Structural and Mechanical Properties of Thin Films of Bovine Submaxillary Mucin versus Porcine Gastric Mucin on a Hydrophobic Surface in Aqueous Solutions

Madsen, Jan; Sotres, Javier; Pakkanen, Kirsi I.; Efler, Petr; Svensson, Birte; Hachem, Maher Abou; Arnebrant, Thomas; Lee, Sang M.

doi:10.1021/acs.langmuir.6b02057

Cited by 40 publications

(38 citation statements)

References 58 publications

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“…Such high interfacial frictio n might be due to the buffer being squeezed out from the tribo-contacts as well as the adhesive nature of the PDMS-PDMS interface in the absence of any load-bearing lubricating film. 38 Interestingly, native whey protein solution (data not shown) gave similar friction coefficients as phosphate buffer, suggesting no formation of hydration layer between the surfaces. However, the presence of WPM particles significantly reduced the friction coefficient by up to one decade, especially in mixed lubrication regime, that is for sliding speeds 10-300 mm/s, even for extremely low volume fractions (10 vol%) ( Figure 4A).…”

Section: Resultsmentioning

confidence: 87%

Aqueous Lubrication, Structure and Rheological Properties of Whey Protein Microgel Particles

et al. 2017

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Aqueous lubrication has emerged as an active research area in recent years due to its prevalence in nature in biotribological contacts and its enormous technological soft-matter applications. In this study, we designed aqueous dispersions of biocompatible whey-protein microgel particles (WPM) (10-80 vol %) cross-linked via disulfide bonding and focused on understanding their rheological, structural and biotribological properties (smooth polydimethylsiloxane (PDMS) contacts, R < 50 nm, ball-on-disk set up). The WPM particles (D = 380 nm) displayed shear-thinning behavior and good lubricating performance in the plateau boundary as well as the mixed lubrication regimes. The WPM particles facilitated lubrication between bare hydrophobic PDMS surfaces (water contact angle 108°), leading to a 10-fold reduction in boundary friction force with increased volume fraction (ϕ ≥ 65%), largely attributed to the close packing-mediated layer of particles between the asperity contacts acting as "true surface-separators", hydrophobic moieties of WPM binding to the nonpolar surfaces, and particles employing a rolling mechanism analogous to "ball bearings", the latter supported by negligible change in size and microstructure of the WPM particles after tribology. An ultralow boundary friction coefficient, μ ≤ 0.03 was achieved using WPM between O plasma-treated hydrophilic PDMS contacts coated with bovine submaxillary mucin (water contact angle 47°), and electron micrographs revealed that the WPM particles spread effectively as a layer of particles even at low ϕ∼ 10%, forming a lubricating load-bearing film that prevented the two surfaces from true adhesive contact. However, above an optimum volume fraction, μ increased in HL+BSM surfaces due to the interpenetration of particles that possibly impeded effective rolling, explaining the slight increase in friction. These effects are reflected in the highly shear thinning nature of the WPM dispersions themselves plus the tendency for the apparent viscosity to fall as dispersions are forced to very high volume fractions. The present work demonstrates a novel approach for providing ultralow friction in soft polymeric surfaces using proteinaceous microgel particles that satisfy both load bearing and kinematic requirements. These findings hold great potential for designing biocompatible particles for aqueous lubrication in numerous soft matter applications.

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Section: Resultsmentioning

confidence: 87%

Aqueous Lubrication, Structure and Rheological Properties of Whey Protein Microgel Particles

et al. 2017

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“…Noteworthy, porcine mucin was used in the artificial saliva to simulate the human salivary viscosity at comparable concentrations present in human saliva. However, bovine submaxilliary mucin could be a promising alternative considering its ability to form more elastic films and its higher lubricating properties particularly in elastomeric contact surfaces (Madsen, et al, 2016).…”

Section: Preparation Of Artificial Salivamentioning

confidence: 99%

On relating rheology and oral tribology to sensory properties in hydrogels

et al. 2019

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“…An examination of the literature provides several studies that each examine isolated aspects of mucus and mucin properties, but these properties are often not connected, especially within the same body of work. The microstructure and mechanical properties of mucin have been characterized using rheology 6,29,30 , light scattering techniques 15,31 , zeta potential 32,33 , infrared spectroscopy 32,34 , and various other techniques. Of these methods, IR spectroscopy is the most recently used tool (as it was not used prior to 1995 24 ) and shows promise for illustrating supramolecular interactions between glycosylated domains in mucin 35 .…”

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confidence: 99%

Chemical and Microstructural Characterization of pH and [Ca2+] Dependent Sol-Gel Transitions in Mucin Biopolymer

Curnutt

Smith

Darrow

et al. 2020

Sci Rep

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Mucus is responsible for controlling transport and barrier function in biological systems, and its properties can be significantly affected by compositional and environmental changes. In this study, the impacts of pH and cacl 2 were examined on the solution-to-gel transition of mucin, the primary structural component of mucus. Microscale structural changes were correlated with macroscale viscoelastic behavior as a function of pH and calcium addition using rheology, dynamic light scattering, zeta potential, surface tension, and ftiR spectroscopic characterization. Mucin solutions transitioned from solution to gel behavior between pH 4-5 and correspondingly displayed a more than tenfold increase in viscoelastic moduli. Addition of CaCl 2 increased the sol-gel transition pH value to ca. 6, with a twofold increase in loss moduli at low frequencies and tenfold increase in storage modulus. changing the ionic conditions-specifically [H + ] and [ca 2+ ]-modulated the sol-gel transition pH, isoelectric point, and viscoelastic properties due to reversible conformational changes with mucin forming a network structure via non-covalent cross-links between mucin chains. Mucin is a polyelectrolyte glycoprotein found in mucus, the structured complex fluid found in all types of organisms from bacteria to humans. In vertebrates, mucus is produced by mucus membranes and can be found lining the eyelids, mouth, and nose, as well as gastrointestinal, respiratory, and genital tracts. Since the 1970s 1 , animal mucus and mucin solutions have been well studied, especially the roles mucus plays in drug delivery 2-6 , disorders like cystic fibrosis 7,8 , and its protective biological functions 9-12. Mucin glycoproteins are present in mucus at concentrations of 1-5%, along with electrolytes (ca. 1%), lipids (1-2%), other proteins (1-2%), and water (90-95%) 13. Despite being present in low concentrations, mucin glycoproteins are primarily responsible for the protective and lubricative functions of mucus within the body. Solubilized mucin behaves as a complex fluid with changing viscoelastic and structural properties in response to its environmental conditions. Mucin glycoproteins are responsible for the majority of the physical properties of mucus, as mucin conformation, intra-and inter-strand bonding, and microstructure changes in response to environmental factors such as pH 6,7,12,14 , temperature 2,15 , and ion content 1,14,16. All these factors affect the reversible supramolecular bonding between functional groups within the protein strands, which modifies the microstructure as well as the mechanical and transport properties of the mucin network. In aqueous solutions, biopolymers like mucin form networks that can change dynamically due to non-covalent crosslinks, including physical entanglements and supramolecular bonding. Mucins resemble a bottle brush polymer with a protein backbone and oligosaccharide (carbohydrate) side chains arranged radially from the backbone. The protein backbone of the mucin biopolymer has areas that are dense w...

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Structural and Mechanical Properties of Thin Films of Bovine Submaxillary Mucin versus Porcine Gastric Mucin on a Hydrophobic Surface in Aqueous Solutions

Cited by 40 publications

References 58 publications

Aqueous Lubrication, Structure and Rheological Properties of Whey Protein Microgel Particles

Aqueous Lubrication, Structure and Rheological Properties of Whey Protein Microgel Particles

On relating rheology and oral tribology to sensory properties in hydrogels

Chemical and Microstructural Characterization of pH and [Ca2+] Dependent Sol-Gel Transitions in Mucin Biopolymer

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