Structural characterization and skin penetration studies on sugar microneedles: Experimental and finite element modelling analyses

Dissolving microneedles are especially attractive for transdermal drug delivery as they are associated with improved patient compliance and safety. Furthermore, microneedles made of sugars offer the added benefit of biomolecule stabilisation making them ideal candidates for delivering biological agents such as proteins, peptides and nucleic acids. In this study, we performed experimental and finite element analyses to study the mechanical properties of sugar microneedles and evaluate the effect of sugar composition on microneedle ability to penetrate the skin. Our results showed that microneedles made of carboxymethylcellulose/maltose and carboxymethylcellulose/trehalose are superior to those made of carboxymethylcellulose/sucrose in terms of both mechanical strength and skin penetration properties. Buckling was predicted to be the main mode of microneedle failure and the order of buckling was positively correlated to the Young’s modulus values of the sugar constituents of each microneedle.