A copper catalyzed click chemistry ligation process is employed to bind azides and terminal acetylenes to provide 1,4-disubstituted 1,2,3-triazole triazoles. The process comprises contacting an organic azide and a terminal alkyne with a source of reactive Cu(I) ion in human blood plasma to form by cycloaddition a 1,4-disubstituted 1,2,3-triazole. The source of reactive Cu(I) ion can be, for example, a Cu(I) salt, Cu(II) ion in the presence of a reducing agent, or copper metal.