Novel Chitosan Derivative-based Anticoagulant Materials

In this work, two different anticoagulant biomaterials were prepared bymodifying chitosan with 5-formyl-2-furansulfonic acid (FFSA) and arginine,respectively. The main contents include two parts as follows:1. A series of N-sulfofurfuryl chitosans(N-Su-CSs) with different molecular weightsand substitution degrees were prepared by coupling FFSA to chitosan via Schiff'sbase reaction in the aqueous solution of acetic acid. The obtained N-Su-CSs werecharacterized by FTIR and elemental analysis. The change in the conformation ofthrombin caused by chitosan and N-Su-CS was evaluated by Circular Dichroism(CD).The result indicated that the contents of sulfonic acid in N-Su-CSs were raised withincreasing the addition amount of FFSA. The CD demonstrated that the N-Su-CSssignificantly altered the conformation of thrombin, whereas no obvious variation inthe conformation of thrombin was observed with the addition of chitosan. AFM imageshowed that the N-Su-CSs could prevent individual fibrinogen molecules fromaggregating and forming networks. The anticoagulation activity of oxidized glucose aldehyde-crosslinked N-Su-CSand chitosan membranes was examined by assaying activated partial thromboplastintime (APTT), prothrombin time (PT) and thrombin time (TT). The result indicatedthat APTTs of N-Su-CS membrane with different molecules and substitution degreeswere prolonged over 10s compared with that of the plasma of healthy people, andshowed a rising trend upon increasing the content of sulfonic acid groups. However,the PT and TT of modified chitosan remained the same level as that of chitosan,suggesting N-Su-CSs prevented blood coagulation via an intrinsic pathway. However,with the same substitution degree, the N-Su-CSs with different molecules showed nodistinct difference of APTT. The result of platelet adhesion on the N-Su-CS andchitosan membranes revealed that N-Su-CS could prevent the adhesion and activationof platelet to some extent. The preliminary experimental results of cytotoxicity ofoxidized glucose-crosslinked chitosan membranes demonstrated that the membraneswere non-cytotoxic with the content of crosslinker below10%.2. Chitosan was modified with arginine using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS) as coupling agents. FTIR, C 13NMR and XPS spectra showed that arginine was chemically coupled to chitosan toform a chitosan-arginine conjugate (CS-ArgC). The CD spectra implied a stronginteraction between CS-ArgC and thrombin. The results of APTT, PT and TT showedthat APTT and PT of glucose aldehyde-crosslinked CS-ArgC membranes wereprolonged with clinical significance compared with that of chitosan counterpart. TheAPTT reached a maximum value 71.2s, and PT 21.6s, indicating that CS-ArgChindered blood coagulation via both intrinsic and extrinsic pathway. Moreover, theincreasing extent of APTT and PT was dependent on the addition amount of arginine.But with the same substitution degree, the CS-ArgC with different molecules showedno obvious difference of APTT and PT. Compared with N-Su-CS, CS-ArgC was morenotable as an anticoagulant.