Silica nanoparticles (SNPs) have been used in several industries, and also been exploited for biomedical research as biosensor, biomarker, DNA/drug delivery, enzyme immobilization and cancer therapy.Recently, we have demonstrated that SPNs within 7~50 nm spared normal L-02 cell, but significantly inhibited cell proliferation and induced apoptosis of human hepatoma HepG2 cells in a size-, time-and dose-dependent manner.