Endo-BCN-PEG-NHS ester is a functionalized compound used in pharmaceutical research and development. It belongs to the class of PEGylation reagents, which are widely used for the modification of biologically active molecules. Endo-BCN-PEG-NHS ester contains two functional groups, the NHS ester and BCN moiety. The NHS ester group allows for efficient conjugation of the compound with amine-containing molecules, while the BCN moiety enables site-specific and bioorthogonal labeling of biomolecules. These features make Endo-BCN-PEG-NHS ester a useful tool for the development of targeted drug delivery systems and imaging probes. The compound has been extensively studied in preclinical research for its potential applications in cancer therapy, inflammation, and cardiovascular disease. The development and optimization of PEGylation reagents such as Endo-BCN-PEG-NHS ester are critical for improving the pharmacokinetic properties and therapeutic efficacy of drug molecules.