Natural blood clots, which include platelets (light blue clumps) and red blood cells in a fibrin mesh, can take minutes to form. Credit: Anne Weston, EM STP, The Francis Crick Institute/Science Photo Library Red blood cells modified with Nobel-prizewinning chemistry can snap together to form clots that staunch bleeding in seconds. That’s according to a study, published on 29 April in Nature 1 , that tested the technology in rats. The method, called click clotting, produces clots that are stronger than either natural clots or a commercial product used to stop bleeding. If shown to be safe and effective in people, the approach could provide a rapid way to induce haemostatis, the body’s natural process for controlling bleeding, and to stem potentially deadly blood loss during surgery or after injuries. “It’s really cool,” says Ashley Brown, a biomedical engineer jointly at the University of North Carolina in Chapel Hill and North Carolina State University in Raleigh, who was not involved in the study.…