Bacterial nanocellulose-hyaluronic acid microneedle patches for skin applications: In vitro and in vivo evaluation.

The aim of the present study was to develop innovative patches for dermo-cosmetic applications based on dissolvable hyaluronic acid (HA) microneedles (MNs) combined with bacterial nanocellulose (BC) as the back layer. HA was employed as an active biomacromolecule, with hydrating and regenerative properties and volumizing effect, whereas BC was used as support for the incorporation of an additional bioactive molecule. Rutin, a natural antioxidant, was selected as the model bioactive compound to demonstrate the effectiveness of the system. The obtained HA-MNs arrays present homogenous and regular needles, with 200 μm in base width, 450 μm in height and 500 μm tip-to-tip distance, and with sufficient mechanical force to withstand skin insertion with a failure force higher than 0.15 N per needle. The antioxidant activity of rutin was neither affected by its incorporation in the MNs system nor by their storage at room temperature for 6 months. Preliminary in vivo studies in human volunteers unveiled their safety and cutaneous compatibility, as no significant changes in barrier function, stratum corneum hydration nor redness were detected. These results confirm the potentiality of this novel system for skin applications, e.g. cosmetics, taking advantage of the recognized properties of HA and the capacity of BC to control the release of bioactive molecules.