Polymersomes are vesicular constructs formed by the self-assembly of polymer amphiphiles. Here we report the fabrication of PEtOx-b-PLA polymersomes at physiological pH/salt concentration and the determination of a f(PEtOx) range, which is one of the most recognized factors that governs the self-assembly of amphiphilic copolymers, for the first time. The findings indicate that PEtOx-b-PLA copolymers, containing PEtOx fractions of varied lengths, self-assemble to form polymersomes in the range of 98.35 to 119.50 nm. The encapsulation potential of PEtOx-b-PLA polymersomes was demonstrated by loading of docetaxel (hydrophobic) with 17.90% encapsulation efficiency and by loading of pDNA (hydrophilic) with 65.03% encapsulation efficiency. In addition, size distribution profiles showed that polymersomes are colloidally stable for 24 h at 37 degrees C and for 3 months at +4 degrees C. The cell viability results showed that PEtOx-b-PLA copolymer and polymersomes are not cytotoxic to HUVEC, HEK293 and hMSC cell lines.