Battery-free and self-propelled bionic microneedle system for chemically controlled on‐demand drug delivery

Developing a promising on-demand controllable microneedle drug delivery system could provide stronger self-control and precision delivery of a large payload capacity. Nevertheless, the efficacy of existing systems has been constrained by limitations in the therapeutic payload capacity and slow diffusion of molecules, as well as the necessity for external resource configurations. Drawing inspiration from the multidimensional biomimetic strategies observed in the material properties and functional mechanisms of the bombardier beetle's defensive secretion system, a battery-free and self-propelled biomimetic microneedle system (BSBMs) is proposed for improving therapeutic outcomes and enabling controlled, on-demand drug delivery. The self-powered microneedle delivery platform fully emulates the structure and spray mechanism of bombardier, employing Pt nanoparticles and H₂O₂ loaded in the reaction chamber, as a built-in fuel source for active and controllable payload delivery. The robust bionic gas injector can serve as an active engine, facilitating the effective permeation of drugs through hollow microneedles without a complex pumping system. This BSBMs triggers the H₂O₂ decomposition reaction through thumb pressure, generating O₂ pressure as an endogenous driving force to achieve transdermally precise and on-demand drug delivery. The pharmacokinetics of drug release from the BSBMs were evaluated in vivo by quantifying the levels of levonorgestrel (LNG). This active delivery system maintains in vivo LNG concentrations within the therapeutic window range, greatly enhancing on-demand, controlled, and stable drug delivery. This versatile and efficient self-propelled bionic microneedle delivery technology holds substantial promise for a broad spectrum of transdermal therapeutic applications, offering a simplified, convenient, and improved method of administration.