Publications by authors named "Jimena S Tuninetti"

7 Publications

  • Page 1 of 1

[email protected] Composite Films for Impedimetric Pesticide Sensors.

Glob Chall 2020 Feb 8;4(2):1900076. Epub 2020 Jan 8.

Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas Departamento de Química Facultad de Ciencias Exactas Universidad Nacional de La Plata CONICET, CC 16 Suc. 4 La Plata B1904DPI Argentina.

Due to its deleterious effects on health, development of new methods for detection and removal of pesticide residues in primary and derived agricultural products is a research topic of great importance. Among them, imazalil (IMZ) is a widely used post-harvest fungicide with good performances in general, and is particularly applied to prevent green mold in citrus fruits. In this work, a composite film for the impedimetric sensing of IMZ built from metal-organic framework nanocrystallites homogeneously distributed on a conductive poly(3,4-ethylene dioxythiophene) (PEDOT) layer is presented. The as-synthetized thin films are produced via spin-coating over poly(ethylene terephtalate (PET) substrate following a straightforward, cost-effective, single-step procedure. By means of impedance spectroscopy, electric transport properties of the films are studied, and high sensitivity towards IMZ concentration in the range of 15 ppb to 1 ppm is demonstrated (featuring 1.6 and 4.2 ppb limit of detection, when using signal modulus and phase, respectively). The sensing platform hereby presented could be used for the construction of portable, miniaturized, and ultrasensitive devices, suitable for pesticide detection in food, wastewater effluents, or the assessment of drinking-water quality.
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http://dx.doi.org/10.1002/gch2.201900076DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7001120PMC
February 2020

Surfactants as mesogenic agents in layer-by-layer assembled polyelectrolyte/surfactant multilayers: nanoarchitectured "soft" thin films displaying a tailored mesostructure.

Phys Chem Chem Phys 2018 Apr;20(14):9298-9308

Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA) - Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata - CONICET, Suc. 4, CC 16, La Plata, Argentina.

Interfacial supramolecular architectures displaying mesoscale organized components are of fundamental importance for developing materials with novel or optimized properties. Nevertheless, engineering the multilayer assembly of different building blocks onto a surface and exerting control over the internal mesostructure of the resulting film is still a challenging task in materials science. In the present work we demonstrate that the integration of surfactants (as mesogenic agents) into layer-by-layer (LbL) assembled polyelectrolyte multilayers offers a straightforward approach to control the internal film organization at the mesoscale level. The mesostructure of films constituted of hexadecyltrimethylammonium bromide, CTAB, and polyacrylic acid, PAA (of different molecular weights), was characterized as a function of the number of assembled layers. Structural characterization of the multilayered films by grazing-incidence small-angle X-ray scattering (GISAXS), showed the formation of mesostructured composite polyelectrolyte assemblies. Interestingly, the (PAA/CTA)n assemblies prepared with low PAA molecular weight presented different mesostructural regimes which were dependent on the number of assembled layers: a lamellar mesophase for the first bilayers, and a hexagonal circular mesophase for n ≥ 7. This interesting observation was explained in terms of the strong interaction between the substrate and the first layers leading to a particular mesophase. As the film increases its thickness, the prevalence of this strong interaction decreases and the supramolecular architecture exhibits a "bulk" mesophase. Finally, we demonstrated that the molecular weight of the polyelectrolyte has a considerable impact on the meso-organization for the (PAA/CTA)n assemblies. We consider that these studies open a path to new rational methodologies to construct "nanoarchitectured" polyelectrolyte multilayers.
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http://dx.doi.org/10.1039/C7CP08203GDOI Listing
April 2018

Polyelectrolyte Capping As Straightforward Approach toward Manipulation of Diffusive Transport in MOF Films.

Langmuir 2018 01 26;34(1):425-431. Epub 2017 Dec 26.

Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CONICET , Calle 64 y Diag. 113, 1900 La Plata, Argentina.

We present experimental results demonstrating the suitability of polyelectrolyte capping as a simple and straightforward procedure to modify hydrophilic/hydrophobic character of porous films, thus allowing additional control on transport properties. In particular, we synthesized ZIF-8 metal organic framework (MOF) films, an archetypal hydrophobic zeolitic imidazolate framework, constituted by Zn ions tetrahedrally coordinated with bidentate 2-methylimidazolate organic linker, and poly(4-styrenesulfonic acid) as capping agent (PSS). MOF films were synthesized via sequential one pot (SOP) steps over conductive substrates conveniently modified with primer agents known to enhance heterogeneous nucleation, followed by dip-coating with PSS aqueous solutions. Crystallinity, morphology, and chemical composition of ZIF-8 films were confirmed with traditional methods. Continuous electron density depth profile obtained with synchrotron light X-ray reflectivity (XRR) technique, suggest that PSS capped-films do not adopt segregated configurations in which PSS remains surface-confined. This affects functional properties conferred by PSS capping, which were assessed using cyclic voltammetry with both positively and negatively charged redox probe molecules. Furthermore, taking advantage of the control attained, we successfully carried in situ synthesis of film-hosted d-block metal nanoparticles (Au and [email protected]+PSS) via direct aqueous chemical reduction of precursors (diffusion-reaction approach).
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http://dx.doi.org/10.1021/acs.langmuir.7b03083DOI Listing
January 2018

Thermally-induced softening of PNIPAm-based nanopillar arrays.

Soft Matter 2017 Mar;13(13):2453-2464

Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA) - Departamento de Química - Facultad de Ciencias Exactas - Universidad Nacional de La Plata - CONICET, 1900 La Plata, Argentina.

The surface properties of soft nanostructured hydrogels are crucial in the design of responsive materials that can be used as platforms to create adaptive devices. The lower critical solution temperature (LCST) of thermo-responsive hydrogels such as poly(N-isopropylacrylamide) (PNIPAm) can be modified by introducing a hydrophilic monomer to create a wide range of thermo-responsive micro-/nano-structures in a large temperature range. Using surface initiation atom-transfer radical polymerization in synthesized anodized aluminum oxide templates, we designed, fabricated, and characterized thermo-responsive nanopillars based on PNIPAm hydrogels with tunable mechanical properties by incorporating acrylamide monomers (AAm). In addition to their LCST, the incorporation of a hydrophilic entity in the nanopillars based on PNIPAm has abruptly changed the topological and mechanical properties of our system. To gain an insight into the mechanical properties of the nanostructure, its hydrophilic/hydrophobic behavior and topological characteristics, atomic force microscopy, molecular dynamics simulations and water contact angle studies were combined. When changing the nanopillar composition, a significant and opposite variation was observed in their mechanical properties. As temperature increased above the LCST, the stiffness of PNIPAm nanopillars, as expected, did so too, in contrast to the stiffness of PNIPAm-AAm nanopillars that decreased significantly. The molecular dynamics simulations proposed a local molecular rearrangement in our nanosystems at the LCST. The local aggregation of NIPAm segments near the center of the nanopillars displaced the hydrophilic AAm units towards the surface of the structure leading to contact with the aqueous environment. This behavior was confirmed via contact angle measurements below and above the LCST.
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http://dx.doi.org/10.1039/c7sm00206hDOI Listing
March 2017

Noncovalent functionalization of solid-state nanopores via self-assembly of amphipols.

Nanoscale 2016 Jan;8(3):1470-8

Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CONICET, CC 16 Suc. 4 (1900) La Plata, Argentina. and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.

In recent years there has been increasing interest in the development of new methods for conferring functional features to nanopore-based fluidic devices. In this work, we describe for the first time the noncovalent integration of amphoteric-amphipathic polymers, also known as "amphipols", into single conical nanopores in order to obtain signal-responsive chemical nanodevices. Highly-tapered conical nanopores were fabricated by single-sided chemical etching of polycarbonate foils. After etching, the surface of the conical nanopores was chemically modified, by first metallizing the surface via gold sputtering and then by amphiphilic self-assembly of the amphipol. The net charge of adsorbed amphipols was regulated via pH changes under the environmental conditions. The pH-dependent chemical equilibrium of the weak acidic and basic monomers facilitates the regulation of the ionic transport through the nanopore by adjusting the pH of the electrolyte solution. Our results demonstrate that functional amphipathic polymers are powerful building blocks for the surface modification of nanopores and might ultimately pave the way to a new means of integrating functional and/or responsive units within nanofluidic structures.
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http://dx.doi.org/10.1039/c5nr08190dDOI Listing
January 2016

pH-responsive ion transport in polyelectrolyte multilayers of poly(diallyldimethylammonium chloride) (PDADMAC) and poly(4-styrenesulfonic acid-co-maleic acid) (PSS-MA) bearing strong- and weak anionic groups.

Phys Chem Chem Phys 2015 Nov 22;17(44):29935-48. Epub 2015 Oct 22.

Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La Plata (UNLP), CONICET, (1900) La Plata, Argentina.

The layer-by-layer construction of interfacial architectures displaying stimuli-responsive control of mass transport is attracting increasing interest in materials science. In this work, we describe the creation of interfacial architectures displaying pH-dependent ionic transport properties which until now have not been observed in polyelectrolyte multilayers. We describe a novel approach to create pH-controlled ion-rectifying systems employing polyelectrolyte multilayers assembled from a copolymer containing both weakly and strongly charged pendant groups, poly(4-styrenesulfonic acid-co-maleic acid) (PSS-MA), alternately deposited with poly(diallyldimethylammonium chloride) (PDADMAC). The conceptual framework is based on the very contrasting and differential interactions of PSS and MA units with PDADMAC. In our setting, sulfonate groups play a structural role by conferring stability to the multilayer due to the strong electrostatic interactions with the polycations, while the weakly interacting MA groups remain "silent" within the film and then act as on-demand pH-responsive units. When these multilayers are combined with a strong cationic capping layer that repels the passage of cationic probes, a pH-gateable rectified transport of anions is observed. Concomitantly, we also observed that these functional properties are significantly affected when multilayers are subjected to extensive pH cycling as a consequence of irreversible morphological changes taking place in the film. We envision that the synergy derived from combining weak and strong interactions within the same multilayer will play a key role in the construction of new interfacial architectures displaying tailorable ion transport properties.
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http://dx.doi.org/10.1039/c5cp03965gDOI Listing
November 2015

Polydopamine meets solid-state nanopores: a bioinspired integrative surface chemistry approach to tailor the functional properties of nanofluidic diodes.

J Am Chem Soc 2015 May 30;137(18):6011-7. Epub 2015 Apr 30.

†Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La Plata - CONICET, CC 16 Suc. 4, (1900) La Plata, Argentina.

The ability to modulate the surface chemical characteristics of solid-state nanopores is of great interest as it provides the means to control the macroscopic response of nanofluidic devices. For instance, controlling surface charge and polarity of the pore walls is one of the most important applications of surface modification that is very relevant to attain accurate control over the transport of ions through the nanofluidic architecture. In this work, we describe a new integrative chemical approach to fabricate nanofluidic diodes based on the self-polymerization of dopamine (PDOPA) on asymmetric track-etched nanopores. Our results demonstrate that PDOPA coating is not only a simple and effective method to modify the inner surface of polymer nanopores fully compatible with the fabrication of nanofluidic devices but also a versatile platform for further integration of more complex molecules through different covalent chemistries and self-assembly processes. We adjusted the chemical modification strategy to obtain various configurations of the pore surface: (i) PDOPA layer was used as primer, precursor, or even responsive functional coating; (ii) PDOPA layer was used as a platform for anchoring chemical functions via the Michael addition reaction; and (iii) PDOPA was used as a reactive layer inducing the metallization of the pore walls through the in situ reduction of metallic precursors present in solution. We believe that the transversal concept of integrative surface chemistry offered by polydopamine in combination with the remarkable physical characteristics of asymmetric nanopores constitutes a new framework to design multifunctional nanofluidic devices employing soft chemistry-based nanofunctionalization techniques.
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http://dx.doi.org/10.1021/jacs.5b01638DOI Listing
May 2015
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