Novel Temperature-sensitive Hydrogel And Its Applications In Bioseparation

The synthesis and properties of poly (NIPA-co-GMA-Dex) hydrogels and PNIPA/GMA-Dex IPN/semi IPN hydrogels, including the swelling and absorbing behaviors in response to environmental stimuli were studied. The applications of poly (NIPA-co-GMA-Dex) hydrogels in bioseparation were also investigated.Glycidyl methacrylate (GMA) derivatized dextran (GMA-Dex) was synthesized by coupling GMA to dextran in the presence of 4-(N,N-dimethylamino) pyridine using DMSO as an aprotic solvent. Through copolymerization of this active monomer with N-isopropylacrylamide (NIPA) in aqueous solution, a series of novel hydrogels (poly (NIPA-co-GMA-Dex)) with different weight ratio r(r=GMA-Dex/(GMA-Dex+NIPA)) were prepared using radical polymerization method. Both GMA-Dex monomer and poly (NIPA-co-GMA-Dex) gels were characterized using FTIR spectra and 1H-NMR, and the influence of r on the swelling ratio (SR), deswelling/reswelling kinetics has been studied. It is found that poly (NIPA-co-GMA-Dex) gels are temperature-, pH- and ionic strength-sensitive. Their SR(20℃C) decreased and the lower critical solution temperature(LCST) increased with increase of r, and the LCSTs of poly (NIPA-co-GMA-Dex) gels are all higher than that of PNIPA gel(32℃). The smaller the r is, the faster the gels deswell; but the reswelling speed increased with increase of r. The results also indicated that the SR of poly (NIPA-co-GMA-Dex) gels was affected by ionic strength of solution. When ionic strength<0.5mol L-1, the SR remained high; when ionic strength was increased to 2mol L-1 gradually, the gels shrinked significantly.PNIPA/GMA-Dex IPN/semi-IPN gels were also synthesized successfully. The influence of c (weight concentration of GMA) on SR, deswelling/reswelling kinetics has been studied. It has found that PNIPA/GMA-Dex IPN/semi-IPN gels are also temperature-sensitive. The SR and deswell/reswell speeds are affected greatly by the component of the hydrogel.The mechanical properties of poly (NIPA-co-GMA-Dex) hydrogels were investigated using uni-axis compressive experiments in this study. We found that poly (NIPA-co-GMA-Dex) hydrogel show much better mechanical properties than PNIPA hydrogel, which is too soft to measure. The shear modulus and the effective cross-linking density increased with the increase of r.The applications of poly (NIPA-co-GMA-Dex) hydrogels in bioseparation have been investigated. The results indicated that the interactions between poly (NIPA-co-GMA-Dex) hydrogels and sodium dodecylsulfate (SDS) or Rutin or DL-a -Alanine show obvious dependence on the temperature. At higher temperature(>LCST), poly (NIPA-co-GMA-Dex) hydrogels deswelled and were susceptible to absorb larger amount of SDS or Rutin or DL- a -Alanine, some of them could be desorbed at lower temperature(