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Mesoporous oxide thin films (MOTF) present very high surface areas and highly controlled monodisperse pores in the nanometer range. These features spurred their possible applications in separation membranes and permselective electrodes. However, their performance in real applications is limited by their reactivity. Here, we perform a basic study of the stability of MOTF toward dissolution in aqueous media using a variety of characterization techniques. In particular, we focus in their stability behavior under the influence of ionic strength, adsorption of electrochemical probes, and applied electrode potential. Mesoporous silica thin films present a limited chemical stability after electrochemical cycling, particularly under high ionic strength, due to their high specific surface area and the interactions between the electrochemical probes and the surface. In contrast, TiO₂ or Si0.9Zr0.1O₂ matrices present higher stability; thus, they are an adequate alternative to produce accessible, sensitive, and robust permselective electrodes or membranes that perform under a wide variety of conditions., Facultad de Ciencias Exactas, Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas

Conductive inks with optimal properties for amperometric sensor fabrication are key materials for low cost and high performance electrodes printed on flexible substrates. In this work, electrodes made with a carbon nanotube (CNT) waterborne ink were prepared and characterized. The electrodes showed mechanical stability and electrocatalytic behavior. Moreover, they were used for the immobilization of horseradish peroxidase (HRP) and their performance as enzymatic biosensors was assessed. Oxygen plasma treatment was used to generate carboxylic functionalities for enzyme immobilization. Its effect on the electrodes was investigated in order to optimize their performance. These electrodes were fabricated with an ink that provides a potentially simple route for roll-to-roll biosensor printing. Fil: Garate, Octavio. Instituto Nacional de Tecnología Industrial; Argentina Fil: Veiga, Lionel. Instituto Nacional de Tecnología Industrial; Argentina Fil: Medrano, Anahí V.. Instituto Nacional de Tecnología Industrial. Centro de Micro y Nanoelectrónica del Bicentenario; Argentina Fil: Longinotti, Gloria. Instituto Nacional de Tecnología Industrial; Argentina Fil: Ybarra, Gabriel. Instituto Nacional de Tecnología Industrial; Argentina Fil: Monsalve, Leandro Nicolas. Instituto Nacional de Tecnología Industrial. Centro de Micro y Nanoelectrónica del Bicentenario; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Plasma nitriding of austenitic stainless steel is of high technological importance due to its ability to improve the surface hardness, wear and corrosion resistance. Therefore, such process presents a significant potential as a treatment of materials for biomedical applications. The resulting properties obtained on the nitrided layer depend on the nitriding parameters used, such as temperature, gases partial pressures, process time, among others. In this work, austenitic stainless steel AISI 316L was nitrided in a DC plasma using two different N2-H2 atmospheres: 25% N2 and 20% N2. A detailed analysis of surface microstructure has been carried out and related to corrosion behaviour in two saline solutions. The results were compared with the 316L unnitrided (UN). The chemical composition of the nitrided layer was determined by GDOES. The phases present in the nitrided layer were analysed by X-ray diffraction (XRD) and the phases in the surface of nitrided layer were analysed by grazing incidence X-ray diffraction mode (GIXRD). The corrosion behaviour of the samples was studied by an electrochemical corrosion test in 3 wt% NaCl and Ringer's solutions. The GDOES (Glow Discharge Optical Emission Spectroscopy) analysis shows a higher N concentration of in the surface of 25% N2 samples, named HN. The phases observed, by GIXRD, in HN samples were expanded austenite γN, CrN, Fe3N and Fe4N and, in the 20% N2 samples, named LN, only peaks of expanded austenite and Fe4N were observed. The corrosion results showed that LN present better corrosion resistance than HN, this could be due to the absence of chromium nitrides in the surface of LN as a consequence of lower N percentage in the nitriding atmosphere. Fil: de Las Heras, Maria Evangelina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina Fil: Ybarra, Gabriel Omar. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Industrial; Argentina Fil: Lamas, Diego Germán. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina Fil: Cabo, Amado. IONAR S.A.; Argentina Fil: Dalibon, Eugenia Laura. Universidad Tecnológica Nacional; Argentina Fil: Brühl, Sonia Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Tecnológica Nacional; Argentina

In this work, a study about the deposition of hydroxyapatite on a titanium substrate employing the biomimetic method is presented. A solution with high content of calcium and phosphorus (SCS) was used. In addition, activation of titanium with hydrogen peroxide and hydrochloric acid and a subsequent heat treatment was performed. The characterization of materials used and the coating obtained was carried out by Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX). As a result of the activation processes a hydrated titanium oxide was formed. On the active surface, a coating of hydroxyapatite was obtained after a period of 24 h, which has a thickness of about 2-4 μm.En el presente trabajo se realizó un estudio de la deposición de hidroxiapatita sobre un sustrato de titanio mediante el método biomimético. Para ello se empleó una disolución con elevado contenido de calcio y fósforo (SCS). Además, se realizó la activación del titanio a partir de la aplicación de procesos de oxidación con peróxido de hidrógeno y ácido clorhídrico con un posterior tratamiento térmico. La caracterización de los materiales empleados, así como de los recubrimientos obtenidos, se realizó mediante Espectroscopia Infrarroja (FT-IR), Difracción de Rayos X (DRX), Microscopia Electrónica de Barrido (MEB) y Espectroscopia de Energía Dispersiva de Rayos X (EDX). Como resultado del proceso de activación se formó un óxido de titanio hidratado. Sobre la superficie activada se logró obtener un recubrimiento de hidroxiapatita en un período de 24 h, caracterizado por su elevada densidad y cristalinidad y por presentar un espesor entre 2-4 μm.

Composite magnetite–gold mesoscopic particles were prepared by deposition of Au onto magnetite nanoparticles. The surface morphology of the mesoparticles could be tuned by controlling the factors that affect the kinetics of the reactions and by adding surfactants that direct the growth of gold crystals. The internal structure of composite mesoparticles was analyzed by focused ion beam and scanning electron microscopy. A particle-mediated growth mechanism of formation was proposed. Fil: Lloret, Paulina. Instituto Nacional de Tecnologia Industrial. Procesos Superficiales; Argentina Fil: Ybarra, Gabriel. Instituto Nacional de Tecnologia Industrial. Procesos Superficiales; Argentina Fil: Granell, Pablo. Instituto Nacional de Tecnología Industrial. Centro de Micro y Nanoelectrónica del Bicentenario; Argentina Fil: Socolovsky, Leandro Martin. Universidad de Buenos Aires. Facultad de Ingenieria. Departamento de Fisica. Laboratorio de Sólidos Amorfos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Moina, Carlos. Instituto Nacional de Tecnologia Industrial. Procesos Superficiales; Argentina

Immunosensors are compact analytical devices in which the event of formation of antigenantibody complexes is detected and converted, by means of a transducer, to an electrical signal, which can be processed, recorded and displayed. Different transducing mechanisms are employed in immunological biosensors, based on signal generation (such as an electrochemical or optical signal) or properties changes (such as mass changes) following the formation of antigen-antibody complexes. In this chapter, the basics of immunosensors are presented focused on the different transduction techniques used in immunosensing.

The biomimetic method is used for the deposition of calcium phosphate coatings (Ca – P) on the surface of different biomaterials. However, the application of this method requires long exposure times in order to obtain a suitable layer thickness for its use in medical devices. In this paper, we present a fast approach to obtain apatite coatings on titanium, using a combination of supersaturated calcification solution (SCS) with chemical modification of the titanium surface. Also, it was evaluated the effect of four different surface treatments on the apatite deposition rate. Commercially pure titanium plates were activated by chemical or thermochemical treatments. Then, the activated samples were immersed in a solution with high content of calcium and phosphate ions at 37 °C for 24 h, mimicking the physiological conditions. The coatings were studied by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The use of SCS solutions allowed the formation of crystalline hydroxyapatite coatings within a period of 24 h with a thickness between 1 and 5.3 μm. Besides, precipitates of hydroxyapatite nanoparticles with a globular configuration, forming aggregates with submicrometer size, were found in SCS solutions. Fil: Paz Ramos, Adrian. Université de Montréal; Canadá Fil: Ybarra, Gabriel O. Instituto Nacional de Tecnología Industrial (INTI); Argentina Fil: Pazos, Leonardo M. Instituto Nacional de Tecnología Industrial (INTI); Argentina Fil: Parodi, María B. Instituto Nacional de Tecnología Industrial (INTI); Argentina Fil: Rodríguez, Laura. Instituto Nacional de Tecnología Industrial (INTI); Argentina Fil: López Hernández, Mónica. Centro Nacional de Investigaciones Cientificas (CNIC); Cuba Fil: González Ruíz, Jesús E. Universidad de La Habana. Centro de Biomateriales (BioMat-UH); Cuba

Diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) with polarized radiation is employed to characterize TiO2 thin films thermally grown on Ti substrates, which exhibit the so-called Berreman effect. The DRIFT analysis of thin films in the context of the Berreman effect is simple and fast, and allows the identification of the crystalline/amorphous structure of TiO2 thin layers even in the presence of other coatings, such as hydroxyapatite deposits, on top of the titanium oxide films.