Halloysite nanotubes are effective nanocarriers for the loading and controlled release of functional molecules. Here, we investigated the influence of the vacuum pumping on the filling mechanism of halloysite cavity for several drugs (salicylic acid, sodium diclofenac, malonic acid and metoprolol tartrate) solubilized in two different solvents (water and ethanol). According to the Knudsen thermogravimetric data, we proved that the solvent confinement within the nanotubes’ cavity is crucial to properly describe the driving process of halloysite loading. Both morphological investigations and thermogravimetric experiments evidenced that the amounts of the drugs encapsulated inside the halloysite cavity can be enhanced by the vacuum pumping in/out procedure. In addition, we detected that the the release kinetics of the drugs can be controlled by the pressure conditions used in the loading protocol. As a general result, we observed that the halloysite/drugs hybrids prepared under vacuum exhibited slower release profiles with respect to the corresponding composites obtained at ambient pressure. In conclusion, this study describes the physico-chemical aspects of the halloysite filling, which is controlled by solvent confinement within the nanotubes’ cavity. The attained knowledge represents a fundamental step for the development of loading protocols into confined spaces of tubular nanoparticles.

Halloysite loading mechanism under vacuum pumping

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.