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Polysaccharide-based systems have very good emulsifying and stabilizing properties, and starch plays a leading role. Their modifications should add new quality features to the product to such an extent that preserves the structure-forming properties of native starch. The aim of this manuscript was to examine the physicochemical characteristics of the combinations of starch with phospholipids or lysozymes and determine the effect of starch modification (surface hydrophobization or biological additives) and preparation temperature (before and after gelatinization). Changes in electrokinetic potential (zeta), effective diameter, and size distribution as a function of time were analyzed using the dynamic light scattering and microelectrophoresis techniques. The wettability of starch-coated glass plates before and after modification was checked by the advancing and receding contact angle measurements, as well as the angle hysteresis, using the settle drop method as a complement to profilometry and FTIR. It can be generalized that starch dispersions are more stable than analogous n-alkane/starch emulsions at room and physiological temperatures. On the other hand, the contact angle hysteresis values usually decrease with temperature increase, pointing to a more homogeneous surface, and the hydrophobization effect decreases vs. the thickness of the substrate. Surface hydrophobization of starch carried out using an n-alkane film does not change its bulk properties and leads to improvement of its mechanical and functional properties. The obtained specific starch-based hybrid systems, characterized in detail by switchable wettability, give the possibility to determine the energetic state of the starch surface and understand the strength and specificity of interactions with substances of different polarities in biological processes and their applicability for multidirectional use. [ABSTRACT FROM AUTHOR]

Porous starch can be applied as an adsorbent and encapsulant for bioactive substances in the food and pharmaceutical industries. By using appropriate modification methods (chemical, physical, enzymatic, or mixed), it is possible to create pores on the surface of the starch granules without disturbing their integrity. This paper aimed to analyze the possibility of obtaining a porous structure for native corn, potato, and pea starches using a combination of ultrasound, enzymatic digestion, and freeze-drying methods. The starch suspensions (30%, w/w) were treated with ultrasound (20 kHz, 30 min, 20 °C), then dried and hydrolyzed with amyloglucosidase (1000 U/g starch, 50 °C, 24 h, 2% starch suspension). After enzyme digestion, the granules were freeze-dried for 72 h. The structure of the native and modified starches were examined using VIS spectroscopy, SEM, ATR-FTIR, and LTNA (low-temperature nitrogen adsorption). Based on the electrophoretic mobility measurements of the starch granules using a laser Doppler velocimeter, zeta potentials were calculated to determine the surface charge level. Additionally, the selected properties such as the water and oil holding capacities, least gelling concentration (LGC), and paste clarity were determined. The results showed that the corn starch was the most susceptible to the combined modification methods and was therefore best suited for the production of porous starch. [ABSTRACT FROM AUTHOR]

Chitosan (Ch) is a polysaccharide mainly used in cosmetics, biotechnology and medicine owing to its biocompatibility, biodegradability and low cytotoxicity. One of the challenges is the development of mechanisms responsible for its action in biomedical applications. In this aspect, it is important to get more profound insight into the chitosan interactions with peptide drugs at the molecular level. The drug of interests was a cyclosporine A (CsA) known for its effective immunosuppressive action against transplant rejection. In this study, the Langmuir technique was used to determine the interactions between Ch (dissolved in the subphase) and the monomolecular films of CsA spread at the air–chitosan solution interface. The surface pressure versus the area per molecule (π–A) measurements of the CsA monolayers on the subphase with or without Ch was conducted at 20 °C and 37 °C. The Ch insertion into the CsA monolayers was monitored by relative changes in the Δ A A area and the compression modulus. The findings demonstrate that the presence of Ch in the subphase provides the CsA monolayer expansion and affects the molecular packing and ordering in the temperature-dependent way. The temperature increase induces conformational changes in the peptide monolayers being a decisive factor which influences the kind and strength of interactions between Ch and CsA. [ABSTRACT FROM AUTHOR]

Abstract: Wettability properties of polyetheretherketone (PEEK) activated and non‐activated by nitrogen plasma have been investigated. Moreover, the PEEK plates were covered with antibacterial chitosan and its wettability properties were also investigated. Surface topography was determined using SEM and optical profilometry and surface composition by FT‐IR and XPS. For determination of apparent surface free energy, the hysteresis approach (CAH), acid base (LWAB), and Owens–Wendt (O–W) theory were used. The equilibrium contact angles were calculated from the Tadmor theory and further used for apparent surface energy calculation applying the above‐mentioned approaches. Due to the surface plasma activation both the roughness of the surface and the polar component of apparent surface free energy increased. It is shown that nitrogen plasma activation of PEEK surface increases the adhesion of chitosan to the surface due to the combination effect of: (i) the increase in surface roughness, (ii) introducing the polar groups onto the surface. [ABSTRACT FROM AUTHOR]

Wetting properties of glass surface covered with a bioglass layer in the hyaluronic acid (HA), alginate (AL) or mixed solution were determined from the contact angle measurements by the sessile drop method. Air plasma modification of plates to increase adhesion was performed in the low-temperature plasma system. Adhesion of bioglass in the polysaccharide solution on the original glass plates usually increases hydrophobic character of glass surface insignificantly in such a way that hydrocarbon chains are directed outwards and the polar part towards the glass surface. However, after the plasma action hydrophilic character of glass (and glass with biological layer) surface increases again. The changes of glass surface wettability are evidently dependent on the kind of used probe liquid and concentration of bioglass in the polysaccharide solution. Using an optical profilometer, the surface roughness of the plates was determined. An effective smoothing of the bioglass/polysaccharide surface was obtained on the plasma treated surface. The correlation between the hysteresis of water (and/or simulated body fluid) wetting angles and the topography of the surface was found for such mixed systems. However these results are somehow preliminary, it seems that cold plasma modification is an interesting tool for the development of the effect of bioglass adhesion and change of hydrophobicity/hydrophilicity character of glass materials in order to increase the spectrum of its pharmaceutical application. [ABSTRACT FROM AUTHOR]

In our studies the hybrid chitosan/1,2-dipalmitoyl- sn -glycero-3-phosphocholine (Ch/DPPC) films on the air plasma treated polyethylene terephthalate (PET) plates were prepared using a few methods: spreading (S), Langmuir–Blodgett (LB) and Langmuir–Schaefer (LS). Wetting properties of the prepared layers were determined measuring the contact angles of water, formamide and diiodomethane. Moreover, the theoretical model proposed by van Oss et al. was used to study the surface thermodynamics, i.e. surface free energy and its components. The surface topography was analyzed based on the images from atomic force microscope (AFM), optical and mechanical profilometers. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) was used for surface chemical analysis. It was found that the way of layers preparation had a significant effect on wetting properties and surface free energy of the PET/Ch/DPPC films. Both topographic features and surface chemistry influenced the material characteristics. Moreover, the study gives information on the film polarity strongly affected by the molecular organization and packing. It is believed that the DPPC molecules, modifying the chitosan coating, can improve its hemostatic properties to obtain a positive assessment of athrombogenicity. Therefore the developed surfaces seem to be promising for the enhanced PET biocompatibility suitable for cardiovascular devices. [ABSTRACT FROM AUTHOR]

The main goal of this paper was to determine interfacial properties of base untreated PET (polyethylene terephthalate) and starch modified PET as a function of time of air plasma processing. Air plasma was applied to improve the interfacial adhesion of starch to PET as an effect of oxidation and cross-linking changes. In turn, starch was used because the poor oxygen permeability of its layer can have a potential for the preservation of numerous food and pharmaceutical products. Wettability of the surfaces and work of adhesion on the basis of measurements of advancing and receding contact angles for the probe liquids on the PET plates base and covered with a starch film were obtained. The short plasma treatment was immediately followed by a sharp decrease of contact angle. Largely, in the course of longer plasma acting the contact angle of all liquids slightly increases due to the reorientation of polar groups towards the surface layer of polymer. Moreover, thermal and mechanical properties of base PET and those modified with air plasma were determined. Significant differences in elongation at break, but small differences in thermal stability and flexural properties of PET after plasma modification were observed. The starch film surface was characterized by FTIR measurements which confirm the contact angle results. Changes of time of plasma treatment and/or starch modification combination led to improvement of PET interfacial properties and biocompatibility. The obtained results expand the characteristics of PET/starch materials, which is of significant importance, particularly to formulate new starch coatings with controlled release and new biocompatible packaging PET/starch films with special properties. [ABSTRACT FROM AUTHOR]

In our studies the low-temperature plasma obtained from oxygen, argon, nitrogen was used to enhance polyetheretherketone PEEK adhesive properties and as “pre-deposition” before the main process which was deposition of layers of biologically active substances, e.g. phospholipid 1,2-dipalmitoyl- sn -glycero-3-phosphocholine (DPPC), lauryl gallate (LG) and mixed layers (DPPC/LG) by means of the Langmuir-Blodgett technique. Thus PEEK was used for creating biointerfaces with model membrane structures. Wettability of both unmodified and modified surfaces of the polymer as well as those covered with the films of biological substances was investigated by measurements of advancing and receding contact angles of water, formamide and diiodomethane. Then the values of the measured contact angles were used for determination of surface free energy and its components of the studied surfaces based on the theoretical models. The topography and roughness parameters were also estimated by optical profilometer. The results demonstrate that the appropriate plasma choice and the deposited film composition influence on wettability and thermodynamic parameters of the studied systems. The changes in the PEEK surface properties affect the interactions between the solid support and the membrane. The molecular packing density of the deposited film can be associated with the strength of adhesion and correlates with the surface energy and its component values. It is believed that plasma treatment will be a source of new information about PEEK surface mostly in the field of biomaterial engineering, adhesion of biomolecules as well as biocompatibility. [ABSTRACT FROM AUTHOR]

Low-temperature plasma effect on changes of physicochemical properties of plastic polymer polyetheretherketone (PEEK) was investigated. Despite extensive use of PEEK, information about adhesion to this polymer is limited. The adhesive and energetic properties of biomaterial and after chitosan modification were studied by contact angles measurements and surface free energy evaluation using the acid-base LWAB theory and contact angle hysteresis (CAH) model. Modification by chitosan can enhance antibacterial properties, native haemostatic and the polymer biocompatibility. Plasma modification led to variation in surface chemistry and morphology determined by an optical profilometer. After air/nitrogen plasma treatment a relatively hydrophobic character of PEEK was changed into more hydrophilic, significant differences in the wettability of sample were observed. Though, practically no differences in thermal and mechanical properties were noticed. The profilometer pictures showed an increase in the surface roughness of plasma modified PEEK due to the formation of additional polar groups with oxygen and nitrogen on the surface. Plasma treated polyetheretherketone surfaces had better adhesive features. Novel and stable chitosan-coated PEEK biomaterials were prepared applicable for different industries, mainly pharmacy and reconstructive medicine. [ABSTRACT FROM AUTHOR]

Novel chitosan-coated PEEK biomaterials were prepared by air plasma modification. Low-temperature plasma effect on changes of specific thermal, mechanical and adhesive properties of polyetheretherketone (PEEK) was investigated. The topography and surface roughness of the prepared materials were determined using an optical profilometer. The wetting and energetic properties of biomaterials were studied by means of advancing and receding contact angles measurements and then apparent surface free energy (and its components) were evaluated applying the LWAB (Lifshitz–van der Waals Acid Base) theory and contact angle hysteresis model. After air plasma treatment a fairly hydrophobic character of PEEK was changed to strongly hydrophilic one. Significant differences in the wettability and thermal stability of samples were observed. However, hardly any differences in excellent mechanical properties were noticed. The profilometer images showed an increase in the surface roughness of PEEK modified surface due to the change of cross-link density, elasticity and formation of additional polar groups on the surface. Plasma treated polyetheretherketone surfaces had better adhesive features and stable chitosan coating was created. Modification by chitosan improved antibacterial properties, inherent haemostatics and polymer biocompatibility. These advantages allowed to obtain new attractive biomaterials from the same polymer differing in properties for a wide spectrum of applications, mainly regenerative medicine and orthopedic surgery. [ABSTRACT FROM AUTHOR]

The objective of this work was to determine surface properties of biopolymer film as a function of temperature and/or after plasma treatment with the aim of further wettability tests and biocompatibility. The examined biopolymers were native starch and starch modified by solution of PC (phosphatidylcholine). Contact angles for polar water (and formamide) and nonpolar diiodomethane on the glass plates covered with starch film before and after gelatinization (25 °C, 37 °C and 60 °C) were measured for the base and plasma modified film. The surface free energy of solid (gel) was determined from the advancing and receding contact angles of these probe liquids, using the contact angle hysteresis model (CAH). The plasma treatment was immediately followed by a sharp decrease of contact angle and in the course of ageing the contact angle also decreased due to the reorientation of polar groups into the polymer surface layer. To depict better changes in hydrophilic/hydrophobic character of the starch surface before and after modification the work of water spreading, W S was calculated. A sharp decrease in negative values of W S takes place which indicates more hydrophilic character of starch surface after modification. Surface morphology and roughness were studied by optical profilometer and FTIR measurements which confirm the contact angle results. It was also proved that a combination of input treatment parameters led to improvement of biopolymer wettability and provided possibilities of starch application where uniform thin films are required. [ABSTRACT FROM AUTHOR]

The main goal of this paper was to determine wettability properties of native starch and starch modified by antibacterial solution of chitosan or lysozyme as a function of temperature and/or after plasma treatment. Contact angles for polar water (and formamide) and nonpolar diiodomethane on glass plates covered with starch film before and after gelatinization (25 °C, 37 °C and 60 °C) were measured. The surface free energy of solid (gel) was determined from the advancing and receding contact angles of these probe liquids, using the contact angle hysteresis model (CAH). The plasma treatment was immediately followed by a sharp decrease of contact angle. In the course of ageing the contact angle also decreased due to the reorientation of polar groups into the surface layer of polymer. Also a sharp decrease in negative values of W S takes place which indicates more hydrophilic character of starch after plasma treatment. The same was after lysozyme modification but to a smaller extent. The opposite trend of changes was visible after chitosan solution treatment. The surface characterization was observed by FTIR measurements and surface topography from the profilometer images and such measurements well support the contact angle results. The arrangement of temperature, plasma treatment or biological modification can lead to improvement of starch surface wettability and stability. The obtained results open up possibilities of starch application in food, paper and packaging industries as well as in pharmacy. [ABSTRACT FROM AUTHOR]

Abstract: The properties of n-tetradecane emulsions with dipalmitoylphosphatidylcholine (DPPC) or dioleoylphosphatidylcholine (DOPC) in 1M ethanol were investigated at 20 and 37°C. The zwitterionic phospholipids having the same headgroup bound to the apolar tail composed of two saturated or unsaturated chains were used as stabilizing agents. Both phospholipids may self-organize into aggregates, which possess different sizes and surface affinities. Electrokinetic properties of the systems at natural pH or pH 8 were investigated taking into account the effective diameter of the droplets as well as the zeta potentials using the dynamic light scattering technique. The effect of both phospholipids decreases the initially negative zeta potential of the n-tetradecane emulsion and is more evident in the case of DPPC especially at a physiological temperature near its main temperature transition. The change of zeta potential by DOPC is visible at both temperatures probably as an effect of a loose packing of this phospholipid on n-tetradecane droplets, because of the presence of double bonds in its molecule. Also, the role of ethanol dipoles on the stability of oil/phospholipid emulsions is obvious. The other aim of paper was the characterization of the phospholipase A2 influence on DOPC hydrolysis in the emulsion environment in order to emphasize the importance of such methodology. The present work is the first study that explores the effects of both electrolyte ions and ethanol molecules on DOPC hydrolysis by phospholipase. The effect of enzyme on the n-tetradecane/DOPC emulsions was investigated at pH 8 with Na+ or Ca2+ ions, which occur in the physiological fluids. The effective diameters do not always correlate with the zeta potentials. A possible reason of such behavior might a mechanism different from the electrostatic stabilization. The particular role of Ca2+ ions in the emulsions with phospholipids was confirmed. Those investigations provide insight into the properties of the PLA2 hydrolysis process enhanced by added ethanol. It is believed that the enzyme effect on the phospholipid aggregation behavior at the oil–water interface will be helpful for understanding other biological phenomena. [Copyright &y& Elsevier]

Abstract: Adsorption of dipalmitoylphosphatidylcholine (DPPC) from NaCl solution on SiO2 particles in suspension was investigated by means of zeta potential and effective diameter measurements as a function of pH using dynamic light scattering. Also, the zeta potential of DPPC aggregates in the same environment was measured. By comprising the results, it was found that DPPC adsorbs on the silica surface, which resulted in decrease of negative zeta potential of the silica suspension. However, DPPC stabilized the SiO2 particle aggregates, which resulted in smaller and smoother changes of the aggregate size during 2h-time experiments, probably due to steric stabilization. In the next series of the experiments the effect of enzymes (phospholipase A2 or lipase Candida Cylindracea) on the behavior of the silica/DPPC suspension was studied. The kind of the enzymes; the hydrolysis products, which were palmitic acid and lysophosphatidylcholine (or glycerylphosphorylcholine), and pH influenced the suspension zeta potential. The lipase was found to be a more active enzyme, both at natural pH=5.8 and pH=8. The evaluated parameters connected with the adsorption process and resulting from enzyme action seem to be helpful for further characterization of the silica/DPPC system, which is discussed in the paper. [Copyright &y& Elsevier]

Abstract: The measurements of the penetration rates of n-octane, water and formamide on bare commercial Al2O3 plates and those covered by dipalmitoylphosphatidylcholine (DPPC) or DPPC+enzyme lipase from 1mM NaCl solution were conducted. Influence of phospholipid and enzyme on the energetic properties of the solid surface was discussed by means of the modified Washburn equation. Additionally, to explain behavior of Al2O3 systems, the measurements of the zeta potential of the same alumina (powder) suspension in NaCl after adding DPPC or DPPC+enzyme lipase, were performed. The van Oss et al.''s approach to interfacial free energy interactions was applied to determine solid surface free energy components after DPPC or lipase treatment. Moreover the work of water spreading was calculated for better description of such systems. On the basis of the obtained results, it is suggested that adsorption of DPPC on the Al2O3 plates increased the hydrophobic character of the alumina surface but after the enzyme action the products of dipalmitoylphosphatidylcholine hydrolysis by lipase, which are glycerylphosphorylcholine and palmitic acid, increased its hydrophilic character again. The most striking were the changes of the electron-donor (γ s −) parameter (which ranged from 15 to 34mJ/m2) and those of acid–base component in the range 13–18mJ/m2 delivering interesting information about the change of Al2O3 surface character. Some correlations found between the surface free energy components and the zeta potential of alumina suspension are discussed. The obtained relationships show usefulness of the applied techniques: the thin layer wicking method and electrokinetic measurements to investigate the enzyme effect on wettability changes of the phospholipid-covered alumina surface. [Copyright &y& Elsevier]

Abstract: Wetting properties of commercial Al2O3 plates contacted with dipalmitoylphosphatidylcholine (DPPC) or DPPC+enzyme (phospholipase PLA2) in NaCl solution were determined by thin layer wicking and with the help of Washburn equation. Van Oss et al.’s approach to interfacial free energy interactions was applied to determining the solid surface free energy components. Wicking experiments were performed both for bare and alumina plates precontacted overnight with the probe liquid saturated vapours, as well as the untreated and DPPC (or DPPC+PLA2) treated alumina plates. For this purpose the penetration rates of n-octane, water and formamide were measured. From these experiments it resulted that original alumina surface is strongly polar with electron–donor interactions originating from the surface hydroxyl groups. Adsorption of DPPC on Al2O3 plates slightly increased the hydrophobic character of the alumina surface (considerable decrease of the electron–donor, parameter and component was visible) in such a way that the hydrocarbon chains were directed outwards and the polar part towards the alumina surface. However, after the enzyme action the products of DPPC hydrolysis by PLA2 (palmitic acid and lysophosphatidylcholine) increased again the hydrophilic character of Al2O3 surface (a minor increase in component and drastic increase of the electron-donor parameter was noticeable). After treatment with DPPC or DPPC+enzyme PLA2 solution the changes of the total surface free energy of alumina and its Lifshits-van der Waals () component were in the range 7–10mJ/m2, but the most considerable and delivering more interesting information were the changes of the electron–donor () parameter ranging from 27 to 35mJ/m2. Moreover, the changes of the alumina surface wettability were dependent on the time of the enzyme contacting with DPPC in NaCl solution. On the basis of the obtained results it seems that the thin layer wicking method can be an additional useful tool in investigations of the effect of phospholipid and PLA2 action on the hydrophilic–hydrophobic character of alumina surface. [Copyright &y& Elsevier]

Abstract: The properties of n-tetradecane/electrolyte emulsions with DPPC or DPPC vesicles in the electrolyte solution were investigated. The DPPC molecules form different aggregates, which possess different surface affinity, size and structure, and therefore we assumed some differences in the adsorption at the oil droplet/water interface. The n-tetradecane emulsions in 1:1, 1:2 and 1:3 electrolytes were prepared by mechanical stirring in the presence of DPPC at natural pH. Electrokinetic properties of the systems were investigated taking into account the effective diameter and multimodal size distribution of the droplets as well as the zeta potentials using the dynamic light scattering technique. The zeta potential of the droplets was negative in all systems with NaCl. In the emulsions with CaCl2 at a higher concentration of electrolyte and emulsions with LaCl3 with all investigated concentrations, positive values were observed. Similar measurements were performed for DPPC vesicles in the electrolyte solution. The pH and ionic strength changes induce those in the electrical charge of DPPC layer or vesicle surface. This is due to the fact that the DPPC molecule contains –PO− and –N(CH3)3 groups, which are in equilibrium with H+ and OH−, as well as other ions present in the solution, i.e. Na+, Ca2+, La3+ or Cl−. In the n-tetradecane/electrolyte emulsion stabilized by DPPC or DPPC vesicles the zeta potential may be also related to acid–base interactions. The effect of the ions from the solution on the DPPC layer adsorbed on n-tetradecane droplets or DPPC vesicles is discussed. [Copyright &y& Elsevier]

Abstract: Adsorption of phospholipid (DPPC) from NaCl electrolyte solution (or from chloroform solution) on Al2O3 particles in suspension was investigated by means of the zeta potential and effective diameter measurements as a function of pH using dynamic light scattering. Al2O3 particles were precovered with an amount of dipalmitoylphosphatidylcholine sufficient to cover the alumina surface by the statistical mono- or bilayer (ML or BL). It was found that DPPC from NaCl solution was adsorbed on Al2O3 surface independently of phospholipid concentration, which resulted in decrease of the initial zeta potential of Al2O3 suspension. When alumina was precovered with DPPC from chloroform (ML or BL) some reorientation of phospholipid molecules could take place. Despite the lowering of the zeta potential value in both cases (from both aqueous and chloroform solution) DPPC stabilized the Al2O3 particle aggregates, which resulted in smaller and smoother changes of the aggregate size during 2-experiment hours due to steric and electrostatic stabilization. In the next series of experiments the effect of enzymes (phospholipase A2 or lipase Candida cylindracea) on the behavior of Al2O3/DPPC particles was studied. The kind of the enzymes, the hydrolysis products, which were palmitic acid and lysophosphatidylcholine (or glycerylphosphorylcholine), and pH changed the suspension zeta potential and influenced the stability of these systems. Lipase was found to be a more active enzyme than phospholipase. The electrokinetic parameters connected with the adsorption process and resulting from the enzyme action seem to be helpful for characterization of the Al2O3/DPPC suspension and the activity of the enzymes, which is discussed in the paper. [ABSTRACT FROM AUTHOR]

Abstract: Wetting properties of silica plates contacted with dipalmitoylphosphatidylcholine (DPPC) or DPPC/enzyme (phospholipase PLA2) in NaCl solution were determined by thin layer wicking and with a help of Washburn equation. The wicking experiments were performed both for bare plates and the silica plates precontacted overnight with the probe liquid saturated vapors the silica plates, as well as untreated and DPPC (or DPPC/enzyme) treated. Adsorption of DPPC on original silica plates increases a bit hydrophobic character of silica surface in such a way that hydrocarbon chains are directed outwards and the polar part towards the silica surface. However, after the enzyme action the products of DPPC hydrolysis by PLA2 (palmitic acid and lysophosphatidylcholine) increase again hydrophilic character of silica surface (an increase in acid–base interactions, ). The changes of silica surface wettability are evidently dependent on the time of enzyme contacting with DPPC in NaCl solution. Although, the changes of total surface free energy of silica after treatment with DPPC/enzyme solution are minor about 2–6mJ/m2, the changes of the electron-donor () and Lifshitz–van der Waals () component of the surface free energy are noticeable. Despite, these results are somehow preliminary, it seems that thin layer wicking method is an interesting tool for investigation of the effect of adsorbed DPPC on hydrophobicity/hydrophilicity of silica surface and influence of enzyme PLA2 action. [Copyright &y& Elsevier]

Abstract: The electrokinetic properties of n-tetradecane/ethanol emulsions in the presence of dipalmitoylphosphatidylcholine (DPPC) and enzyme (lipase Candida cylindracea or phospholipase A2) were investigated. Applying the dynamic light scattering zeta potentials and effective diameters of the emulsions droplets were determined as a function of pH and enzyme concentration. Investigation of the electrokinetic phenomena in the presence of phospholipids and enzymes are important for better understanding processes occurring in biological and pharmaceutical systems at interfaces like solid surfaces, cell membranes and oil–water interfaces. Generally, it was found that the presence of DPPC molecules decrease the negative zeta potentials of n-tetradecane droplets and the charge repulsion. Lipase presence increases the negative zeta potentials of n-tetradecane/DPPC (in ethanol) droplets at acidic and natural pH. In the buffer (pH 8) and pH 12 small decrease in the negative zeta potential of n-tetradecane/DPPC droplets is visible. On the other hand if PLA2 enzyme is used small increase in the negative zeta potential of n-tetradecane/DPPC (in buffer) droplets occurs. It is believed that the differences in the enzyme effect on the measured parameters result from hydrolysis reaction and preferable pH of catalytic reaction. Possible reasons for the observed changes of zeta potential and effective diameter are discussed. [Copyright &y& Elsevier]

In recent decades synthetic polymers have gained increasing popularity, and nowadays they are an integral part of people's daily lives. In addition, owing to their competitive advantage and being susceptible to modification, polymers have stimulated the fast development of innovative technologies in many areas of science. Biopolymers are of particular interest in various branches of medicine, such as implantology of bones, cartilage and skin tissues as well as blood vessels. Biomaterials with such specific applications must have appropriate mechanical and strength characteristics and above all they must be compatible with the surrounding tissues, human blood and its components, i.e. exhibit high hemo- and biocompatibility, low or no thrombo- and carcinogenicity, foreign body response (host response), appropriate osteoconduction, osteoinduction and mineralization. For biocompatibility improvement many surface treatment techniques have been utilized leading to fabricate the polymer biomaterials of required properties, also at nanoscale. This review paper discusses the most important physicochemical and biological factors that affect the biocompatibility, thus the reaction of the living organism after insertion of the polymer-based biomaterials, i.e. surface modification and/or degradation, surface composition (functional groups and charge), size and shapes, hydrophilic-hydrophobic character, wettability and surface free energy, topography (roughness, stiffness), crystalline and amorphous structure, nanostructure, cell adhesion and proliferation, cellular uptake. Particularly, the application of polysaccharides (chitosan, cellulose, starch) in the tissue engineering is emphasized. [Display omitted] • The review outlines a general scheme for creating bio- and hemocompatible polymer materials. • Biomaterials of proper mechanical characteristics and of positive host-response are required. • Biocompatibility is determined by the graft surface physicochemical properties. • Properly selected surface features of polymer provide the conditions for the tissue repair. • Knowledge of processes inducing the host response is a way to find the suitable implant. [ABSTRACT FROM AUTHOR]

Abstract: Extensive investigations of electrokinetic properties of emulsions and suspensions deal among other things with the application of natural stabilizers. Dipalmitoylphosphatidylcholine (DPPC) is present in many biochemical processes including living organisms. In this paper the dynamic properties of n-tetradecane/water emulsions were studied in the presence of DPPC which changes the interfacial free energy and the zeta potential. The zeta potential of the emulsion was determined as a function of pH and electrolyte concentration. H+/OH− ions were found to determine the potential, and also a clearly visible effect of the Na+, Ca2+ and La3+ ions appeared. The decrease in absolute value of the zeta potential was usually accompanied by a growth in effective diameter of the emulsion droplets. To better describe the stabilizing mechanism of DPPC, the electric charge at the shear plane was calculated using the zeta potentials and diameters of the droplets, assuming spherical particles. In n-tetradecane/electrolyte emulsion stabilized by DPPC the zeta potential may be also related to acid–base interactions. From the results, however, repulsion of double layers was concluded to be the main stabilizing mechanism. Possible stabilizing effect of DPPC liposomes and/or other aggregates with adsorbed ions needs further investigations. [Copyright &y& Elsevier]

Abstract: Properties of surface of hydrophobic liquid (e.g. n-alkane) in aqueous solutions are very important for stability of dispersed systems, i.e. emulsions and suspensions, as well as in many biochemical processes including living organisms. Application of natural stabilizers it is a key aspect of wide-ranging investigations of emulsion. One of such systems is oil/lecithin solution. The adsorbed lecithin layer at the oil droplets determines the structural and dynamic properties of oil/water emulsions. It changes the interfacial free energy and the zeta potential. The zeta potentials determined in this paper as a function of time and pH confirm that H+/OH− ions are potential determining and the largest effect of OH− is visible at alkaline pHs. The decrease in absolute value of the zeta potential was accompanied by a growth in the effective diameter of emulsion droplets. Using both the potential and diameters electric charge at the shear plane for spherical particle was calculated. In these systems the zeta potential may be created by immobilized and oriented water dipoles and acid–base interactions. However, on the basis of the results it is concluded that the main stabilizing mechanism is the double layers repulsion, besides possible stabilizing effect of lecithin liposomes and other aggregates. [Copyright &y& Elsevier]

New nonionic surfactants, N-alkyl-[N,N-bis(3-lactobionylamido)propyl] amine (N-alkyl: &z.sbnd;C12H25, &z.sbnd;C16H33, &z.sbnd;C18H38) and a gemini surfactant containing cetyl chain were investigated as stabilizers for n-tetradecane/ethanol (0.5 or 1 M) emulsions. These are nontoxic substances and could be applied for pharmaceutical or dairy emulsion preparation. The dynamic light scattering technique was applied for determination of the average effective diameter and zeta potential of the droplets as a function of time up to two days. These parameters were determined subsequently on the same sample without any mixing of it. Depending on the surfactant concentration (10−6, 10−5 and 10−4 M) and the emulsion pH, an increase or decrease in the droplet size was observed relative to the emulsion in the alcohol solution alone. It seems that the dynamic light scattering technique is a useful one for tracking changes in droplet size distribution in the emulsion systems. Some of the emulsions were more stable in the surfactant presence. However, in some other cases the surfactants destabilized emulsion. The zeta potentials in 10−5 and 10−4 M surfactant solutions were positive at pH natural (5–8) and acidic (pH 4) while at pH 11 they were negative. The isoelectric point of the emulsion droplets occurred in pH range 8–10, depending on the kind and concentration of the surfactant. It indicated that H+ and OH− ions were potential determining via adsorbed on the oil surface the surfactant molecules. In surfactant-free emulsion, the zeta potentials of n-tetradecane droplets were negative in pH range 4–11. It was concluded that hydrogen bondings between surfactant/alcohol and alcohol/water polar groups played an essential role in the emulsion stabilization (the extended DLVO theory). [Copyright &y& Elsevier]

Zeta potential, average diameter and multimodal size distribution were studied for n-tetradecane emulsions in aqueous solution of ethanol (0.5 and 1.0 M) in which bovine serum albumin (BSA), α-lactalbumin or β-casein (1, 2, or 5 mg/100 ml) was also dissolved. The emulsion pH was natural (7.3) or regulated to 4 or 11. The parameters were determined as a function of time, i.e. after 5, 15, 30, 60, 120 min, 1, and 2 days, and 1 week, since the emulsion preparation. The emulsions were prepared by dissolving 0.1 ml of the n-alkane in a proper amount of ethanol and then water or protein solution was added to obtain 100 ml of the emulsion in which total concentration of ethanol was 0.5 or 1.0 M. Next, the emulsion was sonicated for 15 min and the measuring polyacrylic cells of the apparatus were filled with the emulsion. The isoelectric point (i.e.p.) of the droplets in the presence of investigated proteins (2 mg/100 ml) and in 1 M ethanol occurred at pH 4.9, 4.7 and 2.2, for BSA, β-casein and α-lactalbumin, respectively. In pH range 5.5–10, the zeta potentials of freshly prepared emulsions in 1 M ethanol were negative and relatively large, from −45 to −60 mV. In β-casein presence, the n-alkane droplets were larger and negative zeta potentials higher than in the presence of two other investigated proteins. However, in the presence of each of the investigated proteins the droplet size increased slightly relative to that in ethanol solution alone. Nevertheless, the emulsions were relatively stable. In 0.5 M ethanol, the protein presence stabilized the emulsions. On time scale, the changes of negative zeta potential did not correlate in a straight way with changes in the droplet size (the emulsion stability). Experiments showed that without ethanol presence in the emulsion, β-casein alone can be used as an emulsifier already at its concentration of 1 mg/100 ml for 0.1 ml of n-tetradecane content both at natural and alkaline environment. However, no stable emulsion could be obtained using BSA or α-lactalbumin. Multimodal size distribution analysis showed that the droplet sizes in the studied emulsions could be grouped in one or two comparable populations only. [Copyright &y& Elsevier]

Dermatology and cosmetology currently prioritize healthy, youthful-looking skin. As a result, research is being conducted worldwide to uncover natural substances and carriers that allow for controlled release, which could aid in the battle against a variety of skin illnesses and slow the aging process. This study examined the biological and physicochemical features of novel hydrogels containing cannabidiol (CBD) and α-terpineol (TER). The hydrogels were obtained from ε-caprolactone (CL) and poly(ethylene glycol) (PEG) copolymers, diethylene glycol (DEG), poly(tetrahydrofuran) (PTHF), 1,6-diisocyanatohexane (HDI), and chitosan (CHT) components, whereas the biodegradable oligomers were synthesized using the enzyme ring-opening polymerization (e-ROP) method. The in vitro release rate of the active compounds from the hydrogels was characterized by mainly first-order kinetics, without a "burst release". The antimicrobial, anti-inflammatory, cytotoxic, antioxidant, and anti-aging qualities of the designed drug delivery systems (DDSs) were evaluated. The findings indicate that the hydrogel carriers that were developed have the ability to scavenge free radicals and impact the activity of antioxidant enzymes while avoiding any negative effects on keratinocytes and fibroblasts. Furthermore, they have anti-inflammatory qualities by impeding protein denaturation as well as the activity of proteinase and lipoxygenase. Additionally, their ability to reduce the multiplication of pathogenic bacteria and inhibit the activity of collagenase and elastase has been demonstrated. Thus, the developed hydrogel carriers may be effective systems for the controlled delivery of CBD, which may become a valuable tool for cosmetologists and dermatologists. [ABSTRACT FROM AUTHOR]

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]

• Hybrid lignin-containing microspheres were synthesized. • The incorporation of lignin had a positive effect on their electrokinetic properties. • Microspheres containing methacrylated lignin had well-developed porous structures. • They have a great potential for the removal of dyes from aqueous solutions. • The incorporation of biopolymer contributes to better utilization of lignin. Hybrid microspheres of trimethoxyvinylsilane, divinylbenzene and lignin were synthesized by a suspension polymerization method. Commercially available alkali lignin and the methanol fraction of softwood kraft lignin were used as the bio-component of polymeric microspheres. The methanol fraction of lignin had a high content of phenolic groups and low molecular weight which are desirable features for further methacrylation. The physicochemical and electrokinetic properties of the synthesized materials were analyzed in detail. The preliminary modification of the hybrids with lignin had a noticeable positive effect on the stability and electrokinetic properties of the final products compared to those of unmodified microspheres composed of divinylbenzene and trimethoxyvinylsilane (DVB-TMVS). Thermal properties were investigated by differential scanning calorimetry and thermogravimetric analysis, and the morphology was studied using scanning electron microscopy. The microsphere texture was characterized using low-temperature nitrogen adsorption. The microspheres were mesoporous with a specific surface area in the range of 149–305 m2/g. The porosity of the hybrid materials was influenced by the type and modification of the lignin; microspheres with modified lignin in general had more developed porous structures. The applicability of the porous materials obtained as sorbents for the removal of dyes was confirmed in a batch experiment. The mechanism of interactions between dyes and a bio-sorbent containing lignin may involve electrostatic interactions between the positively charged nitrogen atoms of the dye molecule and the dissociated functional groups of the adsorbent, hydrogen bonding and π-π interactions. [ABSTRACT FROM AUTHOR]

The paper presents changes in wettability of the unmodified and modified polyethylene terephthalate (PET) surfaces. A low temperature air plasma was used to activate the polymer surface and to change its hydrophilic-hydrophobic properties. Then, using the Langmuir-Blodgett technique, the Langmuir monolayers of l,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and cyclosporine A (CsA) with different molar fractions, i.e. χ=0.25, 0.50, 0.75, were deposited onto the activated PET surface. Besides, a series of DPPC and CsA monolayers was also transferred onto the chitosan layer, previously produced on the plasma treated PET by the dip- coating method. The wetting properties of such modified PET surfaces were then investigated by the contact angle measurements using three test liquids with well-known surface tension components. The obtained results show that wettability depends on the composition of the deposited DPPC/CsA layer with or without chitosan. Presence of chitosan makes the DPPC/CsA film surface more polar due to specific organization of molecules that expose their polar heads outside. [ABSTRACT FROM AUTHOR]

The studies of model biological membranes consisted of phospholipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) were carried out by means of the Langmuir monolayer technique using subphases containing chitosan (Ch), titanium (IV) oxide (TiO2), hyaluronic acid (HA) or mixture of them. The aim was to determine the effect of individual components of subphase and their respective combinations on behavior of the DPPC membrane. The systems were tested at room temperature (20 °C) and at a natural pH of about 4.8, which was close to the pH of the human skin (4.7–5.6). The surface pressure–area per molecule (π–A) isotherms were obtained. Their analysis showed that all substances studied affected the phospholipid membrane which was revealed in the changes of mean molecular area, compression modulus and pressure of the liquid-expanded/liquid-condensed (LE/LC) phase transition. The results were discussed in terms of the nature and strength of mutual interactions. The more profound effect was found at low surface pressures at which the monolayers occurred in more expanded state. However, at the surface pressure corresponding to that of biological membranes, systems had very similar parameters compared to model DPPC isotherm. [ABSTRACT FROM AUTHOR]

Non steroidal anti-inflammatory drugs (NSAIDs) are those of the most common over the counter (OTC) medications widely used by millions of people every day. Unfortunately, despite their popularity those drugs can cause serious side effects in the digestive system (ulcers, bleeding, and pain). These inconveniences are caused by the changes in the structures of the outer phospholipid layers of gastric mucus and mucosa. As a result the H+ ions from the stomach acid can pass easily through these natural protective barriers and damage the epithelial cells which causes ulcers and bleeding. Chitosan as a polysaccharide known for its unique biocompatibility, drug delivery possibilities and wound healing effect has been chosen to examine if it can induce the reduction of undesirable effects of naproxen. This paper focuses on the interactions of the naproxen with a model biological membrane with and without the presence of chitosan. Applying the Langmuir technique coupled with the surface potential measurements and the Brewster angle microscope imaging allowed to characterize successfully examined systems in terms of the monolayer compressibility, thickness, stability, electric properties and morphology. The results proved that the presence of naproxen alters the mechanical and electrical properties of the model membrane depending on its surface pressure. Moreover, the addition of chitosan to the lipid-drug system causes significant changes in the properties of the layer, i.e. a reduction of its compressibility, thickness and morphology modification. Nevertheless, chitosan suppresses some changes induced by naproxen such as alteration of the apparent dipole moment and film stability. [Display omitted] • The presence of the naproxen and chitosan in the model membrane environment caused its significant perturbations. • Naproxen can remain in the hydrocarbon area of the lipid membrane affecting its electrical properties and thickness. • Chitosan molecules can accumulate in the polar areas of the lipid membrane then penetrate it. • This can act as a shield repelling hydrogen ions from the lipid membrane disrupted by NSAIDs in an acidic environment. [ABSTRACT FROM AUTHOR]

Poly(ethylene terephthalate)—PET—is one of the most frequently used polymers in biomedical applications. Due to chemical inertness, PET surface modification is necessary to gain specific properties, making the polymer biocompatible. The aim of this paper is to characterize the multi-component films containing chitosan (Ch), phospholipid 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), immunosuppressant cyclosporine A (CsA) and/or antioxidant lauryl gallate (LG) which can be utilized as a very attractive material for developing the PET coatings. Chitosan was employed owing to its antibacterial activity and also its ability to promote cell adhesion and proliferation favorable for tissue engineering and regeneration purposes. Moreover, the Ch film can be additionally modified with other substances of biological importance (DOPC, CsA and LG). The layers of varying compositions were prepared using the Langmuir—Blodgett (LB) technique on the air plasma-activated PET support. Then their nanostructure, molecular distribution, surface chemistry and wettability were determined by atomic force microscopy (AFM), time-of-flight secondary ion mass spectrometry (TOF-SIMS), X-ray photoelectron spectroscopy (XPS), contact angle (CA) measurements and the surface free energy and its components' determination, respectively. The obtained results show clearly the dependence of the surface properties of the films on the molar ratio of components and allow for a better understanding of the coating organization and mechanisms of interactions at the molecular level both inside the films and between the films and the polar/apolar liquids imitating the environment of different properties. The organized layers of this type can be helpful in gaining control over the surface properties of the biomaterial, thus getting rid of the limitations in favor of increased biocompatibility. This is a good basis for further investigations on the correlation of the immune system response to the presence of biomaterial and its physicochemical properties. [ABSTRACT FROM AUTHOR]

Polyetheretherketone (PEEK) is a biocompatible, chemically and physically stable radiolucent polymer that exhibits a similar elastic modulus to the normal human bone, making it an attractive orthopedic implant material. However, PEEK is biologically inert, preventing strong enough bonding with the surrounding bone tissue when implanted in vivo. Surface modification and composite preparation are the two main strategies for the improvement of the bioactivity of PEEK. In this study, the plasma activated PEEK surfaces with the embedded bioglass, chitosan, and bioglass-chitosan mixed layers applying from the solution dip-coating technique were investigated. The most prominent factors affecting the coating biocompatibility are strictly connected with the composition of its outer surface (its charge and functional groups), hydrophilic-hydrophobic character, wettability and surface free energy, and topography (size of pores/substructures, roughness, stiffness), as well as the personal characteristics of the patient. The obtained surfaces were examined in terms of wettability and surface-free energy changes. Additionally, FTIR (Fourier Transformation Infrared Spectrometry) and SIMS (Secondary Ion Mass Spectrometry) were applied to establish and control the coating composition. Simultaneously the structure of coatings was visualized with the aid of SEM (Scanning Electron Microscopy). Finally, the obtained systems were incubated in SBF (Simulated Body Fluid) to verify the modifications' influence on the bioactivity/biocompatibility of the PEEK surface. Different structures with variable compositions, as well as changes of the wettability, were observed depending on the applied modification. In addition, the incubation in SBF suggested that the bioglass-chitosan ratio influenced the formation of apatite-like structures on the modified PEEK surfaces. [ABSTRACT FROM AUTHOR]

The Langmuir technique allows for the characterization of monolayers of biological and/or biologically active compounds which have high potential for application in tissue engineering to improve the implants biocompatibility. This group of substances includes 1,2-dioleoyl- sn -glycero-3-phosphocholine (DOPC), cyclosporine A (CsA), lauryl gallate (LG), and chitosan (Ch). The single (DOPC, CsA, LG), binary (DOPC-CsA 1:1) and ternary (DOPC-CsA-LG 3:3:2, 1:1:2, 1:1:6 that correspond to χ LG = 0.25, 0.50, 0.75) monolayers on the acidic subphase with or without chitosan (Ch) were characterized using the Langmuir technique coupled with the surface potential meter. The dependence of the surface pressure and the surface potential on the area per molecule (π − A and ∆ V − A isotherms, respectively) was determined. Based on the above isotherms data, the compression modulus (C s − 1), excess and total Gibbs energy of mixing (∆ G exc and ∆ G mix) as well as the apparent dipole moment (μ a) were calculated. These parameters allowed drawing conclusions about the molecular packing, the orientation of molecules, the type and magnitude of interactions within the monolayers, and finally about their stability, depending on the components proportions and the contribution of Ch molecules. The main findings indicated that the insertion of LG to the binary DOPC-CsA 0.50 monolayer resulted in a shift of the π − A isotherms towards smaller areas per molecule, the smaller areas the higher amount of LG. That correlated with an increase in packing density (larger C s − 1 values) and an attraction between the molecules (revealed by the negative ∆ G exc and ∆ G mix values) in the three-component monolayers. Furthermore, the addition of chitosan (Ch) molecules into the subphase stiffened the multicomponent (DOPC-CsA or DOPC-CsA-LG) films. The strengthening of the attractive interactions and better miscibility were observed for all the DOPC-CsA-LG films. Therefore, these monolayers spread on the Ch subphase were found to be thermodynamically stable (among them the most stable was DOPC-CsA-LG 0.50) and could be successfully used for coating implants in order to improve their biocompatibility with the surrounding tissues. [Display omitted] • Chitosan (Ch) molecules enhance the attraction between the DOPC, CsA and LG molecules. • Presence of Ch increases the surface potential and the apparent dipole moment values. • Ternary DOPC-CsA-LG monolayers on the Ch subphase are thermodynamically stable. • Obtained monolayers can be transferred to a solid support to improve its biocompatibility. [ABSTRACT FROM AUTHOR]

Surface properties of polyethylene terephthalate (PET) coated with the ternary monolayers of the phospholipid 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), the immunosuppressant cyclosporine A (CsA), and the antioxidant lauryl gallate (LG) were examined. The films were deposited, by means of the Langmuir–Blodgett (LB) technique, on activated by air low temperature plasma PET plates (PETair). Their topography and surface chemistry were determined with the help of atomic force microscopy (AFM) and time-of-flight secondary ion mass spectrometry (TOF-SIMS), respectively, while wettability was evaluated by the contact angle measurements. Then, the surface free energy and its components were calculated from the Lifshitz–van der Waals/Acid–Base (LWAB) approach. The AFM imaging showed that the Langmuir monolayers were transferred effectively and yielded smoothing of the PETair surface. Mass spectrometry confirmed compatibility of the quantitative and qualitative compositions of the monolayers before and after the transfer onto the substrate. Moreover, the molecular arrangement in the LB films and possible mechanisms of DOPC-CsA-LG interactions were determined. The wettability studies provided information on the type and magnitude of the interactions that can occur between the biocoatings and the liquids imitating different environments. It was found that the changes from open to closed conformation of CsA molecules are driven by the hydrophobic environment ensured by the surrounding DOPC and LG molecules. This process is of significance to drug delivery where the CsA molecules can be released directly from the biomaterial surface by passive diffusion. The obtained results showed that the chosen techniques are complementary for the characterization of the molecular organization of multicomponent LB films at the polymer substrate as well as for designing biocompatible coatings with precisely defined wettability. [ABSTRACT FROM AUTHOR]

The study aimed to determine the chemical nature, energy state, and topography of chitosan and/or TiO 2 thin layers, which were transferred from different aqueous solutions or dispersions onto a solid support (mica) by a dip-coating method using the Langmuir-Blodgett trough. The surface topography was analysed using an optical profilometer. The performed wettability measurements were used to estimate changes in the total surface free energy based on the theoretical mathematical Lifshitz-van der Waals-Acid-Base model. In addition, the Langmuir technique was employed to determine the effect of Ch-TiO 2 and/or hyaluronic acid (HA) on the model membrane properties in aspect of biocompatibility. The prepared materials can be classified as high-energy, hydrophilic, with roughness in the nanometric scale. Physicochemical parameters have a significant impact on the processes that take place in the surface layer of the biomaterial being in contact with the biological environment. [Display omitted] • Biocompatible chitosan-TiO 2 coating with nano-scale irregularities was obtained on mica. • Surface properties of novel material (Ch-HA-TiO 2) were characterized. • Relationship between wettability and surface microstructure was shown. • Hybrid biomaterial exhibited the high surface free energy. • Presence of the hyaluronic acid increased the biocompatibility of Ch-TiO 2 combination. [ABSTRACT FROM AUTHOR]

The mica supported Langmuir-Blodgett (LB) monolayers composed of 1,2‑dipalmitoyl‐ sn ‑glycero‑3‑phosphocholine (DPPC) and 1,2‑dioleoyl‑ sn ‑glycero‑3‑phosphocholine (DOPC) were used to investigate the effect of cholesterol (Chol) or lauryl gallate (LG) on physicochemical properties of the phospholipid DPPC/DOPC monomolecular film treated as a model leaflet of the bilayer structured membrane. First the surface topography studies of these systems were carried out by means of atomic force microscopy (AFM). Then wettability was investigated via the contact angle measurements and the surface free energy determination. Finally, the time-of-flight secondary ion mass spectrometry (TOF-SIMS) was applied for the surface chemical analysis. Wettability of the monolayers was found to be closely related to the surface chemistry, molecular packing and ordering, miscibility and co-localization of molecules rather than nanoscale roughness. The comparison of the surface polarity determined from the values of contact angle and secondary ion signal intensity provided consistent results. The correlation between the changes of the electron-donor parameter and the 184/57 ratio revealed significance of using the latter quantity as a polarity indicator. The carried out studies show preferential association of components providing a framework for understanding the mechanism of heterogeneities formation within the membrane which reflect the specialization of various regions. Unlabelled Image • Superficial properties of the ternary monolayers with cholesterol and lauryl gallate • Heterogeneities formation within the model leaflet of membrane at molecular level • Wettability of the mixed films closely related to the surface chemistry. [ABSTRACT FROM AUTHOR]

Polyetheretherketone (PEEK) is a highly biocompatible polymer widely used in medicine as an implant production material. In this article, the PEEK surface was characterized in terms of its wettabillity properties after the physicochemical modifications by treatment with the low‐temperature air plasma and covering with the Langmuir–Blodgett (LB) monolayers of polypeptide (cyclosporine A, CsA) and/or phospholipid (1,2‐dipalmitoyl‐sn‐glycero‐3‐phosphocholine, DPPC). The LB deposition was preceded by the analysis of miscibility and morphology of monolayers at the air/water interface by means of the Langmuir technique and Brewster angle microscopy (BAM). Then, wettability of the polymer‐supported films was evaluated by the contact angle measurements of three probe liquids of different characters (two polar—water and formamide, one apolar—diiodomethane). The measured contact angles allowed for determination of the surface free energy and its components based on the Lifshitz‐van der Waals/acid–base (LWAB) approach. Some relations between the kind and magnitude of interactions within the model membranes on the water subphase and those of the PEEK‐supported membranes with the liquids were found out. The results allowed obtaining the interesting models of biological coatings with potential applications. [ABSTRACT FROM AUTHOR]

The aim of the study was to determine the bactericidal properties of popular medical, pharmaceutical, and cosmetic ingredients, namely chitosan (Ch), hyaluronic acid (HA), and titanium dioxide (TiO2). The characteristics presented in this paper are based on the Langmuir monolayer studies of the model biological membranes formed on subphases with these compounds or their mixtures. To prepare the Langmuir film, 1,2-dipalmitoyl-sn-glycero-3-phospho-rac-(1-glycerol) (DPPG) phospholipid, which is the component of most bacterial membranes, as well as biological material-lipids isolated from bacteria Escherichia coli and Staphylococcus aureus were used. The analysis of the surface pressure-mean molecular area (π-A) isotherms, compression modulus as a function of surface pressure, CS−1 = f(π), relative surface pressure as a function of time, π/π0 = f(t), hysteresis loops, as well as structure visualized using a Brewster angle microscope (BAM) shows clearly that Ch, HA, and TiO2 have antibacterial properties. Ch and TiO2 mostly affect S. aureus monolayer structure during compression. They can enhance the permeability of biological membranes leading to the bacteria cell death. In turn, HA has a greater impact on the thickness of E. coli film. [ABSTRACT FROM AUTHOR]

In this study, the effect of increasing concentrations (0, 0.5, 1, 2% w/w) of potassium sorbate (KS) on the release and antimicrobial properties of edible films based on pullulan (PUL), gelatin (GEL) and their blends (75/25, 50/50, and 25/75) was investigated. The 75/25 and 50/50 polymer mixtures separated into GEL-rich microspheres. The biggest microscopic domains were formed at equal amounts of the polymers. As verified by Fourier-transform infrared spectroscopy, the blending did not cause any chemical changes within the functional groups of PUL and GEL. Release of KS from the PUL- and GEL-rich carriers was primarily due to dissolution and swelling of the polymer matrix, respectively. Consequently, basing on time required for 50% release, the GEL100 film offered at least 2.5 times slower release of KS compared to the PUL100 carrier. The gradual replacement of PUL with GEL tended to decrease KS release rate. The large microspheres of the PUL50/GEL50 films gave release profile similar to the blend system with higher GEL content. The KS diffusion mechanism was found to be Quasi-Fickian. The Weibull models were suitable for the efficient simulation of KS release from the films. At the lowest KS concentration (0.5%), the PUL-rich film-forming solutions (FFSs) tended to have the weakest antibacterial activity, likely due to their high pH values, as well as PUL-KS hydrogen bonding interactions. The FFSs with high levels of KS (2%) exhibited strong inhibitory effects on A. alternata , B. cinerea , P. notatum, S. cerevisiae , and K. apiculata. Image 1 • 75/25 and 50/50 pullulan/gelatin (PUL/GEL) blends separate into microspheres. • GEL film releases KS at least 2.5 times slower than PUL carrier. • Weibull models efficiently predict KS release from the films. • PUL-rich film-forming solutions (FFSs) exhibit the weakest antibacterial activity. • The KS-added FFSs are most effective against E. coli, K. apiculata and B. cinerea. [ABSTRACT FROM AUTHOR]