The project SLOW-2

We have discovered by serendipity that a fluorescent, two-photon absorbing and water-soluble dendrimer (hyper-branched macromolecule, having a perfectly defined structure) can induce a new type of “stereo-nano-lithography” (3-D) in a volume of water under the influence of a focused laser beam. This process is very different from classical stereolithography, as it is not a polymerisation reaction, it is slowly reversible with time, it occurs at a low concentration of dendrimer in water, and it can be controlled down to the 200 nm scale. There is no comparable technology to date; this is definitely a break with all that is known in the field of 3-D printing, concerning the nature of the media, the process involved, and the spatial resolution of the imprinted structures. From this first unpublished result, we must now determine what are the parameters which affect this phenomenon, by performing a real chemical engineering of the structure of the dendrimers, by varying the nature of the fluorophore subunit, its two-photon absorption efficiency, its absorption and emission wavelengths, the level at which it must be located within dendrimers structure, the number, the nature of the functions of the dendrimers surface, and the size/generation of the dendrimers.

The phenomenon which we have observed is more stable in the vicinity of a surface, but was obtained in bulk water. It could be used for soft flexible surface labelling, for instance for marking the membrane surface of a single cell among dozens of others.

The Figure bellow is a schematized representation of a fluorescent and water-soluble dendrimer with which we have observed the “stereo-nano-lithography” process.