Switchable Bifunctional Stimuli-Triggered Poly-N-Isopropylacrylamide/DNA Hydrogels

• Published in: Angewandte Chemie International Edition 2014-09, Vol.53 (38), p.10134-10138
• Main Authors: Guo, Weiwei, Lu, Chun-Hua, Qi, Xiu-Juan, Orbach, Ron, Fadeev, Michael, Yang, Huang-Hao, Willner, Itamar
• Format: Article
• Language: English
• Subjects: Acrylic Resins - chemistry; Cooling systems; Copolymers; Cross-Linking Reagents - chemical synthesis; Cross-Linking Reagents - chemistry; Crosslinking; Cysteamine; Deoxyribonucleic acid; DNA; DNA - chemistry; Heating; Hydrogels; Hydrogels - chemical synthesis; Hydrogels - chemistry; Hydrogen-Ion Concentration; Ions - chemistry; Molecular Structure; N-isopropylacrylamide; nucleic acids; phase transitions; reversible hydrogels; Silver - chemistry; Thermal cycling; Thermosensitive; thermosensitive polymers
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201405692

DNA‐tethered poly‐N‐isopropylacrylamide copolymer chains, pNIPAM, that include nucleic acid tethers have been synthesized. They are capable of inducing pH‐stimulated crosslinking of the chains by i‐motif structures or to be bridged by Ag+ ions to form duplexes. The solutions of pNIPAM chains undergo crosslinking at pH 5.2 or in the presence of Ag+ ions to form hydrogels. The hydrogels reveal switchable hydrogel‐to‐solution transitions by the reversible crosslinking of the chains at pH 5.2 and the separation of the crosslinking units at pH 7.5, or by the Ag+ ion‐stimulated crosslinking of the chains and the reverse dissolution of the hydrogel by the cysteamine‐induced elimination of the Ag+ ions. The DNA‐crosslinked hydrogels are thermosensitive and undergo reversible temperature‐controlled hydrogel‐to‐solid transitions. The solid pNIPAM matrices are protected against the OH− or cysteamine‐stimulated dissociation to the respective polymer solutions. All change! Nucleic acid‐functionalized pNIPAM copolymers undergo bi‐triggered phase transitions. In the presence of H+/OH− or Ag+/cysteamine, the polymers undergo cyclic and reversible gel‐to‐solution transitions. The hydrogels undergo further cyclic and reversible hydrogel/solid‐phase transitions upon heating and cooling the systems.