scholarly journals Dependence of Viscosity and Diffusion on β-Cyclodextrin and Chloroquine Diphosphate Interactions

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1433
Author(s):  
Lenka Musilová ◽  
Aleš Mráček ◽  
Eduarda F. G. Azevedo ◽  
M. Melia Rodrigo ◽  
Artur J. M. Valente ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Mutual Diffusion ◽  
Binary Diffusion Coefficient ◽  
Concentration Gradients ◽  
Cross Diffusion ◽  
Taylor Dispersion Technique ◽  
Dispersion Technique ◽  
And Diffusion ◽  
Chloroquine Diphosphate

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.

Diffusion Coefficients of Aqueous Solutions of Carbohydrates as Seen by Taylor Dispersion Technique at Physiological Temperature (37 °C)

2006 ◽  
Vol 258-260 ◽  
pp. 305-309 ◽  
Author(s):  
Ana C.F. Ribeiro ◽  
Cecilia Isabel A.V Santos ◽  
Victor M.M. Lobo ◽  
Artur J.M. Valente ◽  
Pedro M.R.A. Prazeres ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Concentration Dependence ◽  
Diffusion Coefficients ◽  
Taylor Dispersion ◽  
Mutual Diffusion ◽  
Physiological Temperature ◽  
Taylor Dispersion Technique ◽  
Dispersion Technique

Binary mutual diffusion coefficients have been measured for aqueous solutions of some carbohydrates (glucose, fructose, lactose, sucrose, α-cyclodextrin and β- cyclodextrin) at concentrations from 0.002 mol dm-3 to 0.010 mol dm-3. The concentration dependence of the diffusion coefficients at physiological temperature, 37 °C, is discussed on the basis of their structures.

scholarly journals Transport Properties for Pharmaceutical Controlled-Release Systems: A Brief Review of the Importance of Their Study in Biological Systems

Biomolecules ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 178 ◽  
Author(s):  
Ana C. F. Ribeiro ◽  
Miguel A. Esteso
Keyword(s):  
Controlled Release ◽  
Transport Properties ◽  
Diffusion Coefficients ◽  
Drug Carrier ◽  
Strong Association ◽  
Mutual Diffusion ◽  
Mixed Electrolytes ◽  
Coupled Transport ◽  
Concentration Gradients ◽  
Enhanced Solubility

: The goal of this work was to comprehensive study the transport properties of controlled-release systems for the safe and reliable delivery of drugs. Special emphasis has been placed on the measurement of the diffusion of drugs, alone or in combination with carrier molecules for enhanced solubility and facilitated transport. These studies have provided detailed comprehensive information—both kinetic and thermodynamic—for the design and operation of systems for the controlled release and delivery of drugs. Cyclodextrins are among the most important carriers used in these systems. The basis for their popularity is the ability of these materials to solubilize poorly soluble drugs, generally resulting in striking increases in their water solubilities. The techniques used in these investigations include pulse voltammetry, nuclear magnetic resonance (NMR) and Raman spectroscopy, ultrasonic relaxation, and dissolution kinetics. Transport in these systems is a mutual diffusion process involving coupled fluxes of drugs and carrier molecules driven by concentration gradients. Owing to a strong association in these multicomponent systems, it is not uncommon for a diffusing solute to drive substantial coupled fluxes of other solutes, mixed electrolytes, or polymers. Thus, diffusion data, including cross-diffusion coefficients for coupled transport, are essential in order to understand the rates of many processes involving mass transport driven by chemical concentration gradients, as crystal growth and dissolution, solubilization, membrane transport, and diffusion-limited chemical reactions are all relevant to the design of controlled-release systems. While numerous studies have been carried out on these systems, few have considered the transport behavior for controlled-release systems. To remedy this situation, we decided to measure mutual diffusion coefficients for coupled diffusion in a variety of drug–carrier solutions. In summary, the main objective of the present work was to understand the physical chemistry of carrier-mediated transport phenomena in systems of controlled drug release.

Diffusion Coefficients from Capillary Flow

1963 ◽  
Vol 3 (03) ◽  
pp. 256-266 ◽  
Author(s):  
H.R. Bailey ◽  
W.B. Gogarty
Keyword(s):  
Differential Equation ◽  
Diffusion Coefficient ◽  
Numerical Solution ◽  
Diffusion Coefficients ◽  
Molecular Diffusion ◽  
Capillary Flow ◽  
Molecular Diffusion Coefficient ◽  
Flow Method ◽  
And Diffusion ◽  
Flow Experiments

Abstract Methods are presented for determining molecular diffusion coefficients by using data from capillary flow experiments. These methods are based on a numerical solution (presented in a previous paper) of the partial differential equation describing the combined mechanisms of flow and diffusion. Results from this numerical solution are given and compared with the approximate analytical solution of G. I. Taylor. The numerical solution is valid over a much larger time range. These methods are applied to experimental results for the fluid pairs water-potassium permanganate solution and amyl acetateorthoxylene. Both of these fluid pairs have approximately equal densities and viscosities. Graphical and numerical techniques are presented for deters mining diffusion coefficients from the flow data. Values obtained by these techniques are compared with values obtained by other methods. Introduction The molecular diffusion coefficient is known to be a variable in determining the amount of mixing in a miscible displacement process. The effect of molecular diffusion on dispersion in longitudinal flow through porous media has been examined by different investigators. These investigators concluded that at low velocities of flow, the amount of dispersion is approximately proportional to the molecular diffusion coefficient. The influence of diffusion on fingering, channeling, and overriding has been mentioned by other investigators. Recent studies have been made on the effects of molecular diffusion in connection with the problem of gravity segregation. Many different methods have been developed for the experimental determination of molecular diffusion coefficients. These methods differ mainly according to boundary conditions selected and analytical procedures used. Nevertheless, all of these methods have the condition in common that the bulk fluids in which diffusion is occurring are stationary with respect to each other. In connection with a series of papers on mixing in capillary flow, Taylor suggested the use of a flow method for determining molecular diffusion coefficients. Additional studies have been conducted on miscible displacements in capillary tubes, but the data from these studies were not used for the specific purpose of determining diffusion coefficients. The flow method proposed by Taylor results in a single value of the diffusion coefficient for the fluid pair used in the displacement experiments. This single value represents the true value for the fluid pair when the diffusion coefficient is independent of concentration. If the diffusion coefficient is a function of concentration, the single value obtained by the flow method gives an average value for the coefficient of the fluid pair. These average values are based on diffusion taking place over the entire range of concentration, i.e., from 0 per cent of one fluid to 100 per cent of that same fluid. In field applications of the miscible displacement process, gradients occur over the same range of concentration as are found in the displacements in capillary tubes. Molecular diffusion coefficients obtained from the capillary flow method should, therefore, be especially relevant to field operations. This investigation was undertaken to evaluate the feasibility of obtaining molecular diffusion coefficients from capillary flow experiments. In making this evaluation, diffusion coefficients were first determined for two systems from data obtained in capillary flow experiments. These values of the diffusion coefficient were then compared to values obtained by other methods. MIXING IN CAPILLARY FLOW-THEORETICAL The theoretical basis for determining molecular diffusion coefficients from capillary flow experiments is the partial differential equation relating the mechanisms of flow and diffusion. SPEJ P. 256^

Mutual Diffusion Coefficients for the Systems HD–N2 and HD–Ar at 1 atm Pressure and 300 K

1973 ◽  
Vol 51 (19) ◽  
pp. 2101-2107 ◽  
Author(s):  
K. R. Harris ◽  
T. N. Bell
Keyword(s):  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Experimental Error ◽  
Mutual Diffusion ◽  
Intermolecular Potentials ◽  
Mass Effects

Mutual diffusion coefficients, D12, have been measured as a function of concentration for the systems HD–N2 and HD–Ar at 1 atm pressure and 300 K. The data are compared with previously published measurements for the corresponding H2 and D2 containing systems. After the estimated uncertainties due to experimental error and impurities, and corrections due to quantum and mass effects are taken into account, the mass corrected diffusion coefficient, [Formula: see text], for each system is found to lie above those of the corresponding H2 and D2 systems by up to 2%. These effects are attributed to differences in the intermolecular potentials of H2, D2, and HD.

Microscale Mass Diffusion Sensing of Polymer Solutions Using Soret Forced Rayleigh Scattering

2008 ◽  
Author(s):  
Yuji Nagasaka
Keyword(s):  
Diffusion Coefficient ◽  
Polymer Films ◽  
Diffusion Coefficients ◽  
Rayleigh Scattering ◽  
Casting Process ◽  
Scattering Method ◽  
Binary Solutions ◽  
Forced Rayleigh Scattering Method ◽  
Cross Diffusion ◽  
The Cross

In the casting process of highly functional films, the control of complex micro and nano structures inside the polymer films is one of the most critical factors. The control requires the cross diffusion coefficients in multicomponent solutions because it has a direct influence on the formation of fine structures inside polymer films during the casting process [1]. However, most studies on diffusion in polymer solutions concentrate on measuring diffusion coefficients in binary solutions and only a few measurement techniques of the cross diffusion coefficient can be found. We have developed a measurement technique for the mutual diffusion coefficient in binary solutions, namely Soret forced Rayleigh scattering method [2–4]. In the present paper, we have applied Soret forced Rayleigh scattering method to measure the binary mass diffusion coefficient for the clarification of the cross diffusion phenomena in multicomponent diffusion.

Optimization of Taylor Dispersion Technique for Measurement of Mutual Diffusion in Benchmark Mixtures

2016 ◽  
Vol 28 (4) ◽  
pp. 459-465 ◽  
Author(s):  
C. I. A. V. Santos ◽  
V. Shevtsova ◽  
H. D. Burrows ◽  
A. C. F. Ribeiro
Keyword(s):  
Taylor Dispersion ◽  
Mutual Diffusion ◽  
Taylor Dispersion Technique ◽  
Dispersion Technique

The mutual diffusion coefficient of ethanol–water mixtures: determination by a rapid, new method

1974 ◽  
Vol 336 (1606) ◽  
pp. 393-406 ◽  
Keyword(s):  
Experimental Data ◽  
Diffusion Coefficient ◽  
Laminar Flow ◽  
Diffusion Coefficients ◽  
Entire Range ◽  
Liquid Mixtures ◽  
Mutual Diffusion ◽  
Mutual Diffusion Coefficient ◽  
Mechanical Theory ◽  
Statistical Mechanical

Mutual diffusion coefficients for liquid mixtures of ethanol and water have been measured over the entire range of composition and for temperatures from 25 to 65 °C at a pressure of 1 bar (10 5 Pa). At the lowest temperature, the results establish the validity of a new experimental method based upon Taylor’s analysis of solute dispersion in laminar flow. The method offers advantages of simplicity and speed over other techniques, and allows direct measurement of diffusion coefficients at well-defined mixture compositions. The experimental data have an estimated uncertainty of ±2.5% . The results have been utilized to evaluate friction coefficients arising in the statistical mechanical theory of transport in liquid mixtures.

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