Biocompatible Clay Nanotube Formulations for Controlled Delivery of Drugs

Halloysite clay is a naturally occurring clay nanomaterial which with length of approximately 1000 nm, a diameter of 50 nm and a lumen of 15 nm. Traditionally, halloysite is used for ceramics and as an inorganic reinforcing material for polymers. The 15 nm lumen can be loaded with bioactive molecules such as antibiotics and proteins. By doping loaded halloysite into polymers one can achieve a controlled sustained release of the desired molecule into the matrix. The differing chemistries inside and outside the lumen present avenues to modulate the loading and release patterns and attributing smart properties to halloysite-polymer composites. Typically, the addition of 5-8 % wt. halloysite synergistically increases polymer strength by 30-70 %, enhances composite adhesiveness and adds new functions due to release of the bioactive molecules. Halloysites are regarded as environmentally safe and biocompatible as demonstrated by experiments with cell cultures, microworms and small animals. This enables the application of halloysites as slow and sustained release vehicles of antibiotics for bone implants and dental composites. Bioactive molecules like dexamethasone, furosemide and resveratrol were released from the halloysite lumen over 20-30 hours.