Geometrical optimisation of a personalised microneedle eye patch for transdermal delivery of anti-wrinkle small peptide.

Acetyl-hexapeptide-3 (AHP-3) is a small peptide with good anti-wrinkle efficacy and safety profile. However, due to its hydrophilicity and high molecular weight, its skin permeation is generally poor. An innovative microneedle (MN) patch such as the curved, flexible or personalised MN patch is a viable avenue to deliver AHP-3. However, the well-researched geometrical relationship of MN on a flat MN patch cannot be assumed for these novel MN patches due to a complex mix of axial and shear forces. In this study, 3D printing was used for the fabrication of various MN patches with different MN geometries and curvatures. Both mechanical strength and skin penetration efficiency were used to determine the optimal MN geometry. The optimal MN geometry was then applied to the fabrication of a personalized MN patch (PMNP) for anti-wrinkle therapy, via 3D printing. In all, the general principles of MN geometrical effects on mechanical strength and skin penetration efficiency for a curved and a flat MN patch were similar. A MN height of 800 μm, tip diameter of 100 μm, interspacing of 800 μm and base diameter of 400 μm was observed to be the optimal MN geometry across all curvatures. In vitro skin permeation study demonstrated enhanced transdermal delivery of AHP-3 using the fabricated PMNP. Therefore, PMNP with optimized MN geometry can potentially be a novel approach to augment transdermal delivery of AHP-3 for effective wrinkle management.