4-arm PEG is a multi-arm PEG, and each of the arms can have a functional group connected to the end and is connected to a hexaglyceride core. 4-Arm PEG products are good cross-linking agents and have been widely studied in the field of medicine and bio-organic materials, such as hydrogel preparation, drug development, 3D cell culture. CD Bioparticles offers 4-arm PEG derivatives. These derivatives carry acid-, acrylate-, aldehyde-, alkyne-, amine-, azide-, coonhs-, epoxy-, maleimide-, methacrylate-, NHS-, nitrophenyl carbonate- and thiol- groups. They are widely used in various drug development studies. Among them, the molecular weight of PEG in the derivative is optional.