Enzyme-powered bubble robots maneuver drugs directly to tumors

Researchers at Caltech and the University of Southern California have developed enzyme-powered microbubble robots designed for precise drug delivery to tumors. These microrobots simplify previous complex designs by using protein-shelled microbubbles, which are biocompatible and commonly used in medical imaging. The bubbles are functionalized by chemically attaching enzymes, drugs, and nanoparticles to their surface, enabling them to move, sense their environment, and deliver therapy. Propulsion is achieved through the enzyme urease, which reacts with naturally occurring urea in the body to generate thrust, while two versions of the robots have been created: one steered magnetically and tracked via ultrasound, and another fully autonomous version that homes in on tumors by sensing elevated hydrogen peroxide levels through the enzyme catalase. Once the microbubble robots reach the tumor site, focused ultrasound bursts the bubbles, releasing the drug payload and enhancing its penetration into the tumor tissue. In mouse models of bladder cancer, this method resulted in approximately a 60% reduction