Cationic silica nanoparticles are efficiently transferred into mammalian cells

Nanoparticles, as nonviral vectors, are expected as a candidate on highly effective non-viral gene carrier. We prepared organically modified cationic silica nanoparticles toward the high performance nonviral vector. It is to be noted that the complexes of DNA and nanoparticles are regarded as a simple model of chromatin. Furthermore, it is reported that the transcrip-tion activity of DNA is preserved after complexing with small nanoparticles, where the manner of complex formation is strongly dependent on the size of the nanoparticles in vitro. On the other hand, it is confirmed that transcription is completely inhibited in the compact globule state of giant DNA induced by polyamines and related polycations. The future goal of our undergoing studies is to make clear whether nanoparticles can be used for regulation of the higher-order structure of genomic DNA, and hence activate or inhibit transcription. In the present study, we performed experiments of transfecting nanoparticles into cell. Observation by fluorescence confocal microscopy shows that nanoparticles are effectively taken up in both cytoplasm and nucleus in cells. Importantly, it is also demonstrated that the nanoparticles are non-toxic for cell. The difference in the scenario of nanoparticles uptake by cells has been also observed. The results suggest that organically modified cationic silica nanoparticles may be the next new class of DNA binders and carries for biological and biomedical applications in the future.