Knowledge of mass transport parameters, diffusion, and viscosity of hyaluronic acid (HA) in the presence of cyclodextrins is of considerable importance for areas such as food packaging and drug ...delivery, among others. Despite a number of studies investigating the functionalization of HA or the corresponding sodium salt by cyclodextrins, only a few studies have reported the effect of cyclodextrins on the mass transport of HA in the presence of these oligosaccharides. Here, we report the tracer binary and ternary interdiffusion coefficients of sodium hyaluronate (NaHy) in water and aqueous β-cyclodextrin solutions. The diffusion behavior of sodium hyaluronate was dependent on the reduced viscosity of NaHy, which, in turn, presented a concave dependence on concentration, with a minimum at approximately 2.5 g dm
. The significant decrease in the limiting diffusion coefficient of NaHy (at most 45%) at NaHy concentrations below 1 g dm
in the presence of β-cyclodextrin, taking water as the reference, allowed us to conclude that NaHy strongly interacted with the cyclodextrin.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Tracer diffusion coefficients obtained from the Taylor dispersion technique at 25.0 °C were measured to study the influence of sodium, ammonium and magnesium salts at 0.01 and 0.1 mol dm
on the ...transport behavior of sodium hyaluronate (NaHy, 0.1%). The selection of these salts was based on their position in Hofmeister series, which describe the specific influence of different ions (cations and anions) on some physicochemical properties of a system that can be interpreted as a salting-in or salting-out effect. In our case, in general, an increase in the ionic strength (i.e., concentrations at 0.01 mol dm
) led to a significant decrease in the limiting diffusion coefficient of the NaHy 0.1%, indicating, in those circumstances, the presence of salting-in effects. However, the opposite effect (salting-out) was verified with the increase in concentration of some salts, mainly for NH
SCN at 0.1 mol dm
. In this particular salt, the cation is weakly hydrated and, consequently, its presence does not favor interactions between NaHy and water molecules, promoting, in those circumstances, less resistance to the movement of NaHy and thus to the increase of its diffusion (19%). These data, complemented by viscosity measurements, permit us to have a better understanding about the effect of these salts on the transport behaviour of NaHy.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
This systematic review aimed to verify the use of microfluidic devices in the process of implementing and evaluating the effectiveness of therapeutic approaches in glioblastoma on-a-chip, providing a ...broad view of advances to date in the use of this technology and their perspectives. We searched studies with the variations of the keywords "Glioblastoma", "microfluidic devices", "organ-on-a-chip" and "therapy" of the last ten years in PubMed and Scopus databases. Of 446 articles identified, only 22 articles were selected for analysis according to the inclusion and exclusion criteria. The microfluidic devices were mainly produced by soft lithography technology, using the PDMS material (72%). In the microenvironment, the main extracellular matrix used was collagen type I. Most studies used U87-MG glioblastoma cells from humans and 31.8% were co-cultivated with HUVEC, hCMEC/D3, and astrocytes. Chemotherapy was the majority of therapeutic approaches, assessing mainly the cellular viability and proliferation. Furthermore, some alternative therapies were reported in a few studies (22.6%). This study identified a diversity of glioblastoma on-a-chip to assess therapeutic approaches, often using intermediate levels of complexity. The most advanced level implemented the intersection between different biological systems (liver-brain or intestine-liver-brain), BBB model, allowing in vitro studies with greater human genetic similarity, reproducibility, and low cost, in a highly customizable platform.
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Mutual diffusion coefficients of chloroquine diphosphate (CDP) in aqueous solutions both without and with β-cyclodextrin (β-CD) were measured at concentrations from (0.0000 to 0.0100) mol dm−3 and ...298.15 K, using the Taylor dispersion technique. Ternary mutual diffusion coefficients (Dik) measured by the same technique are reported for aqueous CDP + β-CD solutions at 298.15 K. The presence of β CD led to relevant changes in the diffusion process, as showed by nonzero values of the cross-diffusion coefficients, D12 and D21. β-CD concentration gradients produced significant co-current coupled flows of CDP. In addition, the effects of β-CD on the transport of CDP are assessed by comparing the binary diffusion coefficient of aqueous CDP solutions with the main diffusion coefficient (D11) measured for ternary {CDP(1) + β-CD(2)} solutions. These observations are supported by viscosity analysis. All data allow to have a better interpretation on the effect of cyclodextrin on the transport behavior of CDP.
Differential mutual diffusion coefficients of n-alkyltrimethylammonium bromides CH^sub 3^(CH^sub 2^)^sub n-1^N(CH^sub 3^)^sub 3^Br, C^sub n^TAB (n=10, 12, 14, 16) have been measured in aqueous ...solutions at 298.15 K using a conductimetric cell and an automatic apparatus to follow diffusion. The cell is based on an open-ended capillary, and the technique follows the diffusion process by measuring the resistance of a solution inside the capillaries at various times. The electrical conductances of those solutions have also been measured to calculate the critical micellar concentration (cmc). Thermodynamic analysis of the data suggests that the free ion concentration decreases at concentrations above the cmc, in agreement with theoretical predictions. The obtained values of the micellization parameters were used to model the mutual diffusion coefficients of C^sub n^TAB aqueous solutions.PUBLICATION ABSTRACT
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Mutual diffusion coefficients (interdiffusion coefficients) have been measured of chromium(III) chloride in water at 298.15 K and 303.15 K at concentrations between 0.005 mol·dm-3 and 0.05 mol·dm-3 ...using a conductometric cell. The experimental mutual diffusion coefficients are discussed on the basis of the Onsager−Fuoss model. The equivalent conductance at an infinitesimal concentration of the chromium(III) ion in these solutions at 303.15 K has been estimated using these results.
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IJS, KILJ, NUK, PNG, UL, UM
•Binary diffusion coefficients for the systems containing sodium hyaluronate.•Influence of the aggregation on diffusion of the sodium hyaluronate in the aqueous media.•Estimation of the thermodynamic ...and mobility factors from mutual diffusion.
The Taylor dispersion technique has been used for measuring mutual diffusion coefficients of sodium hyaluronate in aqueous solutions at T=298.15K, and concentrations ranging from (0.00 to 0.50)g·dm−3. The results are interpreted on the basis of Nernst, and Onsager and Fuoss theoretical equations. From the diffusion coefficient at infinitesimal concentration, the limiting ionic conductivity and the tracer diffusion coefficient of hyaluronate ion were estimated. These studies have been complemented by molecular mechanics calculations.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The estimation of numerical values for the mean distance of closest approach of ions,
a, of sodium salts in aqueous solutions, determined from activity and diffusion coefficients, and also from ...different theoretical approaches, is presented and discussed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Concepts, approaches, and techniques involved in the determination of the transport properties (TP) in solutions (diffusion, conductivity, and viscosity), their importance in the scientific and ...technologic communities, and the critical analysis of these data are focused in this work.
This chapter focuses on concepts, approaches, and techniques involved in the determination of the transport properties in solutions, their importance in the scientific and technologic communities, and the critical analysis of these data. The transport processes in the aqueous solutions result from a situation in which these systems are far from their thermodynamic equilibrium states, caused for example by heterogeneities of temperature, composition, or electrical potential. A generic treatment of mass transport processes in electrolyte solutions may be done using the thermodynamics of irreversible or non-equilibrium phenomena (TIP). TIP is based on the hypothesis that classical concepts, such as temperature and entropy, are valid in small subvolumes which are assumed to be in “local” equilibrium. The absence of perturbations in the local equilibrium is assumed when temperature, composition, or temperature gradients occur, as well as the transport of heat, matter, or electricity through each sub-volume.
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