Modified Halloysite Nanotubes As Vehicle For Sustained Drug Delivery

ABSTRACT

Halloysite, a natural mineral mined in many parts of the world has gained a lot of

attention recently due to its ability to control and sustain the release of drugs and other

active agents. It is a hollow tubular structure composed of double layer of aluminosilicate

minerals in the nanometric range. They are non-toxic and biocompatible as compared to

other nanocarriers. Its unique structure can be modified to improve its properties for

control drug delivery applications.

In this study, halloysite nanotubes were modified and the effect of these modifications on

sustain drug release was analyzed and evaluated. The two modification techniques

employed were acid-treatment and polymer/ halloysite composite formation. After each

modification, sodium salicylate drug was loaded and their in vitro release properties were

evaluated and compared with raw unmodified halloysite nanotubes. The results obtained

indicate that both acid treatment and polymer/halloysite composite formation have no

effect on the tubular structure and morphology of halloysite. This was shown by SEM,

TEM and FTIR analysis made. However, modification of the halloysite nanotubes

influenced the drug release rate. Results obtained also indicate that in acid–treatment

modification, there was an improved loading of sodium salicylate drug which resulted in

the sustain release of large amount of the sodium salicylate drugs loaded. In

polymer/halloysite composite formation, a consistent layer of polymer formed around the

halloysite during the composite formation and thus delayed and sustained the release of

sodium salicylate drug over a longer period of time as compared to the acid treated and

raw untreated halloysite. In both modifications, the in vitro release was best fit with

v

Higuchi model. However, raw untreated halloysite was best fit with Koresymer-Peppas

model.