Azido-PEG5-CH2CO2-PFP is a PEG derivative that contains an azide group and a PFP group. The azide group can undergo copper-catalyzed Click Chemistry reactions to react with alkynes. The PFP group can react with amines to form stable bonds. PFP moieties are also less susceptible to undergo hydrolysis. The hydrophilic PEG spacer increases the water solubility of the compound. Longer PEG chains enhance the water solubility properties of the chain.