Structure and Property Changes in Self-Assembled Lubricin Layers Induced by Calcium Ion Interactions.

Greene, GW; Thapa, R; Holt, SA; Wang, X; Garvey, CJ; Tabor, RF

Structure and Property Changes in Self-Assembled Lubricin Layers Induced by Calcium Ion Interactions.

Greene, GW Thapa, R Holt, SA Wang, X Garvey, CJ Tabor, RF

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Publisher:: AMER CHEMICAL SOC
Publication Type:: Journal Article
Citation:: Langmuir, 2017, 33, (10), pp. 2559-2570
Issue Date:: 2017-03-14

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Field	Value	Language
dc.contributor.author	Greene, GW
dc.contributor.author	Thapa, R
dc.contributor.author	Holt, SA
dc.contributor.author	Wang, X
dc.contributor.author	Garvey, CJ
dc.contributor.author	Tabor, RF
dc.date.accessioned	2022-10-03T05:34:31Z
dc.date.available	2022-10-03T05:34:31Z
dc.date.issued	2017-03-14
dc.identifier.citation	Langmuir, 2017, 33, (10), pp. 2559-2570
dc.identifier.issn	0743-7463
dc.identifier.issn	1520-5827
dc.identifier.uri	http://hdl.handle.net/10453/162233
dc.description.abstract	Lubricin (LUB) is a "mucin-like" glycoprotein found in synovial fluids and coating the cartilage surfaces of articular joints, which is now generally accepted as one of the body's primary boundary lubricants and antiadhesive agents. LUB's superior lubrication and antiadhesion are believed to derive from its unique interfacial properties by which LUB molecules adhere to surfaces (and biomolecules, such as hyaluronic acid and collagen) through discrete interactions localized to its two terminal end domains. These regionally specific interactions lead to self-assembly behavior and the formation of a well-ordered "telechelic" polymer brush structure on most substrates. Despite its importance to biological lubrication, detailed knowledge on the LUB's self-assembled brush structure is insufficient and derived mostly from indirect and circumstantial evidence. Neutron reflectometry (NR) was used to directly probe the self-assembled LUB layers, confirming the polymer brush architecture and resolving the degree of hydration and level of surface coverage. While attempting to improve the LUB contrast in the NR measurements, the LUB layers were exposed to a 20 mM solution of CaCl2, which resulted in a significant change in the polymer brush structural parameters consisting of a partial denaturation of the surface-binding end-domain regions, partial dehydration of the internal mucin-domain "loop", and collapse of the outer mucin-domain surface region. A series of atomic force microscopy measurements investigating the LUB layer surface morphology, mechanical properties, and adhesion forces in phosphate-buffered saline and CaCl2 solutions reveal that the structural changes induced by calcium ion interactions also significantly alter key properties, which may have implications to LUB's efficacy as a boundary lubricant and wear protector in the presence of elevated calcium ion concentrations.
dc.format	Print-Electronic
dc.language	eng
dc.publisher	AMER CHEMICAL SOC
dc.relation.ispartof	Langmuir
dc.relation.isbasedon	10.1021/acs.langmuir.6b03992
dc.rights	info:eu-repo/semantics/closedAccess
dc.subject.classification	Chemical Physics
dc.title	Structure and Property Changes in Self-Assembled Lubricin Layers Induced by Calcium Ion Interactions.
dc.type	Journal Article
utslib.citation.volume	33
utslib.location.activity	United States
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Life Sciences
utslib.copyright.status	closed_access	*
dc.date.updated	2022-10-03T05:34:29Z
pubs.issue	10
pubs.publication-status	Published
pubs.volume	33
utslib.citation.issue	10

Abstract:

Lubricin (LUB) is a "mucin-like" glycoprotein found in synovial fluids and coating the cartilage surfaces of articular joints, which is now generally accepted as one of the body's primary boundary lubricants and antiadhesive agents. LUB's superior lubrication and antiadhesion are believed to derive from its unique interfacial properties by which LUB molecules adhere to surfaces (and biomolecules, such as hyaluronic acid and collagen) through discrete interactions localized to its two terminal end domains. These regionally specific interactions lead to self-assembly behavior and the formation of a well-ordered "telechelic" polymer brush structure on most substrates. Despite its importance to biological lubrication, detailed knowledge on the LUB's self-assembled brush structure is insufficient and derived mostly from indirect and circumstantial evidence. Neutron reflectometry (NR) was used to directly probe the self-assembled LUB layers, confirming the polymer brush architecture and resolving the degree of hydration and level of surface coverage. While attempting to improve the LUB contrast in the NR measurements, the LUB layers were exposed to a 20 mM solution of CaCl2, which resulted in a significant change in the polymer brush structural parameters consisting of a partial denaturation of the surface-binding end-domain regions, partial dehydration of the internal mucin-domain "loop", and collapse of the outer mucin-domain surface region. A series of atomic force microscopy measurements investigating the LUB layer surface morphology, mechanical properties, and adhesion forces in phosphate-buffered saline and CaCl2 solutions reveal that the structural changes induced by calcium ion interactions also significantly alter key properties, which may have implications to LUB's efficacy as a boundary lubricant and wear protector in the presence of elevated calcium ion concentrations.

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http://hdl.handle.net/10453/162233