Preperation of temperature and pH responsive polymersomes

Polymersomes are polymeric vesicles that can be used in biomedical fields such as drug delivery, nanoreactors, nanomotors etc. Recent years especially stimuli responsive polymersomes have been of great attention for the researchers. Among them, temperature and pH sensitive polymersomes are the most extensively studied drug delivery systems. In this thesis for the first time, temperature and pH sensitive polymersomes were developed by using PEG-b-PDMAEMA block copolymers. For this purpose, PEG-b-PDMAEMA block copolymers with different molecular weights were synthesized by ATRP method and their structures were characterized by FTIR and 1H NMR spectroscopy measurements. Temperature and pH sensitivities of PEG-b-PDMAEMA block copolymers in aqueous solution were determined by UV-Vis spectrophotometer and dynamic light scattering (DLS) measurements. The effects of polymer chain length, temperature, pH and concentration on the polymersome formation were investigated. The formation of polymersomes in polymer solutions was elucidated by DLS, optical microscopy and transmission electron microscopy (TEM) measurements It was determined that well-defined polymersomes were formed in 1% (w/v) aqueous solutions of the two synthesized diblock copolymers (PEG48-b-PDMAEMA77 and PEG48-b-PDMAEMA125). The resulting polymersomes were characterized by TEM measurements and their sizes were determined as 362±69 and 165±7 nm, respectively. The effect of pH on the ability of the PEG48-b-PDMAEMA77 copolymer to form polymersomes was investigated and it was determined that their sizes of stable polymersomes at pH=9 were 235±83 nm.