A complex study over the affinities between synovial fluid's main components and the lipid bilayers found inside synovial joints.

1. 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’10
Iaşi, România

2. 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

3. 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.

4. The synovial model
Hyaluronic
acid
Hydrophile
glucides, L ~ 12 000
Glucydic component: nm
Hyaluronic acid
Volume
+
3 nm
Proteic component: 8 nm Albumin
Synovial gel
Albumin + Globulin
Globular proteins
Which molecule is
+ Lipid bilayers
deficitary in this
model?
0,5 nm
Lipids
2.5 nm
Interface
Glicoproteic component:
Proteo-glycan (PG4-
lubricin-SZP)

5. Adopted strategy
Adhesion force measurements using the “Force
Measurement” mode on the AFM microscope
Proteo-glycan
3 nm Hydrophile
8 nm glucides, L ~ 12 000
nm
Globular proteins
5 nm
Lipid bilayer

6. 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.

7. Preparing the experiment
Polysaccharides
AFM cantilevers
Albumin (BSA)
CMA γ-Globulin
Preoteo-glycan
AFM glass supports Lipid bilayers

8. Experimental Protocol

9. The lipid bilayers
The co-absorbtion of lipid micells and detergent was used to obtain the lipid bilayers
20 mM micelles 1 mol
lipide / 6 mol DDM
2 mM Ca++
2 incubations
Slow dilution
5 nm

10. Results
 The CMA test

11. Results
 The glycoproteic
component

12. Results
 The proteic component - Albumin

13. Results
 The proteic component - γ-
Globulin

14. Results
 The glucidic
component
Without penetration With penetration

15. Conclusions & interpretation
Hills A.B., Internal
Medicine Journal
Trunfio-Sfarghiu 2002
A.M, and all.
BiomMedD'2008
Presence of lipid Presence of lipid
multilamelar vesicles multilamelar layers
0.2 µm
PG4~lubricin~SZP
Hyaluronic acid (AH) AH aids in creating PG4 aids in A high rate of adhesion
A high affinity for the lipid the vesicles. AH and fixing the lipid onto lipid bilayers -
bilayers the seric proteins layers on the Ineractions with the CS
Seric proteins – low remain inside the cartilage groups from the articular
adhesion rates but reticular vesicles cartilage (Rhee D.K., The Journal
with AH (Oates K.M.N. J. R. Soc. of Clinical Investigation, 2005)
Interface, 2005)
Hyaluronic acid +
seric proteins
Cartilage
Lipid layers PG4

16. Conclusions & interpretation
Lipid bilayers
Hyaluronic acid + seric
proteins
Lipid layers Cartilage
PG
Discontinuous structure of synovial liquid  the
hydrodynamic theories do not apply
proteins +
glucids Lipid bilayers
Sliding location betwwen lipid
bilayers  c.f = 0.0015 (Trunfio-
Sfarghiu A.M., Tribology International 2007)
2 µm

17. Thank you for your
attention!