4arm-PEG-SS

4arm PEG SS (4arm PEG Succinimidyl Succinate) is a multi-armed PEG derivative with a succinimidyl NHS ester group at each end of the four arms of the pentaerythritol core. 4arm PEG SS is a kind of PEG-NHS reagent. There is a C2 hydrocarbon ester linkage between the PEG and the NHS ester. NHS is a good leaving group that can react with amine-containing moieties. A cleavable ester linker between PEG and NHS ester enables the properties of a “degradable” hydrogel.