In vivo fluorescence imaging of liver ischemia in mouse models. Finally, we performed fluorescence imaging of liver ischemia of mouse to determine whether T-azoJSiR640 could detect severe hypoxia in vivo. The probe T-azoJSiR640 was administered to mice by intravenous injection, and after 30 min, the portal vein was ligated to induce ischemia. Before ligation of the portal vein, no fluorescence increase was observed in the liver, while a rapid and significant fluorescence increase was observed over the entire liver after the induction of ischemia (Figures )). To confirm that T-JSiR640 was produced, we examined the production of T-JSiR640 by LC-MS/MS analysis (Figures General Procedures and Materials. Reagents and solvents were of the best grade available, purchased from Tokyo Chemical Industries, Wako Pure Chemical, Aldrich Chemical Co., Dojindo, and Invitrogen, and were used without further purification. Reactions were monitored by means of TLC, ESI mass spectrometry and HPLC. All compounds were purified by silica gel chromatography or preparative HPLC.