Advances in the Formulations of Microneedles for Manifold Biomedical Applications

Transdermal delivery systems have recently attracted a great interest due to its minimal invasiveness and convenience. One latest technology in this field is the microneedle technology, which is a single or array of miniaturized needles on the micrometer scale. They pierce the stratum corneum and create transient microchannels for drug diffusion or extraction of skin interstitial fluid. The latest developments of the microneedles are reviewed here by focusing on the materials and fabrication techniques. They are categorized into nonpolymeric and polymeric ones that are made through a wide range of technologies such as lithography, micromolding, droplet-born air blowing. Powered by the unique structures and functional materials, these microneedle platforms can provide solutions for skin diseases, diabetes, obesity, ocular diseases, as well as point-of-care diagnosis.