Optimizing collagen transport through track-etched nanopores

Bueno, Ericka M.; Ruberti, Jeffrey W.

doi:10.1016/j.memsci.2008.04.066

Cited by 8 publications

(6 citation statements)

References 84 publications

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“…4 show that Re ≪ 1 and therefore the flow is of the form of a Stokes flow,

Re = \frac{ρ \bar{U} D_{h}}{μ},

where D h is the hydraulic diameter (in this case H ), Ū is the average velocity ( Ū = Q/wH ), and μ is the dynamic viscosity of the solvent (0.034 Pa.S, [41]).…”

Section: Discussionmentioning

confidence: 99%

Dynamic shear-influenced collagen self-assembly

2009

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The ability to influence the direction of polymerization of a self-assembling biomolecular system has the potential to generate materials with extremely high anisotropy. In biological systems where highly-oriented cellular populations give rise to aligned and often load-bearing tissue such organized molecular scaffolds could aid in the contact guidance of cells for engineered tissue constructs (e.g cornea and tendon). In this investigation we examine the detailed dynamics of pepsin-extracted type I bovine collagen assembly on a glass surface under the influence of flow between two plates. Differential Interference Contrast (DIC) imaging (60x-1.4NA) with focal plane stabilization was used to resolve and track the growth of collagen aggregates on borosilicate glass for 4 different shear rates (500, 80, 20, and 9 s -1 ). The detailed morphology of the collagen fibrils/aggregates was examined using Quick Freeze Deep Etch electron microscopy. Nucleation of fibrils on the glass was observed to occur rapidly (~2 min) followed by continued growth of the fibrils. The growth rates were dependent on flow in a complex manner with the highest rate of axial growth (0.1 microns/sec) occurring at a shear rate of 9 s -1 . The lowest growth rate occurred at the highest shear. Fibrils were observed to both branch and join during the experiments. The best alignment of fibrils was observed at intermediate shear rates of 20 and 80s -1 . However, the investigation revealed that fibril directional growth was not stable. At high shear rates, fibrils would often turn downstream forming what we term "hooks" which are likely the combined result of monomer interaction with the initial collagen layer or "mat" and the high shear rate. Further, QFDE examination of fibril morphology demonstrated that the assembled fibrillar structure did not possess native D-periodicity. Instead, fibrils comprised a collection of generally aligned, monomers which were self-assembled to form a fibril-like aggregate. In conclusion, though constant shear-rate clearly influences collagen fibrillar alignment, the formation of highlyorganized collagenous arrays of native-like D-banded fibrils remains a challenge. Modulation of shear in combination with surface energy patterning to produce a highly-aligned initial mat may provide significant improvement of both the fibril morphology and alignment.

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“…4 show that Re ≪ 1 and therefore the flow is of the form of a Stokes flow,

Re = \frac{ρ \bar{U} D_{h}}{μ},

where D h is the hydraulic diameter (in this case H ), Ū is the average velocity ( Ū = Q/wH ), and μ is the dynamic viscosity of the solvent (0.034 Pa.S, [41]).…”

Section: Discussionmentioning

confidence: 99%

Dynamic shear-influenced collagen self-assembly

2009

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“…where η s denotes the solvent viscosity, C* is the polymer overlap concentration, and k H is the Huggins coefficient. Collagen has an overlap concentration of 2.7 mg/mL, 37 and the Huggins coefficient is estimated to be k H ≈ 0.6. 38 Preparation of Samples for Transmission Electron Microscopy.…”

Section: Methodsmentioning

confidence: 99%

“…The viscosity of a polymer solution η P depends on its concentration C P : , η normalp η normals = 1 + C normalp C * + k normalH true( C normalp C * true) 2 where η s denotes the solvent viscosity, C* is the polymer overlap concentration, and k H is the Huggins coefficient. Collagen has an overlap concentration of 2.7 mg/mL, and the Huggins coefficient is estimated to be k H ≈ 0.6 …”

Section: Methodsmentioning

confidence: 99%

Self-Assembly of Stable Monomolecular Nucleic Acid Lipid Particles with a Size of 30 nm

Rudorf

Rädler

2012

J. Am. Chem. Soc.

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The design of efficient nucleic acid complexes is key to progress in genetic research and therapies based on RNA interference. For optimal transport within tissue and across extracellular barriers, nucleic acid carriers need to be small and stable. In this Article, we prepare and characterize mono-nucleic acid lipid particles (mono-NALPs). The particles consist of single short double-stranded oligonucleotides or single siRNA molecules each encapsulated within a closed shell of a cationic-zwitterionic lipid bilayer, furnished with an outer polyethylene glycol (PEG) shield. The particles self-assemble by solvent exchange from a solution containing nucleic acid mixed with the four lipid components DOTAP, DOPE, DOPC, and DSPE-PEG(2000). Using fluorescence correlation spectroscopy, we monitor the formation of mono-NALPs from short double-stranded oligonucleotides or siRNA and lipids into monodisperse particles of approximately 30 nm in diameter. Small angle neutron and X-ray scattering and transmission electron microscopy experiments substantiate a micelle-like core-shell structure of the particles. The PEGylated lipid shell protects the nucleic acid core against degradation by nucleases, sterically stabilizes the mono-NALPs against disassembly in collagen networks, and prevents nonspecific binding to cells. Hence, PEG-lipid shielded mono-NALPs are the smallest stable siRNA lipid system possible and may provide a structural design to be built upon for the development of novel nucleic acid delivery systems with enhanced biodistribution in vivo.

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“…, where Dm stands for molecular diffusivity. The molecular diffusivity was taken to be 7.8-8.6 10-4 m2/s [17].…”

Section: Estimation Of Shear Stress Profilesmentioning

confidence: 99%

The Effect of Drag Force and Flow Rate on Mesenchymal Stem Cells in Packed-Bed Perfusion Bioreactor

Duruksu

2019

Eskişehir Teknik Üniversitesi Bilim Ve Teknoloji Dergisi - C Yaşam Bilimleri Ve Biyoteknoloji

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Packed-bed bioreactors provide larger surface area to volume ratio compared to the static culture on flasks. Therefore, these systems offer ideal production environment for large-scale culture of mesenchymal stem cells (MSCs), but the effect of fluid dynamics on the cell-behavior of MSCs is not fully elucidated. In this study, packed-bed perfusion reactor loaded with different size of polymethyl methacrylate carriers was used to apply different rates of shear stress and drug forces at constant flow rate. The cell viability, cell-expansion, apoptosis and protein secretion levels were analyzed for both unmodified and Vascular Endothelial Growth Factor-positive (VEGF +) MSCs. The superficial stress was estimated to between 0.21-0.25 N/m 2. The results showed that the shear stress reduced the VEGF secretion, and Caspase-3 was activated at high drag force, which cause the reduction of the cell numbers in the bioreactor. The reduction of cytoskeletal actin structures seemed to play the central role in this adverse effect of the non-planar shear stress. The expression reduction of VEGF might also have critical impacts on the tissue engineering applications, in which the formation of vascular construct is essential.

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Optimizing collagen transport through track-etched nanopores

Cited by 8 publications

References 84 publications

Dynamic shear-influenced collagen self-assembly

Dynamic shear-influenced collagen self-assembly

Self-Assembly of Stable Monomolecular Nucleic Acid Lipid Particles with a Size of 30 nm

The Effect of Drag Force and Flow Rate on Mesenchymal Stem Cells in Packed-Bed Perfusion Bioreactor

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