Surface-active Properties Research Articles

Biological tailoring of novel sophorolipid molecules and their derivatives

AbstractA sophorolipid (SL) is a kind of glycolipid surfactant that has been much studied due to its excellent surface activity and physiological properties. However, the mixed structure of SLs and expensive separation costs have limited their application in advanced industries. Developing a tailored strategy to produce targeted SLs, with specific physicochemical properties, for direct application in various industries like agriculture, cleaning, and medicine, has become one of the main objectives of SL biological production. In this review, different characteristics of various SLs with various structures are classified in detail. The classification corresponds to their specific applications in different industries. Microorganisms for the production of specific SLs are also summarized, with emphasis on the metabolism pathways and regulation mechanisms. Strategies applied for SL biological tailoring, including selection of fermenting substrates, fermentation process optimization, metabolic engineering and downstream separation, are comprehensively reviewed. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd

A comprehensive research on Lactone Sophorolipid (LSL) and Soy Protein Isolate (SPI) interacting mixture

Soy protein isolate (SPI) is a promising biological material, and lactone sophorolipid (LSL) is a non-toxic, completely biodegradable amphiphilic functional biosurfactant. A comprehensive research of interaction mode and mechanism on LSL and SPI composite system was studied using surface tension, turbidity, fluorescence spectroscopy, ultraviolet–visible (UV–Vis) spectroscopy, circular dichroism (CD) spectroscopy, dynamic light scattering (DLS), isothermal microcalorimetric titration (ITC) and molecular docking methods. The properties of surface activity, foam stability, antibacterial ability and so on were evaluated in detail. Compared with a single pure substance, the performance of the composite system shows different performance optimizations in different aspects. For the SPI/LSL systems with different mass ratios studied, the surface activity, foaming performance and foam stability of the composite system with a mass ratio of 1:50 are more prominent than those of other ratios. The fluorescence distribution showed the increase of LSL leading to a significant change in the fluorescence distribution of SPI, the quenching mechanism is mainly static quenching mechanism, and the combination of LSL and SPI is an spontaneous endothermic process. UV–Vis spectroscopy showed that LSL changed the conformation of SPI. The CD spectrum indicated that the combination of LSL and SPI increases the α-helical structure of protein, and is beneficial to the secondary structure of protein. The molecular model presents the conformation of the SPI/LSL complex, indicating that the hydrophobic force and hydrogen bonds are considered to be the main interaction forces between SPI and LSL, which may lead to the flexible conformation of the protein. This research enriches our understanding of the interaction mechanism between SPI and LSL, and provides some important and interesting information for the development and application of biosurfactant-protein mixed systems with environmentally friendly, non-toxic and non-polluting properties.

High Performance Conditioning Shampoo with Hyaluronic Acid and Sustainable Surfactants

Recently, consumers have become invested in more natural and sustainable ingredients contained in personal care products. Unfortunately, cationic surfactants are still heavily relied on as primary conditioning agents in products such as conditioning shampoos because of their ability to cling well to the negatively charged surface of hair follicles. Additionally, sulfates are utilized as cleansing agents because they are highly effective and low cost. The objective of this study is to find a more sustainable formulation for a conditioning shampoo without compromising the desired wet combing, rheological, and surface activity properties. The systems which were investigated contained hyaluronic acid (HA) at a variety of molecular weights and concentrations, in combination with a surfactant, either acidic sophorolipid (ASL) or alkyl polyglucoside (APG), and varying the presence of sodium chloride. A Dia-stron was utilized to test the wet combing force, a rheometer recorded the viscosity at various shear rates, and a tensiometer measured the surface tension of the samples before a visual foaming study was conducted. Molecular weight and concentration seemed to have a large impact on wet combing force, as well as rheology, with the largest molecular weight and concentration producing the lowest friction coefficient and desired rheological profile. The addition of a surfactant significantly aids in the reduction in surface tension and increased foamability. Therefore, the optimal system to achieve the largest reduction in wet combing force, large viscosity with shear-thinning behavior, and relatively low surface tension with decent foaming is composed of 1% HA at 800 kDa, 10% ASL and 1% NaCl. This system shows a viable sulfate-free and silicone-free option that can achieve both conditioning and cleansing.

STUDY OF THE SOLUBILIZING CAPACITY OF POLYMER-COLLOID COMPLEXES FORMED WITH SODIUM ALGINATE AND CHLORIDE HEXADECYLPYRIDINIUM

It was examined the behavior of systems which contain surfactants and biopolymers is considered by the example of cationic surfactants and sodium alginate. The rheological and surface-active properties of the systems have been experimentally investigated. It was found that the presence of oppositely charged surfactants in the solution significantly affects the properties of sodium alginate, due to the fact that associates or polymer-colloidal complexes are formed in the solution. Their formation significantly affects the solubilizing ability in relation to non-polar liquids. Hydrodynamic parameters of macromolecules of sodium alginate in comparison with macromolecules of chitosan correspond to the conformation of the loose ball. The state of the SN is determined by the pH of the medium and temperature. The increase in temperature leads to a violation of the structure of the chain, its destruction and a subsequent decrease in viscosity. At a temperature of 293K, the macromolecule is in a more ordered state. In the alkaline environment there is a change in the conformation of the macromolecule. As a result of this change, the viscosity naturally increases. This is explained by the fact that in an alkaline environment, the macromolecule acquires an excess negative charge, there is a repulsion of the carboxyl groups of the same name in the chain links. The macromolecule acquires an expanded configuration. The viscosity increases. In acidic environment, sodium alginate has almost zero charge as a result of protonation of carboxyl groups. The molecule acquires the conformation of a loose ball with the lowest value of viscosity. The isoelectric state of the alginate macromolecule is observed in the pH range of 5.5 to 6.0. The described state of the macromolecule in solution is confirmed by our calculations. The interaction of surface-active cations with carboxyl groups of SN leads first to the formation of associates, then to polymer-colloidal complexes. The association as a result of electrostatic interaction of active groups is enhanced by the hydrophobic interaction of hydrocarbon fragments of surfactant molecules with each other and with the alginate matrix. The association ends with the formation of a polymer-colloidal complex.

Study of Steel Electro-dissolution Behavior in Presence of Some Surfactants. Electrochemical Investigation and Surface Active Properties Determination

Steel electro-dissolution performance was investigated in orthophosphoric acid in the presence of N-oleyl 1.3 diaminopropane, Benzalkounuim chloride, Soduim lauryl sulphate and Di-Isononyl phthalate as a surfactant using potentiodynamic polarization measurements. The retardation performance of these surfactants was examined. The surfactant surface active parameters were estimated based on surface tension measurements. The parameters calculated comprise the critical micelle concentration (CMC), maximum surface excess (Гmax), minimum surface area (Amin) and effectiveness (πCMC). The micellization thermodynamic parameters (ΔGmic, ΔSmic) for the estimated surfactants were also computed. Results obtained from surface active properties are comparable with those gained from galvanostatic polarization measurements. Temperature influence on the steel dissolution performance was examined at 25 to 40oC range. Steel kinetic study in orthophosphoric acid- free solution and orthophosphoric acid containing surfactant was also examined. The dissolution kinetic and activated parameters were computed. Results based on microscopy measurement indicate that, addition of new four surfactants, resulting in the solution shows potential, a discrete progress in the metal texture was monitored. Improvement produced in electro-polishing bath by the investigated SAS that owing to the adsorption of such surface active agents on the anode surface.

Engineered Hydrophobin as a Crystallization Inhibitor for Flufenamic Acid.

Hydrophobins are multifunctional, highly surface-active proteins produced in filamentous fungi. Due to their surface-active properties, resistance to degradation, and potential immunological inertness, hydrophobins have been used in many applications such as protein purification, increasing implant biocompatibility, increasing water solubility of insoluble drugs, and foam stabilizers for food products. To further explore surface-active and self-assembly properties of hydrophobins, we evaluated an engineered, recombinant hydrophobin (class II type 1, HFB1) as a potential crystallization inhibitor for maintaining drug supersaturation for an amorphous drug delivery system. A supersaturation-precipitation method was employed utilizing an ultraviolet (UV) fiber optic system for tracking precipitation kinetics of a model drug, flufenamic acid (FA), that was selected due to its low aqueous solubility in its crystalline form. The effectiveness of HFB1 as a crystallization inhibitor was compared with commonly used pharmaceutical grade polymeric crystallization inhibitors. The following polymers were selected to compare with HFB1: methocel (A4C grade), methocel (K15M grade), Kollidon vinylpyrrolidone-vinyl acetate (VA64), and hydroxypropyl methylcellulose acetate succinate (HPMCAS) (MF grade). The supersaturation-precipitation experiments concluded that HFB1 outperformed all polymers tested in this study and can potentially be used as a crystallization inhibitor at significantly lower concentrations in amorphous drug delivery systems. Dynamic light scattering (DLS) and circular dichroism (CD) results suggest a crystallization inhibition mechanism in which HFB1 functions differently depending on whether flufenamic acid is molecularly dispersed but supersaturated relative to its crystalline solubility or it has exceeded its amorphous solubility limit and exists as a phase-separated drug-rich colloid.

Soybean-Oil-Based CO2-Switchable Surfactants with Multiple Heads.

Oligomeric surfactants display the novel properties of low surface activity, low critical micellar concentration and enhanced viscosity, but no CO2 switchable oligomeric surfactants have been developed so far. The introduction of CO2 can convert tertiary amine reversibly to quaternary ammonium salt, which causes switchable surface activity. In this study, epoxidized soybean oil was selected as a raw material to synthesize a CO2-responsive oligomeric surfactant. After addition and removal of CO2, the conductivity analyzing proves that the oligomeric surfactant had a good response to CO2 stimulation. The viscosity of the oligomeric surfactant solution increased obviously after sparging CO2, but returned to its initial low viscosity in the absence of CO2. This work is expected to open a new window for the study of bio-based CO2-stimulated oligomeric surfactants.

Regioselective synthesis of 6’’-O-lauroyl-1-kestose and 6’’’-O-lauroylnystose by sequential enzymatic reactions of transfructosylation and acylation

Fructan fatty acid esters are amphiphilic compounds with potential applications in the food industry due to their surface-active properties on the air/water interface. In this work, the regioselective synthesis of fatty acid esters of short-chain inulin-type fructooligosaccharides (FOS) was carried out in a two-step process comprising sequential enzymatic reactions of transfructosylation and acylation. In the first step, Schedonorus arundinaceus sucrose:sucrose 1-fructosyltransferase (1-SST, EC 2.4.1.99) converted sucrose (600 g/L) into the trisaccharide 1-kestose and the tetrasaccharide nystose in a ratio 9:1 with their sum accounting for 53% (w/w) of total carbohydrates. In the second step, the FOS mixture was transesterified with vinyl laurate in 2-methyl-2-butanol by immobilized Candida antarctica lipase B (CALB) (EC.3.1.1.3). NMR analysis of the synthesized monolaurate FOS esters revealed a regioselective acylation of the 6-OH of the terminal fructosyl moiety of both 1-kestose and nystose. The hydrophilic-lipophilic balance (HLB) values of 6’’-O-lauroyl-1-kestose and 6’’’-O-lauroylnystose were 14.7 and 15.7, respectively; which suggests their use as oil in water (O/W) emulsifiers. The main compound 6’’-O-lauroyl-1-kestose with critical micelle concentration (CMC) of 0.6 mM and surface tension of 45.8 mN/m proved to be a more efficient surfactant than 6’’’-O-lauroylnystose (CMC 5.38 mM) and surface tension 36.26 mN/m). We report a regioselective method for the synthesis of lauryl-FOS using the abundant and renewable resource sucrose as the starting substrate.

Improvement of Heavy Oil Recovery by Nonionic Surfactant/Alcohol Flooding in Light of the Alkane Carbon Number and Interfacial Tension Properties

In this work, we prepared nonionic surfactants from waste cooking oil materials. Hydrolysis was carried out for palm and palm kernel waste cooking oils to get a mixture of free fatty acids. The mixture of free acids was esterified with sorbitan and then ethoxylated at different ethylene oxide units. Two surfactants exhibited promising surface-active properties among the six prepared surfactants based on the results of surface tension. The interfacial tension (IFT) around the critical micelle concentration was measured against a series of n-hydrocarbon to detect the minimum alkane carbon number (ACN) (Πmin) for each of these surfactants. The effect of normal and branched alcohols on Πmin was also studied to design the surfactant/alcohol mixture for the chemical flooding process. From the results of IFT, the ethoxylated ester derivatives of palm kernel fatty acids (EPK-20) exhibited minimum IFT γmin (0.06 mN m–1) at Πmin equal to 12, and the ethoxylated ester derivatives of palm fatty acids (EP-40) achieved γmin equal to 0.09 mN m–1 at Πmin of 10. Branched alcohols shifted Πmin to a higher value to reach the equivalent ACN of the crude oil and decrease the IFT to lower values. The flooding process showed that the maximum oil recovery was obtained by EPK-20 (54.2% when used purely and 66.2% when used with isoamyl alcohol). In comparison, EP-40 exhibited that oil recovery equals 46% without alcohol and 46.4% with iso-butanol alcohol. The results were interpreted and discussed based on interfacial properties, wettability alteration, and the ACN.

The Synergistic Effects of Rhamnolipids and Antibiotics Against Bacteria

Antibiotics are used to combat bacterial infections by slowing down and preventing the proliferation of bacteria. Antibiotic resistance is a threat to human health, attributed to its overuse and misuse. Altering the membrane permeability to induce antibiotic uptake may be an effective strategy used against both Gram-positive and Gram-negative infectious bacteria. Rhamnolipids (RLs) are biosurfactants produced by Pseudomonas aeruginosa. RLs surface-active properties operate by creating holes in bacterial cell membranes, increasing target cell permeability; allowing antibiotics to penetrate the cell. 
 
 Rhamnolipids enhance the effect of antibiotics by targeting the intracellular machinery of bacteria. This project tested the susceptibility of bacteria when exposed to antibiotics with and without the addition of RLs, to quantitatively determine if RLs increase antibiotic potency. By analyzing the zones of inhibition data, the results demonstrated that RLs potentiated the antibiotics. Notably, kanamycin coupled with RLs had the most effect inhibiting bacterial growth. 
 To further assess rhamnolipid biosynthesis, a BLAST search was performed exclusively on two genes, rhlA and rhlB. These genes code for the production of two proteins necessary for rhamnolipids. The search indicated a 48% correlation with putative proteins found in Burkholderia pseudomallei. Therefore, based on the experimental results and the BLAST analysis, further research should be conducted to explore the possible role of using rhamnolipids as antibiotic enhancers. Specifically, future experiments could focus on isolating the putative proteins of B.pseudomallei to genetically modify E.coli. Furthermore, isolated studies analyzing the genes of proteins to determine their role in the pathogenicity of Burkholderia species.

Synthesis, Characterization, Antibacterial Activity, and Interfacial and Micellar Features of Novel Cationic Gemini Surfactants with Different Spacers

AbstractIn the present study, four novel imidazolium‐based cationic gemini surfactants (IBCGS) have been synthesized, having same hydrocarbon chain lengths and different spacers. The impacts of type and nature of spacer on Krafft temperatures (TK) have been examined. Micellization behaviors of IBCGS have been investigated at different temperatures above TK by both surface tension and specific conductivity measurements. Surface activity properties of aqueous systems have been calculated using the results of the measurement data. Critical micelle concentration (CMC), surface pressure at CMC (ПCMC), minimum area of head group (Amin), degree of counterion binding (β), degree of counterion dissociation (α), and maximum surface excess (Γmax) of IBCGS have been calculated with data of surface tension and specific conductivity. IBCGS have low CMC values than other imidazole categories of gemini and monomeric cationic surfactants. Micelle aggregation number (Nagg) values have been determined with the steady‐state fluorescence quenching method. The values of Nagg have been found in the range of 19–28. Additionally, the antibacterial activities of IBCGS on gram‐positive and gram‐negative bacteria have been investigated. IBCGS studied in this article have showed perfect antibacterial activity particularly against gram‐positive bacteria. The data obtained in this study may be benefical for the surfactant applications in different areas.

Effect of sunflower protein meal and electrostatic complexes of sunflower meal-pectin on the cake crumb structure and color.

Sunflower protein meal could be an alternative and sustainable plant-based protein source, with the potential to add value and replace egg (E) in cakes due to its surface-active properties, however, contains chlorogenic acid and its oxidation leads to greening. Additionally, the electrostatic complexes prepared from the mixture of proteins and polysaccharides can be an important tool to improve the technological properties compared to them are used individually. The aim of this study was the replacement of E in cakes by sunflower protein meal dispersion (SPMD) or electrostatic complexes of sunflower protein meal-pectin (ECSPM-P), evaluating their effects on the cake batter and fresh and aged baked product. Results of the Rapid Visco Analyser (RVA) analysis indicated higher initial viscosity of the cake batters with SPMD and ECSPM-P and lower peak viscosity and less swelling of the starch granules of the cake batter with ECSPM-P. The formulation with SPMD showed the greatest aeration of the cake batter, however resulted in a cake with collapsed structure. The formulation with ECSPM-P showed lighter color (ΔE = 9.95) and improvement in the cake structure, where the cake crumb was similar to the cake with E. During aging, cake formulated with SPMD (ΔE = 36.25) showed intensification in the greening of the cake crumb. The positive effects on the structure and color of the cake crumb showed the potential uses of the ECSPM-P as E replacer in cakes, besides promising ingredient in terms of the trend towards plant-based foods and healthiness.

FLOTATION OF LEAD-ZINC ORE USING A MIXTURE OF DITHIOCARBAMATE AND XANTHATE

The collecting capacity of xanthate, dithiocarbamate and their combination was studied. The effect of activity with respect to the gas-liquid interface of derivative forms of reagents represented by physically sorbed forms of collector was considered. Flotation experiments of lead-zinc ore from the Gorevsky deposit showed an increase in flotation performance when using reagent combinations. The use of a collector with pronounced chemisorbable properties in combination with a reagent having surface-active properties towards the gas-liquid interface caused an increase in the recovery of useful component. It was determined that activity of the physical form of sorption affects the selectivity of lead and zinc recovery - as activity of the physically sorbed form of reagent decreases, the selectivity of recovery grows.

STUDY OF SEDIMENTS OF COLLECTING AGENTS IN ELEMENTARY FLOTATION ACT

The operating mechanism of physically sorbed derivatives of collector obtained at a nonstoichiometric ratio between collecting agents with heavy metal salts is proposed. It is found that by changing the ratio of the components, it is possible to adjust their surface-active properties with respect to the gas-liquid interface and, consequently, the ability to remove the kinetic restriction to the formation of flotation contact. The physical form of sorption on a mineral can be represented by collector sediments and ion-molecular associates. The research results show that when the interlayer breaks through, these forms can desorb from the mineral and spread over the bubble surface, dragging the liquid from the interlayer into motion, thereby “drying” the mineral surface. In turn, the removal of liquid from the interlayer leads to a reduction in the induction time, which affects the efficiency of flotation. The results make it possible to reveal the mechanism of flotation activation with heavy metal salts and can be used in the development of fundamentally new engineering solutions.

Preparation, surface activities, and aggregation behaviors of N-acyl oligopeptide surfactants based on glycylglycine and glycylglycylglycine

With the growing concern about safety and environmental issues, amino acid-based surfactants have great potential as sustainable and eco-friendly substances. In the present study, six N-acyl oligopeptide surfactants were synthesized using fatty acid methyl esters (i.e., methyl caprate, methyl laurate, and methyl myristate) and glycyl oligopeptides (i.e., glycylglycine and glycylglycylglycine). Surface active properties and aggregation behaviors of these surfactants were investigated using surface tension, fluorescence probe, dynamic light scattering, and microscopy measurements. The adsorption at the air-water interface and aggregation in the aqueous solution depend on the structure of both hydrophilic head-groups and hydrophobic tails. Spherical vesicles were observed in the aqueous solutions of glycylglycine derivatives, whereas short tubular aggregates were found in that of corresponding glycylglycylglycine products. Intermolecular hydrogen-bonding interaction between the amide head-groups might be responsible for the different self-assembly behavior and microstructure of N-acyl oligopeptide surfactants in the aqueous solution.

Detergent properties of aqueous extract of Aatreelal (Ammi majus L.) and Babchi (Psoralea corylifolia L.)

Aim of the study: To evaluate the detergent activity of aqueous extract of Ammi majus L. and Psoralea corylifolia L. Materials and methods: The detergent activity of aqueous extract of test drugs was evaluated by using a standard physicochemical test with Sodium lauryl sulfate (SLS) as a standard drug. Surface tension was measured by Du Nouytensiometer; Dirt dispersion by using Indian ink; Cleaning ability by greasy wool yarn test; Foaming properties by cylinder shake method and Wetting ability by canvas disc method. pH values and total saponin was also determined. Both the test and standard drugs were analyzed in 1% and 5% concentrations. Results: The aqueous extract of both the test drugs produced a significant detergent effect at both the concentration but less than SLS as it exhibited a pronounced effect in all the parameters except detergency. The test drugs were found to be acidly balanced; exhibited a prominent surface tension reduction, high foaming, wetting, and cleaning ability with a good quantity of saponin. Conclusions: Based on the above results it can be concluded that the aqueous extract of test drugs has significant surface-active properties thus these drugs can be used as a natural surfactant.

Surface-active Properties of Extracted Saponin from the Leaves of Nephelium Lappaceum.

Synthetic surfactants are widely used in a wide array of cleaning products due to their ability in lowering the surface tension of water. These surfactants also come with bad effects on people's health and the environment. Plant-based surfactant, or saponin, is expected to produce the same desired effect of chemical surfactant, minus the negative effect. The purpose of the current research was to discover the surface-active properties of saponin extracted from Nephelium Lappaceum or rambutan leaves, relative to commercial surfactant, Tween 80, and SDS. Rambutan’s leaves were extracted by maceration technique and liquid-liquid extraction to remove proteins and lipids of the plant. The presence of saponin in crude rambutan leaves was verified by foam test, which showed positive results. The crude rambutan leaves extracts were further analyzed by FTIR, GC-MS, and LC-QTOF-MS. The surface-active test consisted of a wetting test and cleaning test. The results from the IR spectrum show the presence of functional groups of saponin; OH, C=O, C-H, C=C, then, C-O which indicates the glycosides linkages to sapogenins. The wetting time for leave extracts, SDS, and Tween 80 were 32.33s, 7.33s, and 17.62s respectively. The cleaning test of saponin fraction, SDS, and Tween 80 showed the percentage of 20.98, 80.40, and 37.3 respectively. Generally, Rambutan leaves extract showed promising, but lower surface activities compared to commercial surfactants. Considering that the saponin fraction was not yet in the purest or isolated form of a single compound, it can be said the potential can be further enhanced by further isolating a pure surface-active compound from the saponin fraction.

Utilization of distillers dried grains with solubles as a cheaper substrate for sophorolipid production by Rhodotorula babjevae YS3

Sophorolipids (SLs) are a class of glycolipid biosurfactant with excellent surface-active properties, large yields, and appreciable antimicrobial properties. However, their commercial applications remain limited due to high production costs, primarily due to high-priced substrates. Therefore, the present work aims to utilize corn and rice-based distillers dried grains with solubles (DDGS), a by-product of the ethanol production industry, as low-cost substrates for cheaper SL production. Maximum SL production was achieved after 72 h of fermentation at 17.81 gL−1 using rice DDGS (SL-R) and 19.27 gL−1 for corn DDGS (SL-C). SL-C and SL-R reduced surface tension (ST) of water to 34 mN m−1 (CMC 120 mg L−1) and 37 mN m−1 (CMC 110 mg L−1), respectively. SL-R and SL-C both exhibited stable surface activity over a wide range of – pH 2.0–12.0, salinity 2.0–12.0% (w/v), and heating time 0–120 min at 120 °C). SL-R exhibited the highest emulsifying activity (E24 100%) against crude oil. Structural characterization using FT-IR, LC-MS, and GC-MS revealed the SLs to be a mixture of acidic and lactonic forms. The SLs also exhibited potential for application as an antimicrobial agent against a wide range of bacterial and fungal pathogens, confirming its potential for biomedical applications. The results highlight the application of DDGS as a substrate for SL production, which is cheap and readily available, thereby lowering production costs (about $1.5 kg−1 of SL). In comparison to previous studies, we claim that this production process contributed to an almost 50% reduction in production costs.

A Review on Saponin Biosynthesis and its Transcriptomic Resources in Medicinal Plants

Saponins are naturally occurring glycosides which are produced by various plant species with diverse biological properties. The surface-active properties of saponins differentiates them from other glycosides. They are classified mainly into steroid and triterpenoid glycosides based on the structure of hydrophobic aglycone unit. The synthesis of saponins and the genes involved in its biosynthesis can be identified by transcriptome profiling. Using high-throughput sequencing technologies, the steroid or triterpenoid saponin biosynthesis related genes have been discovered which can help boosting the molecular research in this biosynthetic pathway. This review mainly illustrates the importance of saponins and the transcriptome resources of important medicinal plants for identifying genes related to its biosynthesis. Furthermore, the significance of unexplored plants which are rich sources of saponins in future studies are also discussed in the current review.

Foam and rheological behavior of polydentate phosphonate-modified polymers under cement system

Polymer superplasticizer and residual polyether have a key effect on the quantity and size distribution of air-voids in hardened concrete. In this study, the surface activity and foam properties of polydentate phosphonate-modified polymers RM-1 and RM-2 in aqueous solution were studied. Results revealed that the propylene oxide (PO) units in the polymer structure affected the foaming properties of polymers. The compounding performance of polymers RM-1 and RM-2 with ester-type polycarboxylate superplasticizer (PCE-1) in aqueous solution and cement mortar was also studied. This kind of phosphonate-modified polymers can be used as excellent concrete rheological modifier agents because they generate many small bubbles when compounded with PCE-1. Analysis of the foam properties of polymer RM-1 in aqueous solution and cement pore solution revealed that the calcium ions in cement pore solution are beneficial to stabilize the bubbles produced by the polymer. This study provides a new way to study the properties of phosphonate admixture and its combination with PCE from the perspective of bubble and rheology in aqueous solution and cement mortar.