*3.5. Ex Vivo Adhesion Studies*

Patch loaded with ZnAl-KET showed a bioadhesion force of 0.513 ± 0.015 N vs. 0.411 ± 0.011 N measured for the same patch without HTlc (blank). This increase was probably due to the wrinkled surface of the loaded patch, able to promote the contact and adhesion with the skin surface. Moreover, it can be hypothesized that ZnAl-KET establishes hydrophilic interactions (hydrogen bonds) with NaCMC chains involving −OH and C=O groups. This should improve the hydrophobicity of patch surface due to the exposition of NaCMC lipophilic groups (as-CH3) freely available to bind the skin. In fact, the binding to the stratum corneum is mainly attributable to hydrophobic interactions.
