TBTA covers most of the practical applications for Click Chemistry except for a completely aqueous conjugation reaction. The benefits of a completely aqueous reaction include the biological labeling of live cells or the labeling of proteins without the concern of denaturing secondary structures. The water-soluble tris(3-hydroxypropyltriazolylmethyl)amine (THPTA)click ligand further simplifies Click Chemistry by allowing the entire reaction to be run in water, affording biological compatibility for Click reactions. The THPTA ligand binds Cu(I), blocking the bioavailability of Cu(I) and ameliorating the potential toxic effects while maintaining the catalytic effectiveness in click conjugations. The THPTA ligand was effectively used to label live cells with high efficiency while maintaining cell viability.4