Preparation of intelligent gels with a body-temperature response from unbleached acetic acid pulp

摘要

Hydroxypropyl-cellulose bearing lignin (HPC-L) was prepared from the unbleached acetic acid pulp of Todo-fir by hydroxypropylation using propylene oxide. The HPC-L showed the lower critical solution temperature (LCST) at 37℃ in phosphate buffered saline (pH 7.2), which was approximate three degree lower than that of commercially available hydroxypropyl-cellulose (HPC) with a similar molecular-mass to the HPC-L. These HPC preparations were converted to chemical gels by crosslinking using ethylene glycol diglycidyl ether ( EGDE ). The HPC-L gel indicated the drastic shrinking at 38℃, while the corresponding HPC gel showed the half volume at approximate 45℃ from the volumetric measurements. Differential scanning calorimetric (DSC) analyses supported thermal transition of both gels. These results suggested that the HPC-L gel was considered as a body-temperature responsive gel, expecting utilization in the drug delivery system (DDS). The difference in the LCST and the transition temperature of gel shrinking between HPC-L and HPC were attributable to the hydrophobicity of the residual lignin. Thus, the residual lignin gave cellulose derivatives with new functions.