We have developed a one-pot synthesis of bio-carbon nanowires from the natural product sodium alginate at low temperature, without using any catalyst, for anticoagulation applications. Sodium alginate is carbonized and sulfated/sulfonated in situ by solid state heating of a mixture of sodium alginate and ammonium sulfite. By regulating the heating temperature and the ratio of ammonium sulfite to sodium alginate, we modulated the degree of sulfation/sulfonation and carbonization, as well as the morphology of the carbon nanomaterials. The core-shell sulfated/sulfonated bio-carbon nanowires (CNWs(Alg@sox)) made by the reaction of a mixture of ammonium sulfite and sodium alginate with a mass ratio of 5 (ammonium sulfite to sodium alginate) at 165 degrees C for 3 h, exhibit strong inhibition of thrombin activity due to their ultrahigh binding affinity towards it (dissociation constant (K-d) = 8.7 x 10(-11) M). The possible formation mechanism of the carbon nanowires has been proposed. The thrombin-clotting time delay caused by CNWs(Alg@sox) is similar to 170 times longer than that caused by sodium alginate. Hemolysis and cytotoxicity assays demonstrated the high biocompatibility of CNWs(Alg@sox). Furthermore, the thromboelas-tography of whole-blood coagulation and rat-tail bleeding assays further reveal that CNWs(Alg@sox) have a much stronger anticoagulation activity than sodium alginate and naturally sulfated polysaccharides (e.g., fucoidan). Our results suggest that the low-temperature prepared, cost-effective, and highly biocompatible CNWs(Alg@sox) show great potential as an efficient anticoagulant for the prevention and treatment of diseases associated with thrombosis. (C) 2019 Elsevier Inc. All rights reserved.