Size-dependent cellular uptake efficiency, mechanism, and cytotoxicity of silica nanoparticles toward HeLa cells

► The cellular uptake efficiency of SNPs is size-dependent in the order of 55.6>167.8>307.6 nm. ► The cellular uptake pathways of SNPs toward HeLa cells were found to be size-dependent. ► Different SNPs in size show excellent biocompatibility with little cytotoxicity.