title: Synthesis and self-assembly of biodegradable polyethylene glycol-poly (lactic acid) diblock copolymers as polymersomes for preparation of sustained release system of doxorubicin.
abstract: BACKGROUND
  The copolymer of polyethylene glycol (PEG) and polyesters has many interesting properties, such as amphiphilicity, biocompatibility, biodegradability, and self-assembly in an aqueous environment. Diblock copolymers of PEG-polyester can form different structures such as micelles, polymersome, capsules or micro-container in an aqueous environment according to the length of their blocks.
  
  
  METHODS
  Herein, a series of poly (lactic acid) (PLA) and PEG diblock copolymers were synthesized through the ring-opening polymerization. The polymerization reaction and the copolymer structures were evaluated by nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). The corresponding copolymers were implemented for the formation of polymersome structures using film rehydration method. Impact of methoxy PEG chain length and hydrophobic weight fraction on particle size of polymersomes were studied, and the proper ones were selected for loading of doxorubicin (DOX) via pH gradient method.
  
  
  CONCLUSIONS
  Results obtained from (1)HNMR and GPC revealed that microwave irradiation is a simple and reliable method for the synthesis of PEG-PLA copolymers. Further analysis indicated the copolymer with relative molecular weight of PLA to PEG ratios of 3 or f Eo ~ 25% produced the smallest size polymersomes. Polymersomes prepared from PEG5000 to PLA15000 were more capable in loading and sustained release of DOX than those prepared from PEG2000 to PLA6000.
  
  
  CONCLUSIONS
  In conclusion copolymers of PEG/PLA with f OE ~25% and relatively higher molecular weight are more suitable for encapsulation and providing sustained release of DOX.
authors.affiliation: Biotechnology Research Center, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Mona
authors.initials: M
authors.lastname: Alibolandi
authors.affiliation: Targeted Drug Delivery Research Center, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Sadeghi
authors.affiliation: Student Research Committee, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Seyed Hossein
authors.initials: SH
authors.lastname: Sazmand
authors.affiliation: Targeted Drug Delivery Research Center, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Seyed Mohammad
authors.initials: SM
authors.lastname: Shahrokhi
authors.affiliation: Biotechnology Research Center, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Seifi
authors.affiliation: Biotechnology Research Center, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Farzin
authors.initials: F
authors.lastname: Hadizadeh
keywords: Copolymer; doxorubicin; polyethylene glycol-poly (lactic acid); polymersome; self- assembly