The MIT system is built around a specially designed nanoparticle that can produce "synthetic biomarkers" in urine if a person has cancer, and in previous tests it has proved promising at this job. But the problem is, it couldn't tell where in the body the tumors were located. Now, the team has added this function.The method by which the nanoparticles detect cancer is quite clever. To escape their point of origin and spread throughout the body, many cancers use enzymes called proteases which slice through proteins in the extracellular matrix. The diagnostic nanoparticles are coated in peptides that can also be cut up by these proteases, so if there are tumors present somewhere, the nanoparticles will bear the scars of their encounters by the time they reach the urine.