Thiol
The thiol polyPEG can react specifically with maleimide group at pH 6.5 to 7.5 to form a stable thioether linkage. Furthermore, thiol can also react with alkene in the presence of radical initiator via thiol-ene chemistry.

- Thiol-PEG-CH2COOH
- Amine-PEG-thiol
- Biotin-PEG-Thiol
- PEG-bis-Thiol
- m-PEG-thiol
- DSPE-PEG-SH
- Thiol-PEG-DMG
- 4arm-PEG-Thiol