From Synthesis to Functionality: Tailored Ionic Liquid-Based Electrospun Fibers with Superior Antimicrobial Properties.

Herein, we report an efficient and facile strategy for the preparation of imidazolium-based ionic liquid (IL) monomers ([CnVIm][Br], n = 2, 4, 6, 8, 10, and 12) and their corresponding polymeric ionic liquids (PILs) with potent antimicrobial activities against Gram-negative and Gram-positive bacteria and fungi. The electrospinning technique was utilized to tailor the polymers with the highest antimicrobial potency into porous membranes that can be easily implemented into diverse systems and extend their practical bactericidal application. The antimicrobial mechanism of obtained ILs, polymers, and nanomaterials is considered concerning the bearing chain length, polymerization process, and applied processing technique that provides a unique fibrous structure. The structure composition was selected due to the well-established inherent amphiphilicity that 1-alkylimidazolium ILs possess, coupled with proven antimicrobial, antiseptic, and antifungal behavior. The customizable nature of ILs and PILs complemented with electrospinning is exploited for the development of innovative antimicrobial performances born from the intrinsic polymer itself, offering solutions to the increasing challenge of bacterial resistance. This study opens up new prospects toward designer membranes providing a complete route in their designing and revolutionizing the approach of fabricating multi-functional systems with tunable physicochemical, surface properties, and interesting morphology.

Enhancing Bioactivity of N,N,N-Chelating Rhodium(III) Complexes with Ionic Liquids: Toward Targeted Cancer Therapy.

This study investigates the potential of using ionic liquids as cosolvents to enhance the solubility and activity of poorly soluble rhodium(III) complexes, particularly those with diene, pyridine derivatives, and camphor-derived bis-pyrazolylpyridine ligands, in relation to 5'-GMP, CT-DNA, and HSA as well as their biological activity. Findings indicate that ionic liquids significantly increase the substitution activity of these complexes toward 5'-GMP while only marginally affecting DNA/HSA binding affinities with molecular docking, further confirming the experimental results. Lipophilicity assessments indicated good lipophilicity. Notably, cytotoxicity studies show that Rh2 is selectively effective against HeLa cancer cells, with IL1 and IL10 modulating the cytotoxic effects. Redox evaluations indicate that rhodium complexes induce oxidative stress in cancerous cells while maintaining redox balance in noncancerous cells. By elucidating the role of ionic liquids in modulating these effects, the study proposes a promising avenue for augmenting the efficacy and selectivity of cancer treatments, thus opening new horizons in cancer therapeutics.

Electrolyte-induced aggregation of zein protein nanoparticles in aqueous dispersions.

Ion specific effects on the charging and aggregation features of zein nanoparticles (ZNP) were studied in aqueous suspensions by electrophoretic and time-resolved dynamic light scattering techniques. The influence of mono- and multivalent counterions on the colloidal stability was investigated for positively and negatively charged particles at pH values below and above the isoelectric point, respectively. The sequence of the destabilization power of monovalent salts followed the prediction of the indirect Hofmeister series for positively charged particles, while the direct Hofmeister series for negatively charged ones assumed a hydrophobic character for their surface. The multivalent ions destabilized the oppositely charged ZNPs more effectively and the aggregation process followed the Schulze-Hardy rule. For some multivalent ions, strong adsorption led to charge reversal resulting in restabilization of the suspensions. The experimental critical coagulation concentrations (CCCs) could be well-predicted with the theory developed by Derjaguin, Landau, Verwey and Overbeek indicating that the aggregation processes were mainly driven by electrical double layer repulsion and van der Waals attraction. The ion specific dependence of the CCCs is owing to the modification of the surface charge through ion adsorption at different extents. These results are crucial for drug delivery applications, where inorganic electrolytes are present in ZNP samples.

Application of biodegradable cholinium ionic liquids for the extraction of 5-hydroxymethylfurfural (HMF) from honey.

5-Hydroxymethylfurfural (HMF), a Maillard reaction product, can be formed when honey is subjected to heat treatment or a long storage time, becoming volatile and toxic depending on its concentration. The fact that, until today, there is no literature data on the extraction of 5-hydroxymethylfurfural (HMF) from honey using ionic liquids directed the investigation of the influence of biodegradable cholinium ionic liquids on the formation of aqueous biphasic systems and the application of these systems for the extraction of HMF from honey. The influence of anions of synthesised ionic liquids on the construction of biphasic systems in which an inorganic salt was used as a salting agent was investigated. Then, the extraction of HMF in these systems was examined, and the mechanisms of HMF extraction using ionic liquids were explained using computer simulations. Examining the effect of cholinium ionic liquids (choline chloride ([Ch][Cl]), cholinium nicotinate ([Ch][Nic]), cholinium propionate ([Ch][Prop]), and cholinium butyrate ([Ch][But])) on the formation of aqueous biphasic systems by comparing the phase diagrams, it was concluded that the ability of ionic liquids to form an aqueous biphasic system with tripotassium phosphate (K3PO4) decreases in the following order: [Ch][But] ≈ [Ch][Prop] > [Ch][Nic] > [Ch][Cl]. By applying all tested aqueous biphasic systems for the extraction of HMF from honey, an extraction efficiency of more than 89% was achieved. Complete extraction was achieved using the extraction system with [Ch][But], while the weakest ability to extract HMF was exhibited by the system with [Ch][Cl]. The mechanisms of HMF extraction using ionic liquids are explained on the basis of the optimised structures of the ionic liquid systems with HMF, together with the visualisation of non-covalent interactions, and on the basis of the calculated binding energies ΔGbin, which can be used as a good predictor of the extraction potential of newly synthesised ionic liquids.

Solubility and Solvation Properties of Pharmaceutically Active Ionic Liquid Benzocainium Ibuprofenate in Natural Deep Eutectic Solvent Menthol-Lauric Acid.

Due to their appealing physiochemical properties, particularly in the pharmaceutical industry, deep eutectic solvents (DESs) and ionic liquids (ILs) are utilized in various research fields and industries. The presented research analyzes the thermodynamic properties of a deep eutectic solvent created from natural molecules, menthol and lauric acid in a 2:1 molar ratio, and an ionic liquid based on two active pharmaceutical ingredients, benzocainium ibuprofenate. Initially, the low solubility of benzocainium ibuprofenate in water was observed, and a hydrophobic natural deep eutectic mixture of menthol:lauric acid in a 2:1 ratio was prepared to improve benzocainium ibuprofenate solubility. In order to determine the solvent properties of DESs and ILs mixtures at different temperatures and their molecular interactions to enhance the solvent performance, the apparent molar volume, limiting apparent molar expansibility, and viscosity B coefficient were estimated in temperature range from 293.15 K to 313.15 K and varying concentration of benzocainium ibuprofenate.

Ibuprofen as an Organic Pollutant in the Danube and Effects on Aquatic Organisms.

The presence of emerging substances in surface water is of a great concern knowing they are the main source for community water supply needs. This study describes the development, optimization and application of an analytical method for the determination of ibuprofen in the Danube samples. Caffeine concentrations, as an indicator of human waste, were determined and maximum risk indexes for aquatic organisms were calculated. The Danube samples were collected from ten representative locations. A Solid-phase extraction was used for ibuprofen and caffeine separation and the analysis was performed by High-performance liquid chromatography method. Ibuprofen concentrations ranged (30.62-111.40) ng/L and caffeine (305.94-375.97) ng/L. Low risk on aquatic organisms was determined for ibuprofen and potential sublethal effect for caffeine was obtained. The results indicated that ibuprofen was effectively separated from other substances in the samples under defined chromatographic conditions for short period of time (4 minutes). Applied HPLC method showed good repeatability, accuracy, selectivity and robustness. Further studies including continuous monitoring of caffeine in the Danube are necessary in order to assess the real risks and possible prevention.

Effect of Zwitterionic Additive on Electrode Protection through Electrochemical Performances of Anatase TiO2 Nanotube Array Electrode in Ionic Liquid Electrolyte.

In this work, a functionalized zwitterionic (ZI) compound 1-butylsulfonate-3-methylimidazole (C1C4imSO3) was synthesized and tested as an additive to LiTFSI/C2C2imTFSI ionic liquid-based electrolytes for lithium-ion batteries. The structure and purity of C1C4imSO3 were confirmed by NMR and FTIR spectroscopy. The thermal stability of the pure C1C4imSO3 was examined by simultaneous thermogravimetric-mass spectrometric (TG-MS) measurements and differential scanning calorimetry (DSC). The LiTFSI/C2C2imTFSI/C1C4imSO3 system was tested as a potential electrolyte for lithium-ion batteries by using anatase TiO2 nanotube array electrode as the anode material. This electrolyte with 3% C1C4imSO3 showed significant improvement of lithium-ion intercalation/deintercalation properties, such as capacity retention and Coulombic efficiency compared to electrolyte without additive.

Dynamic In Situ Monitoring of the Salt Counter-ion Effect on Surfactant Effectiveness Using Reconfigurable Janus Emulsions.

A straightforward method for visualization and quantification of surfactant effectiveness within different electrolyte environments based on using reconfigurable Janus emulsions as novel optical probes is reported. More specifically, we investigated the effect of different types and concentrations of salt counter-ions on the surfactant surface excess of commercial ionic and non-ionic surfactants, namely sodium dodecyl sulfate (SDS) and Tween 80 via in situ monitoring the morphological reconfigurations of biphasic Janus emulsions comprising hydrocarbon and fluorocarbon oils. We find that significant variations in interfacial tensions of SDS-stabilized interfaces (up to 15 mN·m-1) can be evoked by titrating mono-, di-, and trivalent cationic counter-ions, which is coherent with the lyotropic (Hofmeister) series. In contrast, the salt counter-ion effect on the surfactant effectiveness was less pronounced for the non-ionic surfactant Tween 80 (∼3 mN·m-1). Our results reveal a facile in situ method for monitoring the central role of electrolyte type and concentration on surfactant effectiveness and, more broadly, illustrate that Janus emulsions serve as powerful optical probes to dynamically study the properties of surfactants at liquid interfaces. We demonstrate the utility of our findings for an electro-induced morphological reconfiguration of Janus droplet morphologies by dynamically tuning Cu2+ concentration in solution using an electrode setup. The latter provides a unique platform for liquid-phase, real-time, and continuous tuning of Janus droplet morphologies, e.g., for their application in sensing and dynamic optical device platforms.

In Search for an Ionic Liquid with the Best Performance during 210Pb/210Bi Cherenkov Counting in Waters on an LS Counter.

The research presented in this paper aims to investigate the performance of several newly synthesized ionic liquids during 210Pb/210Bi detection in water on a liquid scintillation spectrometer Quantulus 1220 via Cherenkov counting. These experiments have been triggered by the recent reports that certain ionic liquids can act as wavelength shifters, thus significantly increasing the detection efficiency of Cherenkov radiation. The benefit of ionic liquid's addition to the analysed samples is reflected in the detection limit's decrement during 210Pb quantification, which is pertinent considering naturally low levels of 210Pb in aqueous samples. Firstly, it was discovered that ionic liquid, 1-butyl-3-methylimidazolium salicylate, is more efficient than the previously explored 2-hydroxypropylammonium salicylate. Consequently, the impact of a few other ionic liquids on Cherenkov counting efficiency with the same cation group (1-butyl-3-methylimidazolium benzoate, 1-butyl-3-methylimidazolium 3-hydroxybenzoate and 1-butyl-3-methylimidazolium 4-hydroxybenzoate) was also explored to test their potential influence. Molecular simulations have been carried out to reveal which structures of ionic liquids assure wavelength-shifting behavior. The obtained results confirmed that, among the investigated ones, only ionic liquids with the salicylate anion exhibited a wavelength shifting effect.

Synthesis and evolution of physicochemical properties of new pharmaceutically active ionic liquids - tetracainium salicylate and tetracainium ibuprofenate.

Tetracainium salicylate and tetracainium ibuprofenate were synthesized as active pharmaceutical ingredient ionic liquids (API-ILs). These ILs represent a combination of a drug for local anaesthesia (tetracaine) and nonsteroidal anti-inflammatory drugs (salicylic acid and ibuprofen). After IL synthesis, spectroscopic investigations were performed using infrared and nuclear magnetic resonance spectroscopy to confirm their structures. Differential scanning calorimetry and thermogravimetric analysis determined the obtained thermal behaviour of the ionic liquids. Experimental density, viscosity, and electrical conductivity measurements were performed in a wide temperature range to understand the interactions occurring in the obtained pharmaceutically active ionic liquids. All experimental values were well-fitted by the empirical equations. According to the theoretical calculations, weaker interactions of tetracaine with ibuprofenate than with salicylate are found, ascribed to the decreasing molecular symmetry, weakened hydrogen bonding, and increasing steric hindrance of ibuprofenate's alkyl chain.

Influence of Sodium Salicylate on Self-Aggregation and Caffeine Solubility in Water-A New Hypothesis from Experimental and Computational Data.

The present study analyzed experimental data from volumetric and viscosimetric measurements and computational simulations to understand caffeine hydration and aggregation properties in 0.1 mol∙kg-1 of sodium salicylate aqueous solution. Sodium salicylate reduces the bitter taste and increases the solubility of caffeine in water, which is the main reason for their combination in food products. The results noted in volumetric and viscosimetric measurements indicate that sodium salicylate promotes the self-aggregation of caffeine in water. After self-aggregation, the hydration number of caffeine significantly increases. Molecular simulations have allowed us to hypothesize how salicylate increases caffeine solubility. At the molecular level, relocating salicylate moiety from the parallel stacking (π-π) aromatic complex with caffeine and its hydration could be the main reason for increasing the solubility of caffeine in water. The presented study provides clear guidelines on the choice of additives to increase caffeine's solubility in aqueous media. The choice of salicylate as an additive to increase the solubility of caffeine is very important because caffeine and salicylate are found in combination in a large number of formulations.

Structure-Stability Relationship in Aqueous Colloids of Latex Particles and Gemini Surfactants.

The influence of gemini surfactants (GSs) on the charging and aggregation features of anionic sulfate modified latex (SL) particles was investigated by light scattering techniques in aqueous dispersions. The GSs of short alkyl chains (2-4-2 and 4-4-4) resembled simple inert salts and aggregated the particles by charge screening. The adsorption of GSs of longer alkyl chains (8-4-8, 12-4-12, and 12-6-12) on SL led to charge neutralization and overcharging of the particles, giving rise to destabilization and restabilization of the dispersions, respectively. The comparison of the interfacial behavior of dimeric and the corresponding monomeric surfactants revealed that the former shows a more profound influence on the colloidal stability due to the presence of double positively charged head groups and hydrophobic tails, which is favorable to enhancing both electrostatic and hydrophobic particle-GS and GS-GS interactions at the interface. The different extent of the particle-GS interactions was responsible for the variation of the GS destabilization power, following the 2-4-2 < 4-4-4 < 8-4-8 < 12-4-12 order, while the length of the GS spacer did not affect the adsorption and aggregation processes. The valence of the background salts strongly influenced the stability of the SL-GS dispersions through altering the electrostatic interactions, which was more pronounced for multivalent counterions. These findings indicate that both electrostatic and hydrophobic effects play crucial roles in the adsorption of GSs on oppositely charged particles and in the corresponding aggregation mechanism. The major interparticle forces can be adjusted by changing the structure and concentration of the GSs and inorganic electrolytes present in the systems.

A new class of half-sandwich ruthenium complexes containing Biginelli hybrids: anticancer and anti-SARS-CoV-2 activities.

In order to discover new dual-active agents, a series of novel Biginelli hybrids (tetrahydropyrimidines) and their ruthenium(II) complexes were synthesized. Newly synthesized compounds were characterized by IR, NMR, and X-ray techniques and investigated for their cytotoxic effect on human cancer cell lines HeLa, LS174, A549, A375, K562 and normal fibroblasts (MRC-5). For further examination of the cytotoxic mechanisms of novel complexes, two of them were chosen for analyzing their effects on the distribution of HeLa cells in the cell cycle phases. The results of the flow cytometry analysis suggest that the proportion of cells in G2/M phase was decreased following the increase of subG1 phase in all treatments. These results confirmed that cells treated with 5b and 5c were induced to undergo apoptotic death. The ruthenium complexes 5a-5d show significant inhibitory potency against SARS-CoV-2 Mpro. Therefore, molecule 5b has significance, while 5e possesses the lowest values of ΔGbind and Ki, which are comparable to cinanserin, and hydroxychloroquine. In addition, achieved results will open a new avenue in drug design for more research on the possible therapeutic applications of dual-active Biginelli-based drugs (anticancer-antiviral). Dual-active drugs based on the hybridization concept "one drug curing two diseases" could be a successful tactic in healing patients who have cancer and the virus SARS-CoV-2 at the same time.

Influence of side-chain length on antifungal efficacy of N-alkyl nicotinamide-based compounds.

This article presents fungicidal properties of 9 synthesized nicotinamide-bromides with different alkyl side chain lengths toward Fusarium graminearum, Sclerotinia sclerotiorum, and Botrytis cinerea which were examined. The fungicidal properties were determined by the measurement of the radial growth of fungi, followed by the calculation of the antifungal index. The obtained results were correlated with the descriptors from DFT calculations to determine structural features that affect the fungicidal properties of nicotinamides. Based on the experimental and theoretical results, it was confirmed that F. graminearum is most resistant to the change of lipophilicity of compounds, while S. sclerotiorum is most sensitive. For all investigated compounds, the growth rate decreased with the increase of carbon atoms in the side chain until tetradecylnicotinamidium bromide, [C14Nic][Br], while the further prolongation of the alkyl side chain increased the growth rate of fungus. This behavior was explained by the distinguished hydrophobic and hydrophilic surfaces in [C14Nic][Br] due to interactions between keto oxygen and bromide anion absent in the case of nicotinamides with a longer chain.

Preparation and characterization of innovative electrospun nanofibers loaded with pharmaceutically applicable ionic liquids.

Keeping up with cutting edge research in the field of drug delivery, the overall goal of this study was to develop innovative electrospun nanofibers loaded with ionic liquids (ILs) as active pharmaceutical ingredients (APIs). For the first time, a novel approach was examined by combining biocompatible polymer, poly (ethylene oxide) (PEO), and pharmaceutical ILs in an electrospinning process to develop nanofibers with high drug loading (up to 47%). Firstly, two well-known local anaesthetic drugs, lidocaine and procaine, were modified into ILs with the salicylate, forming lidocaine salicylate and procaine salicylate. Its dual-functional nature and increased water solubility for 4- to 10-fold depending on the drug used contribute to overcoming current hurdles encountered by APIs such as poor solubility, low bioavailability, and polymorphism of the solid-state. Nanofibers were formulated using solutions tested for density, viscosity, electrical conductivity, and small-angle X-ray scattering by varying PEO molecular weight and the PEO to IL mass ratio. Scanning electron microscopy showed the surface morphology of the obtained nanofibers, while Fourier transform infrared spectroscopy and differential scanning calorimetry confirmed IL in the nanofibers in an amorphous state. Thus, nanofibers with incorporated IL represent well-known drugs in the new form and a novel dermal application delivery system.

Synthesis, Characterization, Antitumor Potential, BSA and DNA Binding Properties, and Molecular Docking Study of Some Novel 3-Hydroxy-3- Pyrrolin-2-Ones.

BACKGROUND: In order to make progress in discovering the new agents for cancer treatment with improved properties and considering the fact that 3-hydroxy-3-pyrrolin-2-ones belong to a class of biologically active compounds, we tested series of eleven novels 1,5-diaryl-4-(2- thienylcarbonyl)-3-hydroxy-3-pyrrolin-2-ones for their antitumor potential. METHODS: All novel compounds were characterized by spectral (IR, NMR, MS) and elemental analysis. All novel 3-hydroxy-3-pyrrolin-2-ones were screened for their cytotoxic activity on two cancer cell lines, SW480 and MDA-MB 231, and non-transformed fibroblasts (MRC-5). RESULTS: Compounds B8, B9, and B10 showed high cytotoxicity on SW480 cells together with good selectivity towards MRC-5 cells. It is important to empathize that the degree of selectivity of B8 and B10 was high (SI = 5.54 and 12.09, respectively). Besides, we explored the mechanisms of cytotoxicity of novel derivatives, B8, B9, and B10. The assay showed that tested derivatives induce an apoptotic type of cell death in SW480 cells, with a minor percent of necrotic cells. Additionally, to better understand the suitability of the compounds for potential use as anticancer medicaments, we studied their interactions with biomacromolecules (DNA or BSA). The results indicated that the tested compounds have a great affinity to displace EB from the EB-DNA complex through intercalation. Also, DNA and BSA molecular docking study was performed to predict the binding mode and the interaction region of the compounds. CONCLUSION: Achieved results indicate that our compounds have the potential to become candidates for use as medicaments.

Thermo-Analytical and Compatibility Study with Mechanistic Explanation of Degradation Kinetics of Ambroxol Hydrochloride Tablets under Non-Isothermal Conditions.

Ambroxol hydrochloride (AMB), used as a broncho secretolytic and an expectorant drug, is a semi-synthetic derivative of vasicine obtained from the Indian shrub Adhatoda vasica. It is a metabolic product of bromhexine. The paper provides comprehensive and detailed research on ambroxol hydrochloride, gives information on thermal stability, the mechanism of AMB degradation, and data of practical interest for optimization of formulation that contains AMB as an active compound. Investigation on pure AMB and in commercial formulation Flavamed® tablet (FT), which contains AMB as an active compound, was performed systematically using thermal and spectroscopic methods, along with a sophisticated and practical statistical approach. AMB proved to be a heat-stable and humidity-sensitive drug. For its successful formulation, special attention should be addressed to excipients since it was found that polyvinyl pyrrolidone and Mg stearate affect the thermal stability of AMB. At the same time, lactose monohydrate contributes to faster degradation of AMB and change in decomposition mechanism. It was found that the n-th order kinetic model mechanistically best describes the decomposition process of pure AMB and in Flavamed® tablets.

Mineral composition and growth of tomato and cucumber affected by imidazolium-based ionic liquids.

Imidazolium-based ionic liquids (ILs) have unique and tunable features with high potential in industrial use. However, the utilization of the ILs in industrial processes has recently arisen the question of their disposal and the effect on the environment. Therefore, in the present study, we investigated the effect of two commercial imidazolium-based ILs, 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) and 1-decyl-3-methylimidazolium chloride ([Dmim][Cl]) on the growth and chemical composition of widely grown vegetables - tomato and cucumber. Different concentrations (10, 100 or 1000 mg L-1) of [Bmim][Cl] and [Dmim][Cl] were applied to the soil on which tomato was cultivated. After the harvest of tomato fruits, the same soil was used to grow and analyze the growth and chemical composition of cucumber. ILs significantly reduced shoot biomass and yield of tomato and significantly changed concentrations of N, K, Ca, Fe and Mn in the leaves, whereas concentrations of P, Cu and Zn were at the level of respected controls. The number of fruits of cucumber, grown on the soil previously treated with ILs, was significantly reduced along with yield, and mineral composition of leaves was significantly altered, with the exception to Cu. [Dmim][Cl] in general affected both tomato and cucumber more than [Bmim][Cl]. The application of IL with a longer alkyl substituent ([Dmim][Cl]) increased the temperature inside the tomato canopy and accelerated the senescence of plants.

Design and analysis of interactions in ionic liquids based on procaine and pharmaceutically active anions.

The present work focuses on modifying a local anaesthetic drug procaine into an ionic liquid and evaluating the resulting thermal behaviour and structural changes. Counter ions, salicylate, ibuprofenate, and docusate, were chosen due to different hydrogen-bonding abilities, molecular size, charge distribution, and functional groups. After synthesis of procaine salicylate, procaine ibuprofenate, and procaine docusate, spectroscopic investigations were performed using infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy to confirm proton transfer. Differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis were used to determine the obtained ionic liquids' thermal behaviour. Experimental measurements of density, viscosity, and electrical conductivity were performed to get insight into the interactions occurring in the obtained ionic liquids. The viscosity and electrical conductivity data were analysed using the Vogel-Fulcher-Tammann (VFT) equation, while thermal expansion coefficients were calculated from measured density data. The obtained results found that the synthesised procaine salicylate and procaine docusate an ionic liquid's behaviours, including weak intermolecular forces, while procaine ibuprofenate showed more liquid co-crystal behaviour due to the absence of proton transfer for ibuprofen. In a theoretical phase of the investigation, the density functional theory (DFT) and molecular dynamics (MD) calculations were conducted. The obtained descriptors and radial distribution functions were used to analyse the interactions between ions of synthesised ionic liquids. In addition, solubility determination results proved that procaine transformation into procaine salicylate and procaine ibuprofenate ionic liquids enhanced its solubility in water, while procaine docusate reduces procaine solubility.

Facile Monitoring of Water Hardness Levels Using Responsive Complex Emulsions.

The cationic content of water represents a major quality control parameter that needs to be followed by a rapid, on-site, and low-cost method. Herein, we report a novel method for a facile monitoring of the mineral content of drinking water by making use of responsive complex emulsions. The morphology of biphasic oil-in-water droplets solely depends on the balance of interfacial tensions, and we demonstrate that changes in the surfactant effectiveness, caused by variations in the mineral content inside the continuous phase, can be visualized by monitoring internal droplet shapes. An addition of metal cations can significantly influence the surfactant critical micelle concentrations and the surface excess values and therefore induce changes in the effectiveness of ionic surfactants, such as sodium dodecyl sulfate. The morphological response of Janus emulsions droplets was tracked via a simple microscopic setup. We observed that the extent of the droplet response was dependent on the salt concentration and valency, with divalent cations (responsive for water hardness), resulting in a more pronounced response. In this way, Ca2+ and Mg2+ levels could be quantitatively measured, which we showcased by determination of the mineral content of commercial water samples. The herein demonstrated device concept may provide a new alternative rapid monitoring of water hardness levels in a simple and cost-effective setup.