Upconverting Nanoparticle-Loaded Microneedles for Near-Infrared Responsive Delivery of Gonadotropins to Increase...

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.