Polyoxazoline thermoresponsive micelles as radionuclide delivery systems.

Thermoresponsive polymer micelles are promising drug and radionuclide carriers with a strong passive targeting effect into solid tumors. We have synthesized ABA triblock copolymers poly[2-methyl-2-oxazoline-block-(2-isopropyl-2-oxazoline-co-2-butyl-2-oxazoline)-block-2-methyl-2-oxazoline]. These polymers are molecularly dissolved in aqueous millieu below the cloud point temperature (CPT) of the thermoresponsive central block and above CPT form polymer micelles at CMC 5-10 × 10(-5) g · mL(-1) with diameter ≈200 nm. The phenolic moiety introduced into the copolymer allowed radionuclide labeling with iodine-125 ongoing in good yield with sufficient in vitro stability under model conditions.