The use of synthetic vascular for cardiovascular and cerebrovascular tissue engineering has made tremendous progress in the past thirty years

but the clinical use of vascular conduits with diameters less than 6 mm remains unsuccessful because of the thrombus formation.Poly(lactic acid) (PLA) was well-suited for applications as tissue engineering materials due to their good biocompatibility and biodegradability.To improve the blood compatibility of polylactide

three polymers based on PLA and poly(malic acid) were synthesized by ring-opening polymerization

namely poly(lactide-co-β-malic acid) (PLMA)

poly(lactide-co-RS-hydroxyethyl-b-malolactonate) (PLMAHE) and PLA with pendant carboxyl arms (PCA-PLA).The structure

composition and molecular weight of the copolymers were confirmed by 1H-NMR and GPC.AFM was first used to observe the morphology of the adhered platelets on the polymer films.The platelet adhesion amount on the polymer films was calculated by Hematology Analyzer.The results showed that the copolymers with functional side chains especially with pendant carboxyl arms could obviously reduce the platelet adhesion capacity on the copolymer films compared with PLA.The platelet amount adhered on PLA

PLMA and PLMAHE was 3.2×103

2.5×103 and 1.8×103 after 30 min

respectively

and there was few platelets adhered on the film with pendant carboxyl arms after 1 hour.The thickness of polymer films was determined by AFM

all films of each polymer were about 50 nm thick.From the images of AFM and SEM

it could be seen that only the polymer with hydroxyl groups could activate the platelet.In conclusion

the copolymer with pendant carboxyl was a hopeful material for vessel substitution with good blood compatibility.