Surfactant Concentration Research Articles

Identification of Surfactant Impact on a Monoclonal Antibody Characterization via HPLC-Separation Based and Biophysical Methods.

Surfactants, including polysorbates and poloxamers, play a crucial role in the formulation of therapeutic proteins by acting as solubilizing and stabilizing agents. They help prevent protein aggregation and adsorption, thereby enhancing the stability of drug substance and products., However, it is important to note that utilizing high concentrations of surfactants in protein formulations can present significant analytical challenges, which can ultimately affect the product characterization. In our study, we specifically investigated the impact of elevated surfactant concentrations on the characterization of monoclonal antibodies. We employed various analytical techniques including size-exclusion chromatography (SEC), capillary electrophoresis (CE-SDS), a cell based functional assay, and biophysical characterization. The findings of our study indicate that higher levels of Polysorbate 80 (PS-80) have adverse effects on the measured purity, biological activity, and biophysical characterization of biologic samples. Specifically, the elevated levels of PS-80 cause analytical interferences, which can significantly impact the accuracy and reliability of analytical studies. Our study results highlight a significant risk in analytical investigations, especially in studies involving the isolation and characterization of impurities. It is important to be cautious of surfactant concentrations, as they can become more concentrated during common sample manipulations like buffer exchange. Indeed, the research presented in this work emphasizes the necessity to evaluate the impact on analytical assays when there are substantial alternations in the matrix composition. By doing so, valuable insights can be gained regarding potential challenges associated with assay development and characterization of biologics with complex formulations.

Surfactants and Microbial Aerosol of Urban Particulate Matter (PM10) in Kuala Lumpur City Centre

Surfactants in the atmosphere potentially influence the global climate and may affect human health. This study aims to determine the compositions of surfactants extracted from urban particulate matter (PM10) and motor vehicle exhaust soot. In addition, microbial aerosol was also determined. A high-volume air sampler (HVAS) has been used to collect PM10 samples in Kuala Lumpur urban area. Meanwhile, the vehicle exhaust soot was collected randomly from the exhaust pipes of various types of diesel and petrol vehicles, using a soft brush during dry days. The concentration of anionic surfactants as Methylene Blue Active Substances (MBAS) was determined by the colorimetric method using a UV-Vis Spectrophotometer. The presence of microorganisms such as bacteria and fungi were investigated by colony count. In addition, the correlation between surfactants and traffic-related air pollutants has also been investigated. Results revealed that the average concentration of MBAS in particulate matter is 107.68 ± 7.91 µgm-3. Diesel vehicles demonstrated higher surfactant concentration in exhaust particulate matter with an average value of 0.227 ± 0.006 µmolg-1 compared to petrol vehicles (0.146 ± 0.003 µmolg-1). Based on this study, various mitigation procedures can be implemented to reduce the impacts of PM and exhaust soot for a better future.

Photovoltaic high-throughput microfluidic platform for the mass-production of hybrid viscous microdroplets towards diverse applications

Scientists have been pursuing a compact, electrodeless microfluidic platform with a simple structure to realize the efficient cascading manipulations of serial aqueous microdroplets. In this study, we present a photovoltaic microfluidic platform to handle viscous Sodium-Alginate-doped aqueous microdroplets dispersed in a continuous surfactant-doped oil phase. Three kinds of optical response (Non-coalescence, Successful coalescence, and Bouncing back) are observed between adjacent microdroplets. Both the surfactant and SA concentrations are employed to optimize the laser-illumination intensity range of successful coalescence. We realized, that by simply applying focused-laser illumination, the sequential cascading of microfluidic manipulations including trapping, coalescence, mixing, and release of viscous aqueous microdroplets could be controlled in a reconfigurable, high-throughput manner. By properly adjusting the laser-illumination intensity, we can control the number of the microdroplets participating in the coalescence as well as the degree of the liquid mixing inside coalescent microdroplets, thus realizing the mass-production of hybrid viscous aqueous microdroplets. With this platform, we prepare Janus microparticles possessing magnetic and phosphorescent properties for assembling a magnetically driven displayer. Moreover, bioreactors are prepared with both immobilized yeast cells for effective fermentation and embedded magnetic nanoparticles for convenient recovery. Additionally, we generate, on this platform, chains of fluorescent double-emulsion microdroplets for optically encoding the information of the target microdroplet. The photovoltaic MHTE platform, with a simple chip design and good integrability with other LN-based photonic components, allows for an electrodeless, biocompatible manipulation of serial aqueous microdroplets with minimal temperature fluctuation, showing great potential in diverse fields including optics, MEMS, biotechnology and chemical sciences.

Novel resveratrol smart lipids; design, formulation, and biological evaluation of anticancer activity.

Although resveratrol (RES) is an efficacious molecule, its therapeutic activity is impeded by significant limitations, such as rapid oral absorption, poor oral bioavailability, and low water solubility. Therefore, the preparation of RES in different pharmaceutical carriers represents an important tool to enhance its therapeutic applications. This study aims to potentiate the anti-cancer activity of RES by formulating it into a novel nanocarrier called Smart Lipid. RES-loaded Smart Lipids were prepared by high-shear hot homogenization method utilizing a 21 × 32 factorial design with three factors at different levels: the total lipid concentration, the concentration of surfactant, and the type of surfactant. The responses were evaluated based on entrapment efficiency percentages and particle size. Our novel optimized RES-loaded Smart Lipid formula showed small particle size (288.63 ± 5.55 nm), good zeta potential (-16.44 ± 0.99 mV), and an entrapment efficiency of 86.346 ± 3.61% with spherical, clearly distinct, and no signs of fusion by transmission electron microscopy. Further characterization was done using differential scanning calorimetry, which showed no interaction between the drug and other components as the optimum lyophilized formula showed a peak at 54.75°C, which represents the lipid mixture, with an undetectable characteristic peak of the drug, which indicates entrapment of the drug, and the structure of the compounds was confirmed by Fourier transform-infrared spectroscopy, in which the majority of the drug's characteristic peaks disappeared when loaded into Smart Lipid, which may indicate Smart Lipid's ability to reduce the stretching and bending between bonds in RES. In addition, the optimized formula showed a sustained release pattern compared to RES suspension. Finally, the cytotoxic activity of the optimized RES-loaded Smart Lipid on different cell lines (human breast adenocarcinoma (MCF7), human hepatocellular carcinoma (HepG2), and human colon cancer cells (HT29)) was assessed through MTT assay (7-fold reduction in the IC50, from 3.7 ± 0.5 μM for free RES to 0.5 ± 0.033 μM for Smart Lipid loaded formula against MCF7, 3-fold reduction in the IC50 against HepG2 cells, from 10.01 ± 0.35 to 3.16 ± 0.21 μMm, and a more than 10-fold reduction in the IC50 from more than 100 to 10 ± 0.57 μM against HT-29 cells) and its effect on cell cycle progression and apoptosis induction were assessed using flow cytometry and annexin V kit, respectively. Our results showed that RES-loaded Smart Lipid significantly reduced cell viability, induced cell cycle arrest at G0/G1 phase, and apoptosis compared to free formula and free RES suspension. Loading RES into this novel kind of nanocarrier enhanced RES absorption, cellular accumulation, and improved its anticancer properties.

Further Exploration of Heat of Immersion as a Method to Quantify Wettability for Particulates: Effect of Temperature.

A previous paper [Weston et al. Ind. Eng. Chem. Res. 2015, 54, 4274-4284] by our group concluded that to distinguish between the wettability of different particles, heat of immersion is the best method, as opposed to the Washburn or sessile drop method. In this paper, heats of immersion of three different particles with three different wettabilities are measured at different temperatures to examine one critical assumption concerning the temperature dependence of the heat of immersion. In addition, surfactants are added to the water, and the effect of surfactant concentration on the heat of immersion is measured. One particularly noteworthy aspect of the current study is that some measurements were made at temperatures greater than 100 °C and hence pressures higher than atmospheric pressure with no more difficulty than measurements made at atmospheric pressure. The previous paper showed that, for certain particles, the relationship used by us and others between the heat of immersion and contact angle gave impossible values for certain surfaces. In this paper, the derivation of that expression is reexamined, and certain assumptions are highlighted. Because of issues with the assumptions, we agree with the conclusion from our previous paper that using the heat of immersion as a qualitative measure of wetting is appropriate. However, without measurement of the values of the liquid-solid interfacial energy with temperature as well as the gas-solid interfacial energy with temperature, conversion to the contact angle directly is not appropriate. However, for the same surface, using this approach to quantify the contact angle as a function of temperature is likely appropriate if the contact angle is measured using some other method at one temperature, at least over the limited temperature range (up to 150 °C) explored in this study.

Structural Analysis of Aggregates Formed by Linear- and Star-type Quaternary Ammonium Salt-Based Trimeric Surfactants Using Rheology and Small-Angle X-ray Scattering.

We performed a structural analysis of aggregates formed by two types of trimeric surfactants based on quaternary ammonium salts─linear-type 3Cnlin-s-Q and star-type 3Cntris-s-Q─featuring varying alkyl chain lengths (n) and spacer chain lengths (s) in aqueous solutions. We performed rheology, dynamic light scattering, and small-angle X-ray scattering measurements on the trimeric surfactants and investigated the effects of the alkyl chain length, spacer chain length, spacer skeleton structure, and surfactant concentration on their aggregation behavior. Linear-type 3C12lin-3-Q transitioned from gel solutions to worm-like micelles at high concentrations, and 3C14lin-3-Q became gel solutions over a wide range of concentrations. In contrast, all other studied surfactants formed ellipsoidal micelles. The minor and major axes of the ellipsoidal micelles formed by liner-type 3Cnlin-3-Q increased with the increasing alkyl chain length. As the spacer chain length of 3Cnlin-s-Q increased from 3 to 6, and as the spacer skeleton expanded from linear-type 3Cnlin-s-Q to star-type 3Cntris-s-Q, the surfactants formed ellipsoidal micelles without the formation of aggregates with a high-order structure, demonstrating this behavior over a broad concentration range.

Surfactant Micelle-Driven High-Efficiency and High-Resolution Length Separation of Carbon Nanotubes for Electronic Applications.

High-efficiency extraction of long single-wall carbon nanotubes (SWCNTs) with excellent optoelectronic properties from SWCNT solution is critical for enabling their application in high-performance optoelectronic devices. Here, a straightforward and high-efficiency method is reported for length separation of SWCNTs by modulating the concentrations of binary surfactants. The results demonstrate that long SWCNTs can spontaneously precipitate for binary-surfactant but not for single-surfactant systems. This effect is attributed to the formation of compound micelles by binary surfactants that squeeze the free space of long SWCNTs due to their large excluded volumes. With this technique, it can readily separate near-pure long (≥500nm in length, 99% in content) and short (≤500nm in length, 98% in content) SWCNTs with separation efficiencies of 26% and 64%, respectively, exhibiting markedly greater length resolution and separation efficiency than those of previously reported methods. Thin-film transistors fabricated from extracted semiconducting SWCNTs with lengths >500nm exhibit significantly improved electrical properties, including a 10.5-fold on-state current and 14.7-fold mobility, compared with those with lengths <500nm. The present length separation technique is perfectly compatible with various surfactant-based methods for structure separations of SWCNTs and is significant for fabrication of high-performance electronic and optoelectronic devices.

High-strength scalable carbon nanostructured sheets through mechanical densification

The fabrication of macrostructures based on carbon nanostructures (CNS), such as CNS sheets, while maintaining the nanoscale mechanical properties of CNS, poses a significant technological and fundamental challenge. The presence of voids in the structure of CNS sheets significantly impacts their mechanical and electrical reliabilities. This study presents the fabrication of high-strength CNS (carbon nanostructures) sheets achieved through the mechanical densification of CNS sheets produced via the filtration process. Utilizing the filtration process as a potentially scalable and cost-efficient method reliably enhances the mechanical properties of CNS sheets. Within these CNS sheets, carbon nanostructures are densely stacked into macroscopically layered films, reducing voids, and enhancing mechanical properties. These CNS sheets hold promise for various applications, including electromagnetic interference shielding, electronics, energy storage, heat dissipation, among others. The CNS sheets obtained through the densification of CNS layers are analyzed to investigate how surfactant concentration and sonication time impact their mechanical properties. These high-strength CNS sheets, with improved mechanical properties, open doors to diverse applications ranging from electronics to energy storage, promising innovation in multiple fields.

Hydrothermal synthesis of hydroxyapatite crystals with and without seed crystals and surfactant

To the best of our knowledge for the first time the hydroxyapatite (HA) crystals were synthesized with different doses of HA seed crystals. HA crystals were synthesized from solutions containing the stoichiometric amounts of ammonium dihydrogen phosphate and calcium hydroxide. The various interactions of the NH4H2PO4 concentrations (0.5–5.5 Molar), surfactant {amino tris (methylene phosphonic acid) [N(CH2PO3H2)3] (ATMP)} [ATMP] concentrations (0–100 ppm), and HA seed crystals doses (0–50%) were investigated and their effects on the HA mean diameter and hardness were studied using the Box-Behnken experimental statistical design. Results have shown that no correlations were obtained between the mean diameters of the HA crystals and the obtained HA hardness. HA synthesis in the absence of surfactant resulted in formation of HA rod-like and/or tabular crystals whereas agglomerated crystals were obtained with surfactant. The results indicate that with increasing the % of HA crystal seed dose, an increase in the HA mean diameter was obtained. Moreover, with increase of surfactant concentration, a high increase in HA hardness was achieved. HA crystal particle sizes were ranged from about 11–18 µm whereas the crystallite sizes were ranged from 22 to 46 nm.

Ultralow interfacial tension achieved by extended anionic surfactants with a short hydrophobic chain

Extended surfactant is a new type of oil displacement agent with excellent performance in enhanced oil recovery (EOR). In this paper, the novel extended surfactants with short hydrophobe (ethylhexyl) have been studied. The dynamic interfacial tensions (IFTs) between extended surfactant (C8PxEyC) solutions and n-alkanes were measured by the spinning drop method. The effect of surfactant concentration, polyoxypropylene (PO) numbers, polyoxyethylene (EO) numbers and electrolyte on the IFTs were investigated. The experimental results show that the interfacial activity of the extended surfactants mainly depends on the PO groups, and the short hydrophobe extended anionic surfactant shows the similar behavior of reducing IFT to that of long alkyl chain one. The IFTs decrease with an increase of the PO numbers against n-alkanes, and an increase of the EO numbers leads to the destruction of the tight arrangement of the adsorption film because the size of EO group is smaller than that of PO group, which results in an increase of IFT. The addition of electrolyte can reduce the IFTs by weakening the electrostatic repulsion between surfactant molecules at the interface, but it has little effect on its HLB. The long EO chain of extended surfactant prevents divalent cation from binding two surfactant counterions, which results in the little effect on reducing IFT. This study is of great significance for the insight of extended surfactants and their application in high-salt reservoirs.

Experimental and theoretical investigation on the mechanism of cationic surfactants-assisted phosphogypsum crystal transformation

The massive discharge and stockpiling of phosphogypsum became an increasingly severe issue on environment. The transformation of phosphogypsum into fibrous alpha-type hemihydrate gypsum (α-HH) with high L/D(ratio of length-to-diameter) is one of the effective routes to achieve the high-valued utilization. In this work, six types of cationic surfactants, including CTAB, STAC, CHEC, CGG, CPAM and PDDA were selected to investigate their different effects on shape of α-HH crystals through hydrothermal method under the condition of 160 °C(0.6 MPa saturated vapour pressure) for 3 h. The results showed that the introduction of all selected surfactants can increase the length-to-diameter (L/D) ratio of α-HH crystals. As the concentration of surfactants increases, the L/D ratio first increases and then decreases, and the highest L/D ratio of 171.3 was obtained by using CTAB at 0.6 %. The mechanism of regulated growth of α-HH crystals into fibrous structure following c-axis in the presence of six cationic surfactants was also demonstrated. Moreover, the adsorption mechanism of cationic surfactants on the α-HH surface was investigated by molecular dynamics simulation and theoretical analysis. It is found that the order of binding energy (Eb) between the addition and α-HH crystal faces is Eb(11¯0) > Eb(110) > Eb(200) > Eb(002). This work provides insightful guidance from both experimental and theoretical perspectives for controlling the crystal form of α-HH and preparing high-strength gypsum.

Efficiency of single pharmaceutical surfactants to mimic intestinal biorelevant media solubilization and dissolution of etravirine: Comparison of intrinsic and film dissolution models

We understand that quality control dissolution media may best anticipate in vivo product performance by mimicking in vivo media, but preferably involve at most a single pharmaceutical surfactant for routine laboratory use. The objective here was to estimate the concentrations of six pharmaceutical surfactants to mimic etravirine solubility and intrinsic dissolution rate, as well as dissolution rate from a film model, in each Fed State Simulated Intestinal Fluid Version 2 (FeSSIF-V2) and Fasted State Simulated Intestinal Fluid Version 2 (FaSSIF-V2). Solubility studies and colloid sizing measurements were conducted. Results indicate that all six surfactants were more efficient than FeSSIF-V2 or FaSSIF-V2 at solubilizing drug, and also exhibited higher micelle diffusivities than FeSSIF-V2 and FaSSIF-V2 mixed-micelles. The rank-order potency (on mM basis) of the six pharmaceutical surfactants to mimic etravirine solubility in each FeSSIF-V2 and FaSSIF-V2 was: polysorbate 80 (PS80) > polysorbate 20 (PS20) > polyoxyethylene(23) lauryl ether (POE23) > POE10 > hexadecyltrimethylammonium bromide (HEX) > sodium lauryl sulfate (SLS). This rank-order potency was almost the same to mimic drug dissolution rate into each FeSSIF-V2 and FaSSIF-V2, except POE10 > POE23. For the most potent surfactant, PS80, 0.461 mM and 0.140 mM PS80 was estimated to mimic etravirine's solubility and dissolution rate into FeSSIF-V2, respectively, using the intrinsic dissolution model. The low PS80 concentration to mimic dissolution rate reflects the relatively high diffusivity of PS80 micelles, compared to FeSSIF-V2 mixed-micelle diffusivity, which was the case for all six pharmaceutical surfactants. Results are also presented in terms of a film dissolution model for surfactant-mediated dissolution, where dissolution enhancement was less than that in the intrinsic dissolution model, and the film model required lower surfactant concentration than in intrinsic dissolution model to mimic FeSSIF-V2-enhanced dissolution. Findings have promised to identify single pharmaceutical surfactant concentrations that mimic key performance attributes of biorelevant media.

Influence of various surfactants on the stability and solidification characteristics of DI water-based CuO NFPCM for cool thermal energy storage system

The current study goals to investigate the stability and solidification characteristics of deionized water (DI water) based copper oxide (CuO) nanofluid phase change materials (NFPCMs) with a nucleating agent, different types of surfactants (SBDS, CTAB, and GA) and different weight concentration of surfactant for cool thermal energy storage systems (CTES). The stability of NFPCMs was assessed through average particle size distribution, zeta potential, and UV–vis absorbance. Among all NFPCMs, 0.1 wt% SDBS - CuO NFPCM showed prolonged stability with −42.7 mV and 212.6 nm of zeta potential and average particle size value. The heat transfer properties of NFPCMs were studied with differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA) and thermal conductivity measurements. The introduction of 0.05 wt% SDBS to NFPCM resulted in a notable 17.84 % and 7.64 % increase in thermal conductivity in solid and liquid states, with a slight decrease in latent heat by 5.2 % and 6.01 % during melting and crystallization as compared to DI water. The solidification experiments of NFPCMs were investigated in a spherical encapsulation at a surrounding bath temperature of −8 °C and − 10 °C. Comparing various surfactants in NFPCMs, the SDBS–CuO NFPCM was the most efficient in reducing the solidification time by 26.3 % and 28.4 % at −8 °C and − 10 °C respectively, compared to the nucleating agent PCM (NAPCM). Further, the different concentrations of SDBS in NFPCM demonstrated that 0.05 wt% SDBS–CuO NFPCM displayed the greatest reduction in solidification time, achieving 29.4 % and 27.7 % at −10 °C and − 8 °C, respectively, compared to the NAPCM.

Molecular simulation of the effect of anionic surfactant on methane diffusion in coal

Coal seam water injection is one of the important means of coal mine disaster prevention and control, which helps to reduce gas concentration. Anionic surfactants can change the hydrophilicity of coal to enhance the wetting effect of coal seam water injection and inhibit the diffusion of methane. However, the research on the effect of surfactants on the diffusion process of methane is still relatively weak. In order to explore the influence mechanism of anionic surfactant on coal surface wettability and methane diffusion from a microscopic point of view. Using wiser coal model and two commonly used anionic surfactants, sodium dodecyl benzene sulfonate (SDBS) and sodium dodecyl sulfate (SDS), the surfactant/water interface configuration, water/coal contact angle configuration and coal seam methane diffusion configuration were constructed. The interfacial stability of surfactant and water was discussed, and the wetting modification effect of surfactant on coal surface and the law of gas diffusion were analyzed. Finally, by studying the microscopic properties of each molecule in the simulation system, the adsorption mode of surfactants, the hydrophilicity of polar groups, the number of hydrogen bonds and the change of the pore volume in the coal seam system were analyzed, and the wetting modification mechanism of surfactants on coal surface and the inhibition effect of methane diffusion were discussed. The results show that with the increase of surfactant concentration, the interface formation energy is constantly enhanced, and the absolute value of electrostatic energy gradually increases, making the effect between surfactant and water stronger. The contact angle of coal surface under the action of SDS surfactant is the smallest, which is 36.230°, indicating that SDS surfactant has the best effect on the wettability of coal surface. The amount of methane diffusion in the surfactant action system decreased significantly compared with the pure water system, and the distribution of methane in the coal seam increased, indicating that the interaction between methane and coal is enhanced under the action of surfactant. With the increase of surfactant concentration, surfactant molecules are easier to spread on the surface of coal seam, and the wettability of coal surface increases. The research results can provide some research ideas and reference significance for anionic surfactants in the prevention and control of coal mine gas disasters.

Comprehensive Evaluation of Tilted Fiber Bragg Grating (TFBG) Sensors for Characterizing Oil–Water Emulsions: A Study on the Impact of Surfactant Concentration and Mixing Speed

Comprehensive Evaluation of Tilted Fiber Bragg Grating (TFBG) Sensors for Characterizing Oil–Water Emulsions: A Study on the Impact of Surfactant Concentration and Mixing Speed

Innovative stearic acid-in-silicone oil (o/o) phase change material lubricating emulsions (PCMLEs): Thermo-rheological and tribological properties

This paper analyses the feasibility of using novel non-aqueous stearic acid-in-silicone oil (o/o) phase change material lubricating emulsions (PCMLEs). The novel use of these dispersions with heat storage capacity for lubricating applications can be considered a new approach since they have not yet been used for such purposes. In this study, PCMLEs consist of stearic acid, with a melting point of roughly 69 °C, as a dispersed phase change material in a continuous silicone oil medium. Samples were prepared by mixing different phase ratios, by high-shear processing and stabilised by a constant concentration of a silicone-based non-ionic surfactant. Taking into consideration the ability of stearic acid to absorb latent thermal energy during machinery operation, the potential application in lubrication has been assessed by means of stationary and temperature ramp friction tests. Moreover, the effect of the phase transition on the PCMLEs’ rheological response has been analysed through stationary flow tests and frequency sweeps within the linear viscoelastic range at constant temperatures, below (40 °C) and above (80 °C) the melting process of the disperse phase. Additionally, their thermal properties and morphology were also studied through X-ray diffraction measurements (XRD), differential scanning calorimetry (DSC) and polarised optical microscopy. As a result, the reported rheological properties and microstructure led to the enhancement in tribological characteristics of PCMLEs since a significant reduction in the friction factor is evidenced, within the whole temperature range, when compared to the silicone oil.

Pulmonary surfactant impacts in vitro activity of selected antifungal drugs against Candida krusei and Candida albicans

PurposeThis study investigates how surfactants affect the in-vitro anti-infective efficacy of micafungin, caspofungin, anidulafungin, and amphotericin B in treating pulmonary mycoses.MethodsMIC values for antifungal agents were determined against Candida krusei (now Pichia kudriavzevii) ATCC 6258, Candida albicans ATCC 90028, and 18 clinical isolates using the broth microdilution method in RPMI medium, following EUCAST recommendations. MIC assays included testing with and without Curosurf® surfactant at 1 mg/mL for C. krusei ATCC 6258 and all C. krusei isolates. Subsequent Time-kill studies in Sabouraud broth involved testing both C. albicans ATCC 90028 and C. krusei ATCC 6258 strains at concentrations equal their respective MIC values, with and without surfactant, using all four antifungals. CFU/mL were assessed at multiple time points up to 24 h. TKCs with different surfactant concentrations for C. krusei ATCC 6258 and mini-TKCs at various concentrations relative to the MIC of C. krusei isolates and the reference strain were conducted with micafungin, anidulafungin, and caspofungin.ResultsMIC results showed that 1 µg/mL surfactant reduced killing of micafungin and anidulafungin against C. krusei, while caspofungin was unaffected. Amphotericin B's MIC decreased by half. TKCs demonstrated significant effects of surfactant on micafungin and anidulafungin against C. krusei, with complete abolition of anidulafungin's activity against C. albicans.ConclusionThis in-vitro study highlights the concentration-dependent inhibitory effect of surfactant on antifungal activity against C. krusei and, to some extent, C. albicans, necessitating further clinical validation for invasive lung mycoses treatment.

Charge Regulation at the Nanoscale as Evidenced from Light-Responsive Nanoemulsions.

Emulsions are indispensable in everyday life, and the demand for emulsions' diversity and control of properties is therefore substantial. As emulsions possess a high internal surface area, an understanding of the oil/water (o/w) interfaces at the molecular level is fundamental but often impaired by experimental limitations to probe emulsion interfaces in situ. Here, we have used light-responsive surfactants (butyl-AAP) that can photoisomerize between E and Z isomers by visible and UV light irradiation to tune the emulsion interfaces. This causes massive changes in the interface tension at the extended o/w interfaces in macroemulsions and a drastic shift in the surfactants' critical micelle concentration, which we show can be used to control both the stability and phase separation. Strikingly different from macroemulsions are nanoemulsions (RH ∼90 nm) as these are not susceptible to E/Z photoisomerization of the surfactants in terms of changes in their droplet size or ζ-potential. However, in situ second-harmonic scattering and pulsed-field gradient nuclear magnetic resonance (NMR) experiments show dramatic and reversible changes in the surface excess of surfactants at the nanoscopic interfaces. The apparent differences in ζ-potentials and surface excess provide evidence for a fixed charge to particle size ratio and the need for counterion condensation to renormalize the particle charge to a critical charge, which is markedly different compared to the behavior of very large particles in macroemulsions. Thus, our findings may have broader implications as the electrostatic stabilization of nanoparticles requires much lower surfactant concentrations, allowing for a more sustainable use of surfactants.

Optimisation of microencapsulation efficiency of propolis phenolic compounds by double emulsion method using response surface methodology

AbstractThe aim of this study was to optimise the microencapsulation efficiency of propolis phenolic compounds by double emulsion solvent evaporation technique (W1/O/W2). The solvent/sample ratio and the polymer and surfactant concentration parameters were optimised using response surface methodology (RSM) through Box–Behnken Design (BBD). For each parameter studied, total phenolic content encapsulation efficiency (TPCEE), free radical scavenging activity (DPPH), and ferric reducing antioxidant power (FRAP) were evaluated. The results showed that the optimal parameters were: 31.60 mg mL−1 for sample/solvent ratio, 606.28 mg mL−1 for poly(ε-caprolactone) (PCL) concentrations, and 2.05 g mL−1 for poly(vinyl alcohol) (PVA) concentration. The optimum values obtained were: 84.62% for encapsulation efficiency of phenolic content, 51.89% for DPPH, and 48,733 mg Trolox Equivalent/100 g dry weight for FRAP. The experimental checking of results revealed the validity of elaborated models and their suitability for the prediction of both responses. The developed mathematical models have expressed a high level of significance through RSM optimisation processes for phenolic antioxidants of propolis.

Lactoferrin Reduces Surfactant Content in the Self-Emulsifying Drug Delivery System.

Self-emulsifying drug delivery systems (SEDDSs) can effectively be employed to formulate drugs with poor oral bioavailability due to low aqueous solubility and high first-pass metabolism. High surfactant content is an existing challenge toward the successful application of SEDDS. A SEDDS is developed with lactoferrin, a natural emulsifier to reduce the Tween content of a fenofibrate (FEN) formulation. FEN SEDDS (SEDDS without lactoferrin) and FEN Lf-SEDDS (SEDDS with lactoferrin) were developed with 30% and 21% Tween content, respectively. Both formulations containing Crodamol GTCC as a lipid component were thermodynamically stable. No significant difference was observed in zeta potential (-9.25 to -12.63 mV), drug content (>85%), and percentage transmittance (>99%) between the two formulations. FEN Lf-SEDDS resulted in higher viscosity and larger particle size than FEN SEDDS. Solidified SEDDS with Aerosil 200 significantly improved in vitro drug release from both formulations than pure FEN. However, FEN SEDDS and FEN Lf-SEDDS did not show a significant difference in cumulative percent release or dissolution efficiency at 120 min. It can be concluded that lactoferrin containing SEDDS with 27% lesser synthetic surfactants (Tween 80 and Span 80) can result in similar physicochemical characteristics. Oral pharmacokinetic study of FEN Lf-SEDDS in a rat model resulted in 1.3 and 5.5 times higher relative bioavailability than marketed product and pure drug, respectively. The addition of lactoferrin could substitute synthetic surfactants in self-emulsifying drug delivery systems significantly.