Norbornene readily reacts with azide and tetrazine and is usefulness for cell labeling with fluorophore and functional molecules. Biotin shows strong affinity towards streptavidin and avidin. The PEG spacer increase the solubility of the resulting complex in aqueous media.
Axispharm offers 3000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.