1,002 results on '"Langmuir monolayers"'
Search Results
2. Formation of Langmuir monolayers from native phospholipids of bacteria of various systematic groups
- Author
-
Kuznetsova, Viktoria A., Kanevsky, Matvey V., Glinskaya, Elena V., and Glukhovskoy, Evgeny G.
- Subjects
phospholipids ,langmuir monolayers ,tight packaging ,staphylococcus aureus 209-p ,bacillus cereus 8035 ,Biology (General) ,QH301-705.5 - Abstract
Phospholipids are the most important structural elements of the bacterial cell wall, participate in the adaptation of microorganisms to the environment and can act as biomarkers for environmental changes and one of the components of environmental monitoring. Native phospholipids are used to form models of cell membranes, the biophysical properties of which can be studied by the Langmuir-Blodgett method. The aim of this work was to isolate and characterize the phospholipids of the cell membranes of the bacteria Staphylococcus aureus and Bacillus cereus and the formation of Langmuir monolayers based on them. The composition and ratio of fatty acids were determined by gas-liquid chromatography of fatty acid methyl esters. Fatty acids, found in the extract of the bacteria S. aureus 209-P and B. cereus 8035, are: hexadecanoic, trans-9-octadecenoic, octadecanoic, tetradecanoic, 13-methyltetradecanoic, 14-methylpentadecanoic, 15-methylhexadecanoic, cis-9-octadecanoic. To form a monolayer, a working solution of native phospholipids in chloroform with a concentration of C = 10-3 М was used. The monolayer formed when a 50 μl solution of a phospholipid mixture is applied to the surface has a more perfect structure, which is manifested in the constancy of its mechanical properties. The analysis of the obtained data has not yet revealed a clear dependence of the monolayer parameters on temperature. The changes in the compression modulus and compressibility were very minor. With an increase in the salt concentration, both an increase and a decrease in the compression modulus, and, consequently, the rigidity of the monolayer, is observed.
- Published
- 2024
- Full Text
- View/download PDF
3. Effects of Bisphenol A on DOPC/Cholesterol Binary Mixtures: Implications for Cell Membrane Integrity.
- Author
-
Lessa, Carlos J. A., Ruiz, Gilia C. M., Alessio, Priscila, and Constantino, Carlos J. L.
- Abstract
This study explored the effects of bisphenol A (BPA), a residual contaminant derived from plastic materials, on binary mixtures of the phospholipid 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and cholesterol (Chol). These mixtures were structured into bilayers, forming giant unilamellar vesicles (GUVs), and monolayers, forming Langmuir films, whose compositions and phases are relevant for mimicking the cell plasma membrane in eukaryotic cells. The composition of the binary mixture of DOPC/Chol 8:2, representing the proportion of the primary lipid groups found in cells, was effective in inducing inward buddings when exposed to BPA, in addition to the multiple shape transformations observed for DOPC vesicles. In monolayers, BPA induced the π–A isotherm expansion of DOPC, Chol, and the binary mixtures, also mainly in the DOPC/Chol 8:2 monolayers. Consistently, polarization-modulated infrared reflection absorption spectroscopy measurements revealed more pronounced interactions between BPA and the DOPC headgroup (hydrogen bonding from the hydrogen of the BPA phenol group and the nitrogen from the DOPC choline group, preferentially) in the DOPC/Chol 8:2 monolayer compared to that in individual DOPC monolayer. The presence of Chol appears to make the DOPC headgroups more accessible for interaction, even in bilayers. These results emphasize the substantial impact of BPA on the DOPC/Chol binary mixture, highlighting its critical role in predicting the potential damage to human cell membranes. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
4. Surface miscibility of Gemini surfactants and DOPE in binary mixed monolayers.
- Author
-
Gillis, Scott C., Lall, Gurmeet K., Lu, Han‐Jin Philip, Qiu, Yilin, and Wettig, Shawn D.
- Abstract
Surface pressure (π)–molecular area (A) isotherms were gathered to characterize the packing of binary mixed Langmuir monolayers of 1,2‐dioleoyl‐sn‐glycero‐3‐phosphoethanolamine (DOPE) and one of two Gemini surfactants (GS), N,N‐bis(dimethyloctadecyl)‐1,7‐nonanediammonium dibromide (18‐7‐18) or 1,9‐bis(octadecyl)‐1,1,9,9‐tetramethyl‐5‐amino‐1,9‐nonanediammonium dibromide (18‐7NH‐18) of varying molar fractions. Information about miscibility behavior was derived from the π–A curves by examining the excess free energy of mixing (ΔGexc) that was calculated through the surface area additivity rule. Surface compressibility modulus (Cs−1) was also used to characterize intermolecular interactions. Mutual interactions between GS and DOPE were analyzed in terms of excess Gibbs energy of mixing and the value of this parameter depended strongly on the composition of the mixed film. GS and DOPE are generally miscible as DOPE reduces intermolecular repulsion between highly charged GS molecules leading to the formation of more densely packed mixed monolayers. However, GS and DOPE are immiscible in equimolar mixtures due to tail group packing mismatch between saturated and unsaturated alkyl chains. The prevalence of attractive synergistic interactions in the monolayers studied differs from a previous finding of antagonistic mixing behavior in GS/DOPE micelles. These results contribute to the understanding of GS‐lipid interactions and packing that are critical to the in vitro and in vivo stability of liposomes composed of these molecules used for non‐viral gene therapy applications. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
5. Susceptibility of Legionella gormanii Membrane-Derived Phospholipids to the Peptide Action of Antimicrobial LL-37—Langmuir Monolayer Studies.
- Author
-
Pastuszak, Katarzyna, Jurak, Małgorzata, Kowalczyk, Bożena, Tarasiuk, Jacek, Wiącek, Agnieszka Ewa, and Palusińska-Szysz, Marta
- Subjects
- *
PEPTIDE antibiotics , *ANTIMICROBIAL peptides , *LEGIONELLA , *PHOSPHOLIPIDS , *MONOMOLECULAR films , *PEPTIDES - Abstract
LL-37 is the only member of the cathelicidin-type host defense peptide family in humans. It exhibits broad-spectrum bactericidal activity, which represents a distinctive advantage for future therapeutic targets. The presence of choline in the growth medium for bacteria changes the composition and physicochemical properties of their membranes, which affects LL-37's activity as an antimicrobial agent. In this study, the effect of the LL-37 peptide on the phospholipid monolayers at the liquid–air interface imitating the membranes of Legionella gormanii bacteria was determined. The Langmuir monolayer technique was employed to prepare model membranes composed of individual classes of phospholipids—phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), cardiolipin (CL)—isolated from L. gormanii bacteria supplemented or non-supplemented with exogenous choline. Compression isotherms were obtained for the monolayers with or without the addition of the peptide to the subphase. Then, penetration tests were carried out for the phospholipid monolayers compressed to a surface pressure of 30 mN/m, followed by the insertion of the peptide into the subphase. Changes in the mean molecular area were observed over time. Our findings demonstrate the diversified effect of LL-37 on the phospholipid monolayers, depending on the bacteria growth conditions. The substantial changes in membrane properties due to its interactions with LL-37 enable us to propose a feasible mechanism of peptide action at a molecular level. This can be associated with the stable incorporation of the peptide inside the monolayer or with the disruption of the membrane leading to the removal (desorption) of molecules into the subphase. Understanding the role of antimicrobial peptides is crucial for the design and development of new strategies and routes for combating resistance to conventional antibiotics. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
6. Dense Monolayer Network Structures of Double Hydrophilic Hyperbranched Copolymers at the Air/Water Interface.
- Author
-
Tu, Yongliang, Wen, Gangyao, Selianitis, Dimitrios, and Pispas, Stergios
- Subjects
- *
COPOLYMERS , *ATOMIC force microscopy , *ETHYLENE glycol , *CRITICAL temperature , *SURFACE pressure , *BLOCK copolymers - Abstract
Influences of subphase pH and temperature on the interfacial aggregation behavior of two double hydrophilic hyperbranched copolymers of poly[oligo(ethylene glycol) methacrylate‐co‐(2‐diisopropylamino)ethyl methacrylate] (P(OEGMA‐co‐DIPAEMA)) at the air/water interface are studied by the Langmuir film balance technique. Morphologies of their Langmuir–Blodgett (LB) films are characterized by atomic force microscopy (AFM). At the interface, P(OEGMA‐co‐DIPAEMA) copolymers tend to form a dense network structure of circular micelles composed of branching agent‐connected carbon backbone cores and mixed shells of OEGMA and DIPAEMA segments (pendant groups). This network structure containing many honeycomb‐like holes with diameters of 6–8 nm is identified for the first time and clearly observed in the enlarged AFM images of their LB films. Under acidic conditions, surface pressure versus molecular area isotherms of the two copolymers in the low‐pressure region show larger mean molecular area than those under neutral and alkaline conditions due to the lack of impediment from DIPAEMA segments. Upon further compression, each isotherm exhibits a wide pseudo‐plateau, which corresponds to OEGMA segments being pressed into the subphase. Furthermore, the isotherms under neutral and alkaline conditions exhibit the lower critical solution temperature behavior of OEGMA segments, and the critical temperature is lower when the hyperbranched copolymer contains higher OEGMA content. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
7. Characteristics of Langmuir monomolecular monolayers formed by the novel oil blends
- Author
-
Kamińska Wiktoria, Cichocki Wojciech, Baranowska Hanna Maria, Walkowiak Katarzyna, Kmiecik Dominik, and Kowalczewski Przemysław Łukasz
- Subjects
langmuir monolayers ,physicochemical properties ,edible oils ,cold-pressed oils ,molecular properties of oils ,fatty acid profile ,Chemistry ,QD1-999 - Published
- 2023
- Full Text
- View/download PDF
8. Photoinduced Control of Phase State of Monolayers Based on Phospholipids and Spirocompounds.
- Author
-
Degtyareva, V. A., Morozov, A. N., Zaichenko, N. L., Lyubimov, A. B., and Raitman, O. A.
- Abstract
The results of a study of the physicochemical and photomechanical properties of mixed Langmuir monolayers based on palmitoyloleoylphosphatidylcholine (POPC), dipalmitoylphosphatidylcholine (DPPC) and amphiphillic spirocompounds are presented. For the first time mixed monolayers based on POPC, DPPC, spiropyran 1',3'-dihydro-1'-hexadecyl-3'3'-dimethyl-6-nitrospiro[2H-benzopyran-2,2'-(2H)indole] and spironaphtoxazine 3,3-dimethyl-1-hexadecyl-1,3-dihydrospiro[indoline-2,3'-naphtho[2,1-b][1,4]oxazine]-9'-ol were formed in various combinations and ratios, and their comparative study was carried out. It has been established that binary mixture of phospholipids and spirocompounds form stable monolayers in which phase transitions can be controlled by UV-light. It has been shown that irradiation of monomolecular phosphatidylcholine films containing small amounts of photosensitive compounds (up to 10% by weight) makes it possible to turn them into a liquid-condensed state at pressures above 10 mN/m. The results obtained open broad prospects for using photochromic spirocompounds to control the permeability of biological membranes using light stimuli. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
9. Arginine Gemini-Based Surfactants for Antimicrobial and Antibiofilm Applications: Molecular Interactions, Skin-Related Anti-Enzymatic Activity and Cytotoxicity.
- Author
-
Sousa, Francisco Fábio Oliveira de, Pinazo, Aurora, Hafidi, Zakaria, García, María Teresa, Bautista, Elena, Moran, Maria del Carmen, and Pérez, Lourdes
- Subjects
- *
CYTOTOXINS , *MOLECULAR interactions , *SURFACE active agents , *RHAMNOLIPIDS , *METHICILLIN-resistant staphylococcus aureus , *ELASTASES , *ARGININE , *ATAZANAVIR , *ANGIOTENSIN I - Abstract
The antimicrobial and antibiofilm properties of arginine-based surfactants have been evaluated. These two biological properties depend on both the alkyl chain length and the spacer chain nature. These gemini surfactants exhibit good activity against a wide range of bacteria, including some problematic resistant microorganisms such us methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. Moreover, surfactants with a C10 alkyl chain and C3 spacer inhibit the (MRSA) and Pseudomonas aeruginosa biofilm formation at concentrations as low as 8 µg/mL and are able to eradicate established biofilms of these two bacteria at 32 µg/mL. The inhibitory activities of the surfactants over key enzymes enrolled in the skin repairing processes (collagenase, elastase and hyaluronidase) were evaluated. They exhibited moderate anti-collagenase activity while the activity of hyaluronidase was boosted by the presence of these surfactants. These biological properties render these gemini arginine-based surfactants as perfect promising candidates for pharmaceutical and biological properties. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
10. Susceptibility of Legionella gormanii Membrane-Derived Phospholipids to the Peptide Action of Antimicrobial LL-37—Langmuir Monolayer Studies
- Author
-
Katarzyna Pastuszak, Małgorzata Jurak, Bożena Kowalczyk, Jacek Tarasiuk, Agnieszka Ewa Wiącek, and Marta Palusińska-Szysz
- Subjects
Legionella bacteria ,phospholipids ,LL-37 ,Langmuir monolayers ,Organic chemistry ,QD241-441 - Abstract
LL-37 is the only member of the cathelicidin-type host defense peptide family in humans. It exhibits broad-spectrum bactericidal activity, which represents a distinctive advantage for future therapeutic targets. The presence of choline in the growth medium for bacteria changes the composition and physicochemical properties of their membranes, which affects LL-37’s activity as an antimicrobial agent. In this study, the effect of the LL-37 peptide on the phospholipid monolayers at the liquid–air interface imitating the membranes of Legionella gormanii bacteria was determined. The Langmuir monolayer technique was employed to prepare model membranes composed of individual classes of phospholipids—phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), cardiolipin (CL)—isolated from L. gormanii bacteria supplemented or non-supplemented with exogenous choline. Compression isotherms were obtained for the monolayers with or without the addition of the peptide to the subphase. Then, penetration tests were carried out for the phospholipid monolayers compressed to a surface pressure of 30 mN/m, followed by the insertion of the peptide into the subphase. Changes in the mean molecular area were observed over time. Our findings demonstrate the diversified effect of LL-37 on the phospholipid monolayers, depending on the bacteria growth conditions. The substantial changes in membrane properties due to its interactions with LL-37 enable us to propose a feasible mechanism of peptide action at a molecular level. This can be associated with the stable incorporation of the peptide inside the monolayer or with the disruption of the membrane leading to the removal (desorption) of molecules into the subphase. Understanding the role of antimicrobial peptides is crucial for the design and development of new strategies and routes for combating resistance to conventional antibiotics.
- Published
- 2024
- Full Text
- View/download PDF
11. Dual mechanical impact of β-escin on model lipid membranes
- Author
-
Lara H. Moleiro, María T. Martín-Romero, Diego Herráez-Aguilar, José A. Santiago, Niccolò Caselli, Carina Dargel, Ramsia Geisler, Thomas Hellweg, and Francisco Monroy
- Subjects
β-escin ,membrane phospholipids ,model lipid membranes ,Langmuir monolayers ,bilayer vesicles ,adsorption kinetics ,Chemistry ,QD1-999 ,Medical physics. Medical radiology. Nuclear medicine ,R895-920 ,Polymers and polymer manufacture ,TP1080-1185 - Abstract
Understanding the mechanical behavior of biological membranes is of paramount importance in cell biophysics and in developing new biomaterials for medicine. In this study, we delve into the mechanical impact of β-escin, commonly referred to as escin, a naturally occurring biosurfactant derived from the seeds of the horse chestnut tree. To examine the modulable interaction between escin and dimyristoylphosphatidylcholine (DMPC), which is an archetypical fluid phospholipid and an essential constituent of the cellular fluid membrane, we have used artificial models based on the liquid crystal structure, such as bilayer vesicles and Langmuir monolayers. We have focused on the energetic and kinetic aspects of escin insertion when transversally adsorbed or longitudinally integrated within these model membranes. By employing surface microscopies of epifluorescence and Brewster angle reflectivity, we have elucidated the structural phase behavior of hybrid escin–phospholipid membranes, which exhibit dual mechanical properties characterized by high rigidity and reduced fluidity. Notably, at low temperatures, we observe a soft, glassy rheological behavior reminiscent of liquid crystalline ordered phases, which turns into a fluid-like viscoelasticity resembling more disordered phases at physiological temperatures. The hybrid membranes behave in one way or another as both are driven by an adsorption potential well imposed by escin cohesivity. These intriguing findings are discussed from a physicochemical perspective, highlighting their potential for future pharmacological designs and biomedical applications that exploit the dual mechanical impact of escin on biological membranes.
- Published
- 2023
- Full Text
- View/download PDF
12. Degradation Behavior of Poly(Lactide-Co-Glycolide) Monolayers Investigated by Langmuir Technique: Accelerating Effect.
- Author
-
Kim, Gayeon, Gavande, Vishal, Shaikh, Vasi, and Lee, Won-Ki
- Subjects
- *
ALKALINE hydrolysis , *MONOMOLECULAR films , *SURFACE pressure , *RENEWABLE natural resources , *LACTIDES - Abstract
Among biodegradable polymers, polylactides (PLAs) have attracted considerable interest because the monomer can be produced from renewable resources. Since their initial degradability strongly affects commercial application fields, it is necessary to manage the degradation properties of PLAs to make them more commercially attractive. To control their degradability, poly(lactide-co-glycolide) (PLGA) copolymers of glycolide and isomer lactides (LAs) were synthesized, and their enzymatic and alkaline degradation rates of PLGA monolayers as functions of glycolide acid (GA) composition were systematically investigated by the Langmuir technique. The results showed that the alkaline and enzymatic degradations of PLGA monolayers were faster than those of l-polylactide (l-PLA), even though proteinase K is selectively effective in the l-lactide (l-LA) unit. Alkaline hydrolysis was strongly affected by their hydrophilicity, while the surface pressure of monolayers for enzymatic degradations was a major factor. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
13. On the relationship between the properties of planar structures of non-ionic surfactants and their vesicular analogues – Niosomes.
- Author
-
Arslanov, Vladimir V., Ermakova, Elizaveta V., Krylov, Daniil I., and Popova, Olga O.
- Subjects
- *
NONIONIC surfactants , *LIPID rafts , *INTERMOLECULAR interactions , *LANGMUIR-Blodgett films , *MONOMOLECULAR films , *LIPOSOMES , *NANOCARRIERS - Abstract
[Display omitted] • Comparative studies of planar and vesicular structures based on the same materials. • Characteristics of niosomes correlate with excess free energy of mixed monolayers. • Composition of shells determine morphology, polarity and microviscosity of niosomes. • Cholesterol increases the compatibility in monolayers and the stability of niosomes. In recent years, the study of niosomes as nanocarriers alternative to liposomes has received increasing attention. In contrast to well-studied liposome membranes, many aspects of the behavior of analogous niosome bilayers have not been studied. This paper considers one of these aspects related to the communication between the physicochemical properties of planar and vesicular objects. We present the first results of comparative studies of Langmuir monolayers of binary and ternary (with cholesterol) mixtures of non-ionic surfactants based on sorbitan esters and niosomal structures assembled from the same materials. The Thin-Film Hydration (TFH) method in the gentle shaking version was used to produce the particles of large sizes, while small unilamellar high quality vesicles with a unimodal distribution of particles were prepared by TFH using ultrasonic treatment and extrusion. An analysis of the structural organization and phase state of monolayers based on compression isotherms and supplemented by thermodynamic calculations, as well as the results of determining the particle morphology, polarity and microviscosity of niosome shells, made it possible to obtain fundamental data on the intermolecular interactions of the components and their packing in shells and to relate these data to the properties of niosomes. This relationship can be used to optimize the composition of niosome membranes and predict the behavior of these vesicular systems. It was shown that cholesterol excess creates regions of bilayers with increased rigidity (like "lipid rafts"), which hinders the process of folding film fragments into small niosomes. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
14. Langmuir–Blodgett Films with Immobilized Glucose Oxidase Enzyme Molecules for Acoustic Glucose Sensor Application.
- Author
-
Gorbachev, Ilya, Smirnov, Andrey, Ivanov, George R., Venelinov, Tony, Amova, Anna, Datsuk, Elizaveta, Anisimkin, Vladimir, Kuznetsova, Iren, and Kolesov, Vladimir
- Subjects
- *
LANGMUIR-Blodgett films , *GLUCOSE , *IMMOBILIZED enzymes , *MOLECULES , *ENZYMES , *GLUCOSE oxidase , *MONOMOLECULAR films - Abstract
In this work, a sensitive coating based on Langmuir–Blodgett (LB) films containing monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) with an immobilized glucose oxidase (GOx) enzyme was created. The immobilization of the enzyme in the LB film occurred during the formation of the monolayer. The effect of the immobilization of GOx enzyme molecules on the surface properties of a Langmuir DPPE monolayer was investigated. The sensory properties of the resulting LB DPPE film with an immobilized GOx enzyme in a glucose solution of various concentrations were studied. It has shown that the immobilization of GOx enzyme molecules into the LB DPPE film leads to a rising LB film conductivity with an increasing glucose concentration. Such an effect made it possible to conclude that acoustic methods can be used to determine the concentration of glucose molecules in an aqueous solution. It was found that for an aqueous glucose solution in the concentration range from 0 to 0.8 mg/mL the phase response of the acoustic mode at a frequency of 42.7 MHz has a linear form, and its maximum change is 55°. The maximum change in the insertion loss for this mode was 18 dB for a glucose concentration in the working solution of 0.4 mg/mL. The range of glucose concentrations measured using this method, from 0 to 0.9 mg/mL, corresponds to the corresponding range in the blood. The possibility of changing the conductivity range of a glucose solution depending on the concentration of the GOx enzyme in the LB film will make it possible to develop glucose sensors for higher concentrations. Such technological sensors would be in demand in the food and pharmaceutical industries. The developed technology can become the basis for creating a new generation of acoustoelectronic biosensors in the case of using other enzymatic reactions. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
15. Investigation on the relationship between lipid composition and structure in model membranes composed of extracted natural phospholipids.
- Author
-
Santamaria, Andreas, Batchu, Krishna C., Fragneto, Giovanna, Laux, Valérie, Haertlein, Michael, Darwish, Tamim A., Russell, Robert A., Zaccai, Nathan R., Guzmán, Eduardo, and Maestro, Armando
- Subjects
- *
NEUTRON reflectometry , *BIOMOLECULES , *BREWSTER'S angle , *LIPIDS , *CELL membranes , *PHOSPHOLIPIDS - Abstract
[Display omitted] Unravelling the structural diversity of cellular membranes is a paramount challenge in life sciences. In particular, lipid composition affects the membrane collective behaviour, and its interactions with other biological molecules. Here, the relationship between membrane composition and resultant structural features was investigated by surface pressure-area isotherms, Brewster angle microscopy and neutron reflectometry on in vitro membrane models of the mammalian plasma and endoplasmic-reticulum-Golgi intermediate compartment membranes in the form of Langmuir monolayers. Natural extracted yeast lipids were used because, unlike synthetic lipids, the acyl chain saturation pattern of yeast and mammalian lipids are similar. The structure of the model membranes, orthogonal to the plane of the membrane, as well as their lateral packing, were found to depend strongly on their specific composition, with cholesterol having a major influence on the in-plane morphology, yielding a coexistence of liquid-order and liquid-disorder phases. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
16. Combining Polymers, Nanomaterials, and Biomolecules: Nanostructured Films with Functional Properties and Applications
- Author
-
Pereira, Andressa R., Melo, Antonio F. A. A., Crespilho, Frank N., Oliveira, Osvaldo N., Jr, Lockwood, David J., Series Editor, Govindaraju, Thimmaiah, editor, and Ariga, Katsuhiko, editor
- Published
- 2022
- Full Text
- View/download PDF
17. DNA Penetration into a Lysozyme Layer at the Surface of Aqueous Solutions.
- Author
-
Chirkov, Nikolay S., Lin, Shi-Yow, Michailov, Alexander V., Miller, Reinhard, and Noskov, Boris A.
- Subjects
- *
LYSOZYMES , *AQUEOUS solutions , *DNA , *DIFFUSION , *ATOMIC force microscopy , *ARTIFICIAL chromosomes , *SURFACE pressure - Abstract
The interactions of DNA with lysozyme in the surface layer were studied by performing infrared reflection–absorption spectroscopy (IRRAS), ellipsometry, surface tensiometry, surface dilational rheology, and atomic force microscopy (AFM). A concentrated DNA solution was injected into an aqueous subphase underneath a spread lysozyme layer. While the optical properties of the surface layer changed fast after DNA injection, the dynamic dilational surface elasticity almost did not change, thereby indicating no continuous network formation of DNA/lysozyme complexes, unlike the case of DNA interactions with a monolayer of a cationic synthetic polyelectrolyte. A relatively fast increase in optical signals after a DNA injection under a lysozyme layer indicates that DNA penetration is controlled by diffusion. At low surface pressures, the AFM images show the formation of long strands in the surface layer. Increased surface compression does not lead to the formation of a network of DNA/lysozyme aggregates as in the case of a mixed layer of DNA and synthetic polyelectrolytes, but to the appearance of some folds and ridges in the layer. The formation of more disordered aggregates is presumably a consequence of weaker interactions of lysozyme with duplex DNA and the stabilization, at the same time, of loops of unpaired nucleotides at high local lysozyme concentrations in the surface layer. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
18. Planar Supramolecular Systems: Assembly and Functional Potential.
- Author
-
Arslanov, V. V., Ermakova, E. V., Kutsybala, D. S., Raitman, O. A., and Selektor, S. L.
- Subjects
- *
PHYSICAL & theoretical chemistry , *SUPRAMOLECULAR chemistry , *LIQUID films , *THIN films , *ISOMERISM , *COLLOIDS , *COORDINATION polymers - Abstract
In this review, we present one of the main areas of the work of the Laboratory of Physical Chemistry of Supramolecular Systems, Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, devoted to studying monolayers and ultrathin films on liquid and solid surfaces. Numerous problems are discussed concerning the peculiarities of the supramolecular organization, behavior, and functional potential of these traditional colloidal systems. The article describes diverse examples of systems that form ultrathin organized films at different interfaces and the processes occurring in them, thereby reflecting the contemporary stage of the interconnection of related fields of science (colloid and supramolecular chemistry, nanotechnology, biomimetics, sensorics, etc.). Such a combination makes it possible to develop new intelligent nanostructured devices. Complexation in ultrathin layers of ligands on liquid and solid substrates is considered in connection with the use thereof as sensitive sensory elements in systems with reduced dimensionality. Substantial attention is focused on the aggregation behavior of diverse ligands and topochemical reactions in organized 2D ensembles, development of new methods for preparing two-dimensional organic networks, and creation of highly stable supramolecular devices based thereon. In the light of the features of 2D systems, several types of mechanochemical transformations occurring under the action of two-dimensional compression–expansion are considered: the phenomenon of redox isomerism in monolayers of lanthanide bis-phthalocyaninates, the phenomenon of forced axial coordination in tetrapyrrole complexes of nickel with a change in its spin number, and the phenomenon of the reversible formation of excimers. Especial attention is given to the problems concerning the behavior of organic photochromes at interfaces and the perspectives of developing molecular switches based on photosensitive compounds. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
19. Controlled Self-Assembly of Low-Dimensional Supramolecular Systems Based on Double-Decker Lanthanide Phthalocyaninates.
- Author
-
Zvyagina, A. I.
- Subjects
- *
THIN films , *COORDINATE covalent bond , *INTERMOLECULAR interactions , *RARE earth metals , *ORGANIC electronics , *LIGHT absorption - Abstract
Possessing unique physicochemical properties, phthalocyanines are widely used as active components of supramolecular ensembles and nanomaterials. The functional properties of phthalocyanine-based materials are governed by not only the structure of their discotic molecules, but also the character of their intermolecular interactions, which determine both the self-assembly mechanism and the structure of such systems. This review discusses the experimental approaches, which are based on the notions of colloid and coordination chemistry that enable one to control intermolecular interactions in low-dimensional supramolecular ensembles based on phthalocyanines and metallocomplexes thereof. Using double-decker crown-substituted lanthanide phthalocyaninates as an example, it is shown how one- and two-dimensional nanomaterials with different properties can be obtained from the same type of building blocks employing a set of colloid-chemical methods. Such materials are, in particular, capable for controlled absorption of visible light in ultrathin films and can be employed as conducting one-dimensional components of planar elements for organic electronics. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
20. Ionizable lipids based on branched fatty acids – An explorative study on Langmuir monolayers.
- Author
-
Pawlowska, Dorota, Erdmann, Nicole, Folz, Manuela, Langner, Andreas, Dobner, Bodo, Wölk, Christian, and Brezesinski, Gerald
- Subjects
- *
CATIONIC lipids , *FATTY acids , *PHASE transitions , *LIPIDS , *NUCLEIC acids - Abstract
[Display omitted] Ionizable lipids are a class of pharmaceutical excipients with a main application in lipid nanoparticles for nucleic acid delivery. New ionizable lipids are needed to tune characteristics of lipid-based nucleic acid delivery systems, e.g. stability, nucleic acid loading capacity and binding strength, as well as bio-distribution. Herein, we present the synthesis of three novel ionizable lipids as putative excipients for lipid-based nucleic acid delivery systems. Langmuir monolayer experiments with classical surface pressure/area isotherm evaluation were used to understand the self-assembly behavior of the lipids. Additional experiments with surface sensitive techniques, namely grazing incidence x-ray scattering and infrared reflection–absorption spectroscopy (IRRAS), were performed to understand structural characteristics of lipid associates. The latter technique was also used to investigate the nucleic acid binding process between DNA and the ionizable lipids. Finally, first transfection experiments with the novel lipids formulated as cationic liposomes were performed providing first efficacy data. Although the alkyl chain pattern was comparable for all three ionizable lipids, the results demonstrated that with increasing head-group size the DNA binding capacity changed and the alkyl chain fluidity was increased. The lipid with the lowest phase transition temperature and the smallest packing parameter showed the highest DNA transfer efficiency. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
21. Arginine Gemini-Based Surfactants for Antimicrobial and Antibiofilm Applications: Molecular Interactions, Skin-Related Anti-Enzymatic Activity and Cytotoxicity
- Author
-
Francisco Fábio Oliveira de Sousa, Aurora Pinazo, Zakaria Hafidi, María Teresa García, Elena Bautista, Maria del Carmen Moran, and Lourdes Pérez
- Subjects
gemini arginine-based surfactants ,antimicrobial activity ,biofilm inhibition ,biofilm eradication ,Langmuir monolayers ,enzymatic activity ,Organic chemistry ,QD241-441 - Abstract
The antimicrobial and antibiofilm properties of arginine-based surfactants have been evaluated. These two biological properties depend on both the alkyl chain length and the spacer chain nature. These gemini surfactants exhibit good activity against a wide range of bacteria, including some problematic resistant microorganisms such us methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. Moreover, surfactants with a C10 alkyl chain and C3 spacer inhibit the (MRSA) and Pseudomonas aeruginosa biofilm formation at concentrations as low as 8 µg/mL and are able to eradicate established biofilms of these two bacteria at 32 µg/mL. The inhibitory activities of the surfactants over key enzymes enrolled in the skin repairing processes (collagenase, elastase and hyaluronidase) were evaluated. They exhibited moderate anti-collagenase activity while the activity of hyaluronidase was boosted by the presence of these surfactants. These biological properties render these gemini arginine-based surfactants as perfect promising candidates for pharmaceutical and biological properties.
- Published
- 2023
- Full Text
- View/download PDF
22. Effect of molecular weight on stereocomplexation of enantiomeric polylactide mixtures and their degradation behaviors by Langmuir technique.
- Author
-
Gavande, Vishal, Kim, Gayeon, Kim, Byeonguk, Jin, Youngeup, Jang, Seong-Ho, Chun, Jae Hwan, and Lee, Won-Ki
- Subjects
- *
MOLECULAR weights , *POLYLACTIC acid , *BIODEGRADABLE plastics , *MIXTURES , *PLASTIC scrap , *MONOMOLECULAR films - Abstract
Biodegradable polymers in bio-based and chemically synthesized polymers are good substitutes to reduce non-degradable massive waste plastics. Biodegradable and CO2-redcible polylactides are widely used in commercial fields. The biodegradability is one of the most important factors affecting their wide applications. The objective of this study was to investigate hydrolytic kinetics of enantiomeric polylactide mixture monolayers with different molecular weights using a Langmuir film balance. The π-A and kinetic behaviors of mixture monolayers were compared with each other to determine the stereocomplexation effect between enantiomeric polylactides as a function of molecular weight. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
23. Evaluation of Emulsifying Ability of Phospholipids by Langmuir Monolayers and Stability of High Oil Ratio O/W Emulsions.
- Author
-
Li, Shanghui, Zhang, Bing, Chang, Minsi, Zhang, Ruirong, Liu, Bei, Yin, Tian, Zhang, Yu, He, Haibing, Gou, Jingxin, Wang, Yanjiao, and Tang, Xing
- Abstract
High oil ratio fat emulsion injections are prone to poor emulsification, rapid creaming, and other quality problems; therefore, the selection of emulsifiers with high emulsifying ability is crucial for the production of fat emulsions. The existing methods used to evaluate the emulsifying ability of emulsifier are to evaluate the emulsifying ability from the emulsifier itself. In the study, Langmuir monolayer selected the most miscible phospholipid with oil phase from the alternative three phospholipids by studying the molecular interaction between oil phase and phospholipid at the air/water interface. The miscibility and thermodynamic stability analyses of the different oil phase/phospholipid mixed monolayers were performed, and the data from Δ A exc and Δ G ex concluded that all three oil phases had the strongest molecular interaction with E80 and the best miscibility. The emulsions were then prepared and analyzed by the results of particle size, ζ-potential, and stability of the emulsions, where the surface free energy in the stability test echoed the results reflected by the Δ G ex values in the thermodynamic stability test. These results indicate that Langmuir monolayers can be used to study the interaction between oil phase and emulsifier, thus providing new ideas for evaluating the emulsifying ability of phospholipids. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
24. Mitochondrial membrane models built from native lipid extracts: Interfacial and transport properties
- Author
-
Olivia Schiaffarino, David Valdivieso González, Inés M. García-Pérez, Daniel A. Peñalva, Víctor G. Almendro-Vedia, Paolo Natale, and Iván López-Montero
- Subjects
outer mitochondrial membrane ,inner mitochondrial membrane ,langmuir monolayers ,supported lipid bilayers ,giant unilamellar vesicles (GUV) ,FRAP ,Biology (General) ,QH301-705.5 - Abstract
The mitochondrion is an essential organelle enclosed by two membranes whose functionalities depend on their very specific protein and lipid compositions. Proteins from the outer mitochondrial membrane (OMM) are specialized in mitochondrial dynamics and mitophagy, whereas proteins of the inner mitochondrial membrane (IMM) have dedicated functions in cellular respiration and apoptosis. As for lipids, the OMM is enriched in glycerophosphatidyl choline but cardiolipin is exclusively found within the IMM. Though the lipid topology and distribution of the OMM and IMM are known since more than four decades, little is known about the interfacial and dynamic properties of the IMM and OMM lipid extracts. Here we build monolayers, supported bilayers and giant unilamellar vesicles (GUVs) of native OMM and IMM lipids extracts from porcine heart. Additionally, we perform a comparative analysis on the interfacial, phase immiscibility and mechanical properties of both types of extract. Our results show that IMM lipids form more expanded and softer membranes than OMM lipids, allowing a better understanding of the physicochemical and biophysical properties of mitochondrial membranes.
- Published
- 2022
- Full Text
- View/download PDF
25. Degradation Behavior of Poly(Lactide-Co-Glycolide) Monolayers Investigated by Langmuir Technique: Accelerating Effect
- Author
-
Gayeon Kim, Vishal Gavande, Vasi Shaikh, and Won-Ki Lee
- Subjects
poly(lactide-co-glycolide) (PLGA) copolymers ,copolymerization ,alkaline hydrolysis ,enzymatic degradation ,Langmuir monolayers ,Organic chemistry ,QD241-441 - Abstract
Among biodegradable polymers, polylactides (PLAs) have attracted considerable interest because the monomer can be produced from renewable resources. Since their initial degradability strongly affects commercial application fields, it is necessary to manage the degradation properties of PLAs to make them more commercially attractive. To control their degradability, poly(lactide-co-glycolide) (PLGA) copolymers of glycolide and isomer lactides (LAs) were synthesized, and their enzymatic and alkaline degradation rates of PLGA monolayers as functions of glycolide acid (GA) composition were systematically investigated by the Langmuir technique. The results showed that the alkaline and enzymatic degradations of PLGA monolayers were faster than those of l-polylactide (l-PLA), even though proteinase K is selectively effective in the l-lactide (l-LA) unit. Alkaline hydrolysis was strongly affected by their hydrophilicity, while the surface pressure of monolayers for enzymatic degradations was a major factor.
- Published
- 2023
- Full Text
- View/download PDF
26. Langmuir–Blodgett Films with Immobilized Glucose Oxidase Enzyme Molecules for Acoustic Glucose Sensor Application
- Author
-
Ilya Gorbachev, Andrey Smirnov, George R. Ivanov, Tony Venelinov, Anna Amova, Elizaveta Datsuk, Vladimir Anisimkin, Iren Kuznetsova, and Vladimir Kolesov
- Subjects
Langmuir–Blodgett films ,Langmuir monolayers ,enzymatic biosensors ,acoustoelectronic glucose sensor ,Chemical technology ,TP1-1185 - Abstract
In this work, a sensitive coating based on Langmuir–Blodgett (LB) films containing monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) with an immobilized glucose oxidase (GOx) enzyme was created. The immobilization of the enzyme in the LB film occurred during the formation of the monolayer. The effect of the immobilization of GOx enzyme molecules on the surface properties of a Langmuir DPPE monolayer was investigated. The sensory properties of the resulting LB DPPE film with an immobilized GOx enzyme in a glucose solution of various concentrations were studied. It has shown that the immobilization of GOx enzyme molecules into the LB DPPE film leads to a rising LB film conductivity with an increasing glucose concentration. Such an effect made it possible to conclude that acoustic methods can be used to determine the concentration of glucose molecules in an aqueous solution. It was found that for an aqueous glucose solution in the concentration range from 0 to 0.8 mg/mL the phase response of the acoustic mode at a frequency of 42.7 MHz has a linear form, and its maximum change is 55°. The maximum change in the insertion loss for this mode was 18 dB for a glucose concentration in the working solution of 0.4 mg/mL. The range of glucose concentrations measured using this method, from 0 to 0.9 mg/mL, corresponds to the corresponding range in the blood. The possibility of changing the conductivity range of a glucose solution depending on the concentration of the GOx enzyme in the LB film will make it possible to develop glucose sensors for higher concentrations. Such technological sensors would be in demand in the food and pharmaceutical industries. The developed technology can become the basis for creating a new generation of acoustoelectronic biosensors in the case of using other enzymatic reactions.
- Published
- 2023
- Full Text
- View/download PDF
27. The Branched Schiff Base Cationic Complexes of Iron(III) with Different Counter-Ions.
- Author
-
Gruzdev, Matvey, Chervonova, Ulyana, and Vorobeva, Valerya
- Subjects
- *
SCHIFF bases , *COUNTER-ions , *LANGMUIR-Blodgett films , *IRON , *ION temperature , *DENDRIMERS - Abstract
The Fe(III) complexes of branched asymmetric dendrimers were obtained by a one-step reaction as the second-generation architectures. Mesomorphic behavior was found for complexes with PF6− and BF4− counter-ions. To obtain knowledge about the existence of HS and LS fractions of iron(III) ion and their evolution with temperature, EPR methods were used. It was demonstrated that compounds contain one low-spin (LS, S = 1/2) and two HS-spin (HS, S = 5/2) of Fe(III) centers and are packed into two magnetic sub-lattices. A floating layers of Fe(III) complexes and Langmuir–Blodgett films on their base were formed and investigated in the presence of a magnetic field. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
28. Impact of Polymer Nanoparticles on DPPC Monolayer Properties.
- Author
-
Bykov, Alexey, Milyaeva, Olga, Akentiev, Alexander, Panaeva, Maria, Isakov, Nikolaj, Miller, Reinhard, and Noskov, Boris
- Subjects
POLYMERIC nanocomposites ,NANOPARTICLES ,MONOMOLECULAR films ,ELASTICITY ,SURFACE active agents - Abstract
The application of surface rheology and Brewster angle microscopy on mixed monolayers of DPPC and polymeric nanoparticles (cationic and anionic) showed that the sign of the particle charge affects the dynamic properties of the monolayers less than the nanoparticles' ability to aggregate. Under almost physiological conditions, the effect of nanoparticles on the elasticity of DPPC monolayer is insignificant. However, the particles prevent the surface tension from decreasing to extremely low values. This effect could affect the functionality of pulmonary surfactants. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
29. Synthesis and Characterization of Magnetic Drug Carriers Modified with Tb 3+ Ions.
- Author
-
Nieciecka, Dorota, Rękorajska, Aleksandra, Cichy, Dariusz, Końska, Paulina, Żuk, Michał, and Krysiński, Paweł
- Abstract
The study aimed to synthesize and characterize the magnetic drug carrier modified with terbium (III) ions. The addition of terbium extends the possibilities of their applications for targeted anticancer radiotherapy as well as for imaging techniques using radioisotopes emitting β+, β−, α, and γ radiation. The synthesis of iron oxide nanoparticles stabilized with citrates using the co-precipitation method (IONP @ CA) was carried out during the experimental work. The obtained nanoparticles were used to synthesize a conjugate containing terbium ions and guanosine-5′-monophosphate as an analog of drugs from the thiopurine group. Conjugates and their components were characterized using Transmission Electron Microscopy, infrared spectroscopy, X-ray microanalysis, spectrofluorimetry, and thermogravimetric analysis. The hybrid was also investigated with Langmuir layers to check the interaction with analogs of biological membranes. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
30. Interactions of polychlorinated cyclodiene pesticides with model fungal membranes – Langmuir monolayer and liposome studies.
- Author
-
Broniatowski, Marcin, Wójcik, Aneta, Stephan, Mareike S., Georgiev, Vasil N., Dimova, Rumiana, Mach, Marzena, and Wydro, Paweł
- Subjects
- *
PERSISTENT pollutants , *FUNGAL membranes , *CELL membranes , *CHLORDECONE , *MEMBRANE lipids - Abstract
Polychlorinated cyclodiene pesticides (CP) are persistent organic pollutants causing widespread soil contamination. CPs-contaminated soils could be purified by mycoremediation, i.e. the introduction of CP-degrading fungal strains into the soils. However, not all mycoremediation attempts are effective, and the microbial cells introduced into the soil die. CP molecules are highly hydrophobic, therefore, their toxicity may largely result from membrane activity, i.e. from the incorporation of CP molecules into membranes disturbing their functions. To test this hypothesis and shed light on the interactions of CPs with plasma membranes, we used lipid Langmuir monolayers and unilamellar liposomes as models of fungal membranes. In our research, we included the four most common CPs polluting soils: aldrin, endrin, endosulfan, and chlordecone. Our studies have shown that CPs can be incorporated into the membranes up to the molar ratio of approximately 0.15. In the case of Langmuir monolayers, greater effects were observed for the model composed of saturated lipids. For this model, however, X-ray diffraction studies have shown that CPs are incorporated into the ergosterol-enriched amorphous phase without disturbing the formation of crystalline phospholipid nanodomains. Langmuir monolayer studies showed that chlordecone disturbs the physical properties of the model membrane to the greatest extent. However, liposome studies have shown that the effect of all CPs is similar – their presence increases the fluidity of the bilayer. Our studies confirmed CPs' membrane activity, however, also showed that the presence of CP molecules in lipid membranes does not cause drastic changes in their physical properties. [Display omitted] • Cyclodiene pesticides are incorporated into model fungal membranes • Cyclodiene pesticides do not disturb the formation of phospholipid crystalline nanodomains • Chlordecone has the greatest impact on the physical properties of Langmuir monolayers • All studied cyclodiene pesticides fluidize the lipid bilayer in liposomes [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
31. Effects induced by η6-p-cymene ruthenium(II) complexes on Langmuir monolayers mimicking cancer and healthy cell membranes do not correlate with their toxicity.
- Author
-
Wrobel, Ellen C., Guimarães, Ivelise Dimbarre Lao, Wohnrath, Karen, and Oliveira, Osvaldo N.
- Subjects
- *
RUTHENIUM , *CANCER cells , *PLASMA instabilities , *REFLECTANCE spectroscopy , *CYTOTOXINS , *CELL membranes , *MEMBRANE lipids , *MONOMOLECULAR films - Abstract
The mechanism of chemotherapeutic action of Ru-based drugs involves plasma membrane disruption and valuable insights into this process may be gained using cell membrane models. The interactions of a series of cytotoxic η6- p -cymene ruthenium(II) complexes, [Ru(η6- p -cymene)P(3,5-C(CH 3) 3 -C 6 H 3) 3 Cl 2 ] (1) , [Ru(η6- p -cymene)P(3,5-CH 3 -C 6 H 3) 3 Cl 2 ] (2) , [Ru(η6- p -cymene)P(4-CH 3 O-3,5-CH 3 -C 6 H 2) 3 Cl 2 ] (3) , and [Ru(η6- p -cymene)P(4-CH 3 O-C 6 H 4) 3 Cl 2 ] (4) , were examined using Langmuir monolayers as simplified healthy and cancerous outer leaflet plasma membrane models. The cancerous membrane (CM1 and CM2) models contained either 40 % 1,2- dipalmitoyl- sn -glycero-3-phosphocholine (DPPC) or 1,2-dioleoyl- sn -glycero-3-phosphocholine (DOPC), 30 % cholesterol (Chol), 20 % 1,2-dipalmitoyl- sn -glycero-3-phosphoethanolamine (DPPE), and 10 % 1,2-dipalmitoyl- sn -glycero-3-phospho- l -serine (DPPS). Meanwhile, the healthy membrane (HM1 and HM2) models were composed of 60 % DPPC or DOPC, 30 % Chol and 10 % DPPE. The complexes affected surface pressure isotherms and decreased compressional moduli of cancerous and healthy membrane models, interacting with the monolayers headgroup and tails according to data from polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS). However, the effects did not correlate with the toxicity of the complexes to cancerous and healthy cells. Multidimensional projection technique showed that the complex (1) induced significant changes in the CM1 and HM1 monolayers, though it had the lowest cytotoxicity against cancer cells and is not toxic to healthy cells. Moreover, the most toxic complexes (2) and (4) were those that least affected CM2 and HM2 monolayers. The findings here support that the ruthenium complexes interact with lipids and cholesterol in cell membrane models, and their cytotoxic activities involve a multifaceted mode of action beyond membrane disruption. [Display omitted] • Ru complexes interact with both healthy and cancer plasma membrane models. • The cytotoxicity of Ru complexes in unrelated to their effect on membrane models. • Ru complexes either cross or penetrate the cell membrane. • The mechanism of action of Ru complexes goes beyond simple cell membrane disruption. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
32. Interactions of model airborne particulate matter with dipalmitoyl phosphatidylcholine and a clinical surfactant Calsurf.
- Author
-
Wu, Min, Wang, Feifei, Chen, Jingsi, Zhang, Hao, Zeng, Hongbo, and Liu, Jifang
- Subjects
- *
PARTICULATE matter , *SURFACE tension , *SURFACE active agents , *ATOMIC force microscopy , *ISOTHERMAL titration calorimetry , *BIOSURFACTANTS , *LANGMUIR-Blodgett films - Abstract
[Display omitted] Lung surfactant protects lung tissue and reduces the surface tension in the alveoli during respiration. Particulate matter with an aerodynamic diameter of less than 2.5 μm (PM 2.5), which invades primely through inhalation, can deposit on and interact with the surfactant layer, leading to changes in the biophysical and morphological properties of the lung surfactant. Langmuir monolayers of 1,2-dipalmitoyl- sn - glycero -3-phosphatidylcholine (DPPC) and clinical surfactant Calsurf were investigated with a PM 2.5 model injected into the water subphase, which were characterized by surface pressure-area isotherms, Brewster angle microscopy, atomic force microscopy, fluorescent microscopy, and x-ray photoelectron spectroscopy. The binding between DPPC/Calsurf and PM 2.5 was studied using isothermal titration calorimetry. PM 2.5 induced the expansion of the monolayers at low surface pressure (п) and film condensation at high п. Aggregation of PM 2.5 mainly occurred at the interface of liquid expanded/liquid condensed (LE/LC) phases. PM 2.5 led to slimmer and ramified LC domains on DPPC and the reduction of nano-sized condensed domains on Calsurf. Both DPPC and Calsurf showed fast binding with PM 2.5 through complex binding modes attributed to the heterogeneity and amphiphilic property of PM 2.5. This study improves the fundamental understanding of PM 2.5 -lung surfactant interaction and shows useful implications of the toxicity of PM 2.5 through respiration process. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
33. X-ray Reflectivity Study of Polylysine Adsorption on the Surface of DMPS Monolayers
- Author
-
Aleksey M. Tikhonov, Victor E. Asadchikov, Yury O. Volkov, Boris S. Roshchin, Alexander D. Nuzhdin, Kirill I. Makrinsky, and Yury A. Ermakov
- Subjects
phase transition ,Langmuir monolayers ,compressibility ,Volta potential ,lipid hydration ,polylysine adsorption ,Chemical technology ,TP1-1185 ,Chemical engineering ,TP155-156 - Abstract
The results of a systematic study on the adsorption of polylysine molecules of different lengths on the surface of a 1,2-dimyristoyl-sn-glycero-3-phospho-L-serine (DMPS) monolayer in the liquid (LE) and condensed (LC) states are presented. A compressibility diagram and the Volta potential were recorded with the Langmuir monolayer technique and further analyzed with the empirical approach. The structure of the monolayer films with adsorbed polypeptides was studied with synchrotron X-ray reflectometry. Two- and three-layer slab models describe the reflectivity data fairly well and reveal both the significant structural changes and the dehydration of the polar groups induced by all polylysines used at the maximal coverage of the monolayer interface in both the LE and LC states. On the one hand, in the LE phase of the monolayer (area per molecule A ≅ 70 Ǻ2), the integrated electron density of the lipid headgroup region is approximately half the density contained in the clean monolayer. This indicates both significant compaction and dehydration in the polar groups of the lipids, caused by the adsorption of polypeptides. On the other hand, in the LC state (A ≅ 40 Ǻ2), the degree of the hydration of the polar region is similar to that for the initial DMPS monolayer. However, both the electron density and the thickness of the head group region differ significantly from the values of these parameters for the clean monolayer in the LC state.
- Published
- 2022
- Full Text
- View/download PDF
34. A Deeper Insight into the Interfacial Behavior and Structural Properties of Mixed DPPC/POPC Monolayers: Implications for Respiratory Health
- Author
-
Yingxue Geng, Yan Cao, Yingjie Li, Qun Zhao, Dan Liu, Ge Fan, and Senlin Tian
- Subjects
lipid monolayers ,pulmonary surfactant ,Langmuir monolayers ,phase behavior ,intermolecular interaction ,Chemical technology ,TP1-1185 ,Chemical engineering ,TP155-156 - Abstract
1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1-palmitoyl-2-oleyl-sn-glycerol-3-phosphorcholine (POPC) are important components in pulmonary surfactants (PSs), of which the relative content is related to lung compliance. Herein, the phase behavior and thermodynamic structure of mixed DPPC/POPC monolayers were studied to elucidate the intermolecular interaction between DPPC and POPC molecules. Surface pressure–molecular area isotherms demonstrated that POPC significantly affected the phase behavior of the lipid domain structure as a function of its concentration. The compression modulus of the mixed monolayers reduced with the increase in POPC proportion, which can be attributed to the intermolecular repulsion between DPPC and POPC. Brewster angle microscopy analysis showed that the ordered structure of the monolayers trended toward fluidization in the presence of POPC. Raman spectroscopy results revealed that the change in C–C skeleton stretching vibration was the main cause of the decrease in the monolayer packing density. These findings provide new insights into the role of different phospholipid components in the function of PS film at a molecular level, which can help us to understand the synergy effects of the proportional relationship between DPPC and POPC on the formation and progression of lung disease and provide some references for the synthesis of lung surfactants.
- Published
- 2022
- Full Text
- View/download PDF
35. DNA Penetration into a Lysozyme Layer at the Surface of Aqueous Solutions
- Author
-
Nikolay S. Chirkov, Shi-Yow Lin, Alexander V. Michailov, Reinhard Miller, and Boris A. Noskov
- Subjects
DNA ,lysozyme ,adsorption kinetics ,dilational surface rheology ,Langmuir monolayers ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
The interactions of DNA with lysozyme in the surface layer were studied by performing infrared reflection–absorption spectroscopy (IRRAS), ellipsometry, surface tensiometry, surface dilational rheology, and atomic force microscopy (AFM). A concentrated DNA solution was injected into an aqueous subphase underneath a spread lysozyme layer. While the optical properties of the surface layer changed fast after DNA injection, the dynamic dilational surface elasticity almost did not change, thereby indicating no continuous network formation of DNA/lysozyme complexes, unlike the case of DNA interactions with a monolayer of a cationic synthetic polyelectrolyte. A relatively fast increase in optical signals after a DNA injection under a lysozyme layer indicates that DNA penetration is controlled by diffusion. At low surface pressures, the AFM images show the formation of long strands in the surface layer. Increased surface compression does not lead to the formation of a network of DNA/lysozyme aggregates as in the case of a mixed layer of DNA and synthetic polyelectrolytes, but to the appearance of some folds and ridges in the layer. The formation of more disordered aggregates is presumably a consequence of weaker interactions of lysozyme with duplex DNA and the stabilization, at the same time, of loops of unpaired nucleotides at high local lysozyme concentrations in the surface layer.
- Published
- 2022
- Full Text
- View/download PDF
36. Interfacial binding of divalent cations to calixarene-based Langmuir monolayers
- Author
-
Shahgaldian, Patrick [Univ. of Applied Science and Arts Northwestern Switzerland, Muttenz (Switzerland)]
- Published
- 2015
- Full Text
- View/download PDF
37. On the role of surrounding regions in the fusion peptide in dengue virus infection.
- Author
-
Cespedes, Graziely F., Nobre, Thatyane M., Oliveira, Osvaldo N., Bong, Dennis, and Cilli, Eduardo M.
- Subjects
- *
VIRUS diseases , *DENGUE viruses , *BREWSTER'S angle , *MEMBRANE fusion , *VIRAL proteins , *ELECTROSTATIC interaction , *ARBOVIRUS diseases , *PLANT viruses - Abstract
Dengue virus infection depends on its fusion with the host membrane, where the binding occurs through interaction between proteins on the virus cell surface and specific viral receptors on target membranes. This process is mediated by the fusion peptide located between residues 98 and 112 (DRGWGNGCGLFGKGG) that forms a loop in domain II of dengue E glycoprotein. In this study, we evaluated the role of fusion peptide surrounding regions (88–97 and 113–123) of the Dengue 2 subtype on its interaction with the membrane and fusion activity. These sequences are important to stabilize the fusion peptide loop and increase fusion activity. Three peptides, besides the fusion peptide, were synthesized by SPPS using the Fmoc chemical approach. The first contains the fusion peptide and the C-terminal region of the loop (sequence 98–123); another contains the N-terminal region (88–112) and the larger peptide contains both regions (88–123). The peptides were able to interact with a model membrane. Differences in morphology of the monolayer promoted by the peptides were assessed by Brewster Angle Microscopy (BAM). Our data indicated that the C-terminal region of fusion peptide loop is more efficient in promoting fusion and interacting with the membrane than the N-terminal sequence, which is responsible for the electrostatic initial interaction. We propose a 2-step mechanism for the interaction of the dengue virus fusion peptide with the host membrane, where the N-terminal sequence docks electrostatically on the headgroups and then the C-terminal interacts via hydrophobic forces in the acyl chains. [Display omitted] • 2-step mechanism for dengue virus fusion peptide. • N-terminal region can be related to the initial interaction in the membrane. • C-terminal is important for dengue virus fusion peptide. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
38. Lithocholic acid-based oligomers as drug delivery candidates targeting model of lipid raft.
- Author
-
Wnętrzak, Anita, Szymczuk, Dawid, Chachaj-Brekiesz, Anna, Dynarowicz-Latka, Patrycja, Lupa, Dawid, Lipiec, Ewelina W., Laszuk, Paulina, Petelska, Aneta D., Markiewicz, Karolina H., and Wilczewska, Agnieszka Z.
- Subjects
- *
LIPID rafts , *OLIGOMERS , *NEAR infrared reflectance spectroscopy , *ATOMIC force microscopy , *NUCLEAR magnetic resonance , *DRUG carriers - Abstract
This study presents a new approach to designing a lithocholic acid functionalized oligomer (OLithocholicAA-X) that can be used as a drug carrier with additional, beneficial activity. Namely, this novel oligomer can incorporate an anti-cancer drug due to the application of an effective backbone as its component (lithocholic acid) alone is known to have anticancer activity. The oligomer was synthesized and characterized in detail by nuclear magnetic resonance, attenuated total reflectance Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy, thermal analysis, and mass spectrometry analysis. We selected lipid rafts as potential drug carrier-membrane binding sites. In this respect, we investigated the effects of OLithocholicAA-X on model lipid raft of normal and altered composition, containing an increased amount of cholesterol (Chol) or sphingomyelin (SM), using Langmuir monolayers and liposomes. The surface topography of the studied monolayers was additionally investigated by atomic force microscopy (AFM). The obtained results showed that the investigated oligomer has affinity for a system that mimics a normal lipid raft (SM:Chol 2:1). On the other hand, for systems with an excess of SM or Chol, thermodynamically unfavorable fluidization of the films occurs. Moreover, AFM topographies showed that the amount of SM determines the bioavailability of the oligomer, causing fragmentation of its lattice. [Display omitted] • The synthesis and physicochemical characterization of OLithocholicAA-X was presented • OLithocholicAA-X can act as a drug carrier with double activity • Model membrane systems were used to study OLithocholicAA-X binding into membrane • OLithocholicAA-X shows affinity to model lipid rafts • SM determines the bioavailability of the oligomer causing fragmentation of its lattice [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
39. In situ interaction between the hormone 17α-ethynylestradiol and the liquid-ordered phase composed of the lipid rafts sphingomyelin and cholesterol.
- Author
-
Ruiz, Gilia Cristine Marques, do Carmo Morato, Luis Fernando, Pazin, Wallance Moreira, Oliveira Jr, Osvaldo N., and Constantino, Carlos José Leopoldo
- Subjects
- *
LIPID rafts , *SPHINGOMYELIN , *CHOLESTEROL , *CELL permeability , *HORMONES - Abstract
[Display omitted] • EE2 interacts with both SM and SM/Chol monolayers at the air/water interface. • The morphology and permeability was induced by EE2 only to SM/Chol GUVs. • The L o phase regulate the permeability of the vesicles in presence of EE2. Hormone treatments are frequently associated with cardiovascular diseases and cancers in women. Additionally, the detrimental effects of their presence as contaminants in water remain a concern. The transport of hormones through cell membranes is essential for their biological action, but investigating cell permeability is challenging owing to the experimental difficulty in dealing with whole cells. In this paper, we study the interaction of the synthetic hormone 17α-ethynylestradiol (EE2) with membrane models containing the key raft components sphingomyelin (SM) and cholesterol (Chol). The models consisted of Langmuir monolayers and giant unilamellar vesicles (GUVs) that represent bilayers. EE2 induced expansion of SM monolayers upon interacting with the non-hydrated amide group of SM head, but it had practically no effect on SM GUVs because these group are not available for interaction in bilayers. In contrast, EE2 interacted with hydrated phosphate group ( P O 2 -) and amide group of SM/Chol mixture monolayer, which could explain the loss in phase contrast of liquid-ordered GUVs suggesting pore formation. A comparison with reported EE2 effects on GUVs in the fluid phase, for which no loss in phase contrast was observed, indicates that the liquid-ordered phase consisting of lipid rafts is relevant to be associated with the changes on cell permeability caused by the hormones. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
40. Study of the correlation between the structure of selected triester of phosphatidylcholine and their impact on physicochemical properties of model mammalian membranes.
- Author
-
Mach, Marzena, Płachta, Łukasz, and Wydro, Paweł
- Subjects
- *
CATIONIC lipids , *LECITHIN , *MEMBRANE lipids , *GENETIC carriers , *DRUG delivery systems , *MEMBRANE permeability (Biology) - Abstract
Cationic lipids are synthetic compounds of amphiphilic character used in Drug Delivery Systems (DDS), especially in gene therapy, as the carriers of genetic material. As it is known, the main limitation of the application of cationic lipids in DDS is their high cytotoxicity after in vivo administration and low bioactivity. This is probably related to not fully known the relationship between the lipid structure and its activity as well as the mechanism of lipofection or drug delivery. Therefore, in this work we determined the impact of a selected group of cationic lipids - triesters of phosphatidylcholine (Et-PCs) - differing in their hydrophobic structure on model mammalian membranes. In the research, as model systems, Langmuir monolayers and liposomes were applied. It was shown that the incorporation of Et-PCs into model mammalian membranes weakens interactions between lipids, causing the increase of fluidity, disordering degree and permeability of membrane. The destabilization of the membrane in this way can facilitate the entry of drugs, carried inside cationic liposomes, into the pathological cell. Moreover, the studies prove that the structure of the hydrophobic part of cationic lipids also affects the properties of lipid membranes. [Display omitted] • The interactions of Et-PCs with mammalian membranes depend on their composition. • The hydrophobic structure of Et-PCs effects on the properties of lipid membranes. • Et-PCs increase the disordering degree of molecules in model mammalian membranes. • Et-PC with unsaturated bonds in hydrophobic part fluidizes lipid membranes more. • EDOPC increases more the permeability of the model membrane than EDPPC. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
41. Interfacial Aβ fibril formation is modulated by the disorder-order state of the lipids: The concept of the physical environment as amyloid inductor in biomembranes.
- Author
-
Alvarez, Alain Bolaño, Rodríguez, Pablo E.A., and Fidelio, Gerardo D.
- Subjects
- *
AMYLOID , *LIPIDS , *BIOLOGICAL membranes , *PHASE transitions , *PEPTIDES , *AMYLOID beta-protein , *PHOSPHOLIPIDS - Abstract
The behavior of amphiphilic molecules such as lipids, peptides and their mixtures at the air/water interface allow us to evaluate and visualize the arrangement formed in a confined and controlled surface area. We have studied the surface properties of the zwitterionic DPPC lipid and Aβ(1–40) amyloid peptide in mixed films at different temperatures (from 15 to 40 °C). In this range of temperature the surface properties of pure Aβ(1–40) peptide remained unchanged, whereas DPPC undergoes its characteristic liquid-expanded → liquid-condensed bidimensional phase transition that depends on the temperature and lateral pressure. This particular property of DPPC makes it possible to dynamically study the influence of the lipid phase state on amyloid structure formation at the interface in a continuous, isothermal and abrupt change on the environmental condition. As the mixed film is compressed the fibril-like structure of Aβ(1–40) is triggered specifically in the liquid-expanded region , independently of temperature, and it is selectively excluded from the well-visible liquid condensed domains of DPPC. The Aβ amyloid fibers were visualized by using BAM and AFM and they were Thio T positive. In mixed DPPC/Aβ(1–40) films the condensed domains (in between 11 mN/m to 20 mN/m) become irregular probably due to the fibril-like structures is imposing additional lateral stress sequestering lipid molecules in the surrounding liquid-expanded phase to self-organize into amyloids. [Display omitted] • Βeta amyloid peptide forms fibril-like structures in phospholipid liquid phase. • Lipid phase acts as an amyloid inductor in biomembranes. • Fibril-like structures can be triggered by the interfacial condition. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
42. The Branched Schiff Base Cationic Complexes of Iron(III) with Different Counter-Ions
- Author
-
Matvey Gruzdev, Ulyana Chervonova, and Valerya Vorobeva
- Subjects
iron(III) complex ,Schiff base ,liquid crystal ,mesophase ,Langmuir monolayers ,Mathematics ,QA1-939 - Abstract
The Fe(III) complexes of branched asymmetric dendrimers were obtained by a one-step reaction as the second-generation architectures. Mesomorphic behavior was found for complexes with PF6− and BF4− counter-ions. To obtain knowledge about the existence of HS and LS fractions of iron(III) ion and their evolution with temperature, EPR methods were used. It was demonstrated that compounds contain one low-spin (LS, S = 1/2) and two HS-spin (HS, S = 5/2) of Fe(III) centers and are packed into two magnetic sub-lattices. A floating layers of Fe(III) complexes and Langmuir–Blodgett films on their base were formed and investigated in the presence of a magnetic field.
- Published
- 2022
- Full Text
- View/download PDF
43. Impact of Polymer Nanoparticles on DPPC Monolayer Properties
- Author
-
Alexey Bykov, Olga Milyaeva, Alexander Akentiev, Maria Panaeva, Nikolaj Isakov, Reinhard Miller, and Boris Noskov
- Subjects
DPPC ,nanoparticles ,surface rheology ,Langmuir monolayers ,Chemistry ,QD1-999 - Abstract
The application of surface rheology and Brewster angle microscopy on mixed monolayers of DPPC and polymeric nanoparticles (cationic and anionic) showed that the sign of the particle charge affects the dynamic properties of the monolayers less than the nanoparticles’ ability to aggregate. Under almost physiological conditions, the effect of nanoparticles on the elasticity of DPPC monolayer is insignificant. However, the particles prevent the surface tension from decreasing to extremely low values. This effect could affect the functionality of pulmonary surfactants.
- Published
- 2022
- Full Text
- View/download PDF
44. Thermodynamic and Mechanical Properties of DMPC/Cholesterol Mixed Monolayers at Physiological Conditions
- Author
-
Alan Bañuelos-Frias, Victor Manuel Castañeda-Montiel, Edgar Rogelio Alvizo-Paez, Emmanuel Antonio Vazquez-Martinez, Eduardo Gomez, and Jaime Ruiz-Garcia
- Subjects
cholesterol ,DMPC ,model membranes ,brewster angle microscopy ,Langmuir monolayers ,isotherms ,Physics ,QC1-999 - Abstract
One of the main known effects of cholesterol is to rigidify the cell membrane throughout the so-called condensing effect. Although many studies have been done in mixtures of cholesterol with different membrane lipids, there are not many studies in a wide concentration range of cholesterol or at physiological conditions. In this work, we studied mixtures of DMPC/Cholesterol monolayers to determine the effect of cholesterol, from very low to physiological concentrations and two pHs. We use a Langmuir balance and Brewster angle microscopy to study their thermodynamic behavior at 37.0 ± 0.1°C at the air/solution interface. From the analysis of the (π−A) isotherms, we determined the excess area and the compressibility elastic modulus to determine the monolayers mechanical properties. Surprisingly, we found three main effects of cholesterol: The first one is a fluidization effect of the monolayer at all cholesterol concentrations. The second effect is the so-called condensing effect that appears due to the non-ideality of the mixture. The third effect is a stiffness of the monolayer as the cholesterol concentration increases. These effects are stronger in pure water, pH ≈ 6.6, than on buffer at physiological pH = 7.4. We also found that all mixtures are thermodynamically stable at all concentrations at a surface pressure of 30.1 ± 1.6 and 27.4 ± 3.2 mN/m in pure water and buffer, respectively. Furthermore, we compared this stability with a fatty acid monolayer that shows a much lower surface pressure equilibrium value that DMPC or its mixtures with cholesterol, indicating a possibly reason why double chain lipids are better than single chain lipids to made up the cell membrane.
- Published
- 2021
- Full Text
- View/download PDF
45. Langmuir-Blodgett monolayers holding a wound healing active compound and its effect in cell culture. A model for the study of surface mediated drug delivery systems
- Author
-
Luciana Fernández, Ana Lucía Reviglio, Daniel A. Heredia, Gustavo M. Morales, Marisa Santo, Luis Otero, Fabrisio Alustiza, Ana Cecilia Liaudat, Pablo Bosch, Enrique L. Larghi, Andrea B.J. Bracca, and Teodoro S. Kaufman
- Subjects
Langmuir monolayers ,Drug-carrier composites ,Cell culture ,Triclisine ,Science (General) ,Q1-390 ,Social sciences (General) ,H1-99 - Abstract
Langmuir and Langmuir-Blodgett films holding a synthetic bioinspired wound healing active compound were used as drug-delivery platforms. Palmitic acid Langmuir monolayers were able to incorporate 2-methyltriclisine, a synthetic Triclisine derivative that showed wound healing activity. The layers proved to be stable and the nanocomposites were transferred to solid substrates. Normal human lung cells (Medical Research Council cell strain 5, MRC-5) were grown over the monomolecular Langmuir-Blodgett films that acted as a drug reservoir and delivery system. The proliferation and migration of the cells were clearly affected by the presence of 2-methyltriclisine in the amphiphilic layers. The methodology is proposed as a simple and reliable model for the study of the effects of bioactive compounds over cellular cultures.
- Published
- 2021
- Full Text
- View/download PDF
46. Self-assembled nanostructures of L-ascorbic acid alkyl esters support monomeric amphotericin B
- Author
-
Natalia E. Nocelli, Yenisleidy de las Mercedes Zulueta Díaz, Marine Millot, María Luz Colazo, Raquel V. Vico, and Maria Laura Fanani
- Subjects
Amphiphilic drugs ,Langmuir monolayers ,Coagels ,Polyene macrolides ,Drug carriers ,Science (General) ,Q1-390 ,Social sciences (General) ,H1-99 - Abstract
Hypothesis: Amphotericin B (AmB) is a highly effective antimicrobial, with broad antimycotic and antiparasitic effect. However, AmB poor water-solubilisation and aggregation tendency limits its use for topical applications. We studied the capacity of nanostructures formed by alkyl esters of L-ascorbic acid (ASCn) to solubilise AmB and tested the relationship between the prevalence of the monomeric form of AmB and its effectiveness as antimicrobial agent. Experiments: We developed self-assembled nanostructures formed by the commercial compound, palmitoyl ascorbic acid, as well as the shorter chained myristoyl and lauroyl ascorbic acid. AmB loaded ASCn nanostructures were studied by a combination of spectroscopic techniques, together with particle analysis, differential scanning calorimetry, microbiological tests, and Langmuir monolayer visualisation. Findings: We found no direct relation between the antimicrobial capacity and the prevalence of the monomeric form of the drug. However, the later was related to chemical stability and colloidal robustness. Nanostructures formed by ASC16 in its anionic state provide an appropriate environment for AmB in its monomeric form, maintaining its antimicrobial capacity. Langmuir film visualisation supports spectrophotometric evidence, indicating that ASC16 allows the in-plane solubilisation of AmB. Coagels formed by ASC16 appear as promising for carrying AmB for dermal delivery.
- Published
- 2021
- Full Text
- View/download PDF
47. Assessing the Influence of Temperature‐Memory Creation on the Degradation of Copolyesterurethanes in Ultrathin Films.
- Author
-
Machatschek, Rainhard, Saretia, Shivam, and Lendlein, Andreas
- Subjects
THIN films ,REFLECTANCE spectroscopy ,INFRARED absorption ,BLOCK copolymers ,COLD (Temperature) ,SHAPE memory polymers - Abstract
Copolyesterurethanes (PDLCLs) based on oligo(ε‐caprolactone) (OCL) and oligo(ω‐pentadecalactone) (OPDL) segments are biodegradable thermoplastic temperature‐memory polymers. The temperature‐memory capability in these polymers with crystallizable control units is implemented by a thermomechanical programming process causing alterations in the crystallite arrangement and chain organization. These morphological changes can potentially affect degradation. Initial observations on the macroscopic level inspire the hypothesis that switching of the controlling units causes an accelerated degradation of the material, resulting in programmable degradation by sequential coupling of functions. Hence, detailed degradation studies on Langmuir films of a PDLCL with 40 wt% OPDL content are carried out under enzymatic catalysis. The temperature‐memory creation procedure is mimicked by compression at different temperatures. The evolution of the chain organization and mechanical properties during the degradation process is investigated by means of polarization‐modulated infrared reflection absorption spectroscopy, interfacial rheology and to some extend by X‐ray reflectivity. The experiments on PDLCL Langmuir films imply that degradability is not enhanced by thermal switching, as the former depends on the temperature during cold programming. Nevertheless, the thin film experiments show that the leaching of OCL segments does not induce further crystallization of the OPDL segments, which is beneficial for a controlled and predictable degradation. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
48. Properties of Langmuir and immobilized layers of betulin diphosphate on aqueous solutions of zinc sulfate and on the surface of zinc oxide nanoparticles.
- Author
-
Melnikova, N. B., Malygina, D. S., Vorobyova, O. A., Solovyeva, A. G., Belyaeva, K. L., Orekhov, D. V., and Knyazev, A. V.
- Subjects
- *
ZINC sulfate , *ZINC oxide synthesis , *BETULIN , *AQUEOUS solutions , *NANOPARTICLES , *COMPRESSIBILITY , *ZINC oxide - Abstract
This work examines the specific features of interaction of betulin diphosphate (BDP), exhibiting antitumor and wound-healing properties, with zinc cations during its immobilization on ZnO nanoparticles. The properties of Langmuir and transferred BDP monolayers from an aqueous subphase of zinc sulfate onto the surface of a solid substrate (CaF2, quartz) by the Langmuir—Schaefer method are investigated using IR and UV spectroscopy. It is shown that there is a twofold increase of the molecular area in the immobilized layers, while the compressibility modulus decreases by a factor of 1.5. Zinc oxide nanoparticles with immobilized BDP 10–20 nm in size (surface concentration of BDP is 100 mg g−1) retain the original hexagonal wurtzite structure. The efficiency of betulin diphosphate immobilized on the surface of zinc oxide nanoparticles is demonstrated in in vivo experiments for burn wounds in rats. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
49. Arginine Gemini-Based Surfactants for Antimicrobial and Antibiofilm Applications: Molecular Interactions, Skin-Related Anti-Enzymatic Activity and Cytotoxicity
- Abstract
The antimicrobial and antibiofilm properties of arginine-based surfactants have been evaluated. These two biological properties depend on both the alkyl chain length and the spacer chain nature. These gemini surfactants exhibit good activity against a wide range of bacteria, including some problematic resistant microorganisms such us methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. Moreover, surfactants with a C10 alkyl chain and C3 spacer inhibit the (MRSA) and Pseudomonas aeruginosa biofilm formation at concentrations as low as 8 µg/mL and are able to eradicate established biofilms of these two bacteria at 32 µg/mL. The inhibitory activities of the surfactants over key enzymes enrolled in the skin repairing processes (collagenase, elastase and hyaluronidase) were evaluated. They exhibited moderate anti-collagenase activity while the activity of hyaluronidase was boosted by the presence of these surfactants. These biological properties render these gemini arginine-based surfactants as perfect promising candidates for pharmaceutical and biological properties.
- Published
- 2023
50. Novel customized age-dependent corneal membranes and interactions with biodegradable nanoparticles loaded with dexibuprofen
- Abstract
Ocular inflammation is one of the most prevalent diseases in ophthalmology and it is currently treated using eye drops of nonsteroidal antiinflammatory drugs such as dexibuprofen (DXI). However, their bioavailability is low and therefore, PLGA nanoparticles constitute a suitable approach to be administered as eyedrops. Therefore, DXI has been encapsulated into PLGA nanoparticles (DXI-NPs). Although the eye, and specifically the cornea, suffers from age-related changes in its composition, current medications are not focused on these variations. Therefore, to elucidate the interaction mechanism of DXI-NPs with the cornea in relation with age, two different corneal membrane models have been developed (corresponding to adult and elder population) using lipid monolayers, large and giant unilamellar vesicles. Interactions of both DXI and DXI-NPs were studied with these models by means of Langmuir balance technique, dipole potential, anisotropy and confocal microscopy. In addition, fluorescently labelled nanoparticles were administered to mice in order to corroborate these data obtained in vitro. It was observed that DXI-NPs interact with lipid membranes through an adhesion process, mainly in the rigid regions and afterwards DXI-NPs are internalized by a wrapping process. Furthermore, differences on the dipole potential caused by DXI-NPs in each corneal membrane have been obtained due to the increase of membrane rigidity on the ECMM. Additionally, it can be confirmed that DXI-NPs adhere to Lo phase and also inside the lipid membrane. Finally, in vitro and in vivo results corroborate that DXI-NPs are adhered to the more ordered phase. Finally, differences between interactions of DXI-NPs with the elder and adult corneal tissue were observed.
- Published
- 2023
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.