Background: In the past decade, considerable attention has been paid for the development of novel strategies for the synthesis of different kind of nano-objects. Most of the current strategies are usually working by the use physical or chemical principles to develop a myriad of nano-objects with multiple applications. Main fields of nanotechnology applications range from catalysis, micro- and nano-electronics (semiconductors, single electrons transistors), non-linear optic devices, photo-electrochemistry to biomedicine, diagnostics, foods and environment, chemical analysis and others.

Results: Two main avenues for nanoparticles synthesis: cell-free extract and cell cultivation have been reported. The state of art of both biotechnological approaches for different type nanoparticles are reviewed in this work.

Conclusions: Nanotechnology is a revolutionary field just at its onset, the trend in the next decades being its integration with the green chemistry approach. Several strategies involving exhaustive strain selection, cultivation modes, recombinant gene expression, metabolic engineering, protein re-design and re-engineering, and predictive modeling will allow to create nanobioreactors, a new nanobiotechnology arena with a high potential impact in many fields.