Scientists guided and tracked algae microrobots in real time. One day, these biohybrid microrobots may deliver precise, targeted therapy for bladder cancer.
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Bladder cancer is the most frequently diagnosed malignancy of the urinary tract and ranks ninth among all cancers globally.1 Conventional therapy typically involves delivering chemotherapeutic drugs directly to the bladder via a catheter. Despite this localized approach, treatment outcomes are often limited by insufficient drug penetration into tumor tissue, lack of precise targeting, and rapid drug clearance from the bladder.2
To overcome these barriers, some researchers have enlisted the help of microscopic robots that can actively seek out diseased tissues, such as tumors, and deliver drugs in a controlled manner.3
In a recent study published in Nature Nanotechnology, researchers engineered a biohybrid microrobot by coating natural microalgae with synthetic magnetite nanoparticles. Artificial intelligence algorithms enabled these microrobots to autonomously track and deliver chemotherapeutic drugs to bladder tumors in mice, leading to enhanced targeting precision and tissue penetration compared to conventional therapies.
Engineering Algae and Nanoparticles to Fabricate Biohybrid Microrobots
To develop their microrobots, the researchers utilized the diatom Coscinodiscus granii, chosen for its easily cultivable nature. Qi Zhou, a biomedical researcher at the University of Edinburgh and study coauthor, explained that the diatom’s intricate hierarchical structure—featuring multi-layered porous silica shells—provides a vast surface area for efficient chemotherapy drug loading. Additionally, its complex shell patterns facilitate slow drug release, enabling gradual and precise drug delivery at the tumor site.
Beyond these capabilities, Zhou noted that algae offer antioxidant properties and have a well-established history in food supplements and therapeutic applications, supporting their potential safety and public acceptance as microrobots, which could streamline regulatory approval.
For the robotic component, the team designed a porous, hollow structure with surface-bound magnetite nanoparticles. Controlled by magnetic forces, microrobots were loaded with chemotherapy drugs using a sealing layer. Testing with doxorubicin, they achieved a loading efficiency of 27.95 percent, validated through spectroscopy and fluorescence imaging.
AI and Ultrasound-Guided Microrobots Deliver Drugs to Tumors
For microrobots to function therapeutically, “[it is not only essential to] control them, but you also need to be able to see them. Otherwise, how do we know when it has arrived at the tumor site?” Zhou emphasized.
The research team demonstrated real-time tracking of microrobot swarms in a bladder cancer mouse model using ultrasound imaging. The magnetite coating on the microalgae enhanced contrast, rendering swarms clearly visible against surrounding tissues.
A deep learning algorithm processed real-time ultrasound video feeds, rapidly identifying bladder tumors and microrobot locations. It automatically calculated optimal navigation paths and adjusted an external magnetic field framework to guide the microrobot swarm directly into the bladder cavity and to the tumor site.
Using this machine-intelligent, ultrasound-guided platform, the researchers delivered drugs to tumors without causing bladder wall damage. Doxorubicin-loaded magnetite C. graniimicrorobots increased drug penetration into tumor tissue by over 10-fold within 30 minutes of treatment. The microrobots reduced tumor burden to less than three percent in mice after one week, outperforming standard bladder therapy.
These results highlight the potential of drug-loaded algae microrobots as a safe, noninvasive treatment for bladder cancer. Zhou and his team believe this targeted approach could significantly reduce chemotherapy drug dosages and treatment duration, offering meaningful benefits to patients.
Samuel Sánchez Ordóñez, a biomedical scientist at the Institute for Bioengineering of Catalonia specializing in biohybrid robotics, praised the study’s comprehensive approach. He described the research as “a very, very complete paper” and noted that current results are a promising proof-of-concept requiring validation in larger animal models. He expressed enthusiasm about the team’s progress in advancing the concept of microrobots for bladder cancer treatment to this high level.
Researchers are optimistic about the potential of chemotherapeutic drug-loaded algal microrobots for treating human bladder cancer, addressing the urgent need for more effective therapies amid high recurrence rates. Zhou envisions this strategy to accelerate drug penetration into tumor tissue, potentially applicable to other cancer types as well.