Fabrication and Characterization of 3BDO-Loaded Dissolvable Microneedle Patches for Hair Regrowth in C57BL/6 Mice

Conventional treatments for androgenetic alopecia (AGA) have limitations, motivating alternative delivery approaches. This protocol describes the fabrication, characterization, and application of 3BDO-loaded hyaluronic acid/chitosan (HA/CS) dissolvable microneedle (MN) patches in a C57BL/6 mouse hair-regrowth model. The method uses a two-step molding process in a polydimethylsiloxane (PDMS) mold to concentrate 3BDO in the needle tips while forming a drug-free HA/CS backing layer. The patch is characterized by scanning electron microscopy (SEM) imaging, mechanical testing, skin insertion and dissolution testing, in vitro release testing, antibacterial assays, cytotoxicity testing, and in vivo hair-regrowth assessment. Upon insertion, the MN tips dissolve, releasing 3BDO locally. In vivo evaluation showed that the 3BDO-loaded MN group had more uniform hair regrowth than the subcutaneous injection and control groups tested. This protocol also supports assessment of patch morphology, insertion performance, and local biocompatibility. This method provides a preclinical workflow to evaluate MN-mediated delivery of 3BDO for hair-regrowth applications.