Nystatin complexation with -cyclodextrin: Spectroscopic evaluation of inclusion by FT-Raman, photoacoustic spectroscopy, and 1H NMR

The inclusion complex of Nystatin (NYS) with β-cyclodextrin (β-CD) can increase the solubility of the antibiotic in aqueous media. The complexes were obtained by freeze-drying (FD) and spray-drying (SD) methods. The spectroscopic techniques used to analyze the complexes were FT-Raman, photoacoustic spectroscopy (PAS), and 1H NMR. FT-Raman allowed the identification of the interactions of β-CD with NYS molecule through the vibrational modes assigned to tetraene, heptaene and C=O. PAS confirms that the main part of interaction from NYS is heptaene. The 1H NMR showed that the hydrogens inside the cavity of β-CD interact with NYS. These techniques confirmed the complex formation and that the drying method affects the form of complexation: by the FD method one molecule of β-CD is sufficient to form the complex with NYS. In contrast, the inclusion complex of NYS: β-CD by the SD method is formed by two molecules of β-CD. These results showed the effectiveness of these techniques in evaluating the inclusion complex and demonstrate that the drying method affects how this complexation occurs.