Bis-PEG-endo-BCN is a functional molecule that belongs to the family of polyethylene glycol derivatives. It contains two PEG chains, which are terminated by BCN functional groups. BCN stands for bicyclononyne, a strained alkyne that can react with azide groups to form covalent bonds via a click reaction. Bis-PEG-endo-BCN is widely used in pharmaceutical research and development due to its unique properties. It can be used to link drugs to nanoparticles or to other therapeutic molecules, improving their stability and efficacy. Additionally, Bis-PEG-endo-BCN can be used to modify proteins, allowing the introduction of fluorescent probes or other functional moieties for imaging or diagnostic purposes.Bis-PEG-endo-BCN is a versatile tool that has opened up new possibilities for drug delivery and protein modification in the field of pharmaceutical research and development.