We have developed and applied nanomanipulation strategies to the build-up of nanoscale-controlled electrochemical systems. We use distinct lithography procedures to be applied for nanoelectrodes manipulation in the build-up of an electrochemical cell with nanometric dimensions. We have demonstrate the possibility of immobilizing an indium tin oxide (ITO) nanowire electrode on gold contacts deposited atop of a microchip (oxidized Si wafer). A polymer protect layer containing an aperture over the sample area was photolithographically deposited over the microchip to isolate the metallic contacts. We have applied this cell in electrochemical experiments with current rage lower than 10 pA.
Nanostructured Films Modified Electrodes
The use of nanostructured films to modify electrochemical electrodes has allowed a whole host of new systems/devices to be fabricated, with properties that may be tuned upon synergistic interactions between the film components. Films produced with the Layer-by-Layer (LbL) technique, in particular, have opened up the way for new approaches in electrochomism, electrocatalysis, bioelectrochemistry and electroanalysis, for organic and inorganic-organic hybrid nanoarchitectures may be achieved. In addition to the fabrication of novel, optimized materials, with the LbL method fundamental processes such as charge transfer mechanisms involving biomolecules and nanoparticles can be investigated at the molecular level. In this research area, we develop electrochemistry of LbL films, with emphasis on their promising technological applications in electrochemical devices.
Molecular Architecture and Charge-Transfer Reactions of Metallophthalocyanine
The properties of solid-state supramolecular architectures can be controlled by tuning hydrogen bonding and electrostatic interactions in coordination compounds containing metallic centers and distinct coordination spheres. An interesting strategy to self-assemble highly organized nanostructures is the use of coordination chemistry strategies, where the molecules employed play a key role in the development of supramolecular systems. For example, nickel(II) and iron(II) metallic ions, in 3d8 and 3d6 low-spin electronic configurations, respectively, may be present in metallophthalocyanines (MPc, where M is metallic ion), when coordinated to the phthalocyanine ligand (Pc). In water solution, this adduct exhibits high kinetic and thermal stability regarding substitution in the equatorial plane, in addition to being an effective probe for molecular recognition.
Biological Molecules and Nanostructures
We have exploited the molecular engineering capability of aminoacids to produce a biological hybrid composite, and investigate in detail the mechanisms of formation of the nanostructures, including theoretical modeling. We focus on understanding the mechanisms involved in the formation of the hybrid nanostructures, which is not straightforward, since interactions may occur via non-specific, electrostatic interactions, specific H-bonding and even molecular recognition abilities. The molecular interaction between biological and nanoparticles (Au, Pt, Fe, oxides, etc.) has been investigated using FTIR, UV-Vis and electrochemical datas combined with a DFT theoretical modeling.