PISA Printing Microneedles with Controllable Aqueous Dissolution Kinetics

This study focused on the development of high-resolution polymeric structures using polymer-induced self-assembly (PISA) printing with commercially available digital light-processing (DLP) printers. Significantly, soluble solids could be 3D-printed using this methodology with controllable aqueous dissolution rates. This was achieved using a highly branched macrochain transfer agent (macro-CTA) containing multiple covalently attached CTA groups. In this work, the use of acrylamide as the self-assembling monomer in isopropyl alcohol was explored with the addition of N-(butoxymethyl)acrylamide to modulate the aqueous dissolution kinetics. PISA-printed microneedles were observed to have feature sizes as small as 27 μm, which was close to the resolution limit of the DLP printer. Atomic force measurements confirm the presence of a complex mixture of PISA morphologies, including spheres and worms. Additionally, “poke and release” microneedles were fabricated; their base dissolved rapidly in physiological fluids, leaving behind more slowly dissolving tips, thereby demonstrating the potential for sustained drug delivery.