High mobility graphene ion-sensitive field-effect transistors by noncovalent functionalization.

Noncovalent functionalization is a well-known nondestructive process for property engineering of carbon nanostructures, including carbon nanotubes and graphene. However, it is not clear to what extend the extraordinary electrical properties of these carbon materials can be preserved during the process. Here, we demonstrated that noncovalent functionalization can indeed delivery graphene field-effect transistors (FET) with fully preserved mobility. In addition, these high-mobility graphene transistors can serve as a promising platform for biochemical sensing applications.

Force-conductance correlation in individual molecular junctions.

Conducting atomic force microscopy is an attractive approach enabling the correlation of mechanical and electrical properties in individual molecular junctions. Here we report on measurements of gold-gold and gold-octanedithiol-gold junctions. We introduce two-dimensional histograms in the form of scatter plots to better analyze the correlation between force and conductance. In this representation, the junction-forming octanedithiol compounds lead to a very clear step in the force-conductance data, which is not observed for control monothiol compounds. The conductance found for octanedithiols is in agreement with the idea that junction conductance is dominated by a single molecule.

Induction of catharanthine synthesis and stimulation of major indole alkaloids production by Catharanthus roseus cells under non-growth-altering treatment with Pythium vexans extracts.

A Catharanthus roseus cell line was selected that synthesised catharanthine exclusively under elicitation.From the first day of culture, treatment with very low concentrations of a Pythium extract did not alter the growth of the suspension but, within 24 hours, induced the synthesis of catharanthine and stimulated the production of ajmalicine. Kinetic analysis showed that serpentine then began to accumulate and that all of these effects lasted more than 7 days. Elicitation also induced changes in the cell/medium distribution of the alkaloids. Higher, although non-lethal, concentrations of the fungal elicitor were shown to impair alkaloid production. This cell line will serve as a model to study the conditions for the expression of catharanthine synthesis at the molecular level.

Stimulation of somatic embryogenesis and plant regeneration from anther culture of Vitis vinifera cv. Cabernet-Sauvignon.

Somatic embryogenesis and subsequent diploid plants have been obtained from anthers of Vitis vinifera Cabernet-Sauvignon, a cultivar so far considered as recalcitrant to in vitro regeneration. Anthers enclosing microspores near the first pollen mitosis were found to be the most responsive. However, from a practical point of view anther length proved to be an easier criterium for determining the optimal physiological anther stage. Calli derived from the anther somatic tissues produced embryoids only when cultured on a medium supplemented with casein hydrolysate. Glutamine and adenine were found to stimulate this embryoid production. Evidence is presented that early removal of cotyledons increases the frequency of normal development of embryoids into plantlets.