Photo-Responsive Self-Assembled Polymeric Nanoparticle Probes for ¹⁹F MRI Theranostics

F-19 magnetic resonance imaging (MRI)-assisted drug deliveryprovides the possibility to monitor and track drug transportationdetails in situ. A series of photo-responsive amphiphilic block copolymersconsisting of hydrophilic poly-(ethylene glycol) and F-19-containinghydrophobic segments, poly-(2,2,2-trifluoroethyl acrylate) (PTFEA),with different chain lengths were synthesized by reversible addition-fragmentationchain-transfer polymerization. In particular, the photo-sensitivefunctional group of o-nitrobenzyl oxygen was introducedto control the photolysis behavior of the copolymers under ultravioletirradiation. With the extension of the hydrophobic chain length, thedrug loading capacity and photoresponsivity were both enhanced, whilethe chain mobility of PTFEA was suppressed, and the (FMRI)-F-19 signal was attenuated. When the polymerization degree of PTFEAwas about 10, the nanoparticles exhibit detectable (FMRI)-F-19 signals and sufficient drug loading capacity (loading efficiency= 10%, cumulative release = 49%). These results offer a promising"smart" theranostic platform for F-19 MRI.