Targeted Drug Delivery: From Chemistry to Robotics at Small Scales

The limited bioavailability, susceptibility to degradation, and adverse side effects of novel drugs often hinder their effective administration. Nanoparticles, with customizable properties and small size, have emerged as potential carriers, though their delivery efficiency remains low. With their ability to navigate fluid environments, micro- and nanorobots offer promising solutions to improve the delivery and retention of drugs at targeted tissues. The design and composition of these motile devices, often inspired by natural locomotion mechanisms, are currently being refined for improved biocompatibility, adaptability, and collective task performance. Recent research has focused on loading these devices with therapeutic agents and evaluating their efficacy in living organisms. While chemotherapy has been predominant, micro- and nanorobots also show significant potential for biological and physical therapies, and hybrid methods combining multiple therapies have demonstrated synergistic benefits. This review identifies major challenges, including the need for application-specific solutions, standardized performance evaluation methods, and the integration of engineering with pharmacology.