The Injectable Polysaccharide-Polypeptide Hydrogel Based On Schiff’s Base

Hydrogels in situ are composed by compounds with three-dimensional network structure which have excellent biocompatibility and controlled degradation rate. Via injection, the solution becomes gels in the part of disease. So there is a wide range of applications in the field of drug delivery and tissue healing. The physical gels based on hydrogen bonding, electrostatic, often have a lower intensity strength, bad mechanical stability and the degradation with short time. The use of new "Click chemistry" reaction, in particular through Schiff’s base bond makes compounds becoming hydrogels in situ, the reaction process is simple and efficient, matching the need of injectable hydrogels in the body application. Therefore, this paper based on primary amino group and a carbonyl group between the reversible Schiff base has been developed a biodegradable hydrogel in situ system, which is used for local transport and release in situ research with anti-cancer drug doxorubicin.Based on Dextran, Oxidized Dextran(ODEX) with the different oxidation extent was prepared. At the same time, the tri-block polymers poly(lysine)- polyethylene glycol-poly(lysine)(PLL- PEG2000- PLL) was synthesized.The storage modulus, degradation time of gel, and release of doxorubicin(DOX) were characterized. The results showed that with the increasing density of aldehyde in ODEX, gel strength increased gradually. The rheological test indicates that the storage modulus was reduced, due to the Schiff’s effect between ODEX aldehyde group and DOX amine group. The gel had a long degradation time. Drug release studies showed that DOX released from carrier gel was triggered by the enzyme. In Elastase solution, DOX release rate had reached the highest. The findings reveal that the hydrogel have promising applications in drug delivery in vivo.