**Figure 2.**

*Different methods to prepare inclusion complexes.*

*Strategies to Develop Cyclodextrin-Based Nanosponges for Smart Drug Delivery DOI: http://dx.doi.org/10.5772/intechopen.100182*

#### *4.2.2 Fourier-transform infra-red (FTIR)*

This technique is usually used in solid complexes, generally in the range of 400–4000 cm−1, although it depends on the studied drug [58, 60]. Changes in the characteristics bands of the guest molecule or shifts in the wavenumber can indicate the formation of the complex. In addition, the same principle can be used to follow the CD-NS synthesis.

#### *4.2.3 Nuclear magnetic resonance (NMR) spectroscopy*

NMR is one of the most useful procedures to obtain complete analytical information of the CD-NS and the complex formed. An alteration in the chemical shift of the protons occurs when the drug enters the CD-NS providing specific information about the orientation of the guest molecule inside the cavity.

#### *4.2.4 Thermogravimetric analysis (TGA)*

TGA determines the changes of weight to temperature increases. The comparison of the weight loss profile of pure components, physical mixture, and the complex shows differences correlatives to the complex formation. A stage on TGA around 300°C is found in CD-NS due to CD decomposition [59].

#### *4.2.5 Differential scanning calorimetry (DSC)*

It can provide detailed information about their physical and energetic properties. The comparison of the thermal curves of single components, their physical mixture, and the presumed inclusion compound ought to provide insight into modifications and interactions due to the formation of the inclusion complex. The change that occurs in the fusion point of the guest molecule is usually hiding by the complex formation, while it remains in the physical mixture. This, and several modifications in the shape and temperature peak of the CD dehydration and/or with the disappearance of the drug melting peak among others, are proves of the complexation.
