Fig. 1

Preparation of carrier-free prodrug nanoparticles (F68-FDOX) for preclinical development. a Schematic illustration showing structure of F68-FDOX. b Picture to show large scale synthesis of F68-FDOX at one batch up to 200 g in 2 L volume. c Size distribution and morphology of FRRG-DOX and F68-FDOX nanoparticles. d Zeta potential of FRRG-DOX and F68-FDOX nanoparticles. e Size stability of FRRG-DOX and FRRG-DOX stabilized with Pluronic F68 (F68-FDOX), hyaluronic acid or glycine nanoparticles in mouse serum. f–g Cleavage behavior of F68-FDOX after incubation with f cathepsin B or g other enzymes (cathepsin E, D, L and caspase-3) or saline (hydrolysis). h The size distribution, chemical structure and purity after 24 h reconstitution of lyophilized F68-FDOX powder stored at low (− 4 °C) temperature for 12 months