Controlled delivery systems have already had an enormous impact on applications such as rust coatings, self-healing composites, and selective delivery of drugs. An important prerequisite for designing an efficient controlled delivery system is the ability to release them in a controlled manner at the targeted site. Many drug delivery systems such as nanoparticles, nanocapsules, nanotubes and nanogels, have been introduced. Halloysite nanotubes (HNTs) a naturally occurring biocompatible nanomaterial that are abundantly available and cheap, are promising candidates for controlled delivery vehicles. They are alumosilicate-based tubular clay nanotubes with an inner lumen of 15 nm and a length of 600-900 nm. The size of the inner lumen of HNTs may be adjusted by etching. The lumen can be loaded with functional agents like antioxidants, anticorrosion agents, flame-retardant agents, drugs, or proteins, allowing for a sustained release of these agents for hours. The release times can be further tuned for days and months by the addition of tube end-stoppers. In this work a three-dimensional, time-quantified Monte Carlo model that efficiently describes diffusion through and from nanotubes is implemented. Controlled delivery from HNTs is modeled based on interactions between the HNT’s inner wall and the nanoparticle (NPs) and among the nanoparticles themselves. The validated model is then used to study the effect of multiple parameters like HNT diameter, length, pH, and ambient temperature on the release of the encapsulated agents. The results show that release profiles depend on the size distribution (lumen and length) of the HNT batch used for the experiment. The delivery is also sensitive to pH and temperature. One possible outcome of this work is the development of more complex models for HNT–NP interaction and various other materials used in bioanalytical and other devices.

Tunable, controlled release of molecular species from halloysite nanotubes

251st National Meeting (2016)

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