Compatibility between Paclitaxel and Polymer Carrier

Several polymer-based drug delivery systems are being developed to enhance the extremely low water-solubility of paclitaxel (PTX). It is believed that there is a positive correlation between the compatibility of polymer-drug and the solubilization. In recent years, solubility parameters for polymer and drug were used to evaluate degree of compatibility between a drug and a polymer, which were measured using various experimental methods or estimated using the group contribution menthod (GCM). In this study, degree of compatibility between PTX and polymers were estimated by molar free energy of mixing (Δ̗mix) that was calculated through computer simulation. It is found that the degree of compatibility is: PTX-PTRP > PTX-PLBG > PTX-PLGA > PTX-PCL > PTX-PLA. It has been demonstrated that the result of this study is in accord with the Similar Dissolve Mutually Theory.

The Solubility of Metallic Selenium under Anoxic Conditions

ABSTRACTThe solubility of metallic selenium was measured in a mixture of 0.1M-NaCl and 0.05M-N2H4under anoxic conditions (O2 < 1 ppm) by both oversaturation and undersaturation methods. Equilibrium was attained in 40 days. The aqueous selenium species identified were HSe at pH between 5 and 8, and Se42at pH between 10 and 13, by UV-Vis absorption spectrometry. The solid phase was identified as Se (cr) by X-ray diffraction. The equilibrium constants ofSe(cr) + H+ + 2e- = HSe- logK0 = -6.5±0.5 and4Se(cr) + 2e- = Se42- logK0 = -16.8±0.5were determined. The standard molar free energy of formation of HSe- and Se42-was determined to be (37.1±2.9) and (95.9±2.9) kJ/mol, respectively.

Determination of Thermodynamic Properties of Poly(4-tert-Butylstyrene) by Inverse Gas Chromatography

Some thermodynamic quantities were obtained for the interactions of poly (4-tert-butylstyrene) with alcohols, ketones, acetates, aromatics and alkanes by the inverse gas chromatography method in the temperature range of 343-463 K. The specific retention volumes (Vg°), the adsorption enthalpy of probes (ΔH2), the partial molar free energy of sorption (ΔG1S), the enthalpy of sorption (ΔH1S), the entropy of sorption (ΔS1S), the weight fraction activity coefficients of solute probes at infinite dilution (Ω1∞), and the Flory- Huggins thermodynamic interaction parameters (χ∞12) between polymer and solvents are given. The partial molar free energy (ΔG1∞, the partial molar heat of mixing (ΔH1∞ at infinite dilution and the solubility parameters of the polymer (δ2) were calculated. The solubility parameter of poly (4-tert-butyl- styrene) was determined from either the slope or intercept as 7.25 (cal/cm3)0,5 and 7.00 (cal/cm3)0,5 at 180°C, respectively.

Viscosities and thermodynamics of viscous flow of binary liquid mixtures of 2-(2-butoxyethoxy)ethanol with aniline and N-alkyl anilines

Viscosities and densities of binary mixtures containing 2-(2-butoxyethoxy)ethanol with aniline and N-alkyl-substituted anilines have been determined at five different temperatures over the complete concentration range. Excess volumes, viscosities, and excess molar free energy of activation of flow were calculated and the departure from ideal behavior is explained on the basis of specific interactions between the components in these mixtures. McAllister's approach correlates the viscosity data with a significantly high degree of accuracy for all these systems.

Ultrasonic Velocities, Densities and Viscosities of (Prop-2-en-1-ol+Ethylbenzene or Isopropylbenzene) at 298.15 And 308.15 K

Isentropic compressibility, its excess value, excess molar volume, excess viscosity, and excess molar free energy for the activation of flow have been calculated from the experimental values of the speed of sound, density and viscosity at 298.15 and 308.15 K for mixtures of prop-2-en-1-ol with ethylbenzene or isopropylbenzene. The parameter d, of the Grunberg and Nissan expression, has also been calculated. The variation of the excess functions with composition indicates the absence of any specific interactions. In both the systems at 298.15 K, for alcohol mole fraction less than 0.66, the dissociation of the hydrogen-bonded alcohol agglomerates predominates over the association between unlike molecules. At the higher temperature the dissociation is predominant over the whole composition range.

Viscosities and densities of binary liquid mixtures of m-cresol with substituted anilines. Part 3

Densities and viscosities were determined for the binary systems of m-cresol with aniline, N-methylaniline, N, N-dimethylaniline, N-ethylaniline, and N, N-diethylaniline at five different temperatures. From the experimental results, the excess volume, excess viscosity, excess molar free energy of activation of flow, excess partial molar volume, and partial molar volumes were calculated. Also various thermodynamic parameters of activation of flow were calculated from the dependence of viscosity on temperature. The deviations from ideality of thermodynamic and transport functions are explained on the basis of molecular interactions between the components of the mixture.