Exploring the Properties of Unilamellar Vesicle Bilayers Formed by Ionic Liquid Surfactants for Future Applications in Nanomedicine.

Two ionic liquids (ILs) with amphiphilic properties composed of 1-butyl-3-methylimidazolium dioctylsulfosuccinate (bmim-AOT) and 1-hexyl-3-methylimidazolium dioctylsulfosuccinate (hmim-AOT) form unilamellar vesicles spontaneously simply by dissolving the IL-like surfactant in water. These novel vesicles were characterized using two different and highly sensitive fluorescent probes: 6-propionyl-2-(dimethylaminonaphthalene) (PRODAN) and trans-4-[4-(dimethylamino)-styryl]-1-methylpyridinium iodide (HC). These fluorescent probes provide information about the physicochemical properties of the bilayer, such as micropolarity, microviscosity, and electron-donor capacity. In addition, the biocompatibility of these vesicles with the blood medium was evaluated, and their toxicity was determined using Dictyostelium discoideum amoebas. First, using PRODAN and HC, it was found that the bilayer composition and the chemical structure of the ions at the interface produced differences between both amphiphiles, making the vesicles different. Thus, the bilayer of hmim-AOT vesicles is less polar, more rigid, and has a lower electron-donor capacity than those made by bmim-AOT. Finally, the results obtained from the hemolysis studies and the growth behavior of unicellular amoebas, particularly utilizing the D. discoideum assay, showed that both vesicular systems do not produce toxic effects up to a concentration of 0.02 mg/mL. This elegant assay, devoid of animal usage, highlights the potential of these newly organized systems for the delivery of drugs and bioactive molecules of different polarities.

Suspensions of antibiotics in self-emulsifying oils as a novel approach to formulate eye drops with substances which undergo hydrolysis in aqueous environment.

The aim of this study was to develop eye-drops with cefuroxime (CEF) sodium or vancomycin (VAN) hydrochloride, antibiotics that are instable in water. Anhydrous self-emulsifying oils (SEO) are proposed as a carrier and antibiotics are suspended. In the contact with tear fluid, the formulation should transform into emulsion, with fast dissolution of an antibiotic. CEF or VAN (5% w/w) was suspended in SEO carriers prepared by dissolving surfactants (Tween 20 or Span 80 5% w/w) in Miglyol, castor oil, or olive oil. Formulations with or without sodium citrate (2% w/w) were compared. Six-months or 1-year stability tests were carried out at 40 °C. The content of CEF and VAN was evaluated using HPLC and the potency of the antibiotic was assessed with agar diffusion method. In contact with water, drug particles suspended in SEO dissolved rapidly and o/w emulsion was formed. After 1-year at 40 °C, the content of degradation products was at most 0.5% in CEF and 4.0% in VAN formulations. The agar diffusion assay has shown that CEF and VAN loaded into SEO retained its potency against the sensitive microorganisms comparable to an aqueous solution. Therefore, SEO can be used as a novel carrier for the active substances which may not require improved solubility or absorption but need to be protected from moisture. This is a formulation that can be produced on industrial scale, with no limitation of stability or drug concentration.

Evolution of the structure and interaction in the surfactant-dependent heat-induced gelation of protein.

The addition of a surfactant and/or an increase in temperature disrupt the native structure of proteins, where high temperature further results in protein gelation. However, in a mixed protein-surfactant system, surfactant concentration and temperature have been observed to exhibit both mutually associative and counter-balancing effects towards heat-induced gelation of protein-surfactant dispersion. This study is conducted on globular bovine serum albumin (BSA) protein and cationic surfactant dodecyl trimethyl ammonium bromide (DTAB), which interact strongly owing to their oppositely charged nature. The findings reveal that the BSA-DTAB suspension undergoes gelation with increasing temperature but only at lower concentrations of DTAB, where the presence of the surfactant facilitates gelation (associative effect). Conversely, as the surfactant concentration increases beyond a critical value, temperature-driven gelation of the BSA-DTAB system is completely inhibited, despite surfactant-induced protein denaturation (counter-balancing effect). To conceptualize these results, we compared them with observations made in a system comprising protein and a similarly charged surfactant, sodium dodecyl sulfate (SDS). It has been further demonstrated that the anionic surfactant (SDS) can restrict protein gelation at much lower concentration compared to the cationic surfactant (DTAB). The evolution of the structure and interaction during gel formation/inhibition has been examined to understand the underlying mechanism guiding these sol-gel transitions. We present a comprehensive phase diagram, encompassing the solution/gel states of the protein-surfactant dispersion, with respect to the dispersion temperature, surfactant concentration, and ionic behavior (anionic or cationic) of the surfactants.

Probing the structural evolution on the surface of cardiolipin vesicles with an amphiphilic second harmonic generation and fluorescence probe.

Investigating the influence of the ambient chemical environment on molecular behaviors in liposomes is crucial for understanding and manipulating cellular vitality as well as the capabilities of lipid drug carriers in various environments. Here, we designed and synthesized a second harmonic generation (SHG) and fluorescence probe molecule called Pyr-Py+-N+ (PPN), which possesses membrane-targeting capability. We employed PPN to investigate the response of lipid vesicles composed of cardiolipin to the presence of exogenous salt. The kinetic behaviors, including the adsorption and embedding of PPN on the surface of small unilamellar vesicles (SUVs) composed of cardiolipin, were analyzed. The response of the SUVs to the addition of NaCl was also monitored. A rapid decrease in vesicle size can be evidenced through the rapid drop in SHG emission originating from PPN located on the vesicle surface.

Preparation of Microsponge Drug Delivery System (MSDDS) Followed by a Scale-Up Approach.

In 1987, Won invented the solid-phase porous microsphere (MS), which stores bioactive compounds in many interconnected voids. Spherical particles (5-300 µm), MS, may form clusters of smaller spheres, resulting in many benefits. The current investigation focussed on gel-encased formulation, which can be suitable for dermal usage. First, quasi-emulsion (w/o/w) solvent evaporation was used to prepare 5-fluorouracil (5 FU) MS particles. The final product was characterized (SEM shows porous structure, FTIR and DSC showed drug compatibility with excipients, and gel formulation is shear-thinning) and further scaled up using the 8-fold method. Furthermore, CCD (Central Composite Design) was implemented to obtain the optimized results. After optimizing the conditions, including the polymer (600 mg, ethyl cellulose (EC), eudragit RS 100 (ERS)), stirring speed (1197 rpm), and surfactant concentration (2% w/v), we achieved the following results: optimal yield (63%), mean particle size (152 µm), drug entrapment efficiency (76%), and cumulative drug release (74.24% within 8 h). These findings are promising for industrial applications and align with the objectives outlined in UN Sustainable Development Goals 3, 9, and 17, as well as the goals of the G20 initiative.

High-Throughput Fluorometric Assay For Quantifying Polysorbate In Biopharmaceutical Products Using Micelle Activated Fluorescence Probe N-Phenyl-1-Naphthylamine.

PURPOSE: Polysorbates are among the most used surfactants in biopharmaceutical products containing proteins. Our work aims to develop a high-throughput fluorometric assay to further diversify the analytical toolbox for quantification of PSs. METHOD: The assay leverages the micelle activated fluorescence signal from N-Phenyl-1-Naphthylamine (NPN). The development and optimization of assay parameters were guided by the pre-defined analytical target profile. Furthermore, NMR was used to probe the interaction between protein, PS80 and NPN in the measurement system and understand protein interference. RESULTS: All assay parameters including excitation and emission wavelengths, standard curve, NPN concentration, and incubation time have been optimized and adapted to a microplate format, making it compatible with automated solutions that will be pursued in the near future to drive consistency and efficiency in our workflows. The specificity, accuracy, and precision of the assay have been demonstrated through a case study. Furthermore, NMR results provided additional insight into the change of the interaction dynamics between PS80 and NPN as the protein concentration increases. The results indicate minimal interaction between the protein and PS80 at lower concentration. However, when the concentration exceeds 75 mg/mL, there is a significant interaction between the protein and PS-80 micelle and monomer. CONCLUSION: A high-throughput fluorometric assay has been developed for quantification of polysorbates in biopharmaceutical samples including in-process samples, drug substance and drug product. The assay reported herein could serve as a powerful analytical tool for polysorbate quantification and control, complementing the widely used liquid chromatography with charged aerosol detection method.

Cooling rate uncovers epimer-dependent supramolecular organization of carbohydrate amphiphiles.

We show distinct CH-π interactions and assembly pathways for the amphiphile N-(fluorenylmethoxycarbonyl)-galactosamine and its epimer N-(fluorenylmethoxycarbonyl)-glucosamine. These differences result in the formation of supramolecular nanofibrous systems with opposite chirality. Our results showcase the importance of the carbohydrates structural diversity for their specific biointeractions and the opportunity that their ample interactome offers for synthesis of versatile and tunable supramolecular (bio) materials.

Self-assembling short peptide amphiphiles as versatile delivery agents: a new frontier in antibacterial research.

Self-assembling short peptide amphiphiles, crafted through a minimalistic approach, spontaneously generate well-ordered nanostructures, facilitating the creation of precise nanostructured biomaterials for diverse biomedical applications. The seamless integration of bioactive metal ions and nanoparticles endows them with the potential to serve as pioneering materials in combating bacterial infections. Nanomanipulation of these molecules' binary structures enables effective penetration of membranes, forming structured nanoarchitectures with antibacterial properties. Through a comprehensive exploration, we attempt to reveal the innovative potential of short peptide amphiphiles, particularly in conjugation with metal cations and nanoparticles, offering insights for future research trajectories.

Preferential Partitioning of Per- and Polyfluoroalkyl Substances (PFAS) and Dissolved Organic Matter in Freshwater Surface Microlayer and Natural Foam.

Per- and polyfluoroalkyl substances (PFAS) are surfactants that can accumulate in the surface microlayer (SML) and in natural foams, with potential elevated exposure for organisms at the water surface. However, the impact of water chemistry on PFAS accumulation in these matrices in freshwater systems is unknown. We quantified 36 PFAS in water, the SML, and natural foams from 43 rivers and lakes in Wisconsin, USA, alongside measurements of pH, cations, and dissolved organic carbon (DOC). PFAS partition to foams with concentration ranging 2300-328,200 ng/L in waters with 6-139 ng/L PFAS (sum of 36 analytes), corresponding to sodium-normalized enrichment factors ranging <50 to >7000. Similar enrichment is observed for DOC (∼70). PFAS partitioning to foams increases with increasing chain length and is positively correlated with [DOC]. Modest SML enrichment is observed for PFOS (1.4) and FOSA (2.4), while negligible enrichment is observed for other PFAS and DOC due to low specific surface area and turbulent conditions that inhibit surfactant accumulation. However, DOC composition in the SML is distinct from bulk water, as assessed using high-resolution mass spectrometry. This study demonstrates that natural foams in unimpacted and impacted waters can have elevated PFAS concentrations, whereas SML accumulation in surface waters is limited.

Enhanced chemiluminescence resonance energy transfer using surfactant-modified AIE carbon dots.

Chemiluminescence resonance energy transfer (CRET) efficiency can be enhanced by confining CRET donors and acceptors within nanoscale spaces. However, this enhanced efficiency is often affected by uncertainties stemming from the random distribution of CRET donors and acceptors in such confined environments. In this study, a novel confined nanospace was created through the surfactant modification of carbon dots (CDs) exhibiting aggregation-induced emission (AIE) characteristics. Hydrophobic CRET donors could be effectively confined within this nanospace. The distance between the CRET donors and acceptors could be controlled by anchoring the AIE-CDs as the CRET acceptors, resulting in significantly improved CRET efficiency. Furthermore, this AIE-CDs-based CRET system was successfully applied to the detection of hydrogen peroxide (H2O2) in rainwater, showcasing its potential for practical applications.

Intact NMR Approach Quickly Reveals Synchronized Microstructural Changes in Oil-in-Water Nanoemulsion Formulations.

A soft-core oil-in-water (o/w) nanoemulsion (NE) is composed of nanometer (nm) sized oil droplets, stabilized by a surfactant layer and dispersed in a continuous bulky water phase. Characterization of the o/w NE molecule arrangements non-invasively, particularly the drug phase distribution (DPD) and its correlation to oil globule size (OGS), remains a challenge. Here we demonstrated the analytical methods of intact 19F Nuclear Magnetic Resonance (NMR) and 1H diffusion ordered spectroscopy (DOSY) NMR for their specificity in measuring DPD and OGS, respectively, on three NE formulations containing the active ingredient difluprednate (DFPN) at the same concentration. The results illustrated synchronized molecular rearrangement reflected in the DPD and OGS upon alterations in formulation. Addition of surfactant resulted in a higher DPD in the surfactant layer, and concomitantly smaller OGS. Mechanic perturbation converted most of the NE globules to the smaller thermodynamically stable microemulsion (ME) globules, changing both DPD and OGS to ME phase. These microstructure changes were not observed using 1D 1H NMR; and dynamic light scattering (DLS) was only sensitive to OGS of ME globule in mechanically perturbed formulation. Collectively, the study illustrated the specificity and essential role of intact NMR methods in measuring the critical microstructure attributes of soft-core NE systems quickly, accurately, and non-invasively. Therefore, the selected NMR approach can be a unique diagnostic tool of molecular microstructure or Q3 property in o/w NE formulation development, and quality assurance after manufacture process or excipient component changes.

System-agnostic prediction of pharmaceutical excipient miscibility via computing-as-a-service and experimental validation.

We applied computing-as-a-service to the unattended system-agnostic miscibility prediction of the pharmaceutical surfactants, Vitamin E TPGS and Tween 80, with Copovidone VA64 polymer at temperature relevant for the pharmaceutical hot melt extrusion process. The computations were performed in lieu of running exhaustive hot melt extrusion experiments to identify surfactant-polymer miscibility limits. The computing scheme involved a massively parallelized architecture for molecular dynamics and free energy perturbation from which binodal, spinodal, and mechanical mixture critical points were detected on molar Gibbs free energy profiles at 180 °C. We established tight agreement between the computed stability (miscibility) limits of 9.0 and 10.0 wt% vs. the experimental 7 and 9 wt% for the Vitamin E TPGS and Tween 80 systems, respectively, and identified different destabilizing mechanisms applicable to each system. This paradigm supports that computational stability prediction may serve as a physically meaningful, resource-efficient, and operationally sensible digital twin to experimental screening tests of pharmaceutical systems. This approach is also relevant to amorphous solid dispersion drug delivery systems, as it can identify critical stability points of active pharmaceutical ingredient/excipient mixtures.

Biosurfactant complexed with arginine has antibiofilm activity against methicillin-resistant Staphylococcus aureus.

Aim: The present study investigated the antimicrobial effectiveness of a rhamnolipid complexed with arginine (RLMIX_Arg) against planktonic cells and biofilms of methicillin-resistant Staphylococcus aureus (MRSA). Methodology: Susceptibility testing was performed using the Clinical & Laboratory Standards Institute protocol: M07-A10, checkerboard test, biofilm in plates and catheters and flow cytometry were used. Result: RLMIX_Arg has bactericidal and synergistic activity with oxacillin. RLMIX_Arg inhibits the formation of MRSA biofilms on plates at sub-inhibitory concentrations and has antibiofilm action against MRSA in peripheral venous catheters. Catheters impregnated with RLMIX_Arg reduce the formation of MRSA biofilms. Conclusion: RLMIX_Arg exhibits potential for application in preventing infections related to methicillin-resistant S. aureus biofilms.

[Box: see text].

Amphiphilic coumarin-based probes for live-cell STED nanoscopy of plasma membrane.

Plasma membranes are vital biological structures, serving as protective barriers and participating in various cellular processes. In the field of super-resolution optical microscopy, stimulated emission depletion (STED) nanoscopy has emerged as a powerful method for investigating plasma membrane-related phenomena. However, many applications of STED microscopy are critically restricted by the limited availability of suitable fluorescent probes. This paper reports on the development of two amphiphilic membrane probes, SHE-2H and SHE-2N, specially designed for STED nanoscopy. SHE-2N, in particular, demonstrates quick and stable plasma membrane labelling with negligible intracellular redistribution. Both probes exhibit outstanding photostability and resolution improvement in STED nanoscopy, and are also suited for two-photon excitation microscopy. Furthermore, microscopy experiments and cytotoxicity tests revealed no noticeable cytotoxicity of probe SHE-2N at concentration used for fluorescence imaging. Spectral analysis and fluorescence lifetime measurements conducted on probe SHE-2N using giant unilamellar vesicles, revealed that emission spectra and fluorescence lifetimes exhibited minimal sensitivity to lipid composition variations. These novel probes significantly augment the arsenal of tools available for high-resolution plasma membrane research, enabling a more profound exploration of cellular processes and dynamics.

Treatment of swine manure by hydrothermal carbonization: The influential effect and preliminary mechanism of surfactants.

Treatment of swine manure by hydrothermal carbonization (HTC) with the aid of different surfactants was first explored in this study. PEG 400 (polyethylene glycol 400) and Tween 80 facilitated the formation of bio-oil. SLS (sodium lignosulfonate) and SDS (sodium dodecyl sulfate) promoted the formation of water-soluble matters/gases. Span 80 enhanced the formation of hydrochar, which resulted in a 50.19 % mass yield, 92.39 % energy yield, and a caloric value of 28.68 MJ/kg. The hydrochar obtained with Span 80 presented a similar combustion performance to raw swine manure and the best pyrolysis performance. The use of Span 80 promoted the transfer of degradation products to hydrochar, especially hydrophobic ester and ketone compounds. Notedly, Span 80 suppressed the synthesis of PAHs during the HTC process, which was reduced to 0.92 mg/kg. Furthermore, the hydrochar produced with Span 80 contained lower contents of heavy metals. On the whole, Span 80 has shown great potential in enhancing the HTC of swine manure. The acting mechanisms of surfactants in the HTC of swine manure included adsorption, dispersion, and electrostatics repulsion.

Self-Assembled Borneol-Guanidine-Based Amphiphilic Polymers as an Efficient Antibiofilm Agent.

Biofilm-associated infections remain a tremendous obstacle to the treatment of microbial infections globally. However, the poor penetrability to a dense extracellular polymeric substance matrix of traditional antibacterial agents limits their antibiofilm activity. Here, we show that nanoaggregates formed by self-assembly of amphiphilic borneol-guanidine-based cationic polymers (BGNx-n) possess strong antibacterial activity and can eliminate mature Staphylococcus aureus (S. aureus) biofilms. The introduction of the guanidine moiety improves the hydrophilicity and membrane penetrability of BGNx-n. The self-assembled nanoaggregates with highly localized positive charges are expected to enhance their interaction with negatively charged bacteria and biofilms. Furthermore, nanoaggregates dissociate on the surface of biofilms into smaller BGNx-n polymers, which enhances their ability to penetrate biofilms. BGNx-n nanoaggregates that exhibit superior antibacterial activity have the minimum inhibitory concentration (MIC) of 62.5 µg·mL-1 against S. aureus and eradicate mature biofilms at 4 × MIC with negligible hemolysis. Taken together, this size-variable self-assembly system offers a promising strategy for the development of effective antibiofilm agents.

The essential role of aggregation for the emulsifying ability of a fungal CYS-rich protein.

Biosurfactants are in demand by the global market as natural commodities suitable for incorporation into commercial products or utilization in environmental applications. Fungi are promising producers of these molecules and have garnered interest also for their metabolic capabilities in efficiently utilizing recalcitrant and complex substrates, like hydrocarbons, plastic, etc. Within this framework, biosurfactants produced by two Fusarium solani fungal strains, isolated from plastic waste-contaminated landfill soils, were analyzed. Mycelia of these fungi were grown in the presence of 5% olive oil to drive biosurfactant production. The characterization of the emulsifying and surfactant capacity of these extracts highlighted that two different components are involved. A protein was purified and identified as a CFEM (common in fungal extracellular membrane) containing domain, revealing a good propensity to stabilize emulsions only in its aggregate form. On the other hand, an unidentified cationic smaller molecule exhibits the ability to reduce surface tension. Based on the 3D structural model of the protein, a plausible mechanism for the formation of very stable aggregates, endowed with the emulsifying ability, is proposed. KEY POINTS: • Two Fusarium solani strains are analyzed for their surfactant production. • A cationic surfactant is produced, exhibiting the ability to remarkably reduce surface tension. • An identified protein reveals a good propensity to stabilize emulsions only in its aggregate form.

Antimicrobial and Anesthetic Niosomal Formulations Based on Amino Acid-Derived Surfactants.

BACKGROUND: This work proposes the development of new vesicular systems based on anesthetic compounds (lidocaine (LID) and capsaicin (CA)) and antimicrobial agents (amino acid-based surfactants from phenylalanine), with a focus on physicochemical characterization and the evaluation of antimicrobial and cytotoxic properties. METHOD: Phenylalanine surfactants were characterized via high-performance liquid chromatography (HPLC) and nuclear magnetic resonance (NMR). Different niosomal systems based on capsaicin, lidocaine, cationic phenylalanine surfactants, and dipalmitoyl phosphatidylcholine (DPPC) were characterized in terms of size, polydispersion index (PI), zeta potential, and encapsulation efficiency using dynamic light scattering (DLS), transmitted light microscopy (TEM), and small-angle X-ray scattering (SAXS). Furthermore, the interaction of the pure compounds used to prepare the niosomal formulations with DPPC monolayers was determined using a Langmuir balance. The antibacterial activity of the vesicular systems and their biocompatibility were evaluated, and molecular docking studies were carried out to obtain information about the mechanism by which these compounds interact with bacteria. RESULTS: The stability and reduced size of the analyzed niosomal formulations demonstrate their potential in pharmaceutical applications. The nanosystems exhibit promising antimicrobial activity, marking a significant advancement in pharmaceutical delivery systems with dual therapeutic properties. The biocompatibility of some formulations underscores their viability. CONCLUSIONS: The proposed niosomal formulations could constitute an important advance in the pharmaceutical field, offering delivery systems for combined therapies thanks to the pharmacological properties of the individual components.

The Effect of Macromonomer Surfactant Microstructure on Aqueous Polymer Dispersion and Derived Polymer Film Properties.

Water-borne coatings were prepared from poly(methyl methacrylate-co-butyl acrylate) latexes using different methacrylic acid containing macromonomers as stabilizers, and their physical properties were determined. The amphiphilic methacrylic acid macromonomers containing methyl, butyl, or lauryl methacrylate as hydrophobic comonomers were synthesized via catalytic chain transfer polymerization to give stabilizers with varying architecture, composition, and molar mass. A range of latexes of virtually the same composition was prepared by keeping the content of methacrylic acid groups during the emulsion polymerization constant and by only varying the microstructure of the macromonomers. These latexes displayed a range of rheological behaviors: from highly viscous and shear thinning to low viscous and Newtonian. The contact angles of the resulting coatings ranged from very hydrophilic (<10°) to almost hydrophobic (88°), and differences in hardness, roughness, and water vapor sorption and permeability were found.

Production and characterization of extracellular liamocins produced from fungal strains of Aureobasidium spp.

Liamocins, a group of high-density glycolipids, are only produced by certain strains of the yeast-like fungi in the genus Aureobasidium. Until now, few studies have focused on the surfactant properties of liamocins produced from the highly diverse tropical strains of Aureobasidium. Therefore, the aims of this research were to screen the liamocin production from tropical strains of Aureobasidium spp. and to characterize their surfactant properties. A total of 41 strains of Thai Aureobasidium spp. were screened for their ability to produce liamocins, and the products were detected using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and thin-layer chromatography. Of those strains, 30 strains of Aureobasidium spp. tested were found to produce liamocins with yields ranging from 0.53 to 10.60 g/l. The nature of all crude liamocins was heterogeneous, with different compositions and ratios depending on the yeast strain. These liamocins exhibited relatively high emulsifying activity against vegetable oils tested, with an emulsification index of around 40-50%; the emulsion stability of some liamocins was up to 30 days. The obtained critical micelle concentration values were varied, with those ​​of liamocins produced from A. pullulans, A. melanogenum and A. thailandense falling in ranges from 7.70 to 119.78, 10.73 to > 1,000, and 68.56 to > 1,000 mg/l, respectively. The emulsification activity of liamocins was higher than that of the analytical grade rhamnolipids. These compounds showed strong surface tension reduction in a sodium chloride concentration range of 2-12% (w/v), pH values between 3 and 7, and temperatures between 4 and 121 °C. This is the first report of liamocins produced by A. thailandense.