In Vitro Analysis of Microneedle Patches for Transdermal Drug Delivery: A Minimally Invasive Route to Systemic Circulation

Nanoparticles offer great potential as drug delivery vehicles but conveniently administering them systemically at therapeutically relevant doses remains a challenge. To date, systemic delivery of nanoparticles is achieved through intravenous injection or oral administration; however, each of these approaches are limited by shortcomings (e.g., painful delivery, low bioavailability). In the present study, we explore the development and in vitro testing of alginate-based microneedle patches and their potential to deliver various nanoparticles. We demonstrate that therapeutics encapsulated in these MNPs effectively release from the polymer matrix, and that released therapeutics retain their bioactivity and can be taken up by cells of interest. Here, curcumin released from alginate MNPs retained its antimicrobial activity, and nanogels were uptaken by both cancerous and normal breast epithelial cells. When antibodies were conjugated to the nanogel surface, they remained functional for efficient ligand-based targeting. Finally, released extracellular vesicles were successfully uptaken by fibroblasts. Taken together, these results demonstrate the payload versatility of this system. Furthermore, we show that these microneedle patches can successfully penetrate the epidermis of skin ex vivo, allowing encapsulated nanoparticles to permeate into deeper tissue. Overall, these studies highlight the capacity of microneedle patches to release functional nanoparticles in vitro, suggesting the potential of this system to enhance the bioavailability of therapeutics in a minimally invasive and self-administered fashion.