Nanosensors Could Help Diagnose and Treat Cancerous Tumors

Peptide-carrying nanoparticles are enclosed in a magnetically-sensitive outer layer for release at tumor sites. (Image courtesy of Christine Daniloff/MIT.)

A team of engineers and researchers from MIT has developed nanosensors to profile cancerous tumors. The sensors are activated at specific sites in the body, where tumors are known to be located, meaning their results aren’t skewed by body background noise. The technology could eventually help doctors create more personalized treatments for cancer patients.

Activating Nanosensors with Magnets

The researchers previously demonstrated a method in which they used nanoparticles to diagnose cancer. The nanoparticles carry short protein fragments, called peptides, that interact with enzymes in the body called matrix metalloproteinases (MMPs). MMPs break down proteins and peptides, and are heavily involved in the formation of tumors.

The method involves administering the peptide-carrying nanoparticles, and then testing the patient’s urine. If you detect hundreds of cleaved peptides in the urine, you can ascertain that the patient has elevated MMP levels, and therefore is likely to have a cancerous tumor.

But the researchers wanted to adapt the method to examine the traits of known tumours in specific locations. MMPs are present all over the body, so the team needed a way to activate the nanoparticles at specific sites to eliminate the body’s natural background noise.

“It has been challenging to examine tumor-specific protease activities from patients’ biofluids because these proteases are also present in blood and other organs,” said Ji Ho (Joe) Park, an associate professor of bio and brain engineering who was not involved in the research.

The team’s solution to this challenge? Magnets.

An illustration of the AMF-triggered nanosensors. First, they’re directed to a known tumor site, and then an AMF triggers the release of the peptides. Finally, the tiny Pac-men within your body get to work breaking the peptides down. (Image courtesy of Nano Letters.)

Alternating Magnetic Fields (AMFs) are a good option for remote triggering of the sensors because magnetic fields can penetrate deep within the body without affecting normal biological processes. The team encapsulated their peptides within magnetic nanoparticles (MNPs) that heat up and dissipate in the presence of AMFs. Applying a 515 kHz AMF when the sensors are in position releases the peptides and allows doctors to profile the MMP levels of the tumor.

Tailored Tumor Treatments

“The strength of this work is the magnetothermally responsive protease nanosensors with spatiotemporal controllability,” said Park, in what is possibly the most cumbersome sentence I’ve ever read. “With these nanosensors, the MIT researchers could assay protease activities involved more in tumor progression by reducing off-target activation significantly.”

With the AMF-triggering capability, the nanosensors could help determine exactly how aggressive a patient’s tumor is. This information would help doctors in determining the best treatment options.

“This approach is exciting because people are developing therapies that are protease-activated,” said researcher Sangeeta Bhatia. “Ideally you’d like to be able to stratify patients based on their protease activity and identify which ones would be good candidates for these therapies.”

While the researchers conducted their initial experiments with mice, they were successful in profiling different types of colon tumors. And with protease-based cancer treatments currently in clinical trials, the team’s nanosensors could soon find their way into oncologists’ toolkits. You can read more about the nanosensors in the team’s paper in Nano Letters.

For another example of how engineers are fighting cancer, find out how engineers target cancerous tumors with nanobots.