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Trabajo presentado a la XXXVI Reunión Bienal de la Real Sociedad Española de Física, celebrada en Santiago de Compostela del 17 al 21 de julio de 2017.

7 páginas, 5 figuras., In this manuscript we demonstrate the spatially controlled immobilization of ferritin proteins by directly writing them on a wide range of substrates of technological interest. Optical and fluorescence microscopy, AFM and TOF-SIMS studies confirm the successful deposition of the protein on those surfaces. Control on nanostructure shape and size, by miniaturizing the dot-like features down to a 100 nm, demonstrates the particular capabilities of the DPN approach. Ultimately, this study gives the opportunity to design nanoparticle-based arrays regarding the growing interest in the use of nanoparticles as structural and functional elements for fabricating nanodevices. Herein, we demonstrate how the protein shell of ferritins can be removed by a simple heat-treatment process while maintaining the encapsulated inorganic nanoparticle intact on the same location of the nanoarray. As a result, this study establishes how direct-write DPN approach could give the opportunity to design not only protein-based nanoarrays but also nanoparticle-based nanoarrays with high-resolution and control., D. M. thanks the Ministerio de Ciencia y Tecnología for a RyC contract. A. L. thanks ARAID for financial support. R. de M. is indebted to MICINN for receiving a predoctoral FPU fellowship.

10 p.-5 fig.-8 tab., Many flavoproteins are non-covalent complexes between FMN and an apoprotein. To understand better the stability of flavoproteins, we have studied the energetics of the complex between FMN and the apoflavodoxin from Anabaena PCC 7119 by a combination of site-directed mutagenesis, titration calorimetry, equilibrium binding constant determinations, and x-ray crystallography. Comparison of the strength of the wild type and mutant apoflavodoxin-FMN complexes and that of the complexes between wild type apoflavodoxin and shortened FMN analogues (riboflavin and lumiflavin) allows the dissection of the binding energy into contributions associated with the different parts of the FMN molecule. The estimated contribution of the phosphate is greatest, at 7 kcal mol(-1); that of the isoalloxazine is of around 5-6 kcal mol(-1) (mainly due to interaction with Trp-57 and Tyr-94 in the apoprotein) and the ribityl contributes least: around 1 kcal mol(-1). The stabilization of the complex is both enthalpic and entropic although the enthalpy contribution is dominant. Both the phosphate and the isoalloxazine significantly contribute to the enthalpy of binding. The ionic strength does not have a large effect on the stability of the FMN complex because, although it weakens the phosphate interactions, it strengthens the isoalloxazine-protein hydrophobic interactions. Phosphate up to 100 mM does not affect the strength of the riboflavin complex, which suggests the isoalloxazine and phosphate binding sites may be independent in terms of binding energy. Interestingly, we find crystallographic evidence of flexibility in one of the loops (57-62) involved in isoalloxazine binding., This work was supported by Grants PB96-1439, PB97-1027, and PB97-1237 (Dirección General de Enseñanza Superior, Spain) and Grant P15/97 (Consejo Superior de I+ D, Diputación General de Aragón, Spain).

Máster en Materiales Nanoestructurados para Aplicaciones Nanotecnológicas (Nanostructured Materials for Nanotechnology Applications)., Nowadays, nanotechnology’s challenge remains in the generation of functional nanostructured materials to keep up with demands in a world of continuous technological innovation. In this context, graphene has become incredibly popular for applications in nanoelectronics. Due to its electrical and spin properties, graphene is being considered as a revolutionary material for nanoscale applications in electronic devices and sensors. Currently, the attention is placed in the strategies to produce graphene nanoribbons for the production of field effect transistors at room temperature. However, the diverse fabrication methods still present limitations for scaling up the process. In this work, direct write Dip Pen Nanolithography (DPN) was used for the fabrication of graphene ribbons reaching micrometre resolution. Initially, a polystyrene ink was used as a physical mask to create patterns on epitaxial graphene by DPN. The remaining graphene was removed through a controlled oxygen plasma etching, either by a conventional technique or by plasma enhanced chemical vapour deposition. Finally, the process concluded with a wet etching to remove the remaining PS patterns. In this last step, different conditions were tested to study which provided the best results for the scope of the work. The performance of the process was evaluated by Atomic Force Microscopy (AFM) at ambient conditions while the quality of the remaining graphene was studied by Raman Spectroscopy and by the analysis of electrical conductivity in a Dual Beam equipment. As mentioned, the process has reached micrometre resolution which is a promising scenario to scale down to the nanometre resolution.