Nanoscale insight into the degradation mechanisms of the cartilage articulating surface preceding OA

Shoaib, Tooba; Yuh, Catherine; Wimmer, Markus A.; Schmid, Thomas; Espinosa‐Marzal, Rosa M.

doi:10.1039/d0bm00496k

Cited by 12 publications

(6 citation statements)

References 58 publications

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“…One advantage of this method is that the measurements of the film thickness are also possible during shear loading, so that it can determine the change in thickness with sliding velocity. Recent experiments on cartilage [80,81] have demonstrated the capability of the SFA to investigate hydrogel-like materials, specifically their response to compression and steady shear. The SFA has been also used to investigate the nanorheology of polymer films [77,82,83], and we believe that extensions of the SFA could help understand the interfacial rheology of hydrogels under tribological conditions at the nanoscale, as well.…”

Section: Closing Remarks and Future Perspectivesmentioning

confidence: 99%

Advances in Understanding Hydrogel Lubrication

Shoaib

Espinosa‐Marzal

2020

Colloids and Interfaces

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Since their inception, hydrogels have gained popularity among multiple fields, most significantly in biomedical research and industry. Due to their resemblance to biological tribosystems, a significant amount of research has been conducted on hydrogels to elucidate biolubrication mechanisms and their possible applications as replacement materials. This review is focused on lubrication mechanisms and covers friction models that have attempted to quantify the complex frictional characteristics of hydrogels. From models developed on the basis of polymer physics to the concept of hydration lubrication, assumptions and conditions for their applicability are discussed. Based on previous models and our own experimental findings, we propose the viscous-adhesive model for hydrogel friction. This model accounts for the effects of confinement of the polymer network provided by a solid surface and poroelastic relaxation as well as the (non) Newtonian shear of a complex fluid on the frictional force and quantifies the frictional response of hydrogels-solid interfaces. Finally, the review delineates potential areas of future research based on the current knowledge.

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Section: Closing Remarks and Future Perspectivesmentioning

confidence: 99%

Advances in Understanding Hydrogel Lubrication

Shoaib

Espinosa‐Marzal

2020

Colloids and Interfaces

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“…A superficial free surface layer rich in glycoconjugates on bovine cartilage was directly observed with high resolution SEM and AFM [633]. The lubrication was depleted with increased friction in cartilage specimens with enhanced calcium centration which degraded the surface layer [634]. Lubrication of degraded cartilage with chondroitinase ABC was shown to be restored through re-establishing lamina splendens with a bioinspired mucoadhesive biopolymer chitosan catechol [635].…”

Section: Natural Synovial Joints and Artificial Joint Replacementsmentioning

confidence: 99%

A review of advances in tribology in 2020–2021

Meng

et al. 2022

Friction

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Around 1,000 peer-reviewed papers were selected from 3,450 articles published during 2020–2021, and reviewed as the representative advances in tribology research worldwide. The survey highlights the development in lubrication, wear and surface engineering, biotribology, high temperature tribology, and computational tribology, providing a show window of the achievements of recent fundamental and application researches in the field of tribology.

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“…63 The 17.5 wt % polyacrylamide hydrogel surfaces cast herein at an air−liquid interface may be more loosely cross-linked than the literature reports for polyacrylamide hydrogels cast against molding surfaces despite higher polymer concentrations in the bulk (see Table S7). 21,41,42,61,63,[66][67][68][69][70]82 These results highlight that the surface effects of oxygen inhibition are best observed and exploited at a free surface where oxygen can easily diffuse throughout the duration of the reaction, as demonstrated in more detail in Section 3.4. Moreover, increasing the oxygen concentration results in a significantly different surface structure despite having a minimal effect on the mechanical properties of the gel at larger indentation depths.…”

Section: Microindentation Measurements and Analysismentioning

confidence: 99%

Designing Superlubricious Hydrogels from Spontaneous Peroxidation Gradients

Chau,

Edwards,

Helgeson

et al. 2023

ACS Appl. Mater. Interfaces

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Hydrogels are hydrated three-dimensional networks of hydrophilic polymers that are commonly used in the biomedical industry due to their mechanical and structural tunability, biocompatibility, and similar water content to biological tissues. The surface structure of hydrogels polymerized through freeradical polymerization can be modified by controlling environmental oxygen concentrations, leading to the formation of a polymer concentration gradient. In this work, 17.5 wt % polyacrylamide hydrogels are polymerized in low (0.01 mol % O 2 ) and high (20 mol % O 2 ) oxygen environments, and their mechanical and tribological properties are characterized through microindentation, nanoindentation, and tribological sliding experiments. Without significantly reducing the elastic modulus of the hydrogel (E* ≈ 200 kPa), we demonstrate an order of magnitude reduction in friction coefficient (from μ = 0.021 ± 0.006 to μ = 0.002 ± 0.001) by adjusting polymerization conditions (e.g., oxygen concentration). A quantitative analytical model based on polyacrylamide chemistry and kinetics was developed to estimate the thickness and structure of the monomer conversion gradient, termed the "surface gel layer". We find that polymerizing hydrogels at high oxygen concentrations leads to the formation of a preswollen surface gel layer that is approximately five times thicker (t ≈ 50 μm) and four times less concentrated (≈ 6% monomer conversion) at the surface prior to swelling compared to low oxygen environments (t ≈ 10 μm, ≈ 20% monomer conversion). Our model could be readily modified to predict the preswollen concentration profile of the polyacrylamide gel surface layer for any reaction conditions�monomer and initiator concentration, oxygen concentration, reaction time, and reaction media depth�or used to select conditions that correspond to a certain desired surface gel layer profile.

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Nanoscale insight into the degradation mechanisms of the cartilage articulating surface preceding OA

Abstract: Osteoarthritis (OA) is a degenerative disease and leading cause of disability globally. We report the a fundamental study of the mechanisms underlying deterioration of hydrated cartilage in the presence of elevated calcium content preceding OA.

Cited by 12 publications

References 58 publications

Advances in Understanding Hydrogel Lubrication

Advances in Understanding Hydrogel Lubrication

A review of advances in tribology in 2020–2021

Designing Superlubricious Hydrogels from Spontaneous Peroxidation Gradients

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