Nano assembly , or 'bottom-up' approach, similar to molecular engineering, the synthesis of a nanostructured material by assembly of its previously prepared nano-building-blocks (nanoscopic particles, or even atoms and molecules). There are number of nano-assembly techniques currently investigated. For example, nanoscopic particles can be created in gas phase (by evaporation of a material and clustering of atoms and molecules in the gas phase) and then assembled together by a condensation/nucleation process, using possibly another material (surfactant) to prevent merging (agglomeration, coalescence) of clusters. Careful monitoring of thermodynamical parameters during this process can result in nanostructured materials with varying properties. Some futurists (Drexler) propose nanoscopic 'assemblers' (nanobots) which would compose a nanoscopic particle or another nanobot on a molecule-by-molecule basis. This is, of course, only speculative fiction concerning the present state of science and technology. It is also questionable whether the science we know about allows for such nanomachines (Maxwell demons). Nevertheless, the operation of atomic force microscope in assembling artificial structures such as corals can be considered as a rather primitive example of this fiction.

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