Halloysite Nanoclay for Controlled Release Applications

Nanoclays have shown great potential in the field of controlled release. In particular, the cylindrical geometry and surface chemistry of halloysite nanotubes make them attractive for use as nanocarriers. Halloysite’s tubular cavity can be filled with drug which later diffuses out of the lumen, enabling controlled release behavior over several hours. When halloysite is incorporated into polymer matrices, such as polyvinyl alcohol (PVOH) and poly(methyl methacrylate) (PMMA), release has been shown to be extended even further, on the order of days. In this chapter, the principles and mechanisms used in controlled release applications are presented, and recent studies of controlled release from halloysite nanotubes are reviewed. Particular attention is paid to two studies on the incorporation of tetracycline-loaded halloysite into polymer films to prepare monolithic controlled release systems. Factors affecting the release from halloysite are explored, particularly loading method and material properties.