Size and conformation of Ficoll as determined by size-exclusion chromatography followed by multiangle light scattering

Fissell, William H.; Hofmann, Christina L.; Smith, Ronan J.; Chen, Michelle H.

doi:10.1152/ajprenal.00312.2009

Cited by 50 publications

(57 citation statements)

References 33 publications

(18 reference statements)

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“…This suggests that a net surface charge may alter the size of ficoll, most likely changing it from a compact sphere to perhaps a branching dendrimer or random coil. 27 This is consistent with reports showing the ficoll becomes more open when a negative charge is added. 28 This is most likely due to the opposing negative electrostatic charges repelling each other, forcing the structure to open.…”

Section: Diffusion In Free Solutionsupporting

confidence: 90%

“…He also considered that ficoll may have many intermediate shapes, or that it may have the ability to change its shape under pressure. 27 Dextrans are thought to be linear, flexible molecules, with a loose, open structure, and a high degree of deformability, which renders them more permeable than a more rigid globular protein such as albumin, and indeed even more permeable than ficoll, at least with respect to the glomerulus. 22 These studies indicate that, in combination, dextran, ficoll and albumin serve as useful molecules with which to study the effect of shape and conformability on diffusion across tissue.…”

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confidence: 99%

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Influence of molecular shape, conformability, net surface charge, and tissue interaction on transscleral macromolecular diffusion

Srikantha

Mourad

Suhling

et al. 2012

Experimental Eye Research

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Purpose: To study the influence of molecular shape, conformability, net surface charge and tissue interaction on transscleral diffusion.Methods: Unfixed, porcine sclera was clamped in an Ussing chamber. Fluorophore labelled, neutral, albumin, dextran, or ficoll were placed in one hemi-chamber and the rate of transscleral diffusion was measured over 24 hours using a spectrophotometer. Experiments were repeated using dextrans and ficoll with positive, or negative, net surface charges.Fluorescence recovery after photobleaching (FRAP) was undertaken to compare transscleral diffusion with diffusion through a solution.All molecules were 70 kDa.Results: Using FRAP, mean ± SD diffusion coefficient (D) was highest for albumin, followed by ficoll, then dextran (p = 0.0005). Positive dextrans diffused fastest, followed by negative, then neutral dextrans (p = 0.0005). Neutral ficoll diffused the fastest, followed by positive then negative ficoll (p = 0.0008). For the neutral molecules, transscleral D was highest for albumin, followed by dextran, then ficoll (p < 0.0001). D was highest for negative ficoll, followed by neutral, then positive ficoll (p < 0.0001). By contrast, D was highest for positive dextran, followed by neutral, then negative dextran (p = 0.0021).Conclusions: Diffusion in free solution does not predict transscleral diffusion and the molecular-tissue interaction is important. Molecular size, shape, and charge may all markedly influence transscleral diffusion, as may conformability to a lesser degree, but all need to be considered when selecting or designing drugs for transscleral delivery.Drugs directed against vascular endothelial growth factor (VEGF) have proven efficacy in some of the most common retinal diseases. The ANCHOR and MARINA studies demonstrated efficacy in wet age-related macular degeneration (AMD), 1,2 and studies such as CRUISE, BRAVO 3,4 and several from the DRCnet Group have shown favourable results in retinal vein occlusion and diabetic macular oedema. Whilst the data in these studies have led to improved clinical care, the need for regular intravitreal injections represents a burdensome regimen of treatment. A less invasive mode of delivery would have potential advantages in terms of reduced cost, discomfort, and complication rate.Systemic administration is impeded by the blood-aqueous and blood-retinal-barriers. High drug concentrations may be required to overcome these barriers to diffusion, with the attendant risk of systemic side effects. 5 A topical route would have obvious advantages. Delivery to the retina is however difficult for several reasons, such as lacrimation, low corneal permeability to large molecules, counter directional intraocular convection, and importantly the long diffusional distance. 53 Blood flow in the conjunctiva, episclera and choroid can also reduce drug concentration. 33,50 Notwithstanding these potential difficulties, transscleral delivery has a number of potential advantages. 6,7,8,9 The sclera has a large and accessible surface area, and a high d...

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Section: Diffusion In Free Solutionsupporting

confidence: 90%

mentioning

confidence: 99%

Influence of molecular shape, conformability, net surface charge, and tissue interaction on transscleral macromolecular diffusion

Srikantha

Mourad

Suhling

et al. 2012

Experimental Eye Research

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“…Further investigations suggested that transport of globular proteins through the membrane was similar to that predicted from first principles by Dechadilok and Deen (11), leading to the conclusion that Ficoll, as had previously been suggested by Rippe, was not a sphere and was possibly not rigid (19). Using a combination of size-exclusion chromatography with online multiangle light scattering (SEC-MALS) and viscometry, we concluded that Ficoll's conformation in aqueous solution was intermediate between a sphere and a random coil, but we were unable to distinguish conformational flexibility from dispersion in shape (18).…”

mentioning

confidence: 59%

“…Our own work in engineering of ultrafiltration membranes led us to explore the properties of Ficoll, a globular polymer of sucrose and epichlorohydrin (17)(18)(19). In brief, a silicon membrane of extremely uniform slit pores did not retain Ficolls with hydrodynamic radii larger than the pore size of the membrane (19).…”

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confidence: 99%

Molecular conformation and filtration properties of anionic Ficoll

Groszek

Ferrell

et al. 2010

American Journal of Physiology-Renal Physiology

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The physiology of glomerular permselectivity remains mechanistically obscure, despite its importance in human disease. Although electrical contributions to glomerular permselectivity have long been considered important, two recent reports demonstrated enhanced glomerular permeability to anionic versus neutral polysaccharides. The interpretation of these observations is complicated by confounding of the effects of chemical modification on charge with effects on size and shape. In this report, neutral and anionic Ficoll are characterized by size-exclusion chromatography with online light scattering and viscometry and filtration through a highly defined anionic filtration membrane. Neutral and carboxymethylated Ficoll are nearly identical in size and conformation, yet carboxymethylated Ficoll is retained by an anionic membrane in excess of neutral Ficoll. This suggests that comparisons between clearances of neutral and carboxymethylated Ficoll may be a sensitive probe of electrostatic interactions independent of size and conformation.

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“…The critical length L* corresponding to a fibril−fibril distance of half a crowder diameter, d = σ/2, is defined by the following condition The results of this calculation are plotted in Figure 9. The parameters used are listed in Table 1 following Fissell et al 33 It is clear that at the lower concentrations rather long fibrils are formed through the addition of monomers, until these start interacting between them through depletion forces. However, at concentrations of the order of 15 mg·mL −1 , depletion forces set in much earlier, i.e., for shorter fibrils of the order of a few collagen monomers in length and diameter.…”

Section: ■ Appendix IImentioning

confidence: 99%

Synergistic Rate Boosting of Collagen Fibrillogenesis in Heterogeneous Mixtures of Crowding Agents

et al. 2015

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ABSTRACT:The competition for access to space that arises between macromolecules is the basis of the macromolecular crowding phenomenon, known to modulate biochemical reactions in subtle ways. Crowding is a highly conserved physiological condition in and around cells in metazoans, and originates from a mixture of heterogeneous biomolecules. Here, using collagen fibrillogenesis as an experimental test platform and ideas from the theory of nonideal solutions, we show that an entropy-based synergy is created by a mixture of two different populations of artificial crowders, providing small crowders with extra volume occupancy when in the vicinity of bigger crowders. We present the physiological mechanism by which synergistic effects maximize volume exclusion with the minimum amount of heterogeneous crowders, demonstrating how the evolutionarily optimized crowded conditions found in vivo can be reproduced effectively in vitro.

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Size and conformation of Ficoll as determined by size-exclusion chromatography followed by multiangle light scattering

Abstract: Fissell WH, Hofmann CL, Smith R, Chen MH. Size and conformation of Ficoll as determined by size-exclusion chromatography followed by multiangle light scattering.

Cited by 50 publications

References 33 publications

Influence of molecular shape, conformability, net surface charge, and tissue interaction on transscleral macromolecular diffusion

Influence of molecular shape, conformability, net surface charge, and tissue interaction on transscleral macromolecular diffusion

Molecular conformation and filtration properties of anionic Ficoll

Synergistic Rate Boosting of Collagen Fibrillogenesis in Heterogeneous Mixtures of Crowding Agents

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