Enhancing Penetration Performance and Drug Delivery of Polymeric Microneedles Using Silica Nanoparticle Coatings

Microneedle (MN) technology offers a powerful approach for transdermal delivery enabling painless injection and facilitating self-administration without the need for professional assistance. However, the weak mechanical strength of MNs can lead to inefficient drug delivery and serious skin irritation if the MNs fracture during administration and leave fragments under the skin. Thus, the MNs need to be mechanically robust to avoid fracture during penetration through the skin while maintaining efficient drug delivery. Herein, the polymer-based MNs with layer-by-layer (LbL) films of silica (SiO₂) nanoparticles (NPs) and a polycation (poly(diallyldimethylammonium chloride) (PDADMAC)) followed by hydrothermal calcination are reinforced. The mechanical strength of the MNs is significantly improved after LbL assembly and shows lower threshold pressure to penetrate skins. Moreover, their drug loading and releasing properties are significantly enhanced due to an increase in the surface area and interfacial interaction. These SiO₂ nanoparticle-containing LbL thin films have great potential for the surface modification of 3D microstructured devices such as MNs, as evidenced by their enhanced mechanical strength and drug coating efficiency that result in a promising MN drug delivery model.