Upconverting Nanoparticle‐Loaded Microneedles for Near‐Infrared Responsive Delivery of Gonadotropins to Increase Success of In Vitro Fertilization

In vitro fertilization (IVF) requires repeated bolus injections of gonadotropins at precise times, making it a painful and stressful experience for women. Polymeric microneedles (MNs) present a painless alternative to hypodermic needles, but controlling the release of drugs through MNs remains a challenge. Here, we report the development of a hydrogel MN patch integrated with upconverting nanoparticles coated with light-breakable mesoporous silica (UCNP@LBMS) that releases the IVF gonadotropin, leuprolide, in response to near-infrared (NIR) light, while retaining the UCNPs within the MN patch. In rats, a 5 min NIR pulse of 2 W cm^-2 results in a significant increase in leuprolide release in both skin and plasma, with MN length playing an important role in drug bioavailability. Beyond IVF, UCNP-integrated MN patches offer a painless, automated alternative in any application that requires daily, repeated, time-sensitive hypodermic needle injections, such as diabetes or multiple sclerosis.