High-frequency measurements of interfacial friction using quartz crystal resonators integrated into a surface forces apparatus

2002 ◽  
Vol 65 (2) ◽  
Author(s):  
Steffen Berg ◽  
Marina Ruths ◽  
Diethelm Johannsmann
Keyword(s):  
High Frequency ◽  
Quartz Crystal ◽  
Surface Forces ◽  
Interfacial Friction ◽  
Surface Forces Apparatus ◽  
Frequency Measurements ◽  
Quartz Crystal Resonators

scholarly journals Glycosaminoglycans and glycoproteins influence the elastic response of synovial fluid nanofilms on model oxide surfaces

2021 ◽  
Author(s):  
Amar S. Mann ◽  
Ariell M. Smith ◽  
Joyce O. Saltzherr ◽  
Arvind Gopinath ◽  
Roberto C. Andresen Eguiluz
Keyword(s):  
Synovial Fluid ◽  
Quartz Crystal ◽  
Tribological Performance ◽  
Surface Forces ◽  
Elastic Response ◽  
Surface Forces Apparatus ◽  
Implant Surface ◽  
Load Bearing ◽  
Synergistic Interactions ◽  
Insight Into

Synovial fluid (SF) is the natural lubricant found in articulated joints, providing unique cartilage surface protecting films under confinement and relative motion. While it is known that the synergistic interactions of the macromolecular constituents provide its unique load-bearing and tribological performance, it is not fully understood how two of the main constituents, glycosaminoglycans (GAGs) and glycoproteins, regulate the formation and mechanics of robust load-bearing films. Here, we present evidence that the load-bearing capabilities, rather than the tribological performance, of the formed SF films depend strongly on its components' integrity. For this purpose, we used a combination of enzymatic treatments, quartz crystal microbalance with dissipation (QCM-D) and the surface forces apparatus (SFA) to characterize the formation and load-bearing capabilities of SF films on model oxide (i.e., silicates) surfaces. We find that, upon cleavage of proteins, the elasticity of the films is reduced and that cleaving GAGs results in irreversible (plastic) molecular re-arrangements of the film constituents when subjected to confinement. Understanding thin film mechanics of SF can provide insight into the progression of diseases, such as arthritis, but may also be applicable to the development of new implant surface treatments or new biomimetic lubricants.

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