Study of nanomaterials strengthened dissolving polymer microneedles

Abstract

Dissolving Polymer has been used as a major material to produce Microneedles that leave behind no biohazardous sharp medical waste after application. In this project, a dissolving polymer Carboxymethylcellulose (CMC) was selected as the base material for study. The CMC was being selected due to its biocompatible properties and the history of use in FDA-approval parenteral formulations. Still, the Polymer Microneedles are now facing two problems before it can be used is practical application. The dissolving polymer is not mechanical strong enough to insert into the skin. The dissolving polymers usually mechanically weak and they cannot reliably pierce skin’s outer barrier of stratum corneum to deliver drugs. Different approaches have been tested to see whether they can enhance the mechanical properties of the Dissolving Polymer. By adding nanocomposites, in case the composites can be well-dispersed in CMC and they can form a strong bonding with CMC, the mechanical properties of CMC may sharply increase. Three kinds of nanomaterials has been used for testing in this project, namely Layered Double Hydroxide, Silica nanoparticles, Graphene Oxide. Among the other nanocomposites, addition of 5wt% Silica nanoparticles in CMC can achieve the best improvement in the mechanical properties. The 5wt% silica nanoparticles can best reinforce the mechanical properties of CMC may due to the following reason. There are strong linkages between silica nanoparticles, like hydrogen bond and the formation of an immobilized amorphous layer of polymer molecules on the silica nanoparticles. However, increase the wt% of silica nanopartices in CMC more than 5wt% will not give the CMC a better mechanical performance, but even worse. The formation of aggregate due to high wt% of nanoparticles in CMC is the main reason for the out-of-expected decrease in the mechanical properties of CMC when increase the wt% of nanoparticles. Moreover, the current microfabrication methods are not stable to produce more standardized Polymer Microneedles and even not suitable for mass production. The current method by use of centrifuge to produce Microneedles Patch often produced product with projections direct to different direction. A new approach by use of vacuum pump and desiccators has been well studied. The results showed that the Microneedles Patch produced by the new method is more standardized and it shortens the production time.