DLS size profiles (A), representative cryoTEM images (B), and fluorescence spectra (C) of SiNc-PNPs before and after incubation for 2 h in PBS buffer with 5 wt% SDS. (D) The release profiles of SiNc from activatable SiNc-PNP incubated at 37 °C in PBS buffer at pH 7.4, 6.5 and 4.5. DLS size profiles of the developed activatable SiNc-PNP after incubation at 37 °C for 24 h in PBS buffer at pH 7.4, 6.5 and 4.5 in the 0-100 nm (E) and 100-700 nm (F) ranges. Representative cryoTEM images of the developed activatable SiNc-PNP after incubation at 37 °C for 24 h in PBS buffer at pH 7.4 (G), 6.5 (H) and 4.5 (I). Presence of bigger nanoparticles at lower pH is indicated by arrows.