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Sugar fatty acid nonionic surfactants have attracted great attention due to their good biodegradability, biocompatibility, and bio-based characteristics. Regioselective sugar acylation is difficult to control for chemical reactions. The immiscible nature between hydrophilic sugars and hydrophobic fatty acids also negatively affects the reaction eff...
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Biosurfactants are surface-active compounds synthesized by microbes. They have the ability to reduce the surface tension of a liquid and interfacial tension (IFT) between two different phases. Thus, they can be applied in water-oil emulsification. The development of enhanced oil recovery (EOR) technology has led to increased interest in biosurfacta...
Biosurfactant or Bioemulsifier amphiphilic compounds are; produced by microorganisms as primary or secondary metabolites. The unique properties of biosurfactants mean that they have the potential to supplement, or even replace, chemical surfactants used in food, in the cosmetics and pharmaceutical industries; and in the environment. In the present...
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... Tetramethylsilane (TMS) is added as an internal reference. [43,149] NMR spectra provide sufficient information to elucidate RL structures, using parameters such as chemical shifts, coupling constants, and integral curve analysis. [128] The unique structural features of saccharides are particularly useful, as they show distinct NMR parameters that help in structural elucidation. ...
In recent years, biosurfactants (BS) produced by various bacteria, fungi and yeast strains have attracted much interest because of their unique properties and potential applications in many industries ranging from bioremediation to agriculture and biomedical to cosmetics. Glycolipids are a popular group of BS that include rhamnolipids, sophorolipids, mannosylerythritol, trehalose lipids, xylolipids and cellobiose lipids. Lipopeptides e.g., surfactins, iturins and fengycins are of major biotechnological interest because of their antitumor, immunomodulatory, and antimicrobial activities effects. This review addresses the structural properties of glycolipids and lipopeptides, their main domains of application as well as the screening tests of BS production. Glycolipids are mostly composed of a carbohydrate moiety linked to a ß-hydroxy fatty acid chain with a glycosidic bond. The properties of glycolipids are related to the nature of the carbohydrate moiety and the length of the fatty acid chain. The lipopeptide structure is mainly composed of a linear or cyclic peptide linked to fatty acids of different chain lengths. The structural complexity of these compounds requires various analytical techniques for characterization and quantification. As an example, the analytical techniques used for the characterization of rhamnolipids are presented in this review. RLs are very promising BS with a wide range of applications in various fields, such as cosmetics, food science, pharmaceuticals, and environmental remediation.
... This is especially challenging for molecules such as glycolipids that are normally produced as structural mixtures. For SL that might constitute a method to separate the acidic congeners from the lactonic congeners which display completely different behavior [87], or for RL to separate mono-RL from di-RL [88]. ...
... In this process, chloroform was used initially to remove neutral lipids followed by a sequence of chloroform:methanol mobile phases in varying ratios and volumes to elute the mono-RL followed by di-RL at purities ranging from 95% to 100%. In an extension of this work, Miao et al [88] used a silica gel column with a mobile phase consisting of chloroform/methanol/water for purification of a crude RL extract. Upon elution, two separate peaks appeared: the first representing mono-RL and the second di-RL. ...
Glycolipids are microbial surface-active molecules that are composed of a carbohydrate unit linked to a single or multiple fatty acid(s). They are receiving increased research interest due to their green production pathways and their environmental and application benefits. Rhamnolipids, trehalolipids, sophorolipids, and mannosylerythritol lipids are among the most well-characterized glycolipids. Their antibacterial and emulsifying properties impart great potential to glycolipids in areas such as cleaning, cosmetic, and food preservation and can serve as sustainable substitutes for many synthetic surfactants. In addition, the valorization of food wastes through their use as fermentation feedstocks to produce glycolipid biosurfactants has received considerable attention because the process allows the bioconversion of inexpensive renewable by-products to value-added compounds, which may help to decrease production costs. This chapter focuses on the status and future perspectives related to the economical production of glycolipid biosurfactants and their potential application in foods.
... Previous studies showed that in the presence of CTAB micelles, the alkaline hydrolysis of curcumin was greatly inhibited and its solubility was also enhanced [29,30]. In addition to ionic surfactants, nonionic surfactants have attracted increasing attention due to their good biocompatibility and biodegradability [31]. In our previous work, it was found that the solubilization effect of Tween 20/Tween 60 (Figs. ...
Bisdemethoxycurcumin (BDMC), one of the main curcuminoids, has numerous biological activities. However, the low solubility and stability of BDMC limit its application. In this work, in order to improve the solubility and stability of BDMC, we encapsulated BDMC using cetyltrimethylammonium bromide (CTAB) + Tween 20/Tween 60 mixed surfactants. The molar ratio of CTAB to Tween 20/Tween 60 was optimized by response surface analysis. The thermodynamic parameters (binding constant, enthalpy change, entropy change and Gibbs free energy change) for the interaction of BDMC with CTAB + Tween 20/Tween 60 mixed micelles were obtained by fluorescence spectroscopy and UV-visible absorption spectroscopy. Positive enthalpy change and entropy change indicated that hydrophobic interaction was the main driving force. Moreover, due to the longer alkyl chains of Tween 60, the encapsulation of BDMC by CTAB + Tween 60 mixed micelles was stronger. The encapsulation of BDMC in the hydrophobic alkyl chains by the mixed micelles was determined by fluorescence polarization technology, time-resolved fluorescence assay, and ¹H nuclear magnetic resonance spectroscopy. Solubilization and stability experiments showed that the solubility of BDMC was improved and the alkaline hydrolysis of BDMC was inhibited due to the encapsulation of the mixed micelles. The improvement of the solubility and stability of BDMC was more obvious in CTAB + Tween 60 mixed micelles because of the stronger interaction between them. The above results indicated that CTAB + Tween 20/Tween 60 mixed micelles could be used to encapsulate BDMC to improve its solubility and stability.
... Применение таких методов позволяет определять химическую структуру и класс биосурфактантов, но в последнее время к ним также обращаются и для выявления механизмов взаимодействия биосурфактантов с различными объектами, например, с модельными мембранами клеток, водонефтяными эмульсиями, почвами и т. д. В рассматриваемую группу методов входят инфракрасная спектроскопия (ИК-спектроскопия), в частности ИК-фурьеспектроскопия [41,58], методы молекулярной динамики и другие методы компьютерного моделирования [58,59], масс-спектрометрия, тонкослойная хроматография [42,60,61], газовая хроматография, газовая хроматография с масс-спектрометрией [62], масс-спектрометрия c ионизацией электрораспылением [63,64], высокопроизводительная жидкостная хроматография [65], жидкостная хроматография с масс-спектрометрией [60, 66], масс-спектрометрия с бомбардировкой быстрыми атомами, матрично-активированная лазерная десорбция/ионизация с времяпролетным масс-анализатором (MALDI-TOF) [44,60,[67][68][69][70][71][72][73][74][75][76][77][78][79], методы ядерного магнитного резонанса (ЯМР), включая многомерные методики и методы на 13 С-, 31 Р-и 2 Н-ядрах [60- 62,65,67,[69][70][71][72]. ...
... Применение таких методов позволяет определять химическую структуру и класс биосурфактантов, но в последнее время к ним также обращаются и для выявления механизмов взаимодействия биосурфактантов с различными объектами, например, с модельными мембранами клеток, водонефтяными эмульсиями, почвами и т. д. В рассматриваемую группу методов входят инфракрасная спектроскопия (ИК-спектроскопия), в частности ИК-фурьеспектроскопия [41,58], методы молекулярной динамики и другие методы компьютерного моделирования [58,59], масс-спектрометрия, тонкослойная хроматография [42,60,61], газовая хроматография, газовая хроматография с масс-спектрометрией [62], масс-спектрометрия c ионизацией электрораспылением [63,64], высокопроизводительная жидкостная хроматография [65], жидкостная хроматография с масс-спектрометрией [60, 66], масс-спектрометрия с бомбардировкой быстрыми атомами, матрично-активированная лазерная десорбция/ионизация с времяпролетным масс-анализатором (MALDI-TOF) [44,60,[67][68][69][70][71][72][73][74][75][76][77][78][79], методы ядерного магнитного резонанса (ЯМР), включая многомерные методики и методы на 13 С-, 31 Р-и 2 Н-ядрах [60- 62,65,67,[69][70][71][72]. ...
This paper discusses the latest trends in studying and using biosurfactants, surfactant biomolecules produced by microorganisms. Biosurfactants were considered as an alternative to synthetic surfactants. The basic principles of producing, screening and characterizing biosurfactants were reviewed. Their physicochemical properties were singled out. The modern understanding of a relationship between the properties of biosurfactants and their practical use was analyzed. Particular attention was paid to the research works focused on the potential use of biosurfactants, as well as the current and major challenges of their production and application in the real sector of economy. The already existing world biosurfactant market was described. An outlook on its possible future development was provided.
... Both 1 H and 13 C NMR spectroscopy have been applied for the structural analysis of rhamnolipids after purification, with 1 H NMR being more commonly used due to its higher detection sensitivity (Lotfabad et al. 2010;Miao et al. 2014). In the process of 1 H NMR analysis, purified rhamnolipids samples are dissolved in deuterated solvents (typically chloroform-d) with tetramethylsilane added (TMS) as a reference (Miao et al. 2014). ...
... Both 1 H and 13 C NMR spectroscopy have been applied for the structural analysis of rhamnolipids after purification, with 1 H NMR being more commonly used due to its higher detection sensitivity (Lotfabad et al. 2010;Miao et al. 2014). In the process of 1 H NMR analysis, purified rhamnolipids samples are dissolved in deuterated solvents (typically chloroform-d) with tetramethylsilane added (TMS) as a reference (Miao et al. 2014). Structural information is derived from the spectrum based on the chemical shifts, coupling constants and integral curve analysis. ...
Rhamnolipids have extensive potential applications and are the most promising biosurfactants for commercialization. The efficient and accurate identification and analysis of these are important to their production, application and commercialization. Accordingly, significant efforts have been made to identify and analyse rhamnolipids during screening of producing strains, fermentation and application processes. Cationic cetyltrimethylammonium bromide–methylene blue (CTAB-MB) test combines a series of indirect assays to efficiently assist in the primary screening of rhamnolipids-producing strains, while the secretion of rhamnolipids by these strains can be identified through TLC, FTIR, NMR, electrospray ionization mass spectrometry (ESI-MS) and HPLC-MS analysis. Rhamnolipids can be quantified by colorimetric methods requiring the use of concentrated acid, and this approach has the advantages of reliability, simplicity, low-cost and excellent reproducibility with very low technological requirements. HPLC-MS can also be employed as required as a more accurate quantification method. In addition, HPLC-ELSD has been established as the internationally acceptable measure of rhamnolipids for commercial purposes. The preparation of well-accepted rhamnolipids standards and modifications of analysis operations are essential to further enhance the accuracy and improve the simplicity of rhamnolipid analysis.Key points
• Current status of R&D works on determination of rhamnolipids is listed
• Advantages and disadvantages of various types analysis are summarized
• Limitations of current rhamnolipid quantification are discussed
... Bio-based surfactants exhibit great potential as oil-displacement agents in oilfields owing to their outstanding biodegradability and environmental sustainability. [1][2][3] Cellulose is generally considered as one of the most important natural resources, and nanocellulose has received more attention with the advent of nanoscience. However, technical reports on nanocellulose-based surfactants are rare. ...
Nanocellulose surfactants (CSFs) were prepared by grafting sodium allyl sulfonate (C3H5NaO3S) and trifluoroethyl methacrylate (C6H7F3O2) into nanocellulose through free-radical graft copolymerisation. The copolymerisation was carried out by one-step and two-step approaches to preparing CSF-1 and CSF-2 surfactants, respectively. The structure and properties of CSF-1 and CSF-2 were characterised by infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and surface/interfacial tension measurement. Compared with CSF-1, which was prepared with the one-step approach, a higher fluorine (F) content and a lower crystallinity degree were detected for CSF-2, which was prepared with the two-step approach. The surface tension, critical micelle concentration and oil/water interfacial tension values of the CSFs were 32·5 mN/m, 0·36 g/l and 4·8 × 10⁻² mN/m, respectively, for CSF-1 and 27·4 mN/m, 0·33 g/l, 1·9 × 10⁻² mN/m, respectively, for CSF-2. The lower surface and interfacial tensions confirmed that CSF-2 was endowed with superior surface activity and oil-displacement efficiency. Additionally, CSF-2 displayed enhanced emulsification power in comparison with CSF-1.
... However, data are more limited for improvement of the downstream processing of rhamnolipids. Different unit operations have been utilized in downstream processing of rhamnolipids, such as ultrafiltration (Long et al., 2012;Witek and Gruszczyn, 2011), foam fractionation (Beuker et al., 2016;Heyd et al., 2011;Sarachat et al., 2010), precipitation (Shah et al., 2016), solvent extraction (Wei et al., 2005), adsorption (Haba et al., 2003), and chromatography (Lin, 1996;Miao et al., 2014;Sim et al., 1997). For the typical rhamnolipid production by Pseudomonas aeruginosa fermentation, the bacterial cells can also produce alginate and proteins as major extracellular metabolites. ...
Downstream purification processes often determine the manufacturing costs of biotechnological products, particularly for those with high yields in the upstream synthesis processes. Rhamnolipids are important biosurfactants with promising industrial applications. Significant research has been focused on optimizing rhamnolipid production in the upstream fermentation but there are very few studies on downstream processing. The objective of this study is to fill this critical technological gap by (1) tracking the recovery and purity of rhamnolipids processed through different unit operations and (2) developing new and more environmentally friendly downstream processing methods. A biopolymer removal step using alcohol precipitation was found effective in improving the recovery, from 66% to 78%, and giving about 87% purity in the product collected by acid precipitation without further solvent extraction. A reverse aqueous extraction method, which was optimized to recover 97% rhamnolipids from the solvent (ethyl acetate) extract, was examined as an alternative to the commonly used but costly, energy-intensive solvent vaporization. As a polishing step, calcium precipitation was optimized to selectively remove residual impurities while keeping all major rhamnolipid congeners in solution. The study also identified the presence of excess oil substrate/derivatives in the fermentation broth as a strongly negative factor to the downstream processing. The feeding strategy of oil substrate in fermentation should be carefully designed.
... Hence, an attractive van der Waals force is employed over the electrostatic repulsion force between the molecules which increases the surface tension of the cationic polyurethane nanocomposite in the colloidal solutions. Finally, the smaller nanocomposite exhibition, the higher the surface charge density liken to the larger nanocomposite [29]. As a result, the electrostatic repulsion forces between the nanocomposite and the aqueous phase rise. ...
Novel cationic polymeric surfactants were synthesized throughout the reaction of monoester of triethanol amine and two saturated fatty acids (palmitic acid and stearic acid) and TDI (toluene diisocyanate). The obtained polyurethane (PU) then was reacted by acetyl chloride to yield the desired surfactants. The structures of the produced compounds were described by using Fourier Transform Infrared Spectroscopy (FTIR) and their average molecular weights. Silver nanocomposite of the prepared cationic PU surfactants were characterized via physical combination by chemically prepared silver nanoparticles. The structure of the silver composite was determined using: Ultra-violet spectroscopy, Transmission Electron Microscopy (TEM), and Dynamic Light Scattering (DLS) spectroscopy. The effect of the hydrophobic chains on the surface activities of the synthesized cationic polymeric surface active agents and their silver nanocomposite was studied.
... In recent years, carbohydrate-based surfactants (or sugar surfactants) have drawn attention in the interfacial science community due to their environmentally friendly properties including being derived from renewable sources, [1][2][3][4] low toxicity [5][6][7][8] and biodegradability. [9,10] Accordingly, sugar surfactants have tremendous potential for food, [11] biorefining [12] and pharmaceutical applications. [13] Despite these advantages, the application of these carbohydrate surfactants is often limited by their weakly hydrated non-ionic head groups which aggregate due to strong intermolecular interactions. ...
Hypothesis:
Emerging applications of carbohydrate/cationic surfactant mixtures require not only synergistic mixing, but also accessible sugar headgroups at the exterior of micelles. A previous study showed that the glucoside headgroups of octyl-β-d-glucopyranoside aggregate at the interior of mixed micelles with equimolar cetyltrimethylammonium bromide rather than mixing with trimethylammonium groups at the corona. The current study tests the hypothesis that structural characteristics of the surfactants (the relative lengths of the alkyl tails and the type of linker) can be tuned to shift the carbohydrate groups to micelle surfaces.
Experiments:
The structural arrangement of 30 mM equimolar mixed micelle solutions in D2O is investigated using NMR. The dynamics in different regions are probed using (1)H spin-lattice (T1) and spin-spin (T2) relaxation measurements, and relative positioning by nuclear Overhauser effect spectroscopy (NOESY). Additional micellar properties are determined using solvatochromic fluorescent probes.
Findings:
Matching surfactant alkyl tail lengths is found ineffective at "pushing out" the carbohydrate headgroups due to a large mismatch in interactions between the headgroups and D2O. However, inserting a novel polar triazole group between the carbohydrate head group and the hydrophobic tail (e.g. in n-octyl-β-d-xylopyranoside) using click chemistry is able to "pull out" the carbohydrate, thus giving accessible sugar moieties at the surface of mixed micelles.
... Oil soluble surfactants had HLB values in the range of 1-7, water dispersible surfactants had HLB in the range of 7-14, and water soluble surfactants had HLB in the range of 14-20. Surfactants with HLB values higher than 16 are efficient as solubilizing agents [25]. Calculating the HLB values of the synthesized nonionic surfactants (Table 2) using Griffin's method [26] indicates their high tendency to dissolve in aqueous medium and also their high solubilizing tendency. ...
Five novel nonionic surfactants were prepared by the reaction of polyethylene glycol of different molecular weights with toluene diisocyanate. The obtained polyurethane polymers were reacted with oleic acid to obtain the nonionic polyurethane surfactants. The structures of the synthesized compounds were determined by using: Fourier Transform Infrared Spectroscopy (FTIR) and their average molecular weights by means of GC analysis. Silver nanohybrids of the nonionic polyurethane surfactants were prepared via physical combination by chemically prepared silver nanoparticles. The silver nanohybrids were determined using: UV, TEM, and DLS spectroscopy. The influence of the nonionic chain length (polyethylene glycol chains) on the surface activity of the synthesized nonionic polyurethane oleate surface active agents and their silver nanohybrids was studied. The results of surface activity of the nonionic polyurethanes oleate and their nanohybrids showed an increase in the critical micelle concentration by decreasing the polyethylene glycol chain lengths. The nanohybrids were also more surface active. Longer polyethylene glycol chains provide good protection for the formed silver nanoparticles than the shorter chains.