title: Temperature-responsive bioconjugates. 1. Synthesis of temperature-responsive oligomers with reactive end groups and their coupling to biomolecules.
abstract: Using 3-mercaptopropionic acid (MPA) as a chain-transfer agent, the radical oligomerization of N-isopropylacrylamie (IPAAm) was carried out with varying molar ratios of MPA to IPAAm and DMF. The molecular weight of oligo-IPAAm (OIPAAm) could be controlled by the ratio of MPA to IPAAm. The OIPAAm was confirmed to average one carboxyl end group per chain. All OIPAAms samples were highly water-soluble at lower temperatures and exhibited phase separation near 32 degrees C. The optical transmittance of the OIPAAms aqueous solutions changed drastically at 32 degrees C which was independent of OIPAAms molecular weight. In aqueous solutions of OIPAAm having concentrations higher than 1 wt% and molecular weight of 6100, the oligomers were precipitated and recovered in 85 wt% yield of their original content. Further, OIPAAm was grafted to atelo collagen by activated ester-amine coupling. The OIPAAm-collagen conjugates were able to dissolved in cold water and precipitated at 34 degrees C. Temperature-responsive OIPAAm-collagen conjugates are expected to maintain native collagen functionality in the solution state, react at lower temperatures, and be easily removed from the system with small temperature increases.
authors.affiliation: Department of Chemistry, Faculty of Science and Technology, Sophia University, Tokyo, Japan.
authors.forename: Y G
authors.initials: YG
authors.lastname: Takei
authors.forename: T
authors.initials: T
authors.lastname: Aoki
authors.forename: K
authors.initials: K
authors.lastname: Sanui
authors.forename: N
authors.initials: N
authors.lastname: Ogata
authors.forename: T
authors.initials: T
authors.lastname: Okano
authors.forename: Y
authors.initials: Y
authors.lastname: Sakurai
mesh_terms: D015097:3-Mercaptopropionic Acid / Q000737:chemistry*; D000178:Acrylamides / Q000737:chemistry*; D055598:Chemical Phenomena; D011232:Chemical Precipitation; D002627:Chemistry, Physical; D003094:Collagen / Q000737:chemistry; D004126:Dimethylformamide; D046911:Macromolecular Substances; D008970:Molecular Weight; D012996:Solutions; D013696:Temperature; D014867:Water
chemical_list: D000178:Acrylamides; D046911:Macromolecular Substances; D012996:Solutions; D014867:Water; D004126:Dimethylformamide; D003094:Collagen; D015097:3-Mercaptopropionic Acid; C067295:N-isopropylacrylamide