Lipoic acid / LA PEG Aldehyde / Acetal PEG m PEG FA PEG Vinylsulfone，VS PEG Thiol，SH PEG tosyl, mesyl, tresyl PEG Silane PEG Pyrene PEG Phosphate PEG OPSS PEG Alkene PEG Norbornene PEG Nitrophenyl carbonate (NPC) PEG Hydrazide PEG chloride, bromide PEG OH PEG Epoxide PEG Carboxylic acid(COOH) PEG Acrylate PEG PEG Alkyne PEG Biotin NHS PEG DSPE PEG Maleimide PEG Silane （SIL） PEG Cholesterol PEG DBCO PEG FMOC,tBOC PEG OPPS PEG Multi-Arms PEGs Azide PEG, Azido PEG FITC PEG Lipid PEGs NH2 PEG