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See detailMonolayer Properties of Uronic Acid Bicatenary Derivatives at the Air-Water Interface: Effect of Hydroxyl Group Stereochemistry Evidenced by Experimental and Computational Approaches
Razafindralambo, Hary ULiege; Richel, Aurore ULiege; Wathelet, Bernard ULiege et al

in Physical Chemistry Chemical Physics [=PCCP] (2011), 13(33), 1529115298

By screening uronic acid-based surfactant interfacial properties, the effect of the hydroxyl group stereochemistry (OH-4) on the conformation of bicatenary (disubstituted) derivatives at the air–water ... [more ▼]

By screening uronic acid-based surfactant interfacial properties, the effect of the hydroxyl group stereochemistry (OH-4) on the conformation of bicatenary (disubstituted) derivatives at the air–water interface has been evidenced by experimental and computational approaches. Physical and optical properties of a monolayer characterized by Langmuirfilmbalance, Brewster angle microscopy, and ellipsometry at 20°C reveal that the derivative of glucuronate (C14/14–GlcA) forms a more expanded monolayer, and shows a transition state under compression, in the opposite to that of galacturonate (C14/14–GalA). Both films are very mechanically resistant (compression modulus > 300m Nm-1) and stable (collapse pressure exceeding 60mNm-1), while that of C14/14–GalA exhibits a very high compression modulus up to 600mNm-1 like films in the solid state. Computational approaches provide single and assembly molecular models that corroborate the molecule expansion degree and interactions data from experimental results. Differences in the molecular conformation and film behaviours of uronic acid bicatenary derivatives at the air–water interface are attributed to the intra-H-bonding formation, which is more favourable with an OH-4 in the axial (C14/14–GalA) than in the equatorial position (C14/14–GlcA). [less ▲]

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See detailAn Overview Of Methodology For Predicting Activities And Functionalities Of A Wide Range Of Carbohydrate- Based Surfactants From Their Fundamental Properties
Razafindralambo, Hary ULiege; Blecker, Christophe ULiege; Paquot, Michel ULiege

in 8th World surfactant congress and business convention (2011, June 06)

Introduction and Background: Carbohydrate-based surfactants (CBS) are, today, among the most attractive amphiphilic compounds owing to their high potentiality for a large product concept. The main ... [more ▼]

Introduction and Background: Carbohydrate-based surfactants (CBS) are, today, among the most attractive amphiphilic compounds owing to their high potentiality for a large product concept. The main fundamental reasons are the abundance of their precursors from renewable resources, the excellent environmental compatibility, and the quasi-unlimited availability of their molecular structure and geometry. Based on the latter aspect, CBS would be expected to generate a wide range of functionalities and activities for food and non-food applications. All kinds of amphiphilic compounds including small surfactants, bolaforms, geminis, oligomeric, and polymeric molecules with a single or a multiple hydrophobic tails can be designed by synthetic routes thanks to a large number of reactive chemical groups in their basic structure. Consequently, various methodologies are required, and could be used in complementary for identifying all of their potentiality for further development. Methodology: The methodology is based on the characterization in the laboratory scale, i.e. using only small amounts of sample, of CBS properties at fluid and solid interfaces, in bulk liquid phases, and at the solid state with simplified models. Results and Discussion: In this communication, an overview of functionality and activity-predicting methods for a wide range of CBS structures varying in head polar groups, hydrophobic tail and number, and linkers will be presented and discussed. Performances and complementarities of different approaches, methodologies, and techniques will be emphasized. These include sample preparation and analysis procedures, interfacial-characterizing instruments, mainly tensiometers and Langmuir balances used both in dynamic and (quasi)-static modes, particle size and electrical charge analyser, and (micro)calorimeters using differential scanning, isothermal titration, and thermogravimetry methods. Conclusion: The knowledge of these basic properties is helpful for predicting their main activities and functionalities like their aptitude for forming and stabilizing colloidal systems, and for developing biological activities. This is also necessary for the rational design of CBS amphiphilic structure regarding to specific properties. The same approach can also be applied for other required features as the compound stability, toxicity, and biodegradability. [less ▲]

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See detailStructure-Surface Activity Relationships Of Uronic Acid-Derivative Surfactants From Renewable Resources Applications
Razafindralambo, Hary ULiege; Richel, Aurore ULiege; Richard, Gaetan ULiege et al

Poster (2011, June)

Introduction and Background: Uronic acid-derivative surfactants are amphiphilic compounds with growing interests owing to their potential applications in various areas [1]. This class of carbohydrate ... [more ▼]

Introduction and Background: Uronic acid-derivative surfactants are amphiphilic compounds with growing interests owing to their potential applications in various areas [1]. This class of carbohydrate-based surfactants can be easily prepared from renewable raw materials in a wide range of structure by modular synthesis thanks to the presence of one carboxylic and numerous hydroxyl groups. The polar head group configurations according to the stereochemistry of OH groups, and geometry (cyclic or not), the hydrophobic tail (number and length of alkyl chain), and the type of linker (ester, acetal and amide, etc) are among the main variables in their structural entities. Therefore, the investigation of their structure-surface activity relationships appears valuable for increasing backgrounds, and achieving a rational design for selecting the best structures to be used in different industrial fields [2]. Methodology: A few analogous of glucuronic acid-derivative surfactants have been synthesized by chemical or enzymatic routes. After purification, their structure has been confirmed by various spectroscopic techniques (RMN, MS, IR). Surface tensions of true aqueous solution have been then measured in dynamic and static modes using a series of complementary techniques. Critical micelle concentrations, minimum molecular areas, and maximum surface excesses have also been determined. Results and Discussion: Glucuronic acid derivative surfactants under investigation vary in the polar head group configuration including cyclic or non-cyclic structure and α or β anomeric form, in the hydrophobic tail regarding to the chain length (C8 to C14), the presence of a double bond, as well as an OH group at the terminal carbon, and in the type of linker, ester in C6 or acetal in C1. Results showed that all of these structural attributes affect both dynamic and equilibrium surface properties of glucuronic acid -based surfactants. Conclusion: A set of synthetic glucuronic acid-based surfactants varying in the polar head group, hydrophobic tail, and linker allow us to generate various surface-active properties at the air-water interface, and to increase the knowledge on relationships between their structure and surface-active properties. [1] Laurent, P.; Razafindralambo, H.; Wathelet, B.; Blecker, C.; Wathelet, J.-P.; Paquot, M., Synthesis and Surface-Active Properties of Uronic Amide Derivatives, Surfactants from Renewable Organic Raw Materials. Journal of Surfactants and Detergents 2010, in press. [2] Razafindralambo, H.; Blecker, C.; Mezdour, S.; Deroanne, C.; Crowet, J.; Brasseur, R.; Lins, L.; Paquot, M., Impacts of the Carbonyl Group Location of Ester Bond on Interfacial Properties of Sugar-Based Surfactants: Experimental and Computational Evidences. The Journal of Physical Chemistry B 2009, 113 (26), 8872-8877. Acknowledgment: This work was supported by Belgian Walloon Region within DGTRE research project of excellence (TECHNOSE). [less ▲]

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See detailAn Overview Of Methodology For Predicting Activities And Functionalities Of A Wide Range Of Carbohydrate- Based Surfactants From Their Fundamental Properties
Razafindralambo, Hary ULiege

Conference (2011, June)

Introduction and Background: Carbohydrate-based surfactants (CBS) are, today, among the most attractive amphiphilic compounds owing to their high potentiality for a large product concept. The main ... [more ▼]

Introduction and Background: Carbohydrate-based surfactants (CBS) are, today, among the most attractive amphiphilic compounds owing to their high potentiality for a large product concept. The main fundamental reasons are the abundance of their precursors from renewable resources, the excellent environmental compatibility, and the quasi-unlimited availability of their molecular structure and geometry. Based on the latter aspect, CBS would be expected to generate a wide range of functionalities and activities for food and non-food applications. All kinds of amphiphilic compounds including small surfactants, bolaforms, geminis, oligomeric, and polymeric molecules with a single or a multiple hydrophobic tails can be designed by synthetic routes thanks to a large number of reactive chemical groups in their basic structure. Consequently, various methodologies are required, and could be used in complementary for identifying all of their potentiality for further development. Methodology: The methodology is based on the characterization in the laboratory scale, i.e. using only small amounts of sample, of CBS properties at fluid and solid interfaces, in bulk liquid phases, and at the solid state with simplified models. Results and Discussion: In this communication, an overview of functionality and activity-predicting methods for a wide range of CBS structures varying in head polar groups, hydrophobic tail and number, and linkers will be presented and discussed. Performances and complementarities of different approaches, methodologies, and techniques will be emphasized. These include sample preparation and analysis procedures, interfacial-characterizing instruments, mainly tensiometers and Langmuir balances used both in dynamic and (quasi)-static modes, particle size and electrical charge analyser, and (micro)calorimeters using differential scanning, isothermal titration, and thermogravimetry methods. Conclusion: The knowledge of these basic properties is helpful for predicting their main activities and functionalities like their aptitude for forming and stabilizing colloidal systems, and for developing biological activities. This is also necessary for the rational design of CBS amphiphilic structure regarding to specific properties. The same approach can also be applied for other required features as the compound stability, toxicity, and biodegradability. [less ▲]

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See detailEffect of ageing on different egg yolk fractions on surface properties at the air–water interface
Freschi, Jérôme ULiege; Razafindralambo, Hary ULiege; Danthine, Sabine ULiege et al

in International Journal of Food Science & Technology (2011), 46

The aim of this study was to evaluate the impact of egg ageing on the surface properties of whole and fractionated yolk at the air–water interface. Eggs were stored at 4 Cfor 24 h, 1 week and 3 weeks ... [more ▼]

The aim of this study was to evaluate the impact of egg ageing on the surface properties of whole and fractionated yolk at the air–water interface. Eggs were stored at 4 Cfor 24 h, 1 week and 3 weeks after laying.A laboratory scale fractionation process was then applied at each ageing time. Egg yolk was separated into two fractions, plasma composed of low-density lipoproteins (LDLs) and livetins, and granules formed by highdensity lipoproteins (HDLs), phosvitins and LDLg (g = granule). Moreover, recombined plasma and granules fractions were investigated to highlight a potential synergic effect on surface properties. Results have shown the main contribution of LDLs on surface properties of yolk and an improvement of granules surface properties when they are disrupted. Moreover, ageing affected surface properties differently depending on the considered fractions. Broken LDLsand disrupted granules could explain this observed behaviour. Recombined fractions showed different compression isotherms at the air–water interface than whole yolk. [less ▲]

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See detailEtude des interactions membranaires de dérivés de l’acide glucuronique par calorimétrie à titrage isotherme
Laurent, Pascal ULiege; Razafindralambo, Hary ULiege; Paquot, Michel ULiege

Poster (2011)

Dans le cadre de la valorisation de la biomasse et des glucides provenant de l’hydrolyse de matières premières renouvelables, différents dérivés d’acides uroniques ont été synthétisés en vue d’évaluer ... [more ▼]

Dans le cadre de la valorisation de la biomasse et des glucides provenant de l’hydrolyse de matières premières renouvelables, différents dérivés d’acides uroniques ont été synthétisés en vue d’évaluer leurs propriétés en tant qu’agents tensioactifs biocompatibles et biodégradables. Une nouvelle stratégie de synthèse assistée par micro-ondes, efficace et respectueuse de l'environnement, a par ailleurs permis de synthétiser quantitativement différentes D-glucofuranosidurono-6,3-lactones monosubstituées hydrosolubles au départ d'acide D-glucuronique non protégé en utilisant un catalyseur acide supporté. Ces lactones appartiennent à la famille des glycosurfactants non-ioniques dont les applications couvrent un vaste domaine, aussi bien dans l’industrie pharmaceutique, cosmétique ou alimentaire. Une première approche en vue d’évaluer leurs activités biologiques consiste en l’étude des paramètres d’interactions moléculaires de ces lactones vis-à-vis d’une membrane biologique modèle (1-palmitoyl-2-oleyl-sn-glycerol-3-phosphatidylcholine) par calorimétrie à titrage isotherme (Isothermal Titration Calorimetry – ITC). [less ▲]

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See detailSynthesis and Surface-Active Properties of Uronic Amide Derivatives, Surfactants from Renewable Organic Raw Materials
Laurent, Pascal ULiege; Razafindralambo, Hary ULiege; Wathelet, Bernard ULiege et al

in Journal of Surfactants and Detergents (2011), 14(1), 51-63

Short chemical syntheses were developed to produce a new set of surfactants from uronic acids derived from widely available raw material. Three different strategies were used to synthesise uronic amide ... [more ▼]

Short chemical syntheses were developed to produce a new set of surfactants from uronic acids derived from widely available raw material. Three different strategies were used to synthesise uronic amide derivatives, the structures of which were totally characterized by spectrometric methods (IR, MS, 1H-RMN and 13C-RMN). The best one, using an acid chloride as synthetic intermediate, furnished the expected amides as a mixture of anomers in 46 to 58 % global yield. Surface-active properties (CMC, g cmc, Tmax, Amin) of homologous series of uronic acid N-alkylamides from C8 to C18 were also assessed. In general, these sugar-based surfactants exhibited good surface-activities, and appeared as valuable non ionic surfactants compared to Triton X-100, the most well-known non ionic surfactant. Increasing the alkyl chain length influenced the CMC values for both glucuronic and galacturonic N-alkylamide derivatives. The galacturonic N-alkylamides decreased g cmc at slower values than their counterpart's glucuronic N-alkylamides. [less ▲]

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See detailCARBOHYDRATE-BASED SURFACTANTS FOR FORMING AND STABILIZING COLLOIDAL SYSTEMS AS EMULSIONS AND FOAMS
Razafindralambo, Hary ULiege; Blecker, Christophe ULiege; Richel, Aurore ULiege et al

in Abstracts book of 5th edition of world congress on emulsions (2010, October 12)

Carbohydrate-based surfactants (CBS) constitute a class of amphiphilic molecules with particular and common interests. These surface-active compounds can be produced from the most abundant renewable ... [more ▼]

Carbohydrate-based surfactants (CBS) constitute a class of amphiphilic molecules with particular and common interests. These surface-active compounds can be produced from the most abundant renewable materials allowing large product concept possibilities, and may occur in a large structural range with one or more hydrophilic head groups and hydrophobic chains with various linkers/spacers, thanks to numerous reactive functional groups in their basic structure. It is then possible to design a quasi-unlimited number of new compounds by (bio)-synthesis from various raw materials. This structural diversity can generate a wide range of properties, which could be developed in food and non-food applications. Our challenge is now to find out the most suitable molecular structures for the post-development of CBS, mainly for colloidal systems like emulsion, foam, and suspension. A pre-screening of the dynamic and equilibrium interfacial tensions and interfacial rheology properties of various CBS prepared by chemical, enzymatic, or chemo-enzymatic synthesis routes from the derivatives of bio-renewable substrates is carried out. Then, the characterization of emulsifying and foaming properties of pre-selected molecules is performed. These investigations are completed by the characterization of thermal properties of liquid suspensions and powders. Homologous series of two derivative compounds of glucuronic and galacturonic acids with mono- or bicatenar hydrophobic chains and different linkages (linear or cyclic ester, amide) have been chosen as CBS starting compounds. These were full characterized by spectroscopic techniques (RMN, SM, IR). The effect of the hydrophobic chain length and number, polar head group, and the linker on whole properties investigated is easily deduced. [less ▲]

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See detailScreening of basic properties of amphiphilic molecular structures for colloidal system formation and stability: case of carbohydrate-based surfactants
Razafindralambo, Hary ULiege; Blecker, Christophe ULiege; Paquot, Michel ULiege

Conference (2010, March 21)

Carbohydrate-based surfactants (CBS) are amphiphilic molecules with particular interests. These surface-active compounds can be produced from the most abundant renewable materials allowing large product ... [more ▼]

Carbohydrate-based surfactants (CBS) are amphiphilic molecules with particular interests. These surface-active compounds can be produced from the most abundant renewable materials allowing large product concept possibilities. They may occur in a wide range thanks to numerous functional groups. These make possible the design of a quasi-unlimited compounds by (bio)-synthesis of new structures, or by modifying existing natural molecules. This structural diversity can generate a wide range of properties which could be developed in food and non-food applications. Our challenge is to find out the most suitable molecular structures for post)development of CBS according to the specific required properties in various industrial applications. This consists of assessing the interfacial properties of various CBS prepared by chemical, enzymatic, or chemo-enzymatic synthesis routes from the derivatives of bio-renewable materials.The effect of the polar head group, the hydrophobic chains (length, number), and the linker will be presented and discussed. [less ▲]

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See detailThermodynamic Studies Of The Binding Interactions Of Surfactin Analogues To Lipid Vesicles Application Of Isothermal Titration Calorimetry
Razafindralambo, Hary ULiege; Dufour, Samuel; Paquot, Michel ULiege et al

in Journal of Thermal Analysis and Calorimetry (2009), 95(3), 817-821

Isothermal titration calorimetry was applied for studying the binding interactions of cyclic and linear surfactins with different ionic charge (z= –2 and –3) and lipid chain length (n=14 and 18) to 1 ... [more ▼]

Isothermal titration calorimetry was applied for studying the binding interactions of cyclic and linear surfactins with different ionic charge (z= –2 and –3) and lipid chain length (n=14 and 18) to 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidyl-choline (POPC) vesicles in 10mM Tris buffer at pH 8.5 with 150mM NaCl at 25°C. Surfactin analogues interacted spontaneously with POPC vesicles. The binding reactions were endothermic and entropy-driven process. Moreover, significant differences in the binding constant values (K) ranging from 6.6 *10^3 to 9.6* 10^4 M–1 show that cyclic structure and the increase of lipid chain length are favourable on the surfactin binding affinity to POPC vesicles, whereas the rise of the number of negative charges has an opposite effect. [less ▲]

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See detailSynthèse et propriétés tensioactives de nouveaux surfactants provenant de matières premières renouvelables.
Laurent, Pascal ULiege; Razafindralambo, Hary ULiege; Wathelet, Bernard ULiege et al

Poster (2009)

A l'heure actuelle, le bioraffinage se présente de plus en plus comme une alternative prometteuse aux filières pétrochimiques puisqu'il vise à la fois le remplacement d'une partie du pétrole comme source ... [more ▼]

A l'heure actuelle, le bioraffinage se présente de plus en plus comme une alternative prometteuse aux filières pétrochimiques puisqu'il vise à la fois le remplacement d'une partie du pétrole comme source d'énergie et le développement de produits chimiques issus de la biomasse (végétale principalement) tels que détergents, produits phytopharmaceutiques, dissolvants, matières plastiques, etc. La valorisation de carbohydrates provenant de matières premières renouvelables fait ainsi actuellement l'objet de nombreuses recherches. Dans ce cadre, la synthèse de nouveaux tensioactifs non ioniques dérivés des acides Dglucuronique et D-galacturonique a été effectuée. [less ▲]

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See detailHigh-throughput methodology applied to screening of carbohydrate-based surfactant interfacial properties for colloidal system formulations
Razafindralambo, Hary ULiege; Blecker, Christophe ULiege; Deroanne et al

Poster (2009)

Carbohydrate-based surfactants (CBS) constitute an attractive class of amphiphilic molecules owing to their structural diversity generating a wide range of properties which could be developed in food and ... [more ▼]

Carbohydrate-based surfactants (CBS) constitute an attractive class of amphiphilic molecules owing to their structural diversity generating a wide range of properties which could be developed in food and non-food applications. Based on many functional groups of the carbohydrate part, it is possible to design multiple amphiphilic structures of CBS varying in the hydrophilic head groups (mono-, oligo-, or polysaccharides), hydrophobic tail (mono-, di-, tricatenar) but also in the linker/spacer between them. The main structures of CBS include mono- and bicatenar glycolipids, bolaforms, and gemini. Moreover, CBS compounds can be produced from the most abundant renewable materials allowing large product concept possibilities. Among general properties of surfactants, interfacial properties molecules occupy a fundamental key role for colloidal system formulations since they control most of technological aptitudes required for forming and stabilizing food, cosmetic, agrochemical, detergent, and pharmaceutical products. High-throughput methodology applied to screening of CBS interfacial properties appears crucial for achieving optimum formulations of colloidal systems like foams and emulsions for which small amounts of single or mix surface-active agents are often needed and numerous physical and chemical parameters are involved. This general approach may be applied to any amphiphilic molecules produced from other renewable resources of surface-active compounds like micro-organisms and by direct extraction from vegetable materials. One of the key factors for the development of this methodology is the use of automated instrument systems in laboratory scale which are still lacking in this field compared to those existing in the analytical chemistry and biochemistry areas. [less ▲]

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See detailImpacts of the carbonyl group location of ester bond on interfacial properties of sugar-based surfactants: experimental and computational evidences
Razafindralambo, Hary ULiege; Blecker, Christophe ULiege; Mezdour, Samir et al

in Journal of Physical Chemistry B (2009), 113

Interfacial properties of surfactants are dependent on the conformation adopted by the hydrophilic headgroup or/and the hydrophobic tail at the boundary limit of two immiscible phases. Here, we ... [more ▼]

Interfacial properties of surfactants are dependent on the conformation adopted by the hydrophilic headgroup or/and the hydrophobic tail at the boundary limit of two immiscible phases. Here, we demonstrate the impacts of the carbonyl group (-CO-) location of the ester bond of sugar-based surfactants by comparing some properties of two closely related esters, octyl glucuronate and glucose octanoate, at the air-water interface. The carbonyl group location influences the rate and extent of interfacial adsorption and the rheology properties of sugar esters at the air-water interface, which were evaluated by dynamic surface tension and complex surface viscoelastic measurements. Octyl glucuronate adsorbs the fastest at the air-water interface whereas glucose octanoate reduces the dynamic surface tension at the lowest value and exhibits the highest film viscoelasticity. Differences are attributed to molecular conformation constraints inducing relevant changes to the surface coverage kinetic capacity and the interaction strengths of the octyl sugar ester adsorbed films at the air-water interface. All of the results are supported by the minimum cross-sectional area values per molecule determined by both experimental and computational approaches. [less ▲]

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See detailIsothermal titration calorimetry as a tool for improving enzymatic lignocellulose hydrolysis
Razafindralambo, Hary ULiege; Boquel, Pascal; Jacquet, Nicolas ULiege et al

Conference (2008, December)

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See detailDynamic And Equilibrium Surface Tensions Of Surfactin Aqueous Solutions
Razafindralambo, Hary ULiege; Thonart, Philippe ULiege; Paquot, Michel ULiege

in Journal of Surfactants and Detergents (2004), 7(1), 41-46

A homologous series of surfactins containing β-hydroxy fatty acids having 13, 14, or 15 carbon atoms were isolated from the supernatant of Bacillus subtilis strain S499 cultures. Their surface-active ... [more ▼]

A homologous series of surfactins containing β-hydroxy fatty acids having 13, 14, or 15 carbon atoms were isolated from the supernatant of Bacillus subtilis strain S499 cultures. Their surface-active properties at the air-water interface were then evaluated. Dynamic surface tension data were analyzed by the relaxation function γt=γm+(γo−γm)/[1+(t/t*)n]. Based on various parameters t*, n, vmax, γm calculated from this equation, the dynamic surface properties of surfactin were found to depend on both bulk concentration and hydrophobic character of the alkyl chain. At low concentrations of surfactin, the dynamic surface tension (γd) decreased with increasing carbon atom number of the surfactin alkyl chain (n=13 to 15). However, at high concentrations, the maximum decrease of 41-4 was achieved by surfactin-C14. In contrast, more strongly hydrophobic alkyl chains in surfactins always enhanced their ability in reducing the equilibrium surface tensions and their aptitude in forming micelles. [less ▲]

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