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Background and Aim: Knowledge of biodegradability and biocompatibility rate in drug delivery systems is very important. 
Material and Method: This study PCL–PEG–PCL and MPEG-PCL copolymers were synthesized by ring-opening copolymerization. HNMR, FTIR, DSC and GPC techniques were used to confirm successful synthesis and determination of the characteristics of the copolymers. We evaluated biocompatibility by MTT assay on the basis of cytotoxicity effect of these copolymers on HEK293 cells. Biodegradation was evaluated by GPC technique.
Results: The  results of  HNMR and FTIR confirmed synthesis of diblock and tri block copolymers. Using DSC technique, melting point of tri block and  diblock copolymers were 55 °C and 58.68°C and also  the average molecular weights of these copolymers were 16,000 and 12,223 Dalton, respectively. The degradation of these copolymers were performed in buffer solution and at the end of the 31^st day, molecular weights of diblock and tri block
Copolymers were 7852 and 9586 Dalton respectively. Based on IC_{50 ,} diblock and tri block copolymers had no toxic effects on HEK293 cells and are biocompatibile .
Conclusion: diblock and tri block copolymers had high rates of biodegradability and because of not having toxic effects on normal renal cells, they were biocompatible.
Keywords: Copolymer, Cytotoxicity, Biocompatibility, Biodegradability.
 
Received: Nov 7, 2016      Accepted: Feb 28, 2017