Micro/Nanorobot for Drug Delivery—A Review of Material Selections

The concept of utilizing micro/nanorobot (MNR) for drug delivery in vivo was raised decades ago, and numerous prototypes have been created ever since. Other than the application of delivering drugs, nanorobots are also widely researched for noninvasive surgery, cell stimulation, bioimaging, diagnostics and monitoring, sensing, photocatalysis, and environmental remediation. The design of drug‐delivering MNR requires the robot to 1) consist of bio‐friendly materials, 2) be able to propel itself or be propelled by external force, 3) be able to self‐direct or be directed by external control to the target location, and 4) have a basic drug load and release function. However, even though many prototypes can perform all these different nanoscaled functions, they are always staying on the prototype stage instead of leaping into the practical stage. This review aims to explain the latest MNR designs from the perspective of material selection. From the prototypes listed in this review, there are a wide range of materials that can be adopted into design to fulfill various tasks with considerations into biocompatibility, motion, navigation, and drug load and release.