1. Nanoencapsulation as fluorescence enhancer of vitamin L1 (anthranilic acid). An exhaustive study.
- Author
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María Belén, Vázquez, Adrián, Matencio, Francisco, García-Carmona, and José Manuel, López-Nicolás
- Subjects
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AMINOBENZOIC acids , *CYCLODEXTRINS , *INCLUSION compounds , *FLUORESCENCE , *GIBBS' free energy , *COMPLEXATION reactions - Abstract
Abstract This paper describes the guest-host complex formation of anthranilic acid (2-aminobenzoic acid, AA) and different natural and modified cyclodextrins (CDs), using steady state fluorescence. The experimental data point to the formation of 1:1 inclusion complexes with natural (ß and ɣ-CD) and modified (HP-ß, HE-ß and M-ß-CD) CDs. Of the natural CDs, the ß-CD complex showed the highest encapsulation constant (K F) value (14056 ± 1241 M−1). However, modified ß-CDs showed higher binding constants than ß-CDs. Of the modified CDs, M-β-CD showed the highest K F (18622 ± 897 M−1). To gain information on the encapsulation process of M-ß-CD/AA, the thermodynamic parameters of the complexation (ΔH, ΔS and ΔG), were studied. The results showed positive entropy (66 ± 7.9 J mol−1 K−1), negative enthalpy (−5.74 ± 2.96 kJ mol−1) and a change in Gibbs free energy at 25 °C (−24.30 ± 0.27 kJ mol−1). Finally, a computational study carried out using molecular docking simulations showed the high correlation between experimental values and computed scores. The complexation of M-ß-CD/AA depends on several physicochemical factors including temperature and pH. The values of K F exhibited a strong negative relation with temperature and pH. Moreover, the interaction of AA and M-ß-CD was most effective in the pH region where the molecule presents intramolecular hydrogen bonds that neutralize the charge of the protonated species of AA. Graphical abstract Image 108662 Highlights • Inclusion complexation of anthranilic acid with methyl beta cyclodextrin. • Stoichiometry of complexation is 1:1. • The binding constant decreases linearly with increasing temperature. • Anthranillic acid MbCD compleixation constant is higher below pKs region. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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