Use of Nanoparticles to Study and Manipulate Plant cells

Fluorescence microscopy has developed into a key technology of the postgenomic era in biology, because it combines structural information with molecular specificity. However, the resolution of this approach is limited by bleaching and optical cross-reference of the fluorescent labels. Fluorescent semiconductor quantum dots (QDs) provide excellent bleaching stability and tunable emission spectra, and therefore would be an excellent alternative to overcome these limitations. However, to apply them to cell biology, three challenges have to be met: bioconjugation to molecular probes that confer the specificity of the label, passage through the external barriers of the cell, and suppression of toxic side effects of the nanoparticles. In plant cells that are ensheathed by a cellulosic cell wall, these challenges are especially prominent. Moreover, plants are located at the start of the food chain and thus of high relevance for the ecotoxicological assessment of nanomaterials. We have therefore explored the application of nanoparticles to plant cell biology. We have first evaluated different strategies to visualize microtubules by QDs in vitro and in cellula. By using silica-coated QDs coupled to anti-tubulin antibodies we were able to image microtubules in tobacco BY-2 cells by direct immunofluorescence making use of the superior bleaching stability of the nanoparticle label. To adapt this tool for in vivo imaging, we have successfully employed Trojan Peptoids as vehicles into living tobacco cells. We want to extend this strategy not only to use functionalized nanoparticles for life-cell imaging, but also to adapt them as tool to manipulate intracellular architecture.