Two-photon polymerization based reusable master template to fabricate polymer microneedles for drug delivery

Microneedle patches have been widely used in a minimally invasive manner for various drug delivery applications. However, for developing these microneedle patches, master molds are required, which are generally made of metal and are very expensive. Two-photon polymerization (2PP) technique can be used for fabricating microneedles more precisely and at a much lower cost. This study reports a novel strategy for developing microneedle master templates using the 2PP method. The main advantage of this technique is that there is no requirement for post-processing after laser writing, and that for the fabrication of polydimethylsiloxane (PDMS) molds, harsh chemical treatments such as silanization are not required. This is a one-step process for manufacturing of microneedle templates which allows easy replication of negative PDMS molds. This is done by adding resin to the master-template and annealing at a specific temperature, thereby making the PDMS peel-off easy and allowing re-use of the master template multiple times. Using this PDMS mold, two types of polyvinyl alcohol (PVA)-rhodamine (RD) microneedle patches were developed, namely, dissolving (D-PVA) and hydrogel (H-PVA) patches and were characterized using suitable techniques. This technique is affordable, efficient and does not require post-processing for development of microneedle templates required for drug delivery applications. • Two photon polymerization can be used for cost-effective fabrication of polymer microneedles for transdermal drug delivery. • Post-processing or surface-modification procedures are not required for these master templates. • Using a simple annealing step, the master template becomes reusable and robust for peeling off polymers like PDMS.