Heterobifunctional Linear PEG derivatives have the following general structure: X-PEG-Y, where X and Y are two different functional or reactive groups. Heterofunctional PEG derivatives are often used as crosslinkers or spacers between two different chemical entities, including PEGylation of proteins and peptides, or nanoparticles' surface modification. The PEG moiety in the heterobifunctional PEG derivatives provides water solubility, biocompatibility, and flexibility. https://www.cd-bioparticles.ne....t/fluorescent-hetero