Direct microcontact printing of oligonucleotides for biochip applications

BACKGROUND: A critical step in the fabrication of biochips is the controlled placement of probes molecules on solid surfaces. This is currently performed by sequential deposition of probes on a target surface with split or solid pins. In this article, we present a cost-effective procedure namely microcontact printing using stamps, for a parallel deposition of probes applicable for manufacturing biochips. RESULTS: Contrary to a previous work, we showed that the stamps tailored with an elastomeric poly(dimethylsiloxane) material did not require any surface modification to be able to adsorb oligonucleotides or PCR products. The adsorbed DNA molecules are subsequently printed efficiently on a target surface with high sub-micron resolution. Secondly, we showed that successive stamping is characterized by an exponential decay of the amount of transferred DNA molecules to the surface up the 4(th )print, then followed by a second regime of transfer that was dependent on the contact time and which resulted in reduced quality of the features. Thus, while consecutive stamping was possible, this procedure turned out to be less reproducible and more time consuming than simply re-inking the stamps between each print. Thirdly, we showed that the hybridization signals on arrays made by microcontact printing were 5 to 10-times higher than those made by conventional spotting methods. Finally, we demonstrated the validity of this microcontact printing method in manufacturing oligonucleotides arrays for mutations recognition in a yeast gene. CONCLUSION: The microcontact printing can be considered as a new potential technology platform to pattern DNA microarrays that may have significant advantages over the conventional spotting technologies as it is easy to implement, it uses low cost material to make the stamp, and the arrays made by this technology are 10-times more sensitive in term of hybridization signals than those manufactured by conventional spotting technology

Synthesis and mechanical properties of carbon nanotubes produced by the water assisted CVD process

Catalyst activity during the carbon nanotubes (CNTs) growth by chemical vapor deposition (CVD) is enhanced when water, a weak oxidizer, is introduced together with the carbon source. The height as well as the CNTs density can be controlled by fine-tuning the water content. The characterization of the mechanical properties of CNTs produced by the water assisted CVD process clearly indicates that high quality materials are produced. CNTs with diameter smaller than 12 nm exhibit Young's modulus higher than 400 GPa. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

Integration of a carbon nanotube based electrode in silicon microtechnology to fabricate electrochemical transducers

International audienc

Carbon nanotubes

International audienceCarbon nanotubes (CNT s) are remarkable objects that once looked set to revolutionize the technological landscape in the near future. Since the 1990s and for twenty years thereafter, it was repeatedly claimed that tomorrow's society would be shaped by nanotube applications, just as silicon-based technologies dominate society today. Space elevators tethered by the strongest of cables, hydrogen-powered vehicles, artificial muscles: these were just a few of the technological marvels that we were told would be made possible by the science of carbon nanotubes. Of course, this prediction is still some way from becoming reality; most often the possibilities and potential have been evaluated, but actual technological development is facing the unforgiving rule that drives the transfer of a new material or a new device to market: profitability. New materials, even more so for nanomaterials, no matter how wonderful they are, have to be cheap to produce, constant in quality, easy to handle, and nontoxic. Those are the conditions for an industry to accept a change in its production lines to make them nanocompatible. Consider the example of fullerenes – molecules closely related to nanotubes. The anticipation that surrounded these molecules, first reported in 1985, resulted in the bestowment of a Nobel Prize for their discovery in 1996. However, two decades later, very few fullerene applications have reached the market, suggesting that similarly enthusiastic predictions about nanotubes should be approached with caution, and so should it be with graphene, another member of the carbon nanoform family which joined the game in 2004, again acknowledged by a Nobel Prize in 2010. There is no denying, however, that the expectations surrounding carbon nanotubes are still high, because of specificities that make them special compared to fullerenes and graphene: their easiness of production, their dual molecule/nano-object nature, their unique aspect ratio, their robustness, the ability of their electronic structure to be given a gap, and their wide typology etc. Therefore, carbon nanotubes may provide the building blocks for further technological progress, enhancing our standard of living. In this chapter, we first describe the structures, syntheses, growth mechanisms, and properties of carbon nanotubes. Then we introduce nanotube-based materials, which comprise on the one hand those formed by reactions and associations of all-carbon nanotubes with foreign atoms, molecules and compounds, and on the other hand, composites, obtained by incorporating carbon nanotubes in various matrices. Finally, we will provide a list of applications currently on the market, while skipping the potentially endless and speculative list of possible applications

Carbon nanotubes

Carbon nanotubes (CNTs) are remarkable objects that once looked set to revolutionize the technological landscape in the near future. Since the 1990s and for twenty years thereafter, it was repeatedly claimed that tomorrow’s society would be shaped by nanotube applications, just as silicon-based technologies dominate society today. Space elevators tethered by the strongest of cables, hydrogen-powered vehicles, artificial muscles: these were just a few of the technological marvels that we were told would be made possible by the science of carbon nanotubes. Of course, this prediction is still some way from becoming reality; most often the possibilities and potential have been evaluated, but actual technological development is facing the unforgiving rule that drives the transfer of a new material or a new device to market: profitability. New materials, even more so for nanomaterials, no matter how wonderful they are, have to be cheap to produce, constant in quality, easy to handle, and nontoxic. Those are the conditions for an industry to accept a change in its production lines to make them nanocompatible. Consider the example of fullerenes – molecules closely related to nanotubes. The anticipation that surrounded these molecules, first reported in 1985, resulted in the bestowment of a Nobel Prize for their discovery in 1996. However, two decades later, very few fullerene applications have reached the market, suggesting that similarly enthusiastic predictions about nanotubes should be approached with caution, and so should it be with graphene, another member of the carbon nanoform family which joined the game in 2004, again acknowledged by a Nobel Prize in 2010. There is no denying, however, that the expectations surrounding carbon nanotubes are still high, because of specificities that make them special compared to fullerenes and graphene: their easiness of production, their dual molecule/nano-object nature, their unique aspect ratio, their robustness, the ability of their electronic structure to be given a gap, and their wide typology etc. Therefore, carbon nanotubes may provide the building blocks for further technological progress, enhancing our standard of living. In this chapter, we first describe the structures, syntheses, growth mechanisms, and properties of carbon nanotubes. Then we introduce nanotube-based materials, which comprise on the one hand those formed by reactions and associations of all carbon nanotubes with foreign atoms, molecules and compounds, and on the other hand, composites, obtained by incorporating carbon nanotubes in various matrices. Finally, we will provide a list of applications currently on the market, while skipping the potentially endless and speculative list of possible applications