Studies On The Swelling Properties Of Acrylamide Based Hydrogel And Their Application In Biotechnology

Acrylamide hydrogel is hydrophilic polymer with three-dimension network. Due to the merits of controllable network, friendly separation environment and good biocompatibility, such hydrogel has shown a wide application in biotechnology. This thesis reports the synthesis, swelling properties of a series of acrylamide (AAm) and acrylamide-co-sodium methacrylate (AAm-co-NaMA) hydrogels in salts solution or acetone-water mixtures, and the application of such hydrogels in producing chiral drug intermediate R(-)-mandelic acid and concentrating biomacromolecule Pneumcoccal capsular polysaccharide(PnCPs).Swelling experiments were carried out in different salts solutions with various concentrations at 25oC. Results reveal that acrylamide hydrogel has particular swelling properties in chlorides salt aqueous solution. Swelling ratio increases with increasing chloride salt concentration. In addition, the AAm composition can also affect the swelling ratio of hydrogels. Increasing the amount of crosslinking agent or monomer in hydrogel can result in the decrease of swelling ratio. The swelling behavior of AAm-co-NaMA hydrogel in present of acetone was studied. Discontinuous phase transition behavior depends on the mole fraction of ionic co-monomer NaMA (yCo) in hydrogel and concentration of acetone in solution. The minimum acetone concentration for phase transition is 46%, 48% and 52% for AAm-NaMA hydrogel characterized by yCo=3%, 5%, 8%, respectively. Based on the as-obtained AAm hydrogel, immobilized of Saccharomyces cerevisiae cells were prepared for production of chiral drug intermediate R(-)-mandelic acid. The influences of AAm hydrogel compositon and different biotransformation conditions on the product yield were investigated. Experimental results show that acrylamide hydrogel is a feasible carrier for immobilization of cells. The optimum composition of hydrogel in our experiment was 4% crosslinker and 8% monomer. 1g cells/20ml pre-gel was the proper concentration for getting a good mechanical property of such carrier. The best fermentation conditions for production of R(-)-mandelic with immobilized cells were pH6.5, culture temperature 38oC, the initial substrate concentration 20mmol/L. Furthermore, the R(-)-mandelic production in column packed-bed reactor was also studied.In the end, concentration of PnCPs with AAm-NaMA hydrogels was investigated by changing the crosslinking density and charge density of hydrogel, the mass percentage of PnCPs and pH in the dilute solutions. Results reveal that increasing the amount of crosslinking agent MBA in hydrogel makes a reduction of concentration degree. Increasing the amount of ionic comonomer NaMA results in the increase of concentration degree. The effect of pH on the separation is that the concentration degree increased with increasing pH. The mass percentage of PnCPs has a significant influence on the concentration. When the feed concentration is 0.5%, the concentration degree is 1.47. When the value is 0.01%, the concentration degree increases to 25.5. All these indicate that gel extraction can be a good alternative for concentration and separating PnCPs from its dilute solution.