Biotin PEG Amine (Biotin-PEG-NH2) is a biotin-poly(ethylene glycol), biotin-poly(ethylene glycol) with a biotin tag at one PEG end and a primary amine group at the other PEG end ) amines (BPEG) are used to functionalize (polyethylene glycol biotin) surfaces of structures such as hydrogels, microspheres, quantum dots, and nanoparticles to take advantage of biotin-avidin-based targeting . The PEG linker between NH2 and biotin provides better water solubility, flexible linker structure, and enhanced stability.