Urea-powered nanorobots reduce bladder tumours by 90%

The research, which was conducted on mice, demonstrates how these tiny nanomachines are propelled by urea present in urine and precisely target the tumour, attacking it with a radioisotope carried on their surface.

Bladder cancer has one of the highest incidence rates in the world and ranks as the fourth most common tumour in men.

Despite its relatively low mortality rate, nearly half of bladder tumours resurface within five years, requiring ongoing patient monitoring. Frequent hospital visits and the need for repeat treatments contribute to making this type of cancer one of the most expensive to cure.

While current treatments involving direct drug administration into the bladder show good survival rates, their therapeutic efficacy remains low. A promising alternative involves the use of nanoparticles capable of delivering therapeutic agents directly to the tumour. In particular, nanorobots – nanoparticles endowed with the ability to self-propel within the body – are noteworthy.

Now, a study published in the prestigious journal Nature Nanotechnology reveals how a research team successfully reduced the size of bladder tumours in mice by 90 percent through a single dose of urea-powered nanorobots.

These tiny nanomachines consist of a porous sphere made of silica. Their surfaces carry various components with specific functions. Among them is the enzyme urease, a protein that reacts with urea found in urine, enabling the nanoparticle to propel itself. Another crucial component is radioactive iodine, a radioisotope commonly used for the localised treatment of tumours.

The research, led by the Institute for Bioengineering of Catalonia (IBEC) and CIC biomaGUNE in collaboration with the Institute for Research in Biomedicine (IRB Barcelona) and the Autonomous University of Barcelona (UAB), paves the way for innovative bladder cancer treatments. These advancements aim to reduce the length of hospitalisation, thereby implying lower costs and enhanced comfort for patients.

Technological innovation in microscopy to locate nanorobots
Working with nanorobots has posed a significant scientific challenge in bioimaging techniques for visualising these elements in tissues and the tumour itself. Common non-invasive clinical techniques, such as PET, lack the necessary resolution to locate these very small particles at a microscopic level.

Therefore, the Scientific Microscopy Platform at IRB Barcelona employed a microscopy technique using a sheet of laser light to illuminate samples, allowing the acquisition of 3D images through light scattering upon interaction with tissues and particles.

Upon observation that the tumour itself scattered part of the light, generating interference, the scientists developed a new technique based on polarised light that cancels out all scattering from the tumour tissue and cells. This innovation enables the visualisation and location of nanorobots without the need for prior tagging with molecular techniques.

"With a single dose, we observed a 90 percent decrease in tumour volume. This is significantly more efficient, given that patients with this type of tumour typically have six to 14 hospital appointments with current treatments. Such a treatment approach would enhance efficiency, reducing the length of hospitalisation and treatment costs," explains Samuel Sánchez, ICREA Research Professor at IBEC and leader of the study.

The next step, which is already underway, is to determine whether these tumours recur after treatment.