Carbohydrate-based Surfactants Research Articles

Latest Trends in Lipase-Catalyzed Synthesis of Ester Carbohydrate Surfactants: From Key Parameters to Opportunities and Future Development.

Carbohydrate-based surfactants are amphiphilic compounds containing hydrophilic moieties linked to hydrophobic aglycones. More specifically, carbohydrate esters are biosourced and biocompatible surfactants derived from inexpensive renewable raw materials (sugars and fatty acids). Their unique properties allow them to be used in various areas, such as the cosmetic, food, and medicine industries. These multi-applications have created a worldwide market for biobased surfactants and consequently expectations for their production. Biobased surfactants can be obtained from various processes, such as chemical synthesis or microorganism culture and surfactant purification. In accordance with the need for more sustainable and greener processes, the synthesis of these molecules by enzymatic pathways is an opportunity. This work presents a state-of-the-art lipase action mode, with a focus on the active sites of these proteins, and then on four essential parameters for optimizing the reaction: type of lipase, reaction medium, temperature, and ratio of substrates. Finally, this review discusses the latest trends and recent developments, showing the unlimited potential for optimization of such enzymatic syntheses.

Exploring multivalent protein-glycosensitizer interaction with phenalenone derivatives in mixed micelles

Carbohydrates are involved in several biological processes, and they have been widely used in several technological applications. Carbohydrate-based surfactants have low toxicity, and they are environmental friendly, however, their physicochemical properties restrict their use in potential applications. Mixed micelles are an attractive model system to use for carbohydrate–based surfactants since their physical properties may be easily modulated with simple changes in the surfactants mixture ratio.In this study, we design a mixed micelle system composed by new synthesized glycolipids bearing a photosensitizer in their hydrophobic moiety. We hypothesize that this system would have two main functions a) singlet oxygen generation and b) multivalent capability to interact with lectins. These combined capabilities will permit the generation of the short-lived excited oxygen neighboring the targets to be oxidized.In this design, non-ionic mixed micelles were used to modify the interfacial properties and to improve the solubility in water of the synthesized glycosensitizers.In summary, our results show that both glycolipids retain their capability to generate singlet oxygen in homogeneous media and the mixed micelles behave as an adequate multivalent system to interact with Con A. We provide a promising system to be successfully employed in antibacterial photodynamic therapy.

Cationic carbohydrate-based surfactants derived from renewable resources: Trends in synthetic methods

Surfactants are extensively utilized and have become a necessity in our daily lives. On the other hand, increasing surfactant production has raised global warming and environmental issues, necessitating finding new sustainable alternatives. Carbohydrate-based surfactants derived from renewable sources are good candidates for solving this issue. In the last decade, the development of this class was extensively studied. However, the cationic branch has been the least investigated, which is unfortunate because they are environmentally friendly, biocompatible, and biodegradable materials that can be used to treat microbes and dermatologic diseases compared to other surfactants. These features are useful for a variety of applications, including antiseptics and gene delivery. Consequently, developing alternative, sustainable procedures to produce carbohydrate-based surfactants is crucial. This review has compiled and described the present synthetic methodologies for producing carbohydrate cationic-based surfactants.

Cationic Carbohydrate-Based Surfactants Derived from Renewable Resources: Trends in Synthetic Methods

Cationic Carbohydrate-Based Surfactants Derived from Renewable Resources: Trends in Synthetic Methods

Synthesis and Characterization of new Ethoxylated Carbohydrate based Surfactants for Corrosion Inhibition of low LCS Steel in Aqueous Solutions

The heterocyclic compounds, mainly carbohydrate-based surfactant, 1, 4 Sorbitan, namely (Sorbitan Mono-stearate with 20 moles of Ethylene oxide SMS-20-EO, Sorbitan Mono-oleate SMO, and Sorbitan Mono-oleate ethoxylated with 20 moles of Ethylene oxide SMO-20-EO ) have been synthesized and characterized through different spectroscopic methods (FTIR, 1H NMR). Then estimated as corrosion inhibitors of low LCS (LCS) in the aggressive environment 1 M HCl utilizing a weight loss (WL), the destructive and destructive electrochemical techniques. The surface examination was tested using several techniques. The new ethoxylated carbohydrate-based surfactant gave an excellent inhibition performance (IE %). The adsorption of the inhibitors obeys the Langmuir adsorption model. The metal dissolution and inhibitor adsorption phenomena have been studied via the estimation of thermodynamic parameters, which describe the adsorption properties of SMO, SMO-20-EO, and SMS-20-EO.

Rich liquid crystal phase behavior of novel alkyl-tri(ethylene glycol)-glucoside carbohydrate surfactants

Carbohydrates are appealing non-ionic surfactant head-groups as they are naturally abundant, generally biocompatible and biodegradable, and readily functionalized. Herein, we explore the phase behavior of seven novel carbohydrate-based surfactants (CBS) containing a tri-ethylene glycol (TEG) linker between a glucose head-group and alkyl tail-group, with linear saturated (C8–18) and cis-unsaturated (C18:1) alkyl chains. At high aqueous concentrations, these glycolipid-like surfactants transition into a variety of lyotropic liquid crystalline phases following an expected concentration phase sequence: hexagonal (H1) → bicontinuous cubic (V1) → lamellar (Lα). Using polarizing light microscopy (PLM), a binary (surfactant–water) phase diagram for each surfactant was constructed across a temperature range (25–80 °C) revealing thermotropic behavior and a broadening of liquid crystal phase regions with increasing alkyl chain length. There was also a significant difference between saturated and unsaturated alkyl chains, due to the cis-unsaturated ‘statistical bend’ lowering the melting point. Small-angle X-ray scattering (SAXS) measurements were performed to characterize the liquid crystal phases, identifying highly-ordered p6m,Ia3d, and Lα crystallographic space-groups with up to 7 resolved Bragg peaks, likely due to the highly anisometric nature of the TEG-linked surfactants. The phases were shown to be more numerous and exhibited greater thermal-stability compared to well-characterized alkyl glucoside surfactants lacking an oligoethylene spacer in the literature. Finally, the characteristic dimensions of each phase were determined to enable visualization of the internal microstructures, providing insight into the impact of molecular shape and the distribution of hydro-philicity/phobicity on the formation and stability of liquid crystalline mesophases.

Wormlike micelle formation of novel alkyl-tri(ethylene glycol)-glucoside carbohydrate surfactants: Structure–function relationships and rheology

Carbohydrates are appealing non-ionic surfactant head-groups as they are naturally abundant, generally biocompatible and biodegradable, and readily functionalized. Here, seven novel carbohydrate based surfactants (CBS) have been synthesized that contain a tri-ethylene glycol (TEG) linker between a glucose head-group and alkyl tail-group, with linear saturated (C8–18) and unsaturated (C18:1) alkyl chains. The aqueous adsorption and self-assembly of these surfactants was explored using tensiometry and small- and ultra-small-angle neutron scattering (SANS and USANS). With SANS we observed elongation from spherical to cylindrical micelles with increasing alkyl chain length. C16 and C18 chains exhibited pronounced Krafft points, yet formed worm-like micelles as single components upon heating to 43 and 48 °C respectively. The introduction of mono-unsaturation in the form of a C18:1 chain reduced the Krafft point and gave a surfactant that produced worm-like micelles in water without additives at room temperature. We also observed micellar elongation for C12 and C14 chains at 50 °C due to dehydration of the TEG linker. The room temperature worm-like micelles were further characterized using rheo-SANS and rheology, revealing the C18:1 surfactant to exhibit near ideal Maxwell behavior at low concentrations (2.9 wt.%). These results provide insight into structure-function relationships for CBS, and demonstrate a promising molecular candidate for the formation of viscoelastic worm-like micellar solutions.

Photoswitchable carbohydrate-based fluorosurfactants as tuneable ice recrystallization inhibitors

Cryopreservation is an important technique employed for the storage and preservation of biological tissues and cells. The limited effectiveness and significant toxicity of conventionally-used cryoprotectants, such as DMSO, have prompted efforts toward the rational design of less toxic alternatives, including carbohydrate-based surfactants. In this paper, we report the modular synthesis and ice recrystallization inhibition (IRI) activity of a library of variably substituted, carbohydrate-based fluorosurfactants. Carbohydrate-based fluorosurfactants possessed a variable mono- or disaccharide head group appended to a hydrophobic fluoroalkyl-substituted azobenzene tail group. Light-addressable fluorosurfactants displayed weak-to-moderate IRI activity that could be tuned through selection of carbohydrate head group, position of the trifluoroalkyl group on the azobenzene ring, and isomeric state of the azobenzene tail fragment.

Carbohydrate-based surfactants as photocontrollable inhibitors of ice recrystallization

Carbohydrate-based surfactants as photocontrollable inhibitors of ice recrystallization

Inverted Micelle-in-Micelle Configuration in Cationic/Carbohydrate Surfactant Mixtures.

Nuclear magnetic resonance is applied to investigate the relative positions and interactions between cationic and non-ionic carbohydrate-based surfactants in mixed micelles with D2 O as the solvent. This is accomplished by using relaxation measurements [spin-lattice (T1 ) and spin-spin (T2 ) analysis] and nuclear Overhauser effect spectroscopy (NOESY). This study focuses on the interactions of n-octyl β-d-glucopyranoside (C8G1) and β-d-xylopyranoside (C8X1) with the cationic surfactant hexadecyltrimethylammonium bromide (C16 TAB). Whereas the interactions between carbohydrate and cationic surfactants are thermodynamically favorable, the NOESY results suggest that both of the sugar head groups are located preferentially at the interior core of the mixed micelles, so that they are not directly exposed to the bulk solution. The more hydrophilic sugar headgroups of C8G1 have more mobility than sugar heads of C8X1 owing to increased hydration. Herein, an inverted carbohydrate configuration in mixed micelles is proposed for the first time and supported by fluorescence spectroscopy experiments. This inverted carbohydrate headgroup configuration would limit the use of these mixed surfactants when access to the carbohydrate headgroup is important, but may present new opportunities where the carbohydrate-rich core of the micelles can be exploited.

Photomodulation of bacterial growth and biofilm formation using carbohydrate-based surfactants.

Naturally occurring and synthetic carbohydrate amphiphiles have emerged as a promising class of antimicrobial and antiadhesive agents that act through a number of dynamic and often poorly understood mechanisms. In this paper, we provide the first report on the application of azobenzene trans-cis photoisomerization for effecting spatial and temporal control over bacterial growth and biofilm formation using carbohydrate-based surfactants. Photocontrollable surface tension studies and small angle neutron scattering (SANS) revealed the diverse geometries and dimensions of self-assemblies (micelles) made possible through variation of the head group and UV-visible light irradiation. Using these light-addressable amphiphiles, we demonstrate optical control over the antibacterial activity and formation of biofilms against multi-drug resistant (MDR) Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus (MRSA) and Gram-negative Escherichia coli. To probe the mechanism of bioactivity further, we evaluated the impact of trans-cis photoisomerization in these surfactants on bacterial motility and revealed photomodulated enhancement in swarming motility in P. aeruginosa. These light-responsive amphiphiles should attract significant interest as a new class of antibacterial agents and as investigational tools for probing the complex mechanisms underpinning bacterial adhesion and biofilm formation.

Carbohydrate-based surfactants as photocontrollable inhibitors of ice recrystallization

We report the synthesis and photocontrollable ice recrystallization inhibition (IRI) activity of a panel of carbohydrate-based surfactants.

Hemolytic activity and solubilizing capacity of raffinose and melezitose fatty acid monoesters prepared by enzymatic synthesis

The hemolytic activity and solubilizing capacity of two families of non-reducing trisaccharide fatty acid monoesters have been studied to assess their usefulness as surfactants for pharmaceutical applications. The carbohydrate-based surfactants investigated included homologous series of raffinose and melezitose monoesters bearing C10 to C18 acyl chains prepared by lipase-catalyzed synthesis in organic media. The hemolytic activity was determined in vitro using a static method based on the addition of the surfactants to an erythrocyte suspension and subsequent spectrophotometric determination of the released hemoglobin. The effect of the carbohydrate head group, the acyl chain length and the regioisomeric purity was investigated. In all cases, the carbohydrate monoester surfactants decreased their hemolytic activity (with respect to their critical micelle concentration) when increasing the length of the acyl chain. A very similar behaviour was observed either the carbohydrate head-group (raffinose and melezitose) or regardless of the regioisomeric purity. Interestingly, decanoyl (C10) and lauroyl (C12) monoesters were just marginally hemolytic at their critical micelle concentrations while the longer palmitoyl (C16) and (C18) stearoyl monoesters become hemolytic at concentrations much higher than their respective cmc. The palmitoyl and stearoyl monoesters also displayed higher solubilization capacity than the shorter acyl chain monoesters in a solubilization assay of a hydrophobic dye as a model drug mimic. These results suggest that raffinose and melezitose monoesters with long-chain fatty acids (C16 to C18) are promising surfactants for pharmaceutical applications and could be an alternative to the use of current commercial nonionic polyoxyethylene-based surfactants in parenteral formulations.

Light-induced structural evolution of photoswitchable carbohydrate-based surfactant micelles.

We report the light-induced structural evolution of photoswitchable carbohydrate-based surfactant micelles using time-resolved small-angle neutron scattering (TR-SANS), monitoring the structural changes in micellisation in situ over time and demonstrating for the first time the course and implications of this process.

067 Small carbohydrate-based molecules as potent ice recrystallization inhibitors and their application in red blood cell cryopreservation

Red blood cell (RBC) preservation from peripheral blood donations in blood banks has ensured the availability of safe blood supplies for transfusions. RBCs are typically stored refrigerated for a maximum of 42 days. However, more prolonged storage times are required for rare blood type donations and currently the only method available for their long-term storage is cryopreservation. Unfortunately, RBC cryopreservation is costly and time-consuming, requiring extensive washing procedures to reduce the high glycerol cryoprotectant concentration from 40–50% to less than 1%. Consequently, improvements in the RBC cryopreservation process are urgently required. A significant contributor to cellular injury and death during cryopreservation is ice recrystallization. Thus, great interest has arisen in designing ice recrystallization inhibitors for use as novel cryoprotectants. Unfortunately, the structural features necessary for ice recrystallization inhibition (IRI) activity are not known. Potent IRI activity was previously limited to large protein and glycoprotein molecules related to biological antifreezes. However, our laboratory recently reported the first potent small molecule ice recrystallization inhibitors that were carbohydrate-based surfactants and hydrogelators. Further investigation into various other small carbohydrate-based molecules has led to the discovery that several substituted oxygen-linked phenolic-glycosides exhibit potent IRI activity. Structure-function studies have identified that key structural features on these phenolic-glycosides are crucial for potent activity. In particular, the activity of these glycosides is highly sensitive to the position of the functional group on the aromatic ring, as well as hydroxyl group stereochemistry and the nature of the anomeric-linkage on the carbohydrate moiety. The cryoprotective ability of various highly IRI active glycosides with RBCs was also assessed to investigate if glycerol concentrations could be significantly reduced during cryopreservation. These results have indicated that their addition to cryoprotective solutions containing lower glycerol concentrations can decrease post-thaw RBC hemolysis. This is significant as a reduction in glycerol concentration can ultimately decrease deglycerolization times and improve post-thaw RBC quality for transfusions. This presentation will discuss the cryopreservation results and the effectiveness of these highly IRI active glycosides as cryo-additives for RBCs, as well as the structure-function results identifying key structural features important for the IRI activity of phenolic-glycosides. Source of funding: This research was supported by Canadian Blood Services (CBS), Canadian Institutes of Health Research (CIHR) and Natural Sciences and Engineering Research Council of Canada (NSERC). Conflict of interest: None declared. rben@uottawa.ca

Synthesis, surface properties, and biocompatibility of 1,2,3-triazole-containing alkyl β-d-xylopyranoside surfactants

We are interested in the development of surfactants derived from hemicellulosic biomass, as they are potential components in pharmaceuticals, personal care products, and other detergents. Such surfactants should exhibit low toxicity in mammalian cells. In this study we synthesized a series of alkyl or fluoroalkyl β-xylopyranosides from azides and an alkyne using the copper-catalyzed azide-alkyne (CuAAC) ‘click’ reaction in 4 steps from xylose. The purified products were evaluated for both their surfactant properties, and for their biocompatibility. Unlike other carbohydrate-based surfactants, liquid–crystalline behavior was not observed by differential scanning calorimetry. The triazole-containing β-xylopyranosides with short (6 carbons) and long (>12 carbons) chains exhibited no toxicity at concentrations ranging from 1 to 1000μM. Triazole-containing β-xylopyranosides with 8, 10, or 12 carbons caused toxicity via apoptosis, with CC50 values ranging from 26–890μM. The two longest chain compounds did form stable monolayers at the air–water interface over a range of temperatures, although a brief transition to an the unstable monolayer was observed.

Amphiphilic Spruce Galactoglucomannan Derivatives Based on Naturally-Occurring Fatty Acids

A class of nonionic polysaccharides-based surfactants were synthesised from O-acetyl galactoglucomannan (GGM), water-soluble hemicelluloses from spruce, using naturally-occurring saturated fatty acids, CH3(CH2)nCOOH (n = 7, 12, and 16). Hemicelluloses can be recovered from waste-streams of papermaking and agricultural processes or isolated by hot water extraction of plant tissues integrated into a biorefinery process. Fatty acids can be recovered as byproducts of the agricultural and food industries. Different synthesis routes were applied to yield amphiphilic derivatives with either a grafted or block structure. Fatty acids activated with 1,1′-carbonyldiimidazole (CDI) were grafted to the backbone of GGM molecules on their hydroxyl groups. Alternatively, synthesised amino-activated fatty acids using ethylenediamine were reacted with the reducing end of GGM. By adjusting the reagent ratios, GGM-based surfactants with different hydrophilic to hydrophobic ratios were prepared. Their surface activity was assessed by measuring the surface tension in water. This study presents an approach to design carbohydrate-based surfactants using naturally-occurring fatty acids that may find potential applications in such areas as food, cosmetic, and paint formulations.

TMDS as a Dual‐Purpose Reductant in the Regioselective Ring Cleavage of Hexopyranosyl Acetals to Ethers

Abstract1,1,3,3‐Tetramethyldisiloxane (TMDS) has been developed as an excellent dual‐purpose reductant for the highly regioselective ring cleavage of various hexopyranosyl 4,6‐O‐acetals with Cu(OTf)2 or AlCl3 to afford the corresponding primary and secondary ethers. Its application to the concise synthesis of carbohydrate‐based surfactants is highlighted.

Potent inhibition of ice recrystallization by low molecular weight carbohydrate-based surfactants and hydrogelators

Ice recrystallization inhibition (IRI) activity is a very desirable property for an effective cryoprotectant. This property was first observed in biological antifreezes (BAs), which cannot be utilized in cryopreservation due to their ability to bind to ice. To date, potent IRI active compounds have been limited to BAs or synthetic C-linked AFGP analogues (1 and 2), all of which are large peptide-based molecules. This paper describes the first example of low molecular weight carbohydrate-based derivatives that exhibit potent IRI activity. Non-ionic surfactant n-octyl-β-D-galactopyranoside (4) exhibited potent IRI activity at a concentration of 22 mM, whereas hydrogelator N-octyl-D-gluconamide (5) exhibited potent IRI activity at a low concentration of 0.5 mM. Thermal hysteresis measurements and solid-state NMR experiments indicated that these derivatives are not exhibiting IRI activity by binding to ice. For non-ionic surfactant derivatives (3 and 4), we demonstrated that carbohydrate hydration is important for IRI activity and that the formation of micelles in solution is not a prerequisite for IRI activity. Furthermore, using solid-state NMR and rheology we demonstrated that the ability of hydrogelators 5 and 6 to form a hydrogel is not relevant to IRI activity. Structure–function studies indicated that the amide bond in 5 is an essential structural feature required for potent IRI activity.

Linear and cyclic C-glycosides as surfactants

Carbohydrate-based surfactants have long been of interest due to their desirable performance properties and their potential to be derived from renewable feedstocks. Although most carbohydrate based surfactants utilize an O-glycosidic linkage, recent advances in carbohydrate C–C bond formation allows for the facile synthesis of new classes of carbohydrate-based surfactants on a C-glycosidic linkage. Herein is described an approach that can generate a wide variety of C-glycoside surfactants in moderate to very good yield by treating the nonulose C-glycoside intermediate first described by Lubineau et al. with pyrrolidine in the presence of an alkyl aldehyde. Depending on the stoichiometry and reaction conditions, this chemistry will result in either a linear enoneC-glycoside, or a cyclohexenoneC-glycoside, both of which demonstrate interesting surfactant properties. Further, the linear enone series can be photochemically modified or reacted with other alkyl aldehydes to generate additional analogs.