afm study of the interactions between synovial liquid's molecular components in boundary...
DESCRIPTION
A complex study over the affinities between synovial fluid's main components and the lipid bilayers found inside synovial joints.TRANSCRIPT
AFM STUDY OF THE INTERACTIONS BETWEEN
SYNOVIAL LIQUID’S MOLECULAR COMPONENTS IN BOUNDARY LUBRICATION
D.A. Mirea, A-M. Trunfio-Sfarghiu, A. Piednoir, J.P. Rieu, M.G. Blanchin, Y. Berthier
RoTrib’10Iaşi, România
The Synovial Joints
Most joints are freely moveable.They allow different movement, depending on the
shape of the bones meeting in that joint.The shoulder, hip and ankle are susceptible to
injury due to the amount of movement possible at them
The Synovial Fluid
A non-Newtonian fluid found in the cavities of synovial joints
Its principal role is to reduce friction inside the synovial joints during movement
The resorbtion of the synovial fluid can’t be treated. The only option offered by the medicine is the total replacement of the joint.
Highly important! Discovering the components that may be used in developing an artificial synovial liquid.
Lipid bilayers
Synovial gelAlbumin
Hyaluronic acid
Glucydic component:
Hyaluronic acid
Hydrophile glucides, L ~ 12
000 nm
Proteic component:
Albumin + Globulin
Globular proteins
8 nm3 nm
+
Lipids
2.5 nm
0,5 nm
+
Glicoproteic component:
Proteo-glycan (PG4-lubricin-SZP)
Volume
Interface
Which molecule is deficitary in
this model?
The synovial model
Adopted strategy
Adhesion force measurements using the “Force Measurement” mode on the AFM microscope
5 nm
Lipid bilayer
Globular proteins
8 nm3 nm Hydrophile
glucides, L ~ 12 000 nm
Proteo-glycan
Atomic Force Microscopy – Mode Force Measurements
Atomic Force Microscopy is being used mostly for imaging, although the AFM is a very suitable tool for force measurements.
Preparing the experiment
AFM cantilevers
AFM glass supports Lipid bilayers
Polysaccharides
CMA
Albumin (BSA)
γ-Globulin
Preoteo-glycan
Experimental Protocol
The lipid bilayers
2 mM Ca++
2 incubations
20 mM micelles 1 mol lipide / 6 mol DDM
Slow dilution
5 nm
The co-absorbtion of lipid micells and detergent was used to obtain the lipid bilayers
ResultsThe CMA test
ResultsThe glycoproteic
component
Results The proteic component - Albumin
ResultsThe proteic component - γ-
Globulin
ResultsThe glucidic
component
Without penetration With penetration
Conclusions & interpretation
PG4Cartilage
Hyaluronic acid + seric
proteins
Lipid layers
Presence of lipid
multilamelar layers
Hills A.B., Internal
Medicine Journal 2002
Hyaluronic acid (AH)A high affinity for the lipid
bilayersSeric proteins – low adhesion rates but
reticular with AH (Oates K.M.N. J. R. Soc. Interface,
2005)
AH aids in creating the
vesicles. AH and the seric
proteins remain inside the vesicles
PG4~lubricin~SZPA high rate of adhesion
onto lipid bilayers - Ineractions with the CS
groups from the articular cartilage (Rhee
D.K., The Journal of Clinical Investigation, 2005)
PG4 aids in fixing the lipid layers on the
cartilage
Presence of lipid multilamelar vesicles
Trunfio-Sfarghiu A.M, and all.
BiomMedD'2008
0.2 µm
Conclusions & interpretation
Hyaluronic acid + seric proteins
Lipid bilayers
PGCartilageLipid layers
proteins + glucids Lipid bilayers
2 µm
Discontinuous structure of synovial liquid the hydrodynamic theories do not apply
Sliding location betwwen lipid bilayers c.f = 0.0015 (Trunfio-Sfarghiu A.M., Tribology International 2007)
Thank you for your attention!