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Exploring the nature and kinetic of establishment of molecular interactions in aqueous solution: the example
of polysaccharide systems
Alexandre Cordinier, Nicolas Hucher, Michel Grisel
To cite this version:
Alexandre Cordinier, Nicolas Hucher, Michel Grisel. Exploring the nature and kinetic of establishment of molecular interactions in aqueous solution: the example of polysaccharide systems. ESC 2019 European Student Colloid Conference, Jun 2019, VARNA, Bulgaria. �hal-02331886�
Exploring the nature and kinetic of establishment of molecular interactions in aqueous solution: the example of polysaccharide systems
Unité de Recherche en Chimie Organique et Macromoléculaire
Normandie Univ, UNIHAVRE, FR 3038 CNRS, URCOM, 76600 Le Havre, France
Alexandre Cordinier a , Nicolas Hucher a and Michel Grisel a Alexandre.cordinier@univ-lehavre.fr
References
0 3 6 9 12
0 10 20 30 40 50
G' (Pa)
Time (h)
Evolution of the viscoélastique properties of a X/LBG mixture 40/60 (0.2% w/w)*
1. Daas, P. J. H.; Meyer-Hansen, K.; Schols, H. A.; De Ruiter, G. A.; Voragen, A. G. J. Carbohydr. Res. 1999, 318 (1–4), 135–145.
2. Daas, P. J. H.; Schols, H. A.; de Jongh, H. H. J. Carbohydr. Res. 2000, 329 (3), 609–619.
3. R. O. Mannion, C. D. Melia, B. Launay, G. Cuvelier, S. E. Hill, S. E. Harding, J. R. Mitchell, Carbohydr. Polym. 1992, 19, 91–97.
4. S. Secouard, C. Malhiac, M. Grisel, B. Decroix, Food Chem. 2003, 82, 227–234.
5. J. A. Casas, F. García-Ochoa, J. Sci. Food Agric. 1999, 79, 25–31.
6 I. C. M. Dea, E. R. Morris, D. A. Rees, E. J. Welsh, H. A. Barnes, J. Price, Carbohydr. Res. 1977, 57, 249–272 7. M. Tako, A. Asato, S. Nakamura, Agric. Biol. Chem. 1984, 48, 2995–3000.
8. P. Cairns, M. J. Miles, V. J. Morris, G. J. Brownsey, Carbohydr. Res. 1987, 160, 411–423.
9. A. Kato, S. Nakai, Biochim. Biophys. Acta BBA - Protein Struct. 1980, 624, 13–20.
10. M. D. Bilokin’, V. V. Shvadchak, D. A. Yushchenko, G. Duportail, Y. Mély, V. G. Pivovarenko, J. Fluoresc. 2009, 19, 545–553.
11. P. B. Fernandes, J. Food Eng. 1995, 24, 269–283.
Pyruvate group
Acetate group
Context
Xanthane (X)
Galactomannans (GM)
Galactose
Synthesized by bacteria
Used as rheological modifier and stabilizer
Helix
(Ordered form) Rigid chain
Random coil
(Disordered form) Flexible chain pH
Ionic strength
Conformational transion temperature (Tm)
Chemical variability:
Structural variability:
Fermentation conditions => Variability of degrees of
substitution of pyruvate (DS
Py) and acetate (DS
Ac) groups
Extracted from plant seeds
Used mainly as rheological modifier
Main chain = Mannose units (M) substituted by galactose residues (G)
≠ varieties of seeds:
Variation of the M/G ratio
Distribution of G:
Degree of blockiness
1,2(DB)
Ordered Random Blockwise
Structural variability:
Synergy X/GM
Mixed in specific conditions POSITIVE SYNERGY between X and GM
Over the past 50 years, several interaction models have been proposed:
Dea & Morris’ model
6based on polarimetric measurements
Tako’s model
7based on rheological measurements
Cairns’ model
8based on X-ray diffraction measurements
X/GM ratio3
G’ or G’’ (Pa)
Objectives
The aim of this project is to characterize the interactions at the molecular scale between polymers in solution
Shear rate (s-1)5
Viscosity (kg/ms)
X/G
X G
Develop an universal analytical tool to study the interactions at the molecular level
On the ground of the observations done at the macroscopic scale, why one model would be
more accurate than another ?
3 ≠ models based on 3 ≠ techniques
≠ Conformations or ≠ chemical structures of X
Check what happen at microscopic scale !
Arome relative Release (%)
X/GM (%)4; X/LBG X/GG
Conclusions
≠ type of GM:
- Locust Bean Gum (LBG) - Guar Gum (GG)
- Tara Gum (TG) - etc…
Characterization of interactions at the molecular scale ? FLUORESCENCE SPECTROSCOPY
0 50 100 150 200 250 300
350 400 450 500 550 600
EI ( a.u .)
λ (nm)
3HQ-Bf spectra in X/LBG mixture (1:1; 0.2% w/w)
Corrected and normalized spectra at 700 nm
1N* 2N*
T*
λ
1N*λ
2N*λ
T*0 50 100 150 200 250
440 540 640 740
IE ( a.u .)
λ (nm)
ANS spectra in X/LBG mixture (1:1; 0.2% w/w)
Corrected and normalized at 740 nm
λ
IEmaxIE
maxResults
At the macroscopique scale At the molecular scale
X/GM mixing phase
Use of 2 molecular specific probes
Same mixing process between X and GM as at the macroscopic scale
Injection of 1 of the 2 selected fluorescence probes: 8-anilino-1-naphtalen sulfonic acid (ANS) or 2-benzofuryl-3-hydroxy-4(1H)-quinolone (3HQ-Bf) in small quantities
The 3HQ-Bf probe is sensitive to H-Bonds
10in its close environment
3HQ-Bf is not available commercially, it has to be synthesized
3HQ-Bf is a ratiometric probe
Ratio EI
N*/EI
T*≈ Strength of the H-bond network
The ANS probe is sensitive to Hydrophobic interactions
9(EI)
H
2O is a quencher to the fluorescence of ANS probe
The ANS probe is also sensitive to the polarity of the medium (λ)
ANS is t available commercially
X/GM mixtures at 0.2% (w/w)
Use of a phosphate buffer at pH 7.4
X/GM mixture stirred during ~ ½ h +
H
2O H
2O
H
2O H
2O
H
2O
H
2O H
2O
X
G
Magnetic Stirrer
Buffer Buffer
Buffer Buffer
X/GM mixtures preparation
Use of a Discovery Hybrid Rheometer to follow viscoelastic properties of our X/GM mixtures with time High shear rates !
Stabilization of viscoelastic propoerties is not happening suddenly
2 ≠ phases:
1 Structuration phase
2 Stabilized system
The period of the structuration phase is depending on the composition of X/GM mixture
The period of the structuration phase is depending also of the mixture preparation conditions
Few studies have been made about this structuration step
11,51 2
1 2 1 2
2 ≠ phases:
1 Structuration phase
2 Stabilized interactions
Interaction strucuration depends on the composition of X/GM mixture
*For reasons of clarity only the stock modulus G’ was represented
**For reasons of clarity standard deviations were not represented
***Dotted lines only help to read the graphs
Before any stabilization of X/GM mixtures, both molecular interactions (hydrophobic interactions and H-bonds) need a period of time which depend on the preparation conditions and of the composition of the X/GM mixture
Structuration phases can be observed at both scales, macroscopic and molecular
Structuration phases are strongly dependent of the composition of X/GM mixtures and dependent of the preparation conditions
2 2,1 2,2 2,3 2,4 2,5 2,6
-1,2 -1 -0,8 -0,6 -0,4 -0,2 0
Log(EI)
Log(t)
Kinetic of structuration of hydrophobic interactions at short times
0/100 30/70 40/60 50/50 70/30 100/0
Representation « log-log » Representation « log-log »
0 50 100 150 200 250 300 350
0 5 10 15 20 25 30
EI (a.u.)
Time (h)
Evolution of hydrophobic interactions in X/LBG mixtures
(0.2% w/w)**
Corrected and normalized spectra at 740 nm
0/100
30/70
40/60
50/50
70/30
100/0
-0,4 -0,3 -0,2 -0,1 0 0,1 0,2
-1,2 -1 -0,8 -0,6 -0,4 -0,2 0
Log[EI(2N*) /EI(T*)]
Log(t)
Kinetic of structuration of the H-bond network at short times***
0/100 30/70 40/60 50/50 70/30 100/0 Theoritical curve for 50/50a
Theoritical curve for 50/50b
0 0,5 1 1,5 2 2,5
0 5 10 15 20 25 30
Ratio EI(2N*)/EI(T*)
Time (h)
Evolution of the H-Bond network with time in X/LBG mixtures (0.2% w/w)**
0/100 30/70 40/60 50/50 70/30 100/0
a Calculated as follow: EI50/50theo=0.5xEI100/0exp+0.5xEI0/100exp
b Calculated as follow: [EI(2N*)/EI(T*)]50/50theo= 0.5x[EI(2N*)/EI(T*)]100/0 + 0.5x[EI(2N*)/EI(T*)]0/100
