Fabrication of PEG-bl-PPS Nanocarriers

Nanocarriers were fabricated based on the controlled self-assembly of PEG-bl-PPS block copolymers. A variety of different morphologies can be obtained by controlling the molecular weight (MW) ratio of the hydrophilic PEG to hydrophobic PPS blocks. Block copolymers PEG₄₅-bl-PPS₂₆ were synthesized as previously described [19 (link), 22 (link)]. Briefly, PEG thioacetate was deprotected by sodium methoxide for initiation of anionic ring opening polymerization of poly-propylene sulfide. The reaction was run to completion and subsequently protonated with acetic acid to create the PPS thiol-end groups for subsequent fluorophore conjugation. The resulting block copolymer was purified by double precipitation in methanol and then characterized by 1 H NMR (CDCl₃) and gel permeation chromatography (ThermoFisher Scientific) using Waters Styragel columns with refractive index and UV–vis detectors in a tetrahydrofuran (THF) mobile phase.