Algae Microrobots Battle Bladder Cancer

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 developed an innovative, biohybrid microrobot, engineering natural microalgae with a synthetic magnetite coating.⁴ 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 engineer their microrobots, the researchers selected the easily cultivable diatom Coscinodiscus granii as the base. Qi Zhou, a biomedical researcher at the University of Edinburgh and study coauthor, emphasized that the diatom’s complex “hierarchical structure,” comprising multi-layered porous silica shells, provided a remarkably large surface area to efficiently load chemotherapy drugs. Additionally, its intricate shell patterns enable slow drug release, promoting gradual and precise drug delivery at the tumor site.

Beyond these capabilities, Zhou highlighted that algae possess “a lot of beneficial effects,” including antioxidant properties. Their established use in food supplements and recognition as a safe platform for therapeutic applications further support their potential as microrobots, which could facilitate public acceptance and streamline regulatory approval.

For the robotic part of the microrobot, Zhou and his team designed a porous, hollow system with surface-bound magnetite nanoparticles. They controlled the microrobot using magnetic forces and secured drug cargo with a sealing layer. Using doxorubicin as a model therapeutic, they achieved a good loading efficiency of 27.95 percent, confirmed by spectroscopy and fluorescence imaging.

AI and Ultrasound-Guided Microrobots Deliver Drugs to Tumors

For microrobots to be effective therapeutics, “[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 said.

The research team demonstrated real-time tracking of microrobot swarms in a mouse model of bladder cancer using ultrasound imaging. The magnetite coating on the microalgae shells enhanced contrast, making the swarms clearly visible against surrounding tissues.

A deep learning algorithm received the real-time ultrasound video feed and rapidly processed it to pinpoint both the bladder tumor and the moving microrobots. It then 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 robotic platform, the researchers delivered the microrobots to the tumor without causing mechanical damage to the bladder wall. The doxorubicin-loaded magnetite C. granii microrobots increased drug penetration into tumor tissue within just 30 minutes of treatment by more than 10-fold. The microrobots reduced tumor burden in mice to less than three percent after one week, outperforming standard bladder therapy.

These results demonstrate the strong potential of drug-loaded algae microrobots as a safe, noninvasive treatment for bladder cancer. Zhou and his team believe this targeted strategy could significantly lower the drug dosage needed in traditional chemotherapies and reduce treatment time, providing meaningful benefits to patients.

Samuel Sánchez Ordóñez, a biomedical scientist at the Institute for Bioengineering of Catalonia specializing in biohybrid robotics and not involved in the new study, praised the researchers’ work in applying hybrid microrobots to cancer therapy. He described Zhou and colleagues’ research as “a very, very complete paper.” Ordóñez expressed excitement about the team’s progress, saying, “I’m very happy that the idea of using microrobots for bladder cancer, that we started a few years ago, is now being followed up at that high level.” He noted that the current scale of the microrobot study is suitable as a proof-of-concept, but he stressed the importance of advancing to larger animal models for future validation.

These findings have made researchers 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 hopes their microrobots can accelerate drug penetration into tumor tissue, a strategy that could potentially work for other types of cancer as well.