Entanglement Coupling in Porcine Stomach Mucin

Abstract

We present data from small angle neutron scattering (SANS) on the polyelectrolyte side chain liquid crystalline phases of porcine stomach mucin. There is a polydomain nematic phase at concentrations above the point of brush overlap. Also, the proteoglycans were seen to orient under the influence of a magnetic field at concentrations below which the brushes do not extensively overlap. The field can be used to investigate the nature of the entanglement coupling between the molecules. The structure factor peak scales as c 1/3 across the complete concentration range, implying liquidlike behavior (0.4-680 mg/mL). The rheological data present evidence for shear thinning with four regimes: dilute, semidilute, entangled polydomain liquid crystalline, and entangled liquid crystalline. The length and cross-sectional radius of the polymeric brushes could be measured with SANS. Static light scattering and SANS provide evidence for the changes in osmotic compressibility between dilute, semidilute, and entangled brush phases. † This article is part of the special issue of Langmuir devoted to the emerging field of self-assembled fibrillar networks.

Methods to determine the interactions of micro- and nanoparticles with mucus

“…Waigh et al found evidence of a highly organized structure, discussed in terms of polydomain nematic phases above some critical semi-dilute concentration, and polyglycan orientation under magnetic field at lower concentration [62]. They also determined the cross-sectional radius and length of the mucin, obtaining results in agreement with Hong et al…”

“…When investigating relationships between physical properties and molecular structure, the determination of molecular organization within complex systems is fundamental; small-angle neutron scattering (SANS) -a powerful, non-destructive technique that probes organizational structure on a 1-200 nm lengthscale -can be easily applied for the study of delicate biological materials, although most studies published to date have focused on mucin [61][62][63][64][65].…”

Helicobacter pylori moves through mucus by reducing mucin viscoelasticity

“…However, given the strong correlation with the sharp rise in pH in the presence of H. pylori and the subsequent change in rheology in nearly exact parallel with the pH dependence of every measure of viscoelastic response previously established (26), the results here indicate that the dominant effect of H. pylori on gastric mucin rheology is that due to pH elevation. Small differences in moduli are related to use of HCl which leads to different ionic strength than the buffers used in previous studies (26,49,50).…”

Biophysical Analysis of the Molecular Interactions between Polysaccharides and Mucin

“…The detailed macromolecular structure of mucin has previously been investigated using highresolution scattering techniques, such as synchrotron SAXS, 60,61,62 SANS, 61,26,63 , static light scattering (SLS) and DLS 64 to compare the properties of mucin samples with different biological origins and preparation methods. The cylindrical model and the more recent double-globular comb model have therefore been used to account for the complex structure of mucin.…”

“…The cylindrical model and the more recent double-globular comb model have therefore been used to account for the complex structure of mucin. 60,63,64 Aqueous solutions of bovine submaxillary mucin studied by SAXS displayed an expanded chain conformation at low concentrations (1.4-3.6 mg/mL) but a Gaussian chain conformation at higher concentrations (> 7 mg/mL). 62 More recent studies have addressed the impact of concentration on the structure of mucin and the existence of a coil overlap concentration (c*), along with other parameters as measured by a combination of SLS, DLS and rheology, concluding that c* = 1.54 mg/mL in water.…”