as the solvent. The starting reagents need not be completely soluble for the reaction to be successful. In many cases, the product can simply be filtered from the solution as the only purification step required. NH-1,2,3-triazoles are also prepared from alkynes in a sequence called the Banert cascade. The utility of the Cu(I)-catalyzed click reaction has also been demonstrated in the polymerization reaction of a bis-azide and a bis-alkyne with copper(I) and TBTA to a conjugated fluorene based polymer. The degree of polymerization easily exceeds 50. With a stopper molecule such as phenyl azide, well-defined phenyl end-groups are obtained. The copper-mediated azide-alkyne cycloaddition is receiving widespread use in material and surface sciences. Most variations in coupling polymers with other polymers or small molecules have been explored. Current shortcomings are that the terminal alkyne appears to participate in free-radical polymerizations. This requires protection of the terminal alkyne with a trimethyl silyl protecting group and subsequent deprotection after the radical reaction are completed. Similarly the use of organic solvents, copper (I) and inert atmospheres to do the cycloaddition with many polymers makes the "click" label inappropriate for such reactions. An aqueous protocol for performing the cycloaddition with free-radical polymers is highly desirable. The CuAAC click reaction also effectively couples polystyrene and bovine serum albumin (BSA). The result is an amphiphilic biohybrid. BSA contains a thiol group at Cys-34 which is functionalized with an alkyne group. In water the biohybrid micelles with a diameter of 30 to 70 nanometer form aggregates. Copper catalysts The use of a Cu catalyst in water was an improvement over the same reaction first popularized by Rolf Huisgen in the 1970s, which he ran at elevated temperatures. The traditional reaction is slow and thus requires high temperatures. However, the azides and alkynes are both kinetically stable. As mentioned above, copper-catalysed click reactions work essentially on terminal alkynes. The Cu species undergo metal insertion reaction into the terminal alkynes. The Cu(I) species may either be introduced as preformed complexes, or are otherwise generated in the reaction pot itself by one of the following ways: A Cu2+ compound is added to the reaction in presence of a reducing agent (e.g. sodium ascorbate) which reduces the Cu from the (+2) to the (+1) oxidation state. The advantage of generating the Cu(I) species in this manner is it eliminates the need of a base in the reaction. Also the presence of reducing