Pablo Tancredi

Bio: Pablo Tancredi is an academic researcher from National Institute of Industrial Technology. The author has contributed to research in topics: Nanoparticle & Superparamagnetism. The author has an hindex of 8, co-authored 17 publications receiving 142 citations. Previous affiliations of Pablo Tancredi include University of Buenos Aires & National Scientific and Technical Research Council.

Synthesis process, size and composition effects of spherical Fe3O4 and FeO@Fe3O4 core/shell nanoparticles

Abstract: In this work, we investigate the size, composition and magnetic behavior of a series of iron oxide nanoparticles prepared by means of high temperature decomposition of an iron oleate precursor. Different synthesis conditions, such as gas atmosphere, precursor ratio and heating rate were tested to obtain a direct correlation between the final sample structure and the varied parameter. The synthesis products were characterized by X-ray diffraction, transmission electron microscopy and small-angle X-ray scattering, respectively. We studied six samples with rather narrow size distribution and mean diameters from 8 nm to 16 nm. The particles with diameter below 11 nm were found to be spinel-type, monocrystalline, and their magnetic response can be ascribed to a single domain framework. On the other hand, two-phase core–shell FeO@Fe3O4 of mean sizes of 15 nm and 16 nm were obtained by increasing the amount of oleic acid and the heating rate. The magnetic behavior of these samples exhibits interesting interface features, related to the exchange coupling phenomenon between the FeO and Fe3O4. We discuss how the different synthesis conditions may lead to the presence of this FeO phase, and how the core–shell configuration and other structural features affect the macroscopic magnetic behavior.

Physicochemical Studies of Complex Silver–Magnetite Nanoheterodimers with Controlled Morphology

Abstract: This work discusses the influence of synthesis conditions on self-assembly capability and morphology of obtained Ag–Fe3O4 nanoheterostructures. Samples were synthesized in two steps: first silver nanoparticles were synthesized and then used as seeds for the growth of iron oxide nanoparticles in a second step. The silver nanoparticle size was tuned, changing the oleylamine (OAm) and oleic acid (OA) ratio, which enables us to study the influence of chemical agents and seed size on the final magnetic nanoparticle morphology. The mechanism during the formation of these heterostructures has been discussed by several authors; however, it remains an open issue. In this paper we extend the discussion and advance on the understanding of synthesis conditions, related to silver sizes, chemical agents, and physical properties on the obtained nanoparticles. In our Ag–Fe3O4 system, two types of heterostructures were obtained: dimer, flower, or combination of the two. We have found that the final shape depends on silver...

Mn3O4-Graphene Hybrid as a High Capacity Anode Material for Lithium Ion Batteries

Abstract: We developed two-step solution-phase reactions to form hybrid materials of Mn3O4 nanoparticles on reduced graphene oxide (RGO) sheets for lithium ion battery applications. Mn3O4 nanoparticles grown selectively on RGO sheets over free particle growth in solution allowed for the electrically insulating Mn3O4 nanoparticles wired up to a current collector through the underlying conducting graphene network. The Mn3O4 nanoparticles formed on RGO show a high specific capacity up to ~900mAh/g near its theoretical capacity with good rate capability and cycling stability, owing to the intimate interactions between the graphene substrates and the Mn3O4 nanoparticles grown atop. The Mn3O4/RGO hybrid could be a promising candidate material for high-capacity, low-cost, and environmentally friendly anode for lithium ion batteries. Our growth-on-graphene approach should offer a new technique for design and synthesis of battery electrodes based on highly insulating materials.

Surface Functionalization of Iron Oxide Nanoparticles with Gallic Acid as Potential Antioxidant and Antimicrobial Agents.

Abstract: In this research, we report the size-controlled synthesis and surface-functionalization of magnetite with the natural antioxidant gallic acid (GA) as a ligand, using in situ and post-synthesis methods. GA functionalization provided narrow size distribution, with an average particle size of 5 and 8 nm for in situ synthesis of gallic acid functionalized magnetite IONP@GA1 and IONP@GA2, respectively, which are ultra-small particles as compared to unfunctionalized magnetite (IONP) and post functionalized magnetite IONP@GA3 with average size of 10 and 11 nm respectively. All the IONPs@GA samples were found hydrophilic with stable aggregation state. Prior to commencement of experimental lab work, PASS software was used to predict the biological activities of GA and it is found that experimental antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and antimicrobial studies using well diffusion method are in good agreement with the simulated results. Furthermore, the half maximal inhibitory concentration (IC50) values of DPPH antioxidant assay revealed a 2-4 fold decrease as compared to unfunctionalized IONP. In addition to antioxidant activity, all the three IONP@GA proved outstanding antimicrobial activity while testing on different bacterial and fungal strains. The results collectively indicate the successful fabrication of novel antioxidant, antimicrobial IONP@GA composite, which are magnetically separable, efficient, and low cost, with potential applications in polymers, cosmetics, and biomedical and food industries.

Compact Ag@Fe3O4 core-shell nanoparticles by means of single-step thermal decomposition reaction.

Abstract: A temperature pause introduced in a simple single-step thermal decomposition of iron, with the presence of silver seeds formed in the same reaction mixture, gives rise to novel compact heterostructures: brick-like Ag@Fe3O4 core-shell nanoparticles. This novel method is relatively easy to implement, and could contribute to overcome the challenge of obtaining a multifunctional heteroparticle in which a noble metal is surrounded by magnetite. Structural analyses of the samples show 4 nm silver nanoparticles wrapped within compact cubic external structures of Fe oxide, with curious rectangular shape. The magnetic properties indicate a near superparamagnetic like behavior with a weak hysteresis at room temperature. The value of the anisotropy involved makes these particles candidates to potential applications in nanomedicine.