Synthesis and characterization of perfluoro-tert-butyl semifluorinated amphiphilic polymers and their potential application in hydrophobic drug delivery

Abstract

Semifluorinated polymer surfactants, composed of a monomethyl poly(ethylene glycol) (mPEG) hydrophilic head group and 1, 2, or 3 perfluoro-tert-butyl (PFtB) groups as the fluorophilic tail, were synthesized, and their aqueous self-assemblies were investigated as a potential design for theranostic nanoparticles. Polymers with three PFtB groups (PFtB_TRI) solely formed stable, spherical micelles, approximately 12 nm in size. These PFtB_TRI surfactants demonstrate similar characteristics to those of polymers with linear perfluorocarbon tails, despite large differences in the tail structure. For example, PFtB polymer solutions stably emulsified 20 v/v% sevoflurane with perfluorooctyl bromide (PFOB) as a stabilizer. However, these PFtB polymers have the additional potential to serve as F-MRI contrast agents. PFtB_TRI micelles gave one narrow ¹⁹F-NMR signal in D₂O, with T₁ and T₂ parameters of approximately 500 and 100 ms, respectively. ¹⁹F-MR images of PFtB polymer solutions at 1 mM gave an intense signal at 4.7 T without sensitizers or selective excitation sequences. These preliminary data demonstrate the potential of PFtB polymers as a basic design, which can be further modified to serve as dual drug-delivery and imaging vehicles.