Cryoprotective properties of completely synthetic polyampholytes via reversible addition-fragmentation chain transfer (RAFT) polymerization and the effects of hydrophobicity

Abstract

A completely synthetic polyampholyte cryoprotectant was developed with cationic and anionic monomers by reversible addition-fragmentation chain transfer polymerization. The neutralized random polyampholyte, which had an equal composition ratio of monomers, showed high cryoprotective properties in mammalian cells. Introduction of a small amount of hydrophobic monomer enhanced cell viability after cryopreservation, indicating the importance of hydrophobicity. Leakage experiments confirmed that these polyampholytes protected the cell membrane during cryopreservation. Due to low cytotoxicity, this polyampholyte has the potential to replace the convention cryoprotective agent dimethyl sulfoxide. The present study is the first to show that we can design a polymeric cryoprotectant that will protect the cell membrane during freezing using appropriate polymerization techniques.

Keywords:

• biocompatibility
• cryopreservation
• polyampholyte
• reversible addition-fragmentation chain transfer (RAFT)

Acknowledgements

This study was supported in part by a grant from The Canon Foundation (K11-N-028). We thank Prof. H. Kitano and M. Gemmei-Ide, University of Toyama, for critical comments for RAFT polymerization. We also acknowledge Prof. T. Hohsaka and Dr T. Watanabe, Japan Advanced Institute of Science and Technology, for assistance in fluorescence measurements.