TCO ligation is a reaction that takes place between a tetrazine and a strained olefin, such as trans-cyclooctene.
This tetrazine bears a fragment of near infrared dye, Cyanine7. This NIR fluorophore is especially useful for in vivo imaging.
AxisPharm offers 5000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.