Thermodynamics of β-cyclodextrin–ephedrine inclusion complex formation and covering of nanometric calcite with these substances

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• 作者：Małgorzata Wszelaka-Rylik
• 关键词：Isothermal titration calorimetry (ITC) ; β ; Cyclodextrin ; Ephedrine ; Inclusion complex ; Nanometric calcium carbonate ; Coated CaCO3 with ephedrine and its β ; cyclodextrin complex
• 刊名：Journal of Thermal Analysis and Calorimetry
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：127
• 期：2
• 页码：1825-1834
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Physical Chemistry; Analytical Chemistry; Polymer Sciences; Inorganic Chemistry; Measurement Science and Instrumentation;
• 出版者：Springer Netherlands
• ISSN：1588-2926
• 卷排序：127

文摘

Isothermal titration calorimetry (ITC) has been used to characterize inclusion complex formation of β-cyclodextrin (β-CD) with ephedrine in aqueous solutions. ITC measurements were taken at 298.15 K on a MicroCal OMEGA ultrasensitive titration calorimeter (MicroCal Inc.). The experimental data were analyzed on the basis of the model of a single set of identical sites (ITC Tutorial Guide). Based on the experimental values of equilibrium constant (K) and enthalpy of complex formation (ΔH), the Gibbs energy of complex formation (ΔG), and the entropy of complex formation (ΔS), has been calculated. Obtained results showed that β-CD forms inclusion complex of stoichiometry 1:1 with ephedrine and the complex formation is entropy driven. Ephedrine and its complex with β-CD have been further used for covering of the obtained in a controlled way nanometric CaCO₃ (calcite), which served as a solid supports for drug depositing. The calcite coating has been analyzed by the use of thermogravimetric method. The size of aggregates of pure calcite particles as well as CaCO₃ particles covered by ephedrine and its complex with β-CD have been measured by DLS method. It has been found that pure CaCO₃ aggregates are almost monodispersed with the mean diameter equal to 329 nm (±5 nm). Ephedrine and its complex with β-CD layers formed in situ on precipitated calcite surface prevented from crystallites aggregation and decreases particles mean diameter up to 274 nm (±5 nm) for ephedrine and 211 nm (±5 nm) for β-CD complex with ephedrine.