Dissolving microneedle array patches containing mesoporous silica nanoparticles of different pore sizes as a tunable sustained release platform.

Dissolving microneedle array patches (DMAP) enable efficient and painless delivery of therapeutic molecules across the stratum corneum and into the upper layers of the skin. Furthermore, this delivery strategy can be combined with the sustained release of nanoparticles to enhance the therapeutic potential in a wide variety of pathological scenarios. Among the different types of nanoparticles that can be included in microneedle formulations, mesoporous silica nanoparticles (MSN) of tunable pore sizes constitute a promising tool as drug delivery systems for cargos of a wide range of molecular weights. In this work, a new preparation method was developed to produce DMAP containing ca. 2.3 mg of MSN of different pore sizes located mainly in the microneedle tips. The successful insertion of these DMAPs was confirmed in vitro (using Parafilm), ex vivo (using excised neonatal porcine skin) and in vivo (in the back of mice). The dissolution of the microneedles and deposition of the nanoparticles inside the skin were also confirmed both ex vivo and in vivo using fluorescent nanoparticles (with an intradermal deposition of 20.9 ± 7.26 % of the MSN in each DMAP in neonatal porcine skin). Finally, the in vivo release of the cargo from nanoparticles deposited inside mouse skin after microneedle insertion was confirmed through in vivo fluorescence measurements.