点击放大环状聚乙二醇-聚乙二醇臂-马来酰亚胺（n=4）28-crown-9-PEG4-Mal; Mal-terminated PEG arm on a cyclic poly(ethylene glycol) scaffold (arm n=4)
点击放大Y型-双臂-甲氧基-聚乙二醇-马来酰亚胺（n=8）Y-(mPEG8)2-Mal; Y-shaped bis(methoxy-poly(ethylene glycol)) with a single Mal conjugation handle (PEG arm n=8)
