Electro-Mechanochemical Gating of a Metal-Phenolic Nanocage for Controlled Guest-Release Self-Powered Patches and Injectable Gels.

Recent advances have led to the development of intelligent drug-delivery systems such as microchips, micropumps, and soft devices with sensors; however, the facile preparation of transdermal and implantable systems modulable to various stimuli remains elusive. In addition, the use of a battery limits their wearable and implantable applications. Therefore, to overcome these disadvantages, we herein suggest a facile strategy to prepare electro-mechanochemically responsive soft gel composites with molecular gatekeeper-based nanocontainers. We found that a metal-phenolic coordination network can act as an efficient self-healable and adaptive gatekeeper in response to electrical and mechanical stimuli owing to the reversible dynamic bonds and adhesiveness to the silica surface. The porous channels of mesoporous silica nanoparticles are filled with guest molecules, and the exterior is wrapped with metal-tannic acid (TA) networks. Owing to the robustness of metal-phenolic network, the guest molecules are efficiently entrapped in the channels but released by electrical and ultrasound input. Voltage-dependent changes in the guest release rate provide control over the dosage on demand. The combination of hydrogel matrixes with the responsive nanocapsules enables the construction of a series of adaptive gel composites capable of successive guest release in response to electrical, ultrasound, electromechanical, and triboelectric stimuli. The Korsmeyer-Peppas model revealed that the release mechanism is non-Fickian, which indicates the presence of boundaries around the guest-loading channels ( = 0.739, = 0.9574 when 2 V is applied). This study realized efficient platforms for active-type drug-delivery applications based on transdermal patches and implantable gels with remotely controllable release characteristics.