Ultrafast Electrochemical Trigger Drug Delivery Mechanism for Nanographene Micromachines

Nano/micromachines with autonomous motion are the frontier of nanotechnology and nanomaterial research. These self‐propelled nano/micromachines convert chemical energy obtained from their surroundings to propulsion. They have shown great potential in diagnostic and therapeutic applications. This work introduces a high‐speed tubular electrically conductive micromachine based on reduced nanographene oxide (n‐rGO) as a platform for drug delivery and platinum (Pt) as the catalytic inner layer. n‐rGO/Pt micromachines are loaded with doxorubicin (DOX) by a simple physical adsorption with a very high loading efficiency, displaying single‐ or multistrand wrapping of DOX monomers on the micromachine cylinders. More importantly, it is found that electron injection into DOX@n‐rGO/Pt micromachines via electrochemistry leads to expulsion of DOX from micromachines in motion within only a few seconds. An in vitro study confirms this efficient release mechanism in the presence of cancerous cells. The unique properties of the n‐rGO/Pt micromotor enable the effective management of DOX release at the tumor site and thus enhances the therapeutic efficiency and reduces the side toxicity toward the healthy tissue. These micromachine drug carriers combine the high loading capacity of conventional carbon‐based drug carriers with a fast and efficient electrochemical drug‐release mechanism.