Dynamic Tensiometry Research Articles

Methods of Dynamic Tensiometry in Assessing the Biochemical Status of Animals

Introduction . The existing literature explores various aspects of both the method of dynamic tensiometry based on the measurement of dynamic surface tension (DST) of blood, and its use in assessing the biochemical and physiological parameters of animals. Despite the proven usefulness of DPN methods in human medicine, these methods are underestimated in modern physicochemical biology and veterinary medicine. Purpose . In this regard, the aim of the review is to describe the methodological foundations for determining the DPN of animal biological fluids, identifying its features depending on the physiological state of the organism, the biochemical composition of blood serum while improving methods for the early diagnosis of animal diseases. Materials and Methods . The materials are research articles describing blood serum samples of humans, horses and cows, analyzed by two methods of dynamic tensiometry. Results . As a result, a detailed analysis of 84 studies related both to DPN methods and their use in assessing blood parameters was carried out, which made it possible to identify correlations between DPN and biochemical blood parameters in humans, horses and cows. In addition to presenting the measurement features of different methods of dynamic tensiometry, the review of the subject field summarizes their empirically identified prerequisites and consequences in this area. Both for cows and mares, there are a large number of strong correlations between biochemical parameters and blood DPN. Conclusion . Thus, changes in blood biochemistry associated with the structural and functional development of animals in ontogeny are consistent with changes in blood DPN values, which is reflected in the magnitudes of correlations and makes it possible to apply the obtained fundamental results in practice.

Tensiometry as a Simple Analytical Method for Quantification of Solubility and Release of Aroma Molecules in Aqueous Media.

Dynamic tensiometry is shown to be a high-potential analytical tool in assessing physico-chemical characteristics of fragrance molecules, such as solubility limit, volatility as well as much rarely assessed interfacial activity of these amphiphilic molecules. Surface tension of aqueous solutions of selected essential oils has been measured as a function of time and fragrance concentration using maximum bubble pressure method. The effect of the temperature and saline solution on the rate of dissolution in water was assessed. Dynamic surface tension turned to be sensitive to the composition of fragrances, as demonstrated on examples of natural and synthetic mixtures. Furthermore, presented work reveals the possibility of maximum bubble pressure tensiometry method to quantify the amount of fragrance compositions in flavored salts, including the artificially aged carrier samples. Suggested here analytical approach can be used for the detection of the purity of essential oils, for the optimization of compositions and of the manufacturing processes of fragrances-containing products, as well as for the assessment of the release/evaporation of fragrances from carrier systems.

Characterization of reactive interfaces via coupled interfacial tension measurements and interphase mass transfer analysis

To explore the kinetics of reactive interfaces we propose a scheme that couples the interphase mass transfer and interfacial phenomena studied with the profile analysis tensiometer (PAT). Heterogeneous reactions between two immiscible or partially miscible liquid phases were arranged by immersing a pendant droplet into a liquid matrix. This configuration enabled us to distinguish between periods of different phenomena such as diffusion, adsorption/desorption, reaction, unstable dissolution, partial miscibility, and equilibrium state by recording the changes of interfacial and geometric properties of the droplet as a function of time. For case studies, N,N-dimethylcyclohexylamine as a switchable hydrophilicity solvent and acetic acid were used as the reactive agents to provoke chemical reactions imposing desirable physical changes. For reactive and switchable systems, diffusion, reaction, and mass transfer periods could be detected reasonably. Also, the back-and-forth detachment/attachment of the non-reactive agent as an unstable dissolution was observed, which can lead to spontaneous emulsification. For the reactive and partially-miscible systems, four periods of partial miscibility, reaction and adsorption, desorption, and equilibrium could be detected. The material balance of a reactive droplet was also developed as the theoretical foundation to estimate the mass transfer coefficient of the external reactive component. The findings demonstrate that the application of dynamic tensiometry can be generalized into reactive interfaces and interphase mass transfers.

Biochemical parameters, dynamic tensiometry and circulating nucleic acids for cattle blood analysis: a review.

The animal’s blood is the most complicated and important biological liquid for veterinary medicine. In addition to standard methods that are always in use, recent technologies such as dynamic tensiometry (DT) of blood serum and PCR analysis of particular markers are in progress. The standard and modern biochemical tests are commonly used for general screening and, finally, complete diagnosis of animal health. Interpretation of major biochemical parameters is similar across animal species, but there are a few peculiarities in each case, especially well-known for cattle. The following directions are discussed here: hematological indicators; “total protein” and its fractions; some enzymes; major low-molecular metabolites (glucose, lipids, bilirubin, etc.); cations and anions. As example, the numerous correlations between DT data and biochemical parameters of cattle serum have been obtained and discussed. Changes in the cell-free nucleic acids (cfDNA) circulating in the blood have been studied and analyzed in a variety of conditions; for example, pregnancy, infectious and chronic diseases, and cancer. CfDNA can easily be detected using standard molecular biological techniques like DNA amplification and next-generation sequencing. The application of digital PCR even allows exact quantification of copy number variations which are for example important in prenatal diagnosis of chromosomal aberrations.

Small changes in PDMMLA structure influence the adsorption behavior of ECM proteins and syndecan-4 on PDMMLA derivative surfaces: Experimental validation by tensiometric surface force measurements

Cardiovascular diseases are the leading cause of death around the world according to the World Health Organization. In-stent restenosis is an inflammatory response of the immune system to endovascular stent implantation in atherosclerotic patients. Biocompatible and biodegradable polymers are of great interest in this field in order to limit the side effects of stent treatments. Poly([R,S]-3,3-dimethylmalic acid) (PDMMLA) is a new biodegradable statistical polyester which presents promising properties as a stent coating. In this work, we studied by dynamic tensiometry, the adhesion of extracellular matrix proteins (bovine serum albumin, fibronectin, fibrinogen, and vitronectin) and plasma membrane proteoglycan (syndecan-4) on three PDMMLA derivatives with different hydrophilicity levels. The results show that proteins have different adhesion profiles and affinity on these surfaces. They show similar behavior on the most hydrophilic surface, making hydrophilic, ionic and hydrogen type bonds. Then we compared each protein’s individual profile to that of a mixture of all studied proteins. The comparison shows that vitronectin and syndecan-4 are the quantitatively dominating proteins adsorbed by specific interactions. Based on the results from previous studies, this work allowed us to identify the most important PDMMLA surface as a promising biomaterial for bioactive stent-coating.

Change in interfacial behavior by variation of amphiphilic nanosheets/anionic surfactant ratio using dynamic tensiometry

Nanoparticles/surfactant interplays can robustly manipulate interfacial properties, while it is still unclear how their interactions affect interface behavior. This research recap unprecedented research for determination of dynamics of adsorption and dynamic surface properties of amphiphilic sheet-like nanoparticles in anionic surfactant mixtures and generalizing their characteristics in industrial and macroscopic applications by controlling microscopic active mechanism, particularly tuning foam properties and controlling its behavior. Amphiphilic nanosheets are surface-active particles which tend to self-assemble at the air-water interface. In this study, a system of an anionic surfactant (sodium dodecylsulfate (SDS)) and an amphiphilic nanoparticle (Graphene oxide (GO)) is studied at different ratios. It appears that there is a critical value for the minimum number of surfactants per nanosheets (> 160) to make the amphiphilic nanoparticle more hydrophilic. The results set out that below this critical ratio, the amphiphilic nanoparticles are partially hydrophobic and they are surface-active enough to be adsorbed considerably at the air-water interface. The nanoparticle adsorption causes an increase in surface elasticity and a decrease in surface tension (ST). As SDS/GO ratio increases, GO particles are heavily surrounded by SDS molecules rendering them hydrophilic particles. The hydrophilic GO particles start traveling back into the bulk, drastically decreasing elasticity and increasing the ST. When SDS concentration approaches the pure SDS critical micelle concentration (CMC), there appears that some of GO/SDS complexes are still on the air-water interface to slow down the dynamics of ST. The presence of GO/SDS complexes at the interface also decreases ST to lower values compared to the pure SDS near the CMC. The hydrophilic transition of GO nanoparticles is also confirmed by ζ potential and DLS measurements. This suggests a simple way to tune foam properties and behavior by selecting proper nanoparticle/surfactant ratio.

Morphology of Dried Drop Patterns of Saliva from a Healthy Individual Depending on the Dynamics of Its Surface Tension

Background: The study of processes in the drying drops of biological fluids (dried drop patterns) and the method of dynamic surface tensiometry can be attributed to integral methods of assessing the state of the organism. Research objective: to establish the relationship between the type of crystallization patterns and the surface tension of human saliva in normal conditions. Methods: 100 volunteers (40 males, 60 females) that were aged 30–59 participated in the study. In all saliva samples, the parameters of dynamic tensiometry, types of crystallization patterns and 11 biochemical parameters were determined. Results: No statistically significant differences in the saliva crystallization patterns were observed, depending on the age and gender characteristics of the volunteers. A negative correlation of the area of the crystallization zone and the surface tension of saliva is shown. When considering the crystallization patterns, their considerable variability was noted; on this basis, the entire studied sample was divided into four clusters by surface tension. Conclusion: In general, the crystallization patterns that are inside the selected groups remain quite heterogeneous. This increases the likelihood of making an incorrect diagnosis when using visual methods to evaluate the crystallization patterns, which significantly limits the use of such diagnostic methods in clinical practice.

Enzyme‐Compatible Dynamic Nanoreactors from Electrostatically Bridged Like‐Charged Surfactants and Polyelectrolytes

Reported is an unanticipated mechanism of attractive electrostatic interactions of fully neutralized polyacrylic acid (PAA) with like-charged surfactants. Amphiphilic polymer-surfactant complexes with high interfacial activity and a solubilization capacity exceeding that of conventional micelles are formed by bridging with Ca2+ ions. Incorporation of a protease into such dynamic nanoreactors results in a synergistically enhanced cleaning performance because of the improved solubilization of poorly water-soluble immobilized proteins. Competitive interfacial and intermolecular interactions on different time- and length-scales have been resolved using colorimetric analysis, dynamic tensiometry, light scattering, and molecular dynamic simulations. The discovered bridging association mechanism suggests reengineering of surfactant/polymer/enzyme formulations of modern detergents and opens new opportunities in advancing labile delivery systems.

Enzyme‐Compatible Dynamic Nanoreactors from Electrostatically Bridged Like‐Charged Surfactants and Polyelectrolytes

AbstractReported is an unanticipated mechanism of attractive electrostatic interactions of fully neutralized polyacrylic acid (PAA) with like‐charged surfactants. Amphiphilic polymer‐surfactant complexes with high interfacial activity and a solubilization capacity exceeding that of conventional micelles are formed by bridging with Ca2+ ions. Incorporation of a protease into such dynamic nanoreactors results in a synergistically enhanced cleaning performance because of the improved solubilization of poorly water‐soluble immobilized proteins. Competitive interfacial and intermolecular interactions on different time‐ and length‐scales have been resolved using colorimetric analysis, dynamic tensiometry, light scattering, and molecular dynamic simulations. The discovered bridging association mechanism suggests reengineering of surfactant/polymer/enzyme formulations of modern detergents and opens new opportunities in advancing labile delivery systems.

Adsorption of Sodium Dodecyl Sulfate at Water-Dodecane Interface in Relation to the Oil in Water Emulsion Properties.

The control of the behavior of oil in water emulsions requires deeper investigations on the adsorption properties of the emulsion stabilizers at the interfaces, which are fundamental to explain the (de)stabilization mechanisms. In this work, we present an extensive study on oil-in-water emulsions stabilized by sodium dodecyl sulfate (SDS) below its critical micellar concentration. Dynamic tensiometry, dilational rheology, and electrical conductivity measurements are used to investigate the adsorption properties at the droplet interface, whereas the aging of the respective emulsions was investigated by monitoring the macroscopic thickness of the emulsion layer, by microimaging and dynamic light scattering (DLS) analysis, to get information on the drop size distribution. In addition, the droplet coalescence is investigated by a microscopy setup. The results of this multitechnique study allow deriving a coherent scenario where the adsorption properties of this ionic surfactant relate to those of the emulsion, such as, for example, the prevention of droplet coalescence and the presence of other mechanisms, such as Ostwald ripening, responsible for the emulsion aging.

Multiscale evaluation from one bubble to the foam of surface active properties of cellulose derivatives used for a starchy model sponge cake

Interfacial properties of cellulose derivatives (HPMC and MC) were studied to understand their role in structuring a foam during the whipping process. Multiscale studies were performed to explain macroscopic observations with microscopic mechanisms. Results showed that HPMC was more flexible and had higher viscosity and shear-thinning properties than MC, which in turn diffused quicker to the interface due to a smaller molecular weight. Both hydrocolloids showed a good ability to stabilize interfaces through their surface tensions and dilatational moduli measured by static and dynamic tensiometry, respectively. However, only HPMC and HPMC + MC solutions were able to develop a stable foam. Methylcellulose formed more rigid interfaces and the interfacial elasticity was probably too high, leading to a difficult fractionation of bubbles. Moreover, its lower viscosity measured at low shear rate could explain its incapability to retain bubbles in the bulk just after their formation. HPMC and MC display complementarity and synergistic effects when used together, since a foam with much smaller bubbles is formed after only 2 min of whipping this mix. The bubble size was immediately smaller for solutions of HPMC + MC than for HPMC alone, with similar final air quantity. Finally, a hypothesis about the structuring mechanism of cellulose derivatives at air/water interfaces was proposed. MC would adsorb first at the interface and stabilize it but also increase its rigidity too much, hence its fragility against high mechanical stress. HPMC would come afterwards to the interface, but through its higher flexibility it would contribute to a higher resistance of the interface.

Surface behavior of hydrophilic silica nanoparticle-SDS surfactant solutions: I. Effect of nanoparticle concentration on foamability and foam stability

Hydrophilic silica nanoparticles have no tendency to adsorb at the water/air interface and they do not affect the surface behavior of pure water. In this paper, we show that this tendency remains unaltered by addition of anionic sodium dodecyl sulfate (SDS) surfactant, although the surface behavior of SDS solutions considerably changes with the addition of silica particles. Employing dynamic tensiometry, surface rheology, foamability, and foam stability experiments in presence of variable amounts of silica particles, we found that the surface activity of SDS molecules is significantly increased in the presence of nanoparticles and equivalently behaved as if higher concentrations of SDS are used. The so-called equivalent concentration values (EC) were separately measured using the tensiometry and foamability. The consistency of measured EC trends is discussed, and a new predictive tool for the foaming behavior of surfactant solutions is proposed based on the calculated EC trends from tensiometry and surface dilational rheology.The adsorption process and surface structuring of nanoparticles at the water/air interface were investigated by analyzing the surface pressure values as a function of drop surface area. We measured the standard deviation, STD, of drop shapes from their Laplacian profile during the drop compression process. It was found that STD-values abruptly change when particles form closely-packed surface structures. The STD trend is explained in detail and is shown it can be a very powerful tool for analyzing the surface adsorption and surface structuring of nanoparticles.

Fabrication of Superhydrophilic Polyester Fabrics Using Various TiO2Colloidal Dispersions

The purpose of this research was to apply four stable colloidal dispersions, combining di erent TiO2 coreshell nanoparticles, onto polyester fabric, according to exhaustion procedure, in order to enhance fabrics' water and moisture absorption properties. Firstly, all colloidal dispersions were analysed using transmission electron microscopy (TEM) and dynamic light scattering (DLS) and secondly, the morphologies of TiO2 modi ed PES surfaces were evaluated by scanning electron microscopy (SEM). In addition, the superhydrophilic character of brous surfaces was investigated by water contact angle measurement. For this purpose, dynamic tensiometry was employed by measuring the changes in the net force on a surface during the repeated immersion and emersion of a solid into a probe liquid. The obtained results show excellent wettability of TiO2 upgraded PES fabrics depending on the type of applied nano-sized TiO2-hybride.

Dynamic tensiometry studies on interactions of novel therapeutic inhalable powders with model pulmonary surfactant at the air–water interface

Abstract Assessing the influence of therapeutic formulations on biophysical properties of lung surfactant is an essential step in optimal design of pharmaceutical products intended for inhalation. In the present study, maximum bubble pressure (MBP) tensiometry was employed to evaluate the physicochemical impact of several novel multifunctional composite powders, suitable for drug delivery by inhalation, on the dynamic activity of model pulmonary surfactant at the air–water interface. Bi- and tri-component powders consisted of mannitol or dextran, N-acetylcysteine and disodium cromoglycate were obtained by spray drying technique and subsequently their interaction with modified bovine surfactant extract (Survanta) were analysed. Several dynamic surface tension parameters were investigated as measures of alteration of surface activity in Survanta-powder solutions. All discussed powders demonstrated significant impact on surface activity of Survanta solution, either positive or negative, depending on powders composition and concentration. Although it is problematic to explain all observed effects in the framework of known mechanisms, the present study provides a new insight into the possible changes in the dynamic interfacial behaviour of pulmonary surfactant after therapeutic interventions. Obtained results may be applied during development of more effective and safe medical products suitable for drug delivery by inhalation.

Regulation of chicken egg lysozyme functional properties by interaction with 5-methylresorcinol

The surface activity and dynamics of adsorption surface layer formation of individual solutions of 5-methylresorcinol (MR) and its mixed solutions with lysozyme on air/solution (0.05 M phosphate buffer, pH 6.0) interface under conditions of MR maximally exceeding hydrolytic activity of lysozyme are studied using method of dynamic drop tensiometry. The thermodynamic parameters of adsorption are determined based on the isotherms. It is established that MR possesses lower surface activity in comparison to traditional surfactants. Methylresorcinol increases the surface activity and lysozyme adsorption rate at the air/solution interface in the entire concentration range covered.

Structuring in solutions of polydiphenylenesulfophthalide salts and their combined systems with a cationic surfactant

New derivatives of polydiphenylenesulfophthalide, namely its alkali-metal salts and interpolymer complexes with a cationic surfactant, are prepared via polymer-analogous transformations. It is shown that, depending on the type of solvent, solutions of polydiphenylenesulfophthalide salts may feature the properties of polyelectrolytes or ionomers. On the basis of dynamic laser light scattering data, the sizes of associates formed in solutions of salts of polydiphenylenesulfophthalide and its complexes with cetyl pyridinium chloride are determined. With the use of dynamic drop tensiometry, the values of surface tension of the aqueous solutions of lithium polydiphenylenesulfophthalide and its complexes with cetyl pyridinium chloride, as well as viscoelastic characteristics of adsorption layers formed at the solution/air interface, are measured.

Utilizing Dynamic Tensiometry to Quantify Contact Angle Hysteresis and Wetting State Transitions on Nonwetting Surfaces

Goniometric techniques traditionally quantify two parameters, the advancing and receding contact angles, that are useful for characterizing the wetting properties of a solid surface; however, dynamic tensiometry, which measures changes in the net force on a surface during the repeated immersion and emersion of a solid into a probe liquid, can provide further insight into the wetting properties of a surface. We detail a framework for analyzing tensiometric results that allows for the determination of wetting hysteresis, wetting state transitions, and characteristic topographical length scales on textured, nonwetting surfaces, in addition to the more traditional measurement of apparent advancing and receding contact angles. Fluorodecyl POSS, a low-surface-energy material, was blended with commercially available poly(methyl methacrylate) (PMMA) and then dip- or spray-coated onto glass substrates. These surfaces were probed with a variety of liquids to illustrate the effects of probe liquid surface tension, solid surface chemistry, and surface texture on the apparent contact angles and wetting hysteresis of nonwetting surfaces. Woven meshes were then used as model structured substrates to add a second, larger length scale for the surface texture. When immersed into a probe liquid, these spray-coated mesh surfaces can form a metastable, solid-liquid-air interface on the largest length scale of surface texture. The increasing hydrostatic pressure associated with progressively greater immersion depths disrupts this metastable, composite interface and forces penetration of the probe liquid into the mesh structure. This transition is marked by a sudden change in the wetting hysteresis, which can be systematically probed using spray-coated, woven meshes of varying wire radius and spacing. We also show that dynamic tensiometry can accurately and quantitatively characterize topographical length scales that are present on microtextured surfaces.

Exploring the kinetics of switchable polymer surfaces with dynamic tensiometry

Switchable polymer multilayer coatings consisting of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA) were prepared via Layer-by-Layer (LbL) assembly and post-functionalized with poly(ethylene glycol methyl ether) (PEG). This resulted in a soft polar coating that reversibly and repeatedly rearranges from hydrophobic to hydrophilic (or vice versa) when contacted with water (or air). Goniometry is used to quantify the forward surface rearrangement in the form of transient measurements of the water contact angle. By examining the time evolution of the water contact angle at various temperatures, the apparent activation energy for the forward surface rearrangement (Ea,f) can be determined. Further insight can be gained into the kinetics of this surface reconstruction process by utilizing dynamic tensiometry to measure the evolution in the contact angle of a liquid meniscus at several rates and temperatures as it advances or recedes over the multilayer films. A simple first-order thermally-activated rate process is shown to describe the forward and reverse surface reconstruction and enables the shape of the measured tensiometric force curves during repeated immersion and emersion to be predicted quantitatively. Using this model we show that the character of this switchable surface coating can appear to be hydrophobic or hydrophilic depending on a single dimensionless parameter which incorporates the characteristic time-scale for temperature-dependent surface rearrangement, the speed of immersion and the capillary length of the liquid meniscus.

Effects of Perfluorocarbon Gases on the Size and Stability Characteristics of Phospholipid-Coated Microbubbles: Osmotic Effect versus Interfacial Film Stabilization

Micrometer-sized bubbles coated with phospholipids are used as contrast agents for ultrasound imaging and have potential for oxygen, drug, and gene delivery and as therapeutic devices. An internal perfluorocarbon (FC) gas is generally used to stabilize them osmotically. We report here on the effects of three relatively heavy FCs, perfluorohexane (F-hexane), perfluorodiglyme (F-diglyme ), and perfluorotriglyme (F-triglyme), on the size and stability characteristics of microbubbles coated with a soft shell of dimyristoylphosphatidylcholine (DMPC) and on the surface tension and compressibility of DMPC monolayers. Monomodal populations of small bubbles (~1.3 ± 0.2 μm in radius, polydispersivity index ~8%) were prepared by sonication, followed by centrifugal fractionation. The mean microbubble size, size distribution, and stability were determined by acoustical attenuation measurements, static light scattering, and optical microscopy. The half-lives of F-hexane- and F-diglyme-stabilized bubbles (149 ± 8 and 134 ± 3 min, respectively) were about 2 times longer than with the heavier F-triglyme (76 ± 7 min) and 4-5 times longer than with air (34 ± 3 min). Remarkably, the bubbles are smaller than the minimal size values calculated assuming that the bubbles are stabilized osmotically by the insoluble FC gases. Particularly striking is that bubbles 2 orders of magnitude smaller than the calculated collapse radius can be prepared with F-triglyme, while its very low vapor pressure prohibits any osmotic effect. The interface between an aqueous DMPC dispersion and air, or air (or N(2)) saturated with the FCs, was investigated by tensiometry and by Langmuir monolayer compressions. Remarkably, after 3 h, the tensions at the interface between an aqueous DMPC dispersion (0.5 mmol L(-1)) and air were lowered from ~50 ± 1 to ~37 ± 1 mN m(-1) when F-hexane and F-diglyme were present and to ~40 ± 1 mN m(-1) for F-triglyme. Also noteworthy, the adsorption kinetics of DMPC at the interface, as obtained by dynamic tensiometry, were accelerated up to 3-fold when the FC gases were present. The compression isotherms show that all these FC gases significantly increase the surface pressure (from ~0 to ~10 mN m(-1)) at large molecular areas (70 Å(2)), implying their incorporation into the DMPC monolayer. All three FC gases increase the monolayer's collapse pressures significantly (~61 ± 2 mN m(-1)) as compared to air (~54 ± 2 mN m(-1)), providing for interfacial tensions as low as ~11 mN m(-1) (vs ~18 mN m(-1) in their absence). The FC gases increase the compressibility of the DMPC monolayer by 20-50%. These results establish that, besides their osmotic effect, FC gases contribute to bubble stabilization by decreasing the DMPC interfacial tension, hence reducing the Laplace pressure. This contribution, although significant, still does not suffice to explain the large discrepancy observed between calculated and experimental bubble half-lives. The case of F-triglyme, which has no osmotic effect, indicates that its effects on the DMPC shell (increased collapse pressure, decreased interfacial tension, and increased compressibility) contribute to bubble stabilization. F-hexane and F-diglyme provided both the smallest mean bubble sizes and the longest bubble half-lives.

Milk whey proteins and xanthan gum interactions in solution and at the air–water interface: A rheokinetic study

In this contribution, we present experimental information about the effect of xanthan gum (XG) on the adsorption behaviour of two milk whey protein samples (MWP), β-lactoglobulin (β-LG) and whey protein concentrate (WPC), at the air–water interface. The MWP concentration studied corresponded to the protein bulk concentration which is able to saturate the air–water interface (1.0 wt%). Temperature, pH and ionic strength of aqueous systems were kept constant at 20 °C, pH 7 and 0.05 M, respectively, while the XG bulk concentration varied in the range 0.00–0.25 wt%. Biopolymer interactions in solution were analyzed by extrinsic fluorescence spectroscopy using 1-anilino-8-naphtalene sulphonic acid (ANS) as a protein fluorescence probe. Interfacial biopolymer interactions were evaluated by dynamic tensiometry and surface dilatational rheology. Adsorption behaviour was discussed from a rheokinetic point of view in terms of molecular diffusion, penetration and conformational rearrangement of adsorbed protein residues at the air–water interface. Differences in the interaction magnitude, both in solution and at the interface vicinity, and in the adsorption rheokinetic parameters were observed in MWP/XG mixed systems depending on the protein type (β-LG or WPC) and biopolymer relative concentration. β-LG adsorption in XG presence could be promoted by mechanisms based on biopolymer segregative interactions and thermodynamic incompatibility in the interface vicinity, resulting in better surface and viscoelastic properties. The same mechanism could be responsible of WPC interfacial adsorption in the presence of XG. The interfacial functionality of WPC was improved by the synergistic interactions with XG, although WPC chemical complexity might complicate the elucidation of molecular events that govern adsorption dynamics of WPC/XG mixed systems at the air–water interface.