Surface tension, adsorption, and wetting behaviors of natural surfactants on a PTFE surface

Adsorption and wetting properties of biosurfactants, Trtions and their mixtures in aqueous and water-ethanol environment

Adsorption of rhamnolipid (RL) and surfactin (SF) as well as their mixtures with Triton X-100 (TX100) and Triton X-165 (TX165) at the solution-air (S-A), PTFE (polytetrafluoroethylene)-S, PMMA (poly (methyl methacrylate))-S, Q (quartz)-S, PMMA-A, and Q-A as well as their wetting properties regarding the surface tension of the PTFE, PMMA and quartz and its components and parameters were discussed using the literature data. The mutual influence of biosurfactants and Tritons on the S-A, PMMA(quartz)-A and PTFE(PMMA, quartz)-S interfaces tensions was considered in terms of their adsorption at these interfaces for both aqueous and water-ethanol solutions of the biosurfactant mixtures with Tritons. For this purpose there were used different methods on the basis of which the S-A, PMMA(quartz)-A and PTFE(PMMA, quartz)-S interface tensions can be predicted and/or described in the function of concentration and composition of the mixtures. Changes of these interface tensions as a function of concentration and composition of the mixtures were compared to those affected by individual mixture components. In turn, these changes of the interface tension were considered as regards properties of the biosurfactants, Tritons and ethanol layers adsorbed at the S-A, PMMA(quartz)-A and PTFE(PMMA, quartz)-S interfaces. Based on the changes of the contact angle of the aqueous and water-ethanol solutions of the biosurfactants and Tritons as well as biosurfactants mixtures with Tritons on PMMA and quartz as a function of mixture concentration and composition, the changes of the PMMA and quartz surface tension were analyzed using various approaches to the surface and interface tension. The thermodynamic functions change as a results of RL, SF, TX100, TX165, ET as well as the mixtures of RL and SF with Tritons adsorption at different interfaces were also analyzed based on the literature data. These considerations allow to describe and/or predict changes of the interface tension, contact angle of the mixtures as a function of their composition based on these properties of individual mixture components.

Deciphering supramolecular arrangements, micellization patterns, and antimicrobial potential of bacterial rhamnolipids under extreme treatments of temperature and electrolyte

The micellization properties of rhamnolipids (RLs) in extreme electrolyte concentrations and temperatures have gained considerable attention due to their broad industrial applications. In this study, the aggregation behavior, specifically the micellization pattern (critical micelle concentration (CMC)) of RLs produced from a newly isolated thermophilic strain of Pseudomonas aeruginosa from a harsh environment of an oil field, was investigated by a spectrophotometric method at various temperatures (293-393 K) and electrolyte concentrations (NaCl: 2-20%). The result indicated that the CMC values (0.267-0.140 mM⋅dm-3) were both electrolyte- and temperature-dependent exhibiting a U-shaped trend as temperature and NaCl concentration increased. Variations in NaCl concentration and temperature also affected the standard Gibbs free energy (ΔGo mic ), enthalpy (ΔHo mic ), and entropy (ΔSo mic ) of micellization. The molecule also showed stability at a broad range of temperatures, pH, and NaCl concentrations. Thin-layer chromatography (TLC) and Fourier-transform infrared (FTIR) analysis confirmed the similarity in composition between the crude extract and the commercial RL with Rf values of 0.72 for mono-rhamnolipids and 0.28 for di-rhamnolipids. FTIR analysis confirmed the chemical nature particularly key aliphatic functional groups present in the fatty acid tail of RLs and the -COC- bond in the structure of the rhamnose moiety. Additionally, LC-ESI-QTOF analysis confirmed corresponding ionic fragments of mono- and di-rhamnolipids congeners. Furthermore, the antimicrobial potential was determined against different human pathogens in the absence and presence of NaCl by measuring zones of inhibition. The result revealed enhanced inhibitory effects against Gram-positive pathogens (S. aureus, S. epidermidis, and L. monocytogene), with zones of inhibition of 26, 30, and 20 mm in the presence of NaCl. These findings underline the role of NaCl in the micellization of RL molecules and highlight their importance in environmental applications, pharmaceuticals, and various life science sectors.

Synthesis and Performance of Double-Chain Quaternary Ammonium Salt Glucosamide Surfactants

A series of double-chain quaternary ammonium salt surfactants N-[N'[3-(gluconamide)] propyl-N'-alkyl]propyl-N,N-dimethyl-N-alkyl ammonium bromide (C_nDDGPB, where n represents a hydrocarbon chain length of 8, 10, 12, 14 and 16) were successfully synthesized from D (+)-glucose δ-lactone, N,N-dimethyldipropylenetriamine, and bromoalkane using a two-step method consisting of a proamine-ester reaction and postquaternization. Their surface activity, adsorption, and aggregation behavior in aqueous solution were investigated via measurements of dynamic/static surface tension, contact angle, dynamic light scattering, and transmission electron microscopy. An analysis of their application performance in terms of wettability, emulsifying properties, toxicity, and antibacterial properties was conducted. The results show that with increasing the carbon chain length of the C_nDDGPB surfactants, their critical micelle concentration (CMC) increased and the pC₂₀ and efficiency in the interface adsorption of the target product gradually decreased. Moreover, the influence of the hydrophobic carbon chain length on the surface of polytetrafluoroethylene (PTFE) was even greater for the wetting effect, reducing the contact angle to 32° within the length range of C8-C14. The results of the contact angle change and the wettability experiments proved that C₁₀DDGPB exhibited the best wettability. The liquid paraffin and soybean oil emulsification ability of C_nDDGPB showed an upward trend followed by a downward trend with the growth of the carbon chain, with C₁₂DDGPB exhibiting the best emulsification performance. The D_long/D_short ratio was far lower than 1, which indicates mixed-kinetic adsorption. The surfactants formed spherical micelles and showed a unique aggregation behavior in aqueous solution, which showed an increase-decrease-increase trend with the change in concentration. A cell toxicity and acute oral toxicity experiment showed that the C_nDDGPB surfactants were less toxic than the commonly used surfactant dodecyldimethylbenzyl ammonium chloride (1227). In addition, at a concentration of 150 ppm, C_nDDGPB exhibited the same bacteriostatic effect as 1227 at a concentration of 100 ppm. The results demonstrate that sugar-based amide cationic surfactants are promising as environmentally friendly disinfection products.

Elucidating the Impact of Surfactants on the Performance of Dissolving Microneedle Array Patches

The need for biocompatible polymers capable of dissolving in the skin while exhibiting reasonable mechanical features and delivery efficiency limits the range of materials that could be utilized in fabricating dissolving microneedle array patches (MAPs). The incorporation of additives, such as surfactants, during microneedle fabrication might be an alternative solution to overcome the limited range of materials used in fabricating dissolving MAPs. However, there is a lacuna in the knowledge on the effect of surfactants on the manufacture and performance of dissolving MAPs. The current study explores the role of surfactants in the manufacture and performance of dissolving MAPs fabricated from poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) loaded with the model drugs, ibuprofen sodium and itraconazole. Three nonionic surfactants, Lutrol F108, Pluronic F88, and Tween 80, in solutions at varying concentrations (0.5, 1.0, and 2.0% w/w) were loaded into these dissolving MAPs. It was discovered that all of the dissolving MAPs that incorporated surfactant displayed a lower reduction in the microneedle height (≈10%) relative to the control formulation (≈20%) when subjected to a compressive force of 32 N. In addition, the incorporation of surfactants in some instances enhanced the insertion profile of these polymeric MAPs when evaluated using ex vivo neonatal porcine skin. The incorporation of surfactant into ibuprofen sodium-loaded dissolving MAPs improved the insertion depth of MAPs from 400 μm down to 600 μm. However, such enhancement was not apparent when the MAPs were loaded with the model hydrophobic drug, itraconazole. Skin deposition studies highlighted that the incorporation of surfactant enhanced the delivery efficiency of both model drugs, ibuprofen sodium and itraconazole. The incorporation of surfactant enhanced the amount of ibuprofen sodium delivered from 60.61% up to ≈75% with a majority of the drug being delivered across the skin and into the receptor compartment. On the other hand, when surfactants were added into MAPs loaded with the model hydrophobic drug itraconazole, we observed enhancement in intradermal delivery efficiency from 20% up to 30%, although this did not improve the delivery of the drug across the skin. This work highlights that the addition of nonionic surfactant is an alternative formulation strategy worth exploring to improve the performance and delivery efficiency of dissolving MAPs.

Advances in Surfactants in Foliar Application of Agrochemicals on Mango Leaf Surfaces

The surface tension, pH and contact angle of the wetting liquid as well as the complex composition of the leaf surface are important parameters to describe the spreading, wettability and absorption of agrochemicals on the leaf surfaces. The contact angle of aqueous solutions of agrochemicals (multi-micronutrient fertilizers, growth regulator and insecticides) with/without Leaf guard, bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT) and Sapindus mukorrossi (Ritha) were measured over the surface of mango leaves. The order of contact angle (mean) values was found to be AOT < Ritha < Leaf guard, which implies that AOT is a better wetting agent, but Ritha has a higher range of adhesion work because of its acidic nature (low pH). The wetting free energy was found to be more negative in the presence of Leaf guard, Ritha and AOT than in water, which indicates that wetting is more spontaneous in the presence of surfactants. The adaxial surface of mango leaves had a higher surface free energy than the abaxial part and hence showed higher wettability than the abaxial part.

Surface Activity of Natural Surfactants Extracted from Sapindus mukorossi and Sapindus trifoliatus Soapnuts

Surfactants derived from renewable sources such as plants are an ecological alternative to synthetic surfactants. Aqueous solutions of natural surfactants extracted from soapnuts obtained from two plants, Sapindus mukorossi and Sapindus trifoliatus, were studied. Their properties in terms of surface tension reduction and wettability were examinated. The natural surfactants show the ability to reduce the surface tension and increase the wettability of the hydrophobic polytetrafluoroethylene surface. These nuts can be used repeatedly for washing also in hard water. Crude extracts from Sp. trifoliatus exhibit better surface properties than those from Sp. mukorossi. This makes these soapnuts a good potential source of biosurfactants for household use.

Multilevel strategies for the composition and formation of DAAF/HNIW composite crystals

Insensitive energetic materials are still a great challenge for potential applications.

Wetting Behavior and Maximum Retention of Aqueous Surfactant Solutions on Tea Leaves

In this research, the maximum retention and wetting behavior of surfactant solutions (N-200, N-300, Tween-80, Morwet EFW, DTAB, SDS) on the surfaces of tea leaves was investigated based on surface free energy, surface tension, the contact angle, adhesion work, and adhesion force. The results showed that the contact angles of all surfactant solutions were kept constant with low adsorption at the tea leaf–liquid interfaces below 0.005%. With an increase in concentration, the contact angle of Tween-80 decreased sharply because the adsorption of molecules at the solid–liquid interfaces (Γ_SL’) was several times greater than that at the liquid–air interfaces (Γ_LV). Adhesion work decreased sharply and then reached a minimum at the critical micelle concentration (CMC), but then increased until reaching a constant. Moreover, a high adhesion force did not indicate better wettability, as it does with rose petals and peanut leaves. For tea leaf surfaces, an increase in the contact angle brought about an increase in the adhesion force. In addition, the maximum retention for Morwet EFW is at different concentrations compared to N-200, N-300, Tween-80, DTAB, and SDS, where the maximum retention of Morwet EFW on tea leaves was 6.05 mg/cm² at 0.005%.According to the mechanisms of wetting behavior on plant surfaces, a recipe for pesticide formulation can be adjusted with better wettability to reduce loss, improve utilization efficiency, and alleviate adverse effects on the environment.

Comparison of Antibacterial Adhesion When Salivary Pellicle Is Coated on Both Poly(2-hydroxyethyl-methacrylate)- and Polyethylene-glycol-methacrylate-grafted Poly(methyl methacrylate)

Although poly(2-hydroxyethyl methacrylate) (pHEMA) and polyethylene glycol methacrylate (PEGMA) have been demonstrated to inhibit bacterial adhesion, no study has compared antibacterial adhesion when salivary pellicle is coated on polymethyl methacrylate (PMMA) grafted with pHEMA and on PMMA grafted with PEGMA. In this study, PMMA discs were fabricated from a commercial orthodontic acrylic resin system (Ortho-Jet). Attenuated total reflection-Fourier transform infrared spectra taken before and after grafting confirmed that pHEMA and PEGMA were successfully grafted on PMMA. Contact angle measurements revealed PMMA-pHEMA to be the most hydrophilic, followed by PMMA-PEGMA, and then by PMMA. Zeta potential analysis revealed the most negative surface charges on PMMA-PEGMA, followed by PMMA-pHEMA, and then by PMMA. Confocal laser scanning microscopy showed green fluorescence in the background, indicating images that influenced the accuracy of the quantification of live bacteria. Both the optical density value measured at 600 nm and single plate-serial dilution spotting showed that pHEMA was more effective than PEGMA against Escherichia coli and Streptococcus mutans, although the difference was not significant. Therefore, the grafting of pHEMA and PEGMA separately on PMMA is effective against bacterial adhesion, even after the grafted PMMA were coated with salivary pellicle. Surface hydrophilicity, bactericidality, and Coulomb repulsion between the negatively charged bacteria and the grafted surface contributed to the effectiveness.

Anti-Malassezia furfur activity of natural surfactant mediated in situ silver nanoparticles for a better antidandruff shampoo formulation

Anin situone pot synthesis of Ag nanoparticles in aqueousAcaciaplant-surfactant media can be useful as a good anti-dandruff shampoo.