A Novel Hydrogel Of Preparation, Characterization And Application

Poly-?-glutamic acid(?-PGA)has a large number of anionic acid ions in the molecular chain,as an anionic polymer,combined with a cationic polymer easily to form a polyelectrolyte complex.?-PGA is an anionic polymer with excellent biocompatibility,high efficiency of biodegradation,can absorb tens of volumes of water,which has wide range of applications in medical,agricultural,industrial and other related fields.A complete set of circuits for the preparation of low-molecular-weight?-PGA was established in this experiment,?-PGA/CS hydrogel have a highly water capability which was prepared by using a non-toxic cross-linking agent.The mechanism of action,physical properties,and biological activity were studied in?-PGA/CS hydrogel,and conducted a preliminary study on the application of the hydrogel in wound dressings.Bacillus licheniformis WBL-3 was used as a fermentation strain to produce?-PGA in a small-scale fermentation production line.The result showed that at the optimum culture conditions as follows:temperature 37°C,the finally pH 9.0,DO 180 ppm,rotation speed of fermenter 300 r/min,in a 10 L liquid fermentation medium system,cultured 72 hours.Under these culture conditions,the yield of?-PGA was 38.5 g/L.The?-PGA obtained has a relatively large molecular weight by fermentation,we toke use of high temperature,high pressure at the acid conditions to degrade?-PGA.Experimental results show that at these follows conditions:pH 3.0,after degrading at 121°C and 0.1 Mpa at high temperature and high pressure for 90 min,we could obtain the low-molecular-weight(35-100 KDa)?-PGA after purifing.Polygamma-glutamic acid/chito-oligosaccharides(?-PGA/CS)hydrogel were prepared by using non-toxic cross-linker—EDC/NHS.On this basis,the optimal conditions for preparation of?-PGA/CS hydrogel by response surface optimization were as follows:the amount of?-PGA was 75.89 g/L,the amount of CS was 6.12 g/L,the amount of crosslinker was 4.47 g/L,the water absorption of?-PGA/CS hydrogel was 37.24±0.05g/g.The reaction mechanism and characterization of the hydrogel were investigated by FTIR,XRD,~1H-NMR and SEM.It is proved that?-PGA/CS hydrogel is a kind of polyelectrolyte complex with three-dimensional network structure which is bound to each other by amide bond under the action of cross-linking agent.The swelling properties,degradation in vitro properties and antibacterial properties of?-PGA/CS hydrogel were also tested.These results showed that?-PGA/CS hydrogel is a widly used hydrogels which have higher swelling properties,biodegradability and good antibacterial properties.The potential capability of?-PGA/CS hydrogel as a novel hemostatic agent was tested by coagulation assay in vitro.The relationship between coagulation index,liquid absorption rate,porosity and density of?-PGA/CS hydrogel were investigated respectively.The hydrogel has better liquid absorption ability,higher porosity,lower density,and could use of novel hemostasis due to lightness,rapid absorption of blood to stop bleeding rapidly.