A novel transdermal protein delivery strategy via electrohydrodynamic coating of PLGA microparticles onto microneedles

Transdermal delivery of biological therapeutics is emerging as a potent alternative to intravenous or subcutaneous injections. The latter come with major challenges including patient discomfort, the necessity for trained personnel, specialized sharps disposal, and risk of infection. Microneedle (MN) technology circumvents many of the abovementioned challenges, delivering biological material directly into the skin and allowing sustained release of the active ingredient both in animal models and in humans. This study describes the use of electrohydrodynamic atomization (EHDA) to coat ovalbumin (OVA)-encapsulated PLGA nanoparticles onto hydrogel-forming MN arrays. The particles showed extended release of OVA over ca. 28 days. Microscopic analysis demonstrated that EHDA could generate a uniform particle coating on the MNs, with 30% coating efficiency. Furthermore, the coated MN array manifested similar mechanical characteristics and insertion properties to the uncoated system, suggesting the coating should have no detrimental effects on the application of the MNs. The coated MNs resulted in no significance increase in anti-OVA specific IgG titres in C57BL/6 mice in vivo as compared to the untreated mice (paired t-test, p >0.05) indicating that the formulations are non-immunogenic. The approach of using EHDA to coat a MN array thus appears to have potential as a novel non-invasive protein delivery strategy.