Synthesis And Properties Of Poly Amino Acid-Based Anticoagulant Thrombolysis Polymer

Cardiovascular disease is one of the most serious diseases in the world.The death rate due to the cardiovascular disease accounts for more than 40%of the deaths of residents,and ranking the first.The main cause of cardiovascular disease comes from the occurrence of thrombi caused by coagulation disorders,so anticoagulant thrombolytic therapy is the most important treatment.Heparin drugs are currently the most widely used anticoagulant thrombolytic drugs,but the sources are limited,and they are costly,difficult to synthesize,and difficult to control as well.In view of this,heparin mimic polymers have made great progress.In the first part of this paper,the types,structures and properties of heparin mimic polymer are systematically described,and the existing problems are analyzed and illustrated.The thinking and method of this paper are put forward.In order to solve the problem of biodegradability and performance regulation of heparin mimic polymers,in this paper,the glucosamine and glucosamine sulfates of the heparin-specific sugar unit structure are used as raw materials.An anionic glycosylated poly-L-glutamic acid anti-coagulation thrombolytic polymer was obtained by poly（L-glutamic acid methyl ester-co-L-glutamic acid benzyl ester）to amination and hydrolysis.Its structure,molecular weight,enzymatic degradation and cytotoxicity were tested to evaluate the biocompatibility of the polymer,and the plasma recalcification,the whole blood coagulation and the effect of clot lysis in vitro were tested at the same time.The results showed that the polymer could degrade by about 78%in 16 d;the cell activity is about 75%after 72 h of incubation;with the increase of molecular weight and the ratio of functional groups,the activated partial thromboplastin time APTT could be extended to about 27 s,the plasma recalcification time can be extended by about 210 s,the whole blood clotting time can be extended by about 300 s,and the clot lysis in vitro can be dissolved 60%within 2 h.Therefore,the glycosylated polyamino acids with certain biocompatibility and anticoagulant thrombolytic properties were obtained.Although the anti-coagulation and thrombolytic effect of the glycosylated polyamino acid is remarkable,it is difficult to purify the product because of the low solubility in an organic solvent of glucosamine and incomplete aminolysis result.In view of this,designed and synthesized polysulfonated/polycarboxylated polyamino acids,and initiated theα-amino acid N-carboxyl Anhydrides（NCAs）of L-tyrosine and L-glutamic by using the nucleophilic reagent triethylenetetramine（TETA）.The NCAs were subjected to controlled ring-opening polymerization（ROP）,and the product was sulfonated modification to prepare sulfonated poly（L-tyrosine-co-L-glutamic acid）（PTG-SO₃）with anticoagulant activity.The structure,enzymatic degradation,cytotoxicity and blood compatibility of PTG-SO₃ were tested,and the result showed that the structure of PTG-SO₃ was correct,the degradation rate was about 65%in 16 d.At the same time,after 72 h of incubation,the cell activity was about 85%.When the ratio of carboxyl group to sulfonic acid group was 1:2,APTT can be extend by about27 s;the thrombin time TT can be extended by about 23 s;the plasma recalcification can be extended by about 337 s;the whole blood clotting time can be extended by about 787 s;the blood clots in vitro can be dissolved 80%in 2 h.Therefore,excellent enzymatic degradation,low cytotoxicity and good anticoagulant thrombolytic properties are more expected to apply in the field of anticoagulant thrombolytic drugs than glycosylated polyamino acids.In order to optimize the reaction ratio and more precisely control the ratio of the three groups of hydroxyl,carboxyl and sulfonic acid groups,it is better to research the ratio of the group and the effect of the molecular weight of the polymer on the anticoagulant activity.Therefore,a series of anionic poly amino acid PSGC-SO₃ were prepared by using triethylenetetramine（TETA）to initiate the controlled Ring Opening Polymerization of NCAs of L-glutamic,L-serine and L-cysteine.The structure,average molecular weight and distribution,enzymatic degradation and cytotoxicity of the polymer were tested.The results showed that the polymer structure conformed to the expected and can degrade about 67%after 16 d;after 72 h of incubation,the cell activity is about 89%.Therefore,it has good biodegradability and sound bio-compatibility.In order to evaluate the anticoagulant and thrombolytic ability of the obtained polymer,blood compatibility test was carried out,and the results showed that the PSGC-SO₃ has sound anticoagulant property.The main mode of action is the endogenous coagulation pathway,and with the increasing of the polymer molecular weight,the APTT can be extended by about 110 s;the plasma recalcification time can be extended by about 250 s;the whole blood clotting time can be extended by about983 s;the blood clot in vitro can be dissolved 51%within 2 h.At the same time,the polymer obtained by controlled ring-opening polymerization,with a ratio of hydroxyl,carboxyl and sulfonic acid groups is 1:1:4,APTT can be extended by about 73 s;the plasma recalcification time can be extended by about 540 s;the whole blood coagulation time can be extended by about 1000 s,and the blood clot in vitro can be dissolved 60%within 2 h.The above test results showed that the polymers not only have better anti-coagulation and thrombolytic ability in vitro,but also can control the proportion of reactive functional groups in the polymer by changing the monomer feed ratio,thereby achieving its anti-coagulation and thrombolytic properties.Effective regulations can be used to meet a variety of anticoagulant thrombolytic needs.And the polymers could be a series of promising new medical functional material.