lumbar multifidus (LM) cross-sectional area (p=0.02), right obliquus internusabdominis (OI) (p=0.02) and right transversus abdominis (TrA) thickness at rest (p=0.02), as well as the pull of the TrA during contraction on the left (p=0.03). Discussion: Hours of practical exposure may play a role in lumbar pathology. Due to pathology, muscle imbalances of LM, TrA and OI affect the stability of the spine which may lead to recurrences. Conclusion: Practical exposure as well as LM, TrA and OI muscle imbalances were associated with LBP in physiotherapy students. Awareness of the factors associated with LBP while studying at an undergraduate level may lead to better prevention of LBP.

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