Blood used for transfusions has a limited half-life. The concentration of microvesicles (MVs), small phospholipid vesicles released from the membrane of red blood cells, is an important indicator of the age of stored blood. Nevertheless, sensitive and standardized assays that quantify MVs are not available.

Hakho Lee and co-workers, Massachusetts General Hospital, Boston, USA, developed a small sensor for the quantification of MVs in a fast and accurate manner. The new device consists of three elements. The first one, a microfluidic cartridge, collects MVs by inducing them to adhere to polymer microbeads. Subsequently, iron oxide magnetic nanoparticles, the second component of the device, bind to and label the anchored MVs because they are functionalized with antibodies targeting specific proteins present on the MVs surface. Finally, the third element of the sensor, a miniaturized nuclear magnetic resonance system, detects the nanoparticle-labeled MVs, providing a sensitive quantification of their concentration.

The new sensor may improve the quality of the blood used for transfusions and, consequently, the safety of transfusions.

• Magnetic Nanosensor for Detection and Profiling of Erythrocyte-Derived Microvesicles,
  Junsung Rho, Jaehoon Chung, Hyungsoon Im, Monty Liong, Huilin Shao, Cesar M. Castro, Ralph Weissleder, Hakho Lee,
  ACS Nano 2013, 7, 11227–11233.
  DOI: 10.1021/nn405016y