RESUMEN

The present work provides new evidence of the ongoing potential of surface-active ionic liquids (SAILs) and surface-active quaternary ammonium salts (surface-active QASs). To achieve this, a series of compounds were synthesized with a yield of ≥85%, and their thermal analyses were studied. Additionally, antimicrobial activity against both human pathogenic and soil microorganisms was investigated. Subsequently, their surface properties were explored with the aim of utilizing SAILs and surface-active QASs as alternatives to commercial amphiphilic compounds. Finally, we analyzed the wettability of the leaves' surface of plants occurring in agricultural fields at different temperatures (from 5 to 25 °C) and the model plant membrane of leaves. Our results show that the synthesized compounds exhibit higher activity than their commercial analogues such as, i.e., didecyldimethylammonium chloride (DDAC) and dodecyltrimethylammonium bromide (C12TAB), for which the CMC values are 2 mM and 15 mM. The effectiveness of the antimicrobial properties of synthesized compounds relies on their hydrophobic nature accompanied by a cut-off effect. Moreover, the best wettability of the leaves' surface was observed at 25 °C. Our research has yielded valuable insights into the potential effectiveness of SAILs and surface-active QASs as versatile compounds, offering a promising alternative to established antimicrobials and crop protection agents, all the while preserving substantial surface activity.

Asunto(s)

RESUMEN

The surface modification of poly(lactic acid) (PLA) using hydroxyapatite (HAP) particles via Langmuir-Blodgett (LB) and Langmuir-Schaefer (LS) approaches has been reported. The HAP monolayer was characterized at the air/water interface and deposited on three-dimensional (3D) printed poly(lactic acid). The deposition of HAP particles using the LS approach led to a larger surface coverage in comparison to the LB method, which produces a less uniform coating because of the aggregation of the particles. After the transfer of HAP on the PLA surface, the wettability values remained within the desired range. The presence of HAP on the surface of the polymer altered the topography and roughness in the nanoscale, as evidenced by the atomic force microscopy (AFM) images. This effect can be beneficial for the osteointegration of polymeric implants at an early stage, as well as for the reduction of the adherence of the microbial biofilm. Overall, the results suggest that the LS technique could be a promising approach for surface modification of PLA by hydroxyapatite with respective advantages in the biomedical field.

Asunto(s)

RESUMEN

In the past several years there has been a rapid rise in the use of lipid-based drug formulations. In the case of intravenous drug administration the interaction of lipid carrier with serum albumin is crucial for the distribution of the bioactive molecules in the bloodstream and reaching the target tissue. In this work, we have explored the interaction of serum albumin with three-component lipid monolayer build of palmitoyloleoylphosphatidylcholine (POPC), sphingomyelin (SM), and cholesterol (Chol). Using wide range of lipid compositions and various concentrations of serum albumin we identified the factors governing the lipid-protein binding. Our study revealed that albumin can penetrate selectively the monolayers of POPC/SM/Chol depending on the lipid composition in the mixture. Moreover, the interaction of albumin with monolayer can be controlled by the molecular density of the film and the concentration of protein. The adsorbed albumin exists in the film on the top of lipid monolayer. This behavior may lead to the increase of the size and charge of the lipid carrier and affect the drug transport throughout the bloodstream. The results of this work provide essential physicochemical data that can be used for predicting the pharmacokinetic profile of lipid-based formulations.

Asunto(s)

RESUMEN

Oleanolic acid (OLA) and oleic acid (OA) are ubiquitous in the plant kingdom, exhibiting a therapeutic effect on human health, and are components of novel pharmaceutical formulations. Since OLA has limited solubility, the utilization of nanotechnology-based drug delivery systems enhancing bioavailability is highly advantageous. We report on the interfacial behavior of the OLA:OA system at various molar ratios, using the Langmuir technique to assess the dependence of the molar composition on miscibility and rheological properties affecting film stability. Specifically, we evaluate the interfacial properties (morphology, thermodynamics, miscibility, and viscoelasticity) of the OLA:OA binary system in various molar ratios, and indicate how the OLA:OA system exhibits the most favorable molecular interactions. We apply the Langmuir monolayer technique along with the complementary techniques of Brewster angle microscopy, dilatational interfacial rheology, and excess free energy calculations. Results demonstrate that the properties of mixed monolayers depend on OLA:OA molar ratio. Most of the systems (OLA:OA 2:1, 1:1, 1:5) are assumed to be immiscible at surface pressures >10 mN/m. Moreover, the OLA:OA 1:2 is immiscible over the entire surface pressure range. However, the existence of miscibility between molecules of OLA and OA in the 5:1 for every surface pressure tested suggests that OA molecules incorporate into the OLA lattice structure, improving the stability of the mixed film. The results are discussed in terms of providing physicochemical insights into the behavior of the OLA:OA systems at the interface, which is of high interest in pharmaceutical design.

RESUMEN

This study aimed to investigate the potential of 1-alkyl-1-methylpiperidinium bromides as fungicides and evaluate their impact on the human respiratory system when spread in the atmosphere. We investigated the behavior of membrane lipids and model membranes in the presence of a series of amphiphilic 1-alkyl-1-methylpiperidinium bromides ([MePipCn][Br]), differing in the alkyl chain length (n = 4 - 18). The experiments were performed with the Langmuir monolayer technique using 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and ergosterol (ERG)-the main components of lung surfactant and fungal plasma membrane, respectively and their mixtures with phospholipids and sterols. The mixtures were chosen as the representatives of target and non-target organisms. The surface pressure-area isotherms were obtained by compressing monolayers in the presence of [MePipCn][Br] in the subphase. The results were analyzed in terms of area expansion/contraction and compressibility. The surface activity of the studied organic salts was also studied. In addition, the monolayers were deposited on a solid surface and their topography was investigated using atomic force microscopy. This research implies that the studied compounds may destabilize efficiently the fungal plasma membrane. At the same time we demonstrated the significant impact of 1-alkyl-1-methylpiperidinium bromides on the lung surfactant layer. The interaction between [MePipCn][Br] and model membranes depends on the concentration and alkyl chain length of organic salt. The key role of contact time has been also revealed. The results may be helpful in the reasonable development of new agrochemical products aiming at the treatment of fungal infections in plants. In addition, our study indicates the significance of proper safety management while spreading the fungicides in the environment.

Asunto(s)

RESUMEN

Among numerous compounds found in marine organisms, triterpenes have attracted considerable research interest due to a beneficial impact on health including anti-inflammatory, antitumor, antiviral, and antioxidation effects. Specifically, new functionalities of oleanolic acid (OLA) have been revealed recently, indicating possible applications in nutrition and pharmaceuticals. However, this bioactive material has limited value due to low water solubility and stability. Therefore, oleanolic acid needs a carrier that protects it and enables controlled release in the human body. Innovative drug delivery systems provide a promising strategy for overcoming these problems. However, the development of those systems requires a comprehensive understanding of the physicochemical properties of triterpenes and their carriers as well as the interactions between them. Among numerous substances, human serum albumin (HSA) has been widely studied as a drug carrier. In addition, human serum albumin is the main blood plasma protein responsible for the transport of drugs and metabolites; therefore, the interactions between that protein and other substances are of physiological and pharmaceutical importance. Moreover, sensing the HSA level in blood plasma is an important challenge that requires binding studies on a molecular scale. The aim of this study was to investigate the properties of oleanolic acid in the presence of human serum albumin in terms of thermodynamics, morphology, and viscoelasticity at the air/water interface. Moreover, the wettability, surface free energy, and topography of the films after deposition on the solid substrate were determined. The results have been discussed in terms of providing physicochemical insight into the interfacial behavior of the OLA-HSA complex, which is crucial for pharmaceutical and bioanalytical applications.

Asunto(s)

RESUMEN

Among numerous compounds found in marine organisms, astaxathin has received considerable research interest due to beneficial impact on health such as anti-inflammatory, antioxidant and neuroprotective activity. Recently new functionalities of this xanthophyll have been revealed indicating important applications in nutrition and pharmacy. However, astaxanthin, as the bioactive, has limited value without a protecting carrier that provides controlled release in a human body. Fabrication of liposomes as efficient drug delivery systems is promising strategy that may overcome these problems. However, the development of new delivery systems requires comprehensive understanding of physicochemical properties of carotenoids and their carriers as well as the interactions between them. The aim of this study was to investigate the mixed lipid-sterol monolayer in the presence of astaxanthin in terms of thermodynamic, morphological and viscoelastic behaviour. The results have been discussed in relation to pure lipid-sterol films. In addition we determined the surface charge density of the liposomes built of these components. The results are helpful in better understanding the role of interfacial viscoelasticity in the quality of liposomal drug delivery forms.

Asunto(s)

RESUMEN

In the Langmuir monolayer technique, a single layer of molecules is formed on a water subphase. This approach was used to mimic the antitumoricidal lipid-protein complex of oleic acid and bovine α-lactalbumin called the BAMLET complex. Our previous studies have shown that at the interface, the BAMLET complex is stabilized by the hydrophobic forces supported by the hydrogen bonds. This study provides an insight into the influence of calcium ions and the experimental conditions (temperature and subphase pH) on the stability of the complex at the interface. The Langmuir technique was expanded using a dosing pump to exchange the subphase and deliver additional substances to the system. We investigated the interactions between oleic acid monolayer and α-lactalbumin in the presence of Ca2+ in the bulk and the effect of varied experimental conditions on the complex stability. The role of calcium ions in this system is important because (in addition to low pH and relatively high temperature) it affects the conformational changes within the protein molecule and facilitates the transition of α-lactalbumin into the molten globule state. A partially unfolded state is required to form the BAMLET complex. We found that the mixed monolayer spread at the interface is stable despite drastic changes in the process conditions and remains stable even after the subphase exchange. This study of molecular interactions explored by the Langmuir technique with peristaltic pump enabled to understand the role of Ca2+ in BAMLET complex formation.

Asunto(s)

RESUMEN

Functionalized polyhedral oligomeric silsesquioxanes (POSS) derivatives have great potential in biomedical applications such as tissue engineering, drug delivery, biosensors, dental composites and biomedical devices. Having the above in mind, in this paper, the study of the surface characteristics of binary Langmuir-Blodgett films consisting of an open cage silsesquioxane POSS-poly (ethylene glycol) (POSS-PEG) and 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine (DMPE), as a representative of phospholipid was conducted based on contact angle measurements of three liquids. The measured values of the contact angle (with water, formamide and diiodomethane as the wetting liquids) allowed to calculate surface free energy of the films from van Oss et al. approach. The film structure of the deposited layers was evaluated using an atomic force microscope. Analysis of the obtained results led to the conclusion, that the pure DMPE molecules create agglomerates onto a solid substrate, whereas the POSS-PEG molecules form a homogenous monolayer. After an addition of POSS-PEG to lipid film, changes in the surface properties are visible. The wettability as well as surface free energy depend on the molar ratio of both components. The AFM images shed more light on the changes of the DMPE monolayer topography caused by the POSS-PEG addition.

Asunto(s)

RESUMEN

Recently, we reported on the interfacial behavior of mixed oleic acid (OA)-α-lactalbumin monolayer and its relevance in the formation of tumoricidal HAMLET (human α-lactalbumin made lethal to tumor cells)-like complex. This complex is probably formed in the gastrointestinal tract, but it has not been proved so far. The molecular base and the underlying physicochemical forces leading to such complexation remain to be known as well. There are also several other issues related with the complex stoichiometry that need to be fully explained. This study provides insight into the mechanism of temperature, pH, and physical state of monolayer-dependent binding of OA by the milk protein- apo-α-lactalbumin. Using the Langmuir and Langmuir-Blodgett approaches, we investigated the interactions between the OA monolayer and the apo-bovine α-lactalbumin (BLA III) at different pH, temperatures, and molecular packing. We found that the most favorable conditions for the formation of mixed OA-BLA III film are relevant to the gastric environment. The stabilization of OA-BLA III at the interface is associated with the conformational changes of protein in the presence of fatty acids induced by low pH and high temperature in the expanded monolayer. Our approach helps to understand the molecular mechanism of HAMLET/bovine α-lactalbumin made lethal to tumor cells formation in vivo.

Asunto(s)

RESUMEN

The aim of the present study was to investigate the interfacial behaviour of model biomembranes in the presence of ß-carotene (ßC). The Langmuir monolayer technique was used to form the mixed lipid film at the air/water interface. Using the surface pressure-area isotherms, the surface potential-area curves and the Brewster angle microscopy the nature of interactions between carotenoid and lipid components of the monolayers was investigated. The results were obtained for complex models of the lipid bilayer composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and cholesterol (CHOL). It was found that ß-carotene affected the membrane stability, fluidity and rigidity, however this influence varied with the DPPC/CHOL ratio. The membrane permeability which is significant for biological functions was found to be affected by the presence of ß-carotene in the membrane. The morphology of mixed films visualized by Brewster angle microscopy was similar for DPPC/CHOL and DPPC/CHOL/ßC films indicating incorporation of carotenoid into the film. In contrary to previous reports for individual lipids, we did not observed the aggregation of ßC in the mixed lipid monolayer. Moreover, from dilatational rheology experiment we concluded about the significant role of ß-carotene in modulation of the elastic behaviour of the membrane, especially in physiologically significant surface pressure, i.e. at π = 30 mN/m.

Asunto(s)

RESUMEN

Recently, silsesquioxanes have been recognized as a new group of film-forming materials. This study has been aimed at determining the effect of the kind of functional groups present in two different open-cage structure POSS molecules on the possibility of the formation of Langmuir monolayers and their properties. To achieve this goal, two new POSS derivatives (of open-cage structures) containing polyether and fluoroalkyl functional groups have been synthesized on the basis of a hydrosilylation process. An optimization of the process was performed, which makes it possible to obtain the above-mentioned derivatives with high yields. In the next step, the Langmuir technique was applied to measurements of the surface pressure (π) - the mean molecular area (A) isotherms during the compression of monolayers formed by molecules of the two POSS derivatives considered. Subsequently, the monolayers were transferred onto quartz plates according to the Langmuir-Blodgett technique. Both derivatives are able to form insoluble Langmuir films at the air-water interface, which can be transferred onto a solid substrate and effectively change its wetting properties.

RESUMEN

Binary mixtures of cholesterol and fully-condensed octakis[{2-(3,4-epoxycyclohexyl) etyl}dimethyl-silyloxy]octasilsesquioxane (OE-POSS) were characterized using Langmuir trough for obtaining surface pressure-area isotherms. The most characteristic feature of the mixed films is the presence of two collapse points on the isotherms. The first one is attributed to the collapse of less stable OE-POSS and it occurs at similar surface pressures for all compositions, while the second one corresponds to cholesterol collapse. Brewster angle microscopy observations confirmed the collapse behavior of the mixed film. Strong condensing effect was observed for the mean molecular areas dependence on cholesterol content in the film. Moreover, formation of microdomains of each component in the matrix of the other one was confirmed by BAM images. For the reasons of molecular structures and interactions a true mixed and homogenous film did not form in the systems considered. Phase separation was observed for all the compositions experimented. The lack of the interactions of OE-POSS with biomembrane components represented by cholesterol is beneficial for applications of OE-POSS in biomedical devices.

Asunto(s)

RESUMEN

Dynamics of adsorption in micellar and non micellar solutions of derivatives of lysosomotropic substances was studied. The following compounds were considered in our research work: alkyl N,N-dimethyl-alaninates methobromides (DMALM-n), alkyl N,N-dimethylglycinates methobromides (DMGM-n), fatty acids N,N-dimethylaminoethylesters methobromides (DMM-n), fatty acids N,N-dimethylaminopropylesters methobromides (DMPM-n), fatty acids 1-dimethylamino-2-propyl methobromides (DMP(2)M-n), and derivatives of aminoesters with double alkyl chains (M(2)M-n). The examined compounds show interesting biological properties which can be useful, especially in medicine. The exact mechanism of interaction of such compounds with biological membrane is not fully known. However, it is supposed that the presence of micelles has an important role in biological systems. In this paper we show the results of dynamic surface tension measurements in solutions containing the investigated compounds at concentrations above and below cmc. Moreover, we analyzed the influence of the chemical structure of molecules on the diameters of the micelles formed in the solutions. It was found that adsorption dynamics for the studied compounds is strongly affected by the chemical structure of the considered derivatives, especially by the presence of the ester bond, linearity of the molecule, as well as its hydrophobicity. The obtained results show that the structure of the bromide M(2)M-n with two short hydrocarbon chains favors a faster and more efficient adsorption of the molecules at the air/water interface, compared with compounds having one long alkyl chain. Moreover, the double chained derivatives of the M(2)M-n type do not form typical spherical micelles but bilayer structures probably exist in these solutions. The micelles present in the solutions influence the dynamics of adsorption drastically. Moreover, the obtained results indicated that the compounds with especially high biological activity form rather small aggregates.

Asunto(s)

RESUMEN

Equilibrium adsorption at the air/water interface of cationic surfactants belonging in the group of quaternary ammonium bromides was studied. Quaternary ammonium salts, derivatives of lysosomotropic substances with different alkyl chain numbers and hydrophobicities were investigated. Surface properties of considered compounds, were examined and presented against other quaternary ammonium bromides of different chemical structure and with different number of alkyl chains in the molecule. The Frumkin equation and reorientation model were used for a quantitative description of the process of their adsorption. It was found that considered biologically active derivatives reveal strong surface activity. Chemical structure-surface activity relationship was analyzed and referenced to biological activity. Symmetry of the molecules resulting from the number of alkyl chains is the factor determining the behavior of the surfactants at the air/water interface as well as in the bulk. Surfactants with asymmetrical structure show a strong tendency to reorientation, in opposite to tetraalkylammonium bromides and double chain surfactants. Furthermore, the role of ester bond was emphasized.

RESUMEN

Equilibrium and dynamics of adsorption at the air/water interface of cationic surfactants belonging in the group of quaternary ammonium bromides was studied. Static surface tension of aqueous surfactants' solutions was measured in a wide range of surfactant concentrations using du Noüy ring method. Quaternary ammonium salts with different alkyl chain numbers and hydrophobicities were investigated. The Frumkin equation and reorientation model were used for a quantitative description of the process of their adsorption. The adsorption dynamics of the considered salts was described as a supplement to the equilibrium study. It was found that four short alkyl chains in tetraalkylammonium salt build a molecule which is weakly surface active. The number of alkyl chains as well as the symmetry of the molecules are important factors, determining the behavior of the surfactants at the interface and in the bulk solution. Surfactants with asymmetrical structure, like TTABr or MTOABr, show a strong tendency to reorientation, in opposite to tetraalkylammonium bromides and DDABr. Measurements of the dynamic surface tension revealed also strong dependence of the dynamics of adsorption on the chemical structure of the molecules. Measurements of the particle size by the dynamic light scattering method enabled the presence or lack of the micelles in the selected solutions to be confirmed.