HAL Id: hal-02800560
https://hal.inrae.fr/hal-02800560
Submitted on 5 Jun 2020
HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.
L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Mechanical properties of membranes composed of milk polar lipids in the gel or fluid-phase probed by AFM on
liposomes
Oumaima Et Thakafy, N. Delorme, Cédric Gaillard, Christelle Lopez, Fanny Guyomarc’H
To cite this version:
Oumaima Et Thakafy, N. Delorme, Cédric Gaillard, Christelle Lopez, Fanny Guyomarc’H. Mechanical properties of membranes composed of milk polar lipids in the gel or fluid-phase probed by AFM on liposomes. IDF World Dairy Summit 2016, Oct 2016, Rotterdam, Netherlands. 2016. �hal-02800560�
Mechanical properties of membranes composed of milk polar lipids in the gel or fluid phase
probed by AFM on liposomes
O. Et Thakafy1, N. Delorme2, C. Gaillard3, C. Lopez1, F. Guyomarc’h1
1STLO, INRA, Agrocampus Ouest, Rennes, France ; 2IMMM, Le Mans, France ; 3BIBS, INRA, Nantes, France [email protected]
Milk polar lipids for liposome applications :
Fatty acid composition of polar lipids affects the elasticity of membranes
4 µm DOPC vs DPPC
20 60 100 140 180 E (MPa)
100 120
60
20 80
40
Milk-SM
20 60 100 140 180 E (MPa)
40
20 50
30
10 70 80
Outlooks:
Unsaturated (DOPC) and saturated (DPPC) polar lipids versus molecular species of milk sphingomyelin (milk-SM).
DOPC: dioleoylphosphatidylcholine (18:1), DPPC: dipalmitoylphosphatidylcholine (16:0). Milk-SM contains long chain saturated fatty acids and 3% of unsaturated 24:1.
Distribution of elasticity values for DOPC, DPPC and milk-SM vesicles, recorded at 20°C.
DOPC DPPC Milk-SM
Milk-SM fatty acid composition
COUNTSCOUNTS
The elasticity of lipid membranes depends mainly on the physical state of lipids (gel vs. fluid) and consequently on their chemical composition (unsaturated vs. saturated). At 20°C, DOPC bilayers in the fluid state exhibited a lower elasticity (4 MPa) compared to DPPC bilayers in the gel state (130 MPa). Interestingly, milk-SM bilayers in the gel phase had dispersed values ranging from 20 to 200 MPa. This could be interpreted by the coexistence of several molecular species, i.e. the presence of saturated fatty acids with various chain lengths or the presence of unsaturated fatty acid 24:1 which may disturb the organization of the bilayer.
Differential scanning calorimetry thermograms of DOPC, DPPC and milk-SM multilamellar vesicles, showing the gel to fluid phase transition temperature (Tm).
Chemical composition Physical state Mechanical properties
Temperature (°C)
Heat flow (a.u.) Endo Tm = -19°C
Tm = 41°C
Tm = 34°C
DPPC
DOPC
Milk-SM
Ice
melting
AFM force measurements
INRA -AGROCAMPUS OUEST
Sciences and technology of Milk and Egg Rennes , FRANCE
www.rennes.inra.fr
IDF World Dairy Summit, 16-21 October 2016 Rotterdam, The Netherlands Saturated
Unsaturated
T = 20°C pH =6,7
5 nm
150 nm
Atomic force spectroscopy Milk polar lipids
Buttermilk
Liposome fabrication and stability
Homogenization
The milk fat globule membrane (MFGM) has recently gained a lot of attention, due to the growing interest in its nutritional and technological properties. Its composition, rich in polar lipids, has great potential for new product applications with unique physical properties such as liposomes. Milk polar lipids might be advantageous for both the stability and the biological acceptance of the formulation. Milk polar lipids possess different structures of molecules:
saturated with high melting temperatures (Tm),in particular the milk sphingomyelin (SM,Tm 35°C); or unsaturated with low Tm. Does this difference in the molecular structure affect the mechanical properties of the membranes?
F= 150 pN
Confocal microscopy image showing , in situ in milk, the heterogeneity of MFGM due to
gel/fluid segregation
Milk fat globule
Domain rich in saturated polar lipids in gel phase
Fluorescent matrix of unsaturated
polar lipids in fluid phase
These results open perspectives for liposome applications where the mechanical properties of the membrane are essential to ensure stability such as encapsulation in drug delivery or cosmetics. This study will also serve as reference for future investigations on membrane models of the MFGM to increase our knowledge of the role of heterogeneity in the stability of milk fat globule during processing or digestion.
Acknowledgements for co-funding the PhD thesis
Small unilamellar vesicles
Gel phase
Fluid phase
2°C/min
