Temperature-responsive bioconjugates. 1. Synthesis of temperature-responsive oligomers with reactive end groups and their coupling to biomolecules.
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.
Takei
Y G
YG
Department of Chemistry, Faculty of Science and Technology, Sophia University, Tokyo, Japan.
Aoki
T
T
Sanui
K
K
Ogata
N
N
Okano
T
T
Sakurai
Y
Y
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
D000178:Acrylamides; D046911:Macromolecular Substances; D012996:Solutions; D014867:Water; D004126:Dimethylformamide; D003094:Collagen; D015097:3-Mercaptopropionic Acid; C067295:N-isopropylacrylamide