The characteristics of the interactions co-cultures of ultrafine mesoporous silica nanoparticles （MSNs） and the Liriodendron hybrid suspension cells were systematically investigated using laser scanning confocal microscope （LSCM） and scanning elec- tron microscopy （SEM）. Using fluorescein isothiocyanate （FITC） labeling, the LSCM observations demonstrated that MSNs （size, 5-15 nm） with attached FITC molecules efficiently penetrated walled plant cells through endocytic pathways, but free FITC could not enter the intact plant cells, The SEM measurements indicated that MSNs readily aggregated on the surface of intact plant cells, and also directly confirmed that MSNs could enter intact plant cells; this was achieved by determining the amount of silicon present. After 24 h of incubation with 1.0 mg mL-t of MSNs, the viability of the plant cells was analyzed using fluorescein diacetate staining; the results showed that these cells retained high viability, and no cell death was observed. Interestingly, after the incubation with MSNs, the Liriodendron hybrid suspension cells retained the capability for plant regen- eration via somatic embryogenesis. Our results indicate that ultrafine MSNs hold considerable potential as nano-carriers of ex- tracellular molecules, and can be used to investigate in vitro gene-delivery in plant cells.
