Novel nanoparticle-based method for rapid screening of blood clotting
(ED NOTE: You cannot say, “hot off the presses”, in these days of digitalization, because articles like this are new to the net, and have not even been published. Maybe, “hot off the net”)
January 3, 2013
Researchers at MIT (MA, USA) have recently developed a noninvasive urine test capable of detecting blood clots. The system, which relies on nanoparticles to detect the presence of the blood clotting factor, thrombin, could be used to monitor high-risk patients.
According to Sangeeta Bhatia, senior author of the study and Professor of Biochemistry at MIT: “Some patients are at greater risk for clotting, but existing blood tests are not consistently able to detect the formation of new clots.” Current tests for blood clotting are indirect and although they are capable of detecting the breaking down of a clot, they cannot detect its initial formation.
Produced in a complex cascade of protein interactions, blood clots occur from the formation of fibrin, controlled by the enzyme thrombin. Based on technology previously reported by the group for the early detection of colorectal cancer, Bhatia’s team realized the same technology would work for blood clots, she stated: “We took the test we had developed before, which is an injectable nanoparticle, and made it a thrombin sensor.”
In this study, US FDA-approved iron oxide nanoparticles were coated with peptides designed to interact with thrombin. When the nanoparticles encounter thrombin, the peptides are cleaved at a specific location, releasing fragments (tags) that are then excreted in urine. The urine samples are then treated with antibodies specific to the peptide fragments. Tested on mice, the researchers found that the amount of tags found in the urine was directly proportional to the level of blood clotting in mouse lungs.
In their previous study, the researchers relied on mass spectrometry methods to distinguish the fragments by mass, a technique that was both expensive and slow. The team envisages two possible applications for the new and improved method. The first is to screen patients that are entering the emergency room with symptoms of a possible blood clot; the second is to use the test to monitor those at high risk.
According to Bhatia: “Right now they just don’t know how to efficiently define who to do the more extensive workup on. Its one of those things you can’t afford to miss, so patients can get an unnecessarily expensive workup.” She continued: “If a patient is at risk for thrombosis, you could send them home with a 10-pack of these sticks and say, ‘pee on this every other day and call me if it turns blue’.”
With funding from MIT’s Deshpande Center for Technological Innovation (MA, USA), Bhatia will launch a company to commercialize the technology, with the possibility of expanding the concept into other disease areas. Speaking to Nanomedicine, Kevin Lin, coauthor of the study, said: “Our urine test can be tailored for many other human diseases, including cancer and liver fibrosis. We are also developing a paper-based test for urine analysis, similar to a dipstick test for pregnancy, which could be used for global health applications.”
– Written by Phoebe Heseltine
Source: Lin KY, Kwong GA, Warren AD et al. Nanoparticles that sense thrombin activity as synthetic urinary biomarkers of thrombosis. ACS Nano doi:10.1021/nn403550c (2013) (Epub ahead of print).