Publications by authors named "Omar Azzaroni"

123 Publications

Borate-driven ionic rectifiers based on sugar-bearing single nanochannels.

Nanoscale 2021 Jul 21;13(25):11232-11241. Epub 2021 Jun 21.

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.

Recently, much scientific effort has been centered on the control of the ionic transport properties of solid state nanochannels and the rational design and integration of chemical systems to induce changes in the ionic transport by means of interactions with selected target molecules. Here, we report the fabrication of a novel nanofluidic device based on solid-state nanochannels, which combines silane chemistry with both track-etched and atomic layer deposition (ALD) technologies. Nanodevice construction involves the coating of bullet-shaped single-pore nanochannels with silica (SiO) by ALD and subsequent surface modification by reaction between silanol groups exposed on pore walls and N-(3-triethoxysilylpropyl)-gluconamide, in order to create a gluconamide-decorated nanochannel surface. The formation of a boroester derivative resulting from the selective reaction of borate with the appended saccharides leads to important changes in the surface charge density and, concomitantly, in the iontronic properties of the nanochannel. Furthermore, we propose a binding model to rationalize the specific interaction saccharide-borate in the surface. Besides, this unique nanodevice exhibits a highly selective and reversible response towards borate/fructose exposure. On the basis of the surface charge variation resulting from borate binding, the nanochannel can reversibly switch between "ON" and "OFF" states in the presence of borate and fructose, respectively. In addition, this work describes the first report of the functionalization of PET/SiO nanochannels by the ALD technique. We believe that this work provides a promising framework for the development of new nanochannel-based platforms suitable for multiple applications, such as water quality monitoring or directed molecular transport and separation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/d0nr07733jDOI Listing
July 2021

Enzymes hosted in redox-active ionically cross-linked polyelectrolyte networks enable more efficient biofuel cells.

Soft Matter 2021 May;17(20):5240-5247

INQUIMAE (CONICET), Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA Buenos Aires, Argentina.

Redox mediators are pivotal players in the electron transfer process between enzymes and electrodes. We present an alternative approach for redox mediation based on branched polyethyleneimine (BPEI) modified with an osmium complex. This redox polyelectrolyte is crosslinked with phosphate to produce colloidal particles with a diameter of ca. 1 μm, which, combined with glucose oxidase (GOx), can form electroactive assemblies through either layer by layer assembly (LbL) or one-pot drop-casting (OPDC). The addition of NaCl to these colloidal systems induces the formation of films that otherwise poorly grow, presenting an outstanding catalytic current. The system was tested as a bioanode delivering a power output of 148 μW per nmol of mediator. These results are explained in terms of the interactions of the ions with the polyelectrolyte and represent a new route for the development of bioelectrochemical devices involving redox mediators and enzymes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/d1sm00221jDOI Listing
May 2021

High-sensitivity detection of dopamine by biomimetic nanofluidic diodes derivatized with poly(3-aminobenzylamine).

Nanoscale 2020 Sep;12(35):18390-18399

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.

During the last few years, much scientific effort has been devoted to the control of ionic transport properties of solid state nanochannels and the rational integration of chemical systems to induce changes in the ionic transport by interaction with selected target molecules for (bio)sensing purposes. In this work, we present the construction and functional evaluation of a highly sensitive dopamine-responsive iontronic device by functionalization of bullet-shaped track-etched single nanochannels in PET membranes with poly(3-aminobenzylamine) (PABA). The variety of basic groups in this amino-appended polyaniline derivative allows programming of the ion selectivity of the channel by setting the pH conditions. On the other hand, the amino-pendant groups of PABA become suitable binding sites for the selective chemical reaction with dopamine, leading to a change in the nanochannel surface charge. Thus, the exposure of the PABA-modified nanochannel to dopamine solutions selectively produces changes in the iontronic response. By rationally selecting the conditions for both the dopamine binding step and the iontronic reading, we obtained a correlation between the rectification efficiency and dopamine concentration down to the nanomolar range, which was also successfully interpreted in terms of a simple binding model.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/d0nr03634jDOI Listing
September 2020

Mass and charge transport in highly mesostructured polyelectrolyte/electroactive-surfactant multilayer films.

J Colloid Interface Sci 2021 Jan 24;581(Pt B):595-607. Epub 2020 Jul 24.

INQUIMAE, Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires - CONICET, Ciudad Universitaria, Pabellón 2 C1428EHA, Buenos Aires, Argentina. Electronic address:

Hypothesis: Dimensionally stable electroactive films displaying spatially addressed redox sites is still a challenging goal due to gel-like structure. Polyelectrolyte and surfactants can yield highly mesostructured films using simple buildup strategies as layer-by-layer. The use of redox modified surfactants is expected to introduce order and an electroactive response in thin films.

Experiments: The assembly of polyacrylic acid and different combinations of redox-modified and unmodified hexadecyltrimethylammonium bromide yields highly structured and electroactive thin films. The growth, viscoelastic properties, mass, and electron transport of these films were studied by combining electrochemical and quartz crystal balance with dissipation experiments.

Findings: Our results show that the films are highly rigid and poorly hydrated. The mass and charge transport reveal that the ingress (egress) of the counter ions during the electrochemical oxidation (reduction) is accompanied with a small amount of water, which is close to their hydration sphere. Thus, the generated mesostructured films present an efficient charge transport with negligible changes in their structures during the electron transfer process. The control over the meso-organization and its stability represents a promising tool in the construction of devices where the vectorial transfer of electrons, or ions, is required.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jcis.2020.07.060DOI Listing
January 2021

Growth of ZIF-8 MOF Films with Tunable Porosity by using Poly (1-vinylimidazole) Brushes as 3D Primers.

Chemistry 2020 Sep 2;26(54):12388-12396. Epub 2020 Sep 2.

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.

This work reports on a novel and versatile approach to control the structure of metal-organic framework (MOFs) films by using polymeric brushes as 3D primers, suitable for triggering heterogeneous MOF nucleation. As a proof-of-concept, this work explores the use of poly(1-vinylimidazole) brushes primer obtained via surface-initiated atom transfer radical polymerization (SI-ATRP) for the synthesis of Zn-based ZIF-8 MOF films. By modifying the grafting density of the brushes, smooth porous films were obtained featuring inherently hydrophobic microporosity arising from ZIF-8 structure, and an additional constructional interparticle mesoporosity, which can be employed for differential adsorption of targeted adsorbates. It was found that the grafting density modulates the constructional porosity of the films obtained; higher grafting densities result in more compact structures, while lower grafting density generates increasingly inhomogeneous films with a higher proportion of interparticle constructional porosity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/chem.202002493DOI Listing
September 2020

Polyaniline for Improved Blue Energy Harvesting: Highly Rectifying Nanofluidic Diodes Operating in Hypersaline Conditions via One-Step Functionalization.

ACS Appl Mater Interfaces 2020 Jun 15;12(25):28148-28157. Epub 2020 Jun 15.

Instituto de Investigaciones Fisicoquı́micas Teóricas y Aplicadas (INIFTA), Departamento de Quı́mica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (UNLP), CONICET, 64 and 113, 1900 La Plata, Argentina.

Solid-state nanochannels have attracted substantial attention of the scientific community due to their remarkable control of ionic transport and the feasibility to regulate the iontronic output by different stimuli. Most of the developed nanodevices are subjected to complex modification methods or show functional responsiveness only in moderate-ionic-strength solutions. Within this project, we present a nanofluidic device with enhanced ionic current rectification properties attained by a simple one-step functionalization of single bullet-shaped polyethylene terephthalate (PET) nanochannels with polyaniline (PANI) that can work in high-ionic-strength solutions. The integration of PANI also introduces a broad pH sensitivity, which makes it possible to modulate the ionic transport behavior between anion-selective and cation-selective regimes depending on the pH range. Since PANI is an electrochemically active polymer, ionic transport also becomes dependent on the presence of redox stimuli in solution. We demonstrate that PANI-functionalized single-nanochannel membranes function as an efficient salinity gradient-based energy conversion device even in acidic concentrated salt solutions, opening the door to applications under a variety of novel operating conditions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsami.0c05102DOI Listing
June 2020

Mesostructured Electroactive Thin Films Through Layer-by-Layer Assembly of Redox Surfactants and Polyelectrolytes.

Chempluschem 2020 08 20;85(8):1616-1622. Epub 2020 May 20.

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

Electroactive thin films are an important element in the devices devoted to energy conversion, actuators, and molecular electronics, among others. Their build-up by the layer-by-layer technique is an attractive choice since a fine control over the thickness and composition can be achieved. However, most of the assemblies described in the literature show a lack of internal order, and their thicknesses change upon oxidation-state alterations. In this work, we describe the formation of layer-by-layer assemblies of redox surfactants and polyelectrolytes that leads to the construction of mesoscale organized electroactive films. In contrast to thin films prepared with traditional redox polymers, here, the redox surfactant does not only allow the control of the film meso-organization (from 2D hexagonal to circular hexagonal phases) but it also allows the control of the number and position of the redox centers. Finally, these films show high stability and a negligible structural deformation under redox-state changes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/cplu.202000358DOI Listing
August 2020

Dual Monitoring of Surface Reactions in Real Time by Combined Surface-Plasmon Resonance and Field-Effect Transistor Interrogation.

J Am Chem Soc 2020 07 14;142(27):11709-11716. Epub 2020 May 14.

Biosensor Technologies, Austrian Institute of Technology, Konrad-Lorenz-Strasse 24, 3430 Tulln, Austria.

By combining surface plasmon resonance (SPR) and electrolyte gated field-effect transistor (EG-FET) methods in a single analytical device we introduce a novel tool for surface investigations, enabling simultaneous measurements of the surface mass and charge density changes in real time. This is realized using a gold sensor surface that simultaneously serves as a gate electrode of the EG-FET and as the SPR active interface. This novel platform has the potential to provide new insights into (bio)adsorption processes on planar solid surfaces by directly relating complementary measurement principles based on (i) detuning of SPR as a result of the modification of the interfacial refractive index profile by surface adsorption processes and (ii) change of output current as a result of the emanating effective gate voltage modulations. Furthermore, combination of the two complementary sensing concepts allows for the comparison and respective validation of both analytical techniques. A theoretical model is derived describing the mass uptake and evolution of surface charge density during polyelectrolyte multilayer formation. We demonstrate the potential of this combined platform through the observation of layer-by-layer assembly of PDADMAC and PSS. These simultaneous label-free and real-time measurements allow new insights into complex processes at the solid-liquid interface (like non-Fickian ion diffusion), which are beyond the scope of each individual tool.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/jacs.9b11835DOI Listing
July 2020

PEDOT-polyamine composite films for bioelectrochemical platforms - flexible and easy to derivatize.

Mater Sci Eng C Mater Biol Appl 2020 Apr 31;109:110575. Epub 2019 Dec 31.

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; Austrian Institute of Technology - Donau-City-Strasse 1, 1220 Vienna, Austria; CEST-UNLP Partner Lab for Bioelectronics, Diagonal 64 y 113, La Plata 1900, Argentina. Electronic address:

We report a straightforward route for the preparation of flexible, electrochemically stable and easily functionalizable poly(3,4-ethylenedioxythiophene) (PEDOT) composite films deposited on PET foils as biosensing platforms. For this purpose, poly(allylamine) hydrochloride (PAH) was blended with PEDOT to provide amine-bearing sites for further biofunctionalization as well as to improve the mechanical properties of the films. The conducting PEDOT-PAH composite films were characterized by cyclic voltammetry, UV-vis and Raman spectroscopies. An exhaustive stability study was carried out from the mechanical, morphological and electrochemical viewpoint. Subsequent sugar functionalization of the available amine groups from PAH allowed for the specific recognition of lectins and the subsequent self-assembly of glycoenzymes (glucose oxidase and horseradish peroxidase) concomitant with the prevention of non-specific protein fouling. The platforms presented good bioelectrochemical performance (glucose oxidation and hydrogen peroxide reduction) in the presence of redox mediators. The developed composite films constitute a promising option for the construction of all-polymer biosensing platforms with great potential owing to their flexibility, high transmittance, electrochemical stability and the possibility of glycosylation, which provides a simple route for specific biofunctionalization as well as an effective antifouling strategy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.msec.2019.110575DOI Listing
April 2020

Redox-active polyamine-salt aggregates as multistimuli-responsive soft nanoparticles.

Phys Chem Chem Phys 2020 Apr;22(14):7440-7450

Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata - CONICET, Sucursal 4, Casilla de Correo 16, 1900 La Plata, Argentina.

Polyamine-salt aggregates have become promising soft materials in nanotechnology due to their easy preparation process and pH-responsiveness. Here, we report the use of hexacyanoferrate(ii) and hexacyanoferrate(iii) as electroactive crosslinking agents for the formation of nanometer-sized redox-active polyamine-redox-salt aggregates (rPSA) in bulk suspension. This nanoplatform can be selectively assembled or disassembled under different stimuli such as redox environment, pH and ionic strength. By changing the charge of the building blocks, external triggers allow switching the system between two phase states: aggregate-free solution or colloidal rPSA dispersion. The stimuli-activated modulation of the assembly/disassembly processes opens a path to exploit rPSA in technologies based on smart nanomaterials.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/d0cp00077aDOI Listing
April 2020

Self-assembled peptide dendrigraft supraparticles with potential application in pH/enzyme-triggered multistage drug release.

Colloids Surf B Biointerfaces 2020 Jun 22;190:110895. Epub 2020 Feb 22.

Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), (UNLP, CONICET), Sucursal 4, Casilla de Correo 16, 1900 La Plata, Argentina. Electronic address:

Multistage delivery systems with size reduction capacity have been proposed as a powerful strategy for improving tissue drug penetration. Here we developed a simple and fast supramolecular approach to construct size-shrinkable polyamine-salt aggregates by ionic cross-linking of biodegradable poly-L-lysine dendrigraft with tripolyphosphate anion. The use of a peptide dendrimer as a nanobuilding block (∼7 nm in diameter) allows the formation of supraparticles (SPs) with well-defined dimensions (∼200 nm in diameter), narrow size distribution and great capacity to encapsulate different molecules, including chemotherapeutic agents as Curcumin and Doxorubicin. When exposed to slightly acidic environments, the crosslinked matrix is instantaneously disassembled to free dendrimer units. Subsequently, model cargo molecules entrapped in the dendrimer architecture can be released by the action of trypsin enzyme through peptide biodegradation. Therefore, these SPs with proved sequential pH and enzyme-responsiveness could be exploited as nanocarriers in multistage drug delivery systems.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.colsurfb.2020.110895DOI Listing
June 2020

Electrochemically addressable nanofluidic devices based on PET nanochannels modified with electropolymerized poly-o-aminophenol films.

Nanoscale 2020 Mar 2;12(10):6002-6011. Epub 2020 Mar 2.

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.

Nanofluidic field-effect transistors (nFETs) have attracted attention from the scientific community due to their remarkable level of control over ionic transport. Particularly, the combination of nanofluidic systems and electroactive polymers has demonstrated to be an interesting approach to achieve an electrochemically addressable device. In this work, the development of nFETs based on the integration of electropolymerized poly-o-aminophenol (POAP) films into track-etched nanochannels is proposed. The electropolymerization of POAP on the tip side of Au-sputtered asymmetric PET nanochannels not only allowed having a programmable tip diameter but also offered a precise and very rapid control of ionic transport by switching an external bias voltage. Moreover, the system exhibited a reversible behaviour between non-selective and anion-selective states. We believe that this work provides new tools and concepts to design and build high-performance nanofluidic field-effect transistors working under electrochemically controlled conditions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c9nr10336hDOI Listing
March 2020

Nanoporous thin films in optical waveguide spectroscopy for chemical analytics.

Anal Bioanal Chem 2020 May 27;412(14):3299-3315. Epub 2020 Feb 27.

Department of Chemistry and Chemical Engineering, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, 54762, Pakistan.

Spectroscopy with planar optical waveguides is still an active field of research for the quantitative analysis of various supramolecular surface architectures and processes, and for applications in integrated optical chip communication, direct chemical sensing, etc. In this contribution, we summarize some recent development in optical waveguide spectroscopy using nanoporous thin films as the planar substrates that can guide the light just as well as bulk thin films. This is because the nanoporosity is at a spacial length-scale that is far below the wavelength of the guided light; hence, it does not lead to an enhanced scattering or additional losses of the optical guided modes. The pores have mainly two effects: they generate an enormous inner surface (up to a factor of 100 higher than the mere geometric dimensions of the planar substrate) and they allow for the exchange of material and charges between the two sides of the solid thin film. We demonstrate this for several different scenarios including anodized aluminum oxide layers for the ultrasensitive determination of the refractive index of fluids, or the label-free detection of small analytes binding from the pore inner volume to receptors immobilized on the pore surface. Using a thin film of Ti metal for the anodization results in a nanotube array offering an even further enhanced inner surface and the possibility to apply electrical potentials via the resulting TiO semiconducting waveguide structure. Nanoporous substrates fabricated from SiN thin films by colloid lithography, or made from SiO by e-beam lithography, will be presented as examples where the porosity is used to allow for the passage of ions in the case of tethered lipid bilayer membranes fused on top of the light-guiding layer, or the transport of protons through membranes used in fuel cell applications. The final example that we present concerns the replication of the nanopore structure by polymers in a process that leads to a nanorod array that is equally well suited to guide the light as the mold; however, it opens a totally new field for integrated optics formats for direct chemical and biomedical sensing with an extension to even molecularly imprinted structures. Graphical abstract.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00216-020-02452-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7214501PMC
May 2020

Following in Situ the Degradation of Mesoporous Silica in Biorelevant Conditions: At Last, a Good Comprehension of the Structure Influence.

ACS Appl Mater Interfaces 2020 Mar 10;12(12):13598-13612. Epub 2020 Mar 10.

Laboratoire Chimie de la Matière Condensée de Paris, UMR 7574, Sorbonne Université, 4 Place Jussieu 75252 Paris, France.

Mesoporous silica nanoparticles (MSNs) have seen a fast development as drug delivery carriers thanks to their tunable porosity and high loading capacity. The employ of MSNs in biomedical applications requires a good understanding of their degradation behavior both to control drug release and to assess possible toxicity issues on human health. In this work, we study mesoporous silica degradation in biologically relevant conditions through in situ ellipsometry on model mesoporous nanoparticle or continuous thin films, in buffer solution and in media containing proteins. In order to shed light on the structure/dissolution relationship, we performed dissolution experiments far from soluble silicate species saturation. Via a complete decorrelation of dissolution and diffusion contributions, we proved unambiguously that surface area of silica vectors is the main parameter influencing dissolution kinetics, while thermal treatment and open mesoporous network architecture have a minor impact. As a logical consequence of our dissolution model, we proved that the dissolution lag-time can be promoted by selective blocking of the mesopores that limits the access to the mesoporous internal surface. This study was broadened by studying the impact of the organosilanes in the silica structure, of the presence of residual structuring agents, and of the chemical composition of the dissolution medium. The presence of albumin at blood concentration was found affecting drastically the dissolution kinetics of the mesoporous structure, acting as a diffusion barrier. Globally, we could identify the main factors affecting mesoporous silica materials degradation and proved that we can tune their structure and composition for adjusting dissolution kinetics in order to achieve efficient drug delivery.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsami.9b19956DOI Listing
March 2020

[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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/gch2.201900076DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7001120PMC
February 2020

Light-Induced Polymer Response through Thermoplasmonics Transduction in Highly Monodisperse Core-Shell-Brush Nanosystems.

Langmuir 2020 Mar 20;36(8):1965-1974. Epub 2020 Feb 20.

Instituto de Nanosistemas, Universidad Nacional de San Martı́n-CONICET, Av. 25 de Mayo 1021, San Martín, Buenos Aires 1650, Argentina.

Smart nanosystems that transduce external stimuli to physical changes are an inspiring challenge in current materials chemistry. Hybrid organic-inorganic materials attract great attention due to the combination of building blocks responsive to specific external solicitations. In this work, we present a sequential method for obtaining an integrated core-shell-brush nanosystem that transduces light irradiation into a particle size change through a thermoplasmonic effect. We first synthesize hybrid monodisperse systems made up of functionalized silica colloids covered with controllable thermoresponsive poly(-isopropylacrylamide), PNIPAm, brushes, produced through radical photopolymerization. This methodology was successfully transferred to [email protected] nanoparticles, leading to a core-shell-brush architecture, in which the Au core acts as a nanosource of heat; the silica layer, in turn, adapts the metal and polymer interfacial chemistries and can also host a fluorescent dye for bioimaging. Upon green LED irradiation, a light-to-heat conversion process leads to the shrinkage of the external polymer layer, as proven by DLS. Our results demonstrate that modular hybrid nanosystems can be designed and produced with photothermo-physical transduction. These remote-controlled nanosystems present prospective applications in smart carriers, responsive bioscaffolds, or soft robotics.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.langmuir.9b03065DOI Listing
March 2020

A study of the complex interaction between poly allylamine hydrochloride and negatively charged poly(N-isopropylacrylamide-co-methacrylic acid) microgels.

Soft Matter 2020 Jan 16;16(4):881-890. Epub 2020 Jan 16.

Soft Matter Nanotechnology Group, CIC BiomaGUNE, Paseo Miramon 182, 20014, San Sebastian, Spain.

Negatively charged poly(N-isopropylacrylamide-co-methacrylic acid) (P(NIPAm-co-MAA)) microgels undergo size changes in response to changes in temperature and pH. Complexation of these microgels with positively charged polyelectrolytes can greatly affect their physical properties and their capacity for encapsulating active molecules. Here we study the interaction between (P(NIPAm-co-MAA)) microgels and a model positively charged polyelectrolyte, poly allylamine hydrochloride (PAH), with different molecular weights. Experiments were conducted at temperatures below and above the lower critical solution temperature (LCST) of the microgel (30-32 °C), at 20 and 40 °C, respectively, and for PAH at molecular weights of 15, 50, and 140 kDa. Below the LCST, dynamic light scattering and zeta potential measurements with molecular simulation show that for the 15 kDa PAH there is preferential accumulation of PAH inside the microgel, whereas for the higher molecular weight PAH, the polyelectrolyte deposits mainly on the microgel surface. Above the LCST, PAH is preferentially located on the surface of the microgels for all molecular weights studied as a result of charge segregation in the hydrogels. Confocal scanning laser microscopy and flow cytometry were used to quantify rhodamine labelled PAH associated with the microgel. Isothermal titration calorimetry studies give insight into the thermodynamics of the interaction of PAH with the hydrogels, and how this interaction is affected by the molecular weight of PAH. Finally, microgels with encapsulated doxorubicin were exposed to PAH, revealing that the drug is displaced from the microgel by the PAH chains.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c9sm02070eDOI Listing
January 2020

Insulin Delivery from Glucose-Responsive, Self-Assembled, Polyamine Nanoparticles: Smart "Sense-and-Treat" Nanocarriers Made Easy.

Chemistry 2020 Feb 3;26(11):2456-2463. Epub 2020 Feb 3.

Instituto de Investigaciones Fisicoquímicas Teóricas y, Aplicadas Facultad de Ciencias Exactas, Universidad Nacional de La, Plata-CONICET Sucursal, 4, Casilla de Correo 16, 1900, La Plata, Argentina.

Polyamine-salt aggregates (PSA) are biomimetic soft materials that have attracted great attention due to their straightforward fabrication methods, high drug-loading efficiencies, and attractive properties for pH-triggered release. Herein, a simple and fast multicomponent self-assembly process was used to construct cross-linked poly(allylamine hydrochloride)/phosphate PSAs (hydrodynamic diameter of 360 nm) containing glucose oxidase enzyme, as a glucose-responsive element, and human recombinant insulin, as a therapeutic agent for the treatment of diabetes mellitus (GI-PSA). The addition of increasing glucose concentrations promotes the release of insulin due to the disassembly of the GI-PSAs triggered by the catalytic in situ formation of gluconic acid. Under normoglycemia, the GI-PSA integrity remained intact for at least 24 h, whereas hyperglycemic conditions resulted in 100 % cargo release after 4 h of glucose addition. This entirely supramolecular strategy presents great potential for the construction of smart glucose-responsive delivery nanocarriers.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/chem.201905075DOI Listing
February 2020

Multitasking polyamine/ferrioxalate nano-sized assemblies: thermo-, photo-, and redox-responsive soft materials made easy.

Chem Commun (Camb) 2019 Dec;55(97):14653-14656

Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA) (UNLP, CONICET), Sucursal 4, Casilla de Correo 16, 1900 La Plata, Argentina.

Responsive nanomaterials have emerged as key components in materials sciences. Herein, we report the one-step preparation of multi-stimuli responsive polyamine-salt aggregates (PSA) by ionically crosslinking polyethylenimine with potassium ferrioxalate (FeOx). The unique properties of FeOx enables a novel class of soft nanomaterial that disassembles by exposure to light, reducing environments and temperature.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c9cc06942aDOI Listing
December 2019

Acetylcholine biosensor based on the electrochemical functionalization of graphene field-effect transistors.

Biosens Bioelectron 2020 Jan 22;148:111796. Epub 2019 Oct 22.

CEST - Competence Center for Electrochemical Surface Technologies, Konrad Lorenz Strasse 24, 3430, Tulln, Austria; Austrian Institute of Technology, Donau-City-Strasse 1, 1220, Vienna, Austria.

We present a new strategy of Acetylcholinesterease (AchE) immobilization on graphene field-effect transistors (gFETs) for building up Acetylcholine sensors. This method is based on the electrosynthesis of an amino moiety-bearing polymer layer on the graphene channel. The film of the copolymer poly(3-amino-benzylamine-co-aniline) (PABA) does not only provide the suitable electrostatic charge and non-denaturing environment for enzyme immobilization, but it also improves the pH sensitivity of the gFETs (from 40.8 to 56.3 μA/pH unit), probably due to its wider effective pKa distribution. The local pH changes caused by the enzyme-catalyzed hydrolysis produce a shift in the Dirac point of the gFETs to more negative values, which are evidenced as differences in the gFET conductivity and thereby constituted the signal transduction mechanism of the modified transistors. In this way, the constructed biosensors showed a LOD of 2.3 μM and were able to monitor Ach in the range from 5 to 1000 μM in a flow configuration. Moreover, they showed a sensitivity of -26.6 ± 0.7 μA/Ach decade and also exhibited a very low RSD of 2.6%, revealing good device-to-device reproducibility. The biosensors revealed an excellent selectivity to interferences known to be present in the extracellular milieu, and the response to Ach was recovered by 97.5% after the whole set of interferences injected. Finally, the biosensors showed a fast response time, with an average value of 130 s and a good long-term response.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bios.2019.111796DOI Listing
January 2020

The effect of ionic strength and phosphate ions on the construction of redox polyelectrolyte-enzyme self-assemblies.

Phys Chem Chem Phys 2019 Oct;21(41):22947-22954

INQUIMAE (CONICET), Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA Buenos Aires, Argentina.

Layer by layer assembly of polyelectrolytes with proteins is a convenient tool for the development of functional biomaterials. Most of the studies presented in the literature are based on the electrostatic interaction between components of opposite charges, limiting the assembly possibilities. However, this process can be tuned by modifying the environment where the main constituents are dissolved. In this work, the electron transfer behavior between an electroactive polyelectrolyte (polyallylamine derivatized with an osmium complex) and a redox enzyme (glucose oxidase) is studied by assembling them in the presence of phosphate ions at different ionic strengths. Our results show that the environment from which the assembly is constructed has a significant effect on the electrochemical response. Notably, the polyelectrolyte dissolved in the presence of phosphate at high ionic strength presents a globular structure which is preserved after adsorption with substantial effects on the buildup of the multilayer system, improving the electron transfer process through the film.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c9cp04037dDOI Listing
October 2019

Lectin-Recognizable MOF Glyconanoparticles: Supramolecular Glycosylation of ZIF-8 Nanocrystals by Sugar-Based Surfactants.

ACS Omega 2019 Jan 10;4(1):842-848. Epub 2019 Jan 10.

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

A strategy toward the integration of highly functional microporous materials, such as metal-organic frameworks (MOFs), in composites via biochemical recognition interactions is presented. Postsynthetic modification of zeolitic-imidazolate framework-8 MOF nanocrystals with a maltose-exposing biocompatible surfactant (the so-called "Glyco-MOFs") was performed to confer affinity toward lectin protein concanavalin A. The addition of small amounts of concanavalin A to the colloidal Glyco-MOF dispersion triggers the aggregation of these units into self-limited size supramolecular architectures directed by specific sugar-lectin binding interactions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsomega.8b03092DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6648402PMC
January 2019

Redox-Driven Reversible Gating of Solid-State Nanochannels.

ACS Appl Mater Interfaces 2019 Aug 6;11(33):30001-30009. Epub 2019 Aug 6.

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

The design of an electrochemically addressable nanofluidic diode is proposed, which allows tunable and nanofluidic operations via redox gating under electrochemical control. The fabrication process involves the modification of an asymmetric gold-coated solid-state nanopore with a thin layer of a redox polymer, poly(vinylferrocene) (PVFc). The composite nanochannel acts as a gate electrode by changing the electrochemical state and, consequently, the conversion/switching of ferrocene into ferricenium units upon the application of different voltages. It is shown that the electrochemical input accurately controls the surface charge density of the nanochannel walls with a predictable concomitant effect on the rectification properties. PVFc-based nanofluidic devices are able to discriminate the passage of anionic species through the nanochannel in a qualitative and quantitative manner by simply switching the redox potential of the PVFc layer. Experimental data confirmed that a rapid and reversible modulation of the ionic transport regimes can be easily attained by changing the applied potential. This applied potential plays the role of the gate voltage () in field-effect transistors (FET), so these nanofluidic channels behave as ionic FETs. Depending on the values, the iontronic behavior can be switched between ohmic and diode-like regimes. We believe that this system illustrates the potential of redox-active polymers integrated into nanofluidic devices as plausible, simple, and versatile platforms to create electrochemically addressable nanofluidic devices for multiple applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsami.9b05961DOI Listing
August 2019

Molecular Design of Solid-State Nanopores: Fundamental Concepts and Applications.

Adv Mater 2019 Sep 3;31(37):e1901483. Epub 2019 Jul 3.

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

Solid-state nanopores are fascinating objects that enable the development of specific and efficient chemical and biological sensors, as well as the investigation of the physicochemical principles ruling the behavior of biological channels. The great variety of biological nanopores that nature provides regulates not only the most critical processes in the human body, including neuronal communication and sensory perception, but also the most important bioenergetic process on earth: photosynthesis. This makes them an exhaustless source of inspiration toward the development of more efficient, selective, and sophisticated nanopore-based nanofluidic devices. The key point responsible for the vibrant and exciting advance of solid nanopore research in the last decade has been the simultaneous combination of advanced fabrication nanotechnologies to tailor the size, geometry, and application of novel and creative approaches to confer the nanopore surface specific functionalities and responsiveness. Here, the state of the art is described in the following critical areas: i) theory, ii) nanofabrication techniques, iii) (bio)chemical functionalization, iv) construction of nanofluidic actuators, v) nanopore (bio)sensors, and vi) commercial aspects. The plethora of potential applications once envisioned for solid-state nanochannels is progressively and quickly materializing into new technologies that hold promise to revolutionize the everyday life.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/adma.201901483DOI Listing
September 2019

Reversible Switching of the Dirac Point in Graphene Field-Effect Transistors Functionalized with Responsive Polymer Brushes.

Langmuir 2019 Jun 4;35(24):8038-8044. Epub 2019 Jun 4.

Departamento de Química, Facultad de Ciencias Exactas , Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La Plata (UNLP), CONICET , Suc. 4-C.C.16, 1900 La Plata , Argentina.

The reversible control of the graphene Dirac point using external chemical stimuli is of major interest in the development of advanced electronic devices such as sensors and smart logic gates. Here, we report the coupling of chemoresponsive polymer brushes to reduced graphene oxide (rGO)-based field-effect transistors to modulate the graphene Dirac point in the presence of specific divalent cations. Poly[2-(methacryloyloxy)ethyl] phosphate (PMEP) brushes were grown on the transistor channel by atom transfer radical polymerization initiated from amine-pyrene linkers noncovalently attached to rGO surfaces. Our results show an increase in the Dirac point voltage due to electrostatic gating effects upon the specific binding of Ca and Mg to the PMEP brushes. We demonstrate that the electrostatic gating is reversibly controlled by the charge density of the polymer brushes, which depends on the divalent cation concentration. Moreover, a theoretical formalism based on the Grahame equation and a Langmuir-type binding isotherm is presented to obtain the PMEP-cation association constant from the experimental data.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.langmuir.9b00910DOI Listing
June 2019

Chemical Stability of Mesoporous Oxide Thin Film Electrodes under Electrochemical Cycling: from Dissolution to Stabilization.

Langmuir 2019 May 6;35(19):6279-6287. Epub 2019 May 6.

Instituto de Nanosistemas , UNSAM, CONICET , Avenida 25 de Mayo 1021 , 1650 San Martín , Buenos Aires , Argentina.

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, TiO or SiZrO 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.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.langmuir.9b00224DOI Listing
May 2019

A Patterned Butyl Methacrylate--2-Hydroxyethyl Acrylate Copolymer with Softening Surface and Swelling Capacity.

Polymers (Basel) 2019 Feb 9;11(2). Epub 2019 Feb 9.

Instituto de Ciencia y Tecnología de Polímeros, ICTP-CSIC, Juan de la Cierva 3, 28006 Madrid, Spain.

The tunable swelling and mechanical properties of nanostructures polymers are crucial parameters for the creation of adaptive devices to be used in diverse fields, such as drug delivery, nanomedicine, and tissue engineering. We present the use of anodic aluminum oxide templates as a nanoreactor to copolymerize butyl methacrylate and 2-hydroxyethyl acrylate under radical conditions. The copolymer obtained under confinement showed significant differences with respect to the same copolymer obtained in bulk conditions. Molecular weights, molecular weight dispersities, Young's modulus, and wetting behaviors were significantly modified. The combination of selected monomers allowed us to obtain nanopillar structures with an interesting softening surface and extraordinary swelling capacity that could be of special interest to surface science and specifically, cell culture.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/polym11020290DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6419064PMC
February 2019

Polyamine Colloids Cross-Linked with Phosphate Ions: Towards Understanding the Solution Phase Behavior.

Chemphyschem 2019 04 5;20(8):1044-1053. Epub 2019 Apr 5.

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

Ionically crosslinked poly(allylamine)/phosphate (PAH/Pi) colloids consist of self-assembled nanostructures stabilized by supramolecular interactions. Under physiological conditions, these interactions should be present at high ionic strength and only in a narrow pH window to be effective as drug delivery agents. In this work we study the effect of the pH and ionic strength in the chemical behaviour of inorganic phosphate (Pi), poly(allylamine hydrochloride) (PAH) and their mixture in aqueous solution (PAH-Pi). By combination of experimental measurements and a theoretical model, we demonstrate that the driving force that leads to the formation of colloids is the electrostatic pairing between the positively charged amino groups in PAH and negatively charged HPO ions. Increasing the ionic strength of the system by addition of KCl weakens the PAH-Pi interactions and narrows the pH stability window from 4 to 1.8 pH units. In addition, a fully reversible system was obtained in which the colloids assemble and disassemble by changing the pH between 6.8 and 7.1 at high ionic strength, making them suitable for use as pH-responsive nanocarriers.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/cphc.201900046DOI Listing
April 2019

Continuous assembly of supramolecular polyamine-phosphate networks on surfaces: preparation and permeability properties of nanofilms.

Soft Matter 2019 Feb;15(7):1640-1650

Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), (UNLP, CONICET), Sucursal 4, Casilla de Correo 16, 1900 La Plata, Argentina.

Supramolecular self-assembly of molecular building blocks represents a powerful "nanoarchitectonic" tool to create new functional materials with molecular-level feature control. Here, we propose a simple method to create tunable phosphate/polyamine-based films on surfaces by successive assembly of poly(allylamine hydrochloride) (PAH)/phosphate anions (Pi) supramolecular networks. The growth of the films showed a great linearity and regularity with the number of steps. The coating thickness can be easily modulated by the bulk concentration of PAH and the deposition cycles. The PAH/Pi networks showed chemical stability between pH 4 and 10. The transport properties of the surface assemblies formed from different deposition cycles were evaluated electrochemically by using different redox probes in aqueous solution. The results revealed that either highly permeable films or efficient anion transport selectivity can be created by simply varying the concentration of PAH. This experimental evidence indicates that this new strategy of supramolecular self-assembly can be useful for the rational construction of single polyelectrolyte nanoarchitectures with multiple functionalities.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c8sm02387eDOI Listing
February 2019

Practical use of polymer brushes in sustainable energy applications: interfacial nanoarchitectonics for high-efficiency devices.

Chem Soc Rev 2019 Feb;48(3):814-849

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

The discovery and development of novel approaches, materials and manufacturing processes in the field of energy are compelling increasing recognition as a major challenge for contemporary societies. The performance and lifetime of energy devices are critically dependent on nanoscale interfacial phenomena. From the viewpoint of materials design, the improvement of current technologies inevitably relies on gaining control over the complex interface between dissimilar materials. In this sense, interfacial nanoarchitectonics with polymer brushes has seen growing interest due to its potential to overcome many of the limitations of energy storage and conversion devices. Polymer brushes offer a broad variety of resources to manipulate interfacial properties and gain molecular control over the synergistic combination of materials. Many recent examples show that the rational integration of polymer brushes in hybrid nanoarchitectures greatly improves the performance of energy devices in terms of power density, lifetime and stability. Seen in this light, polymer brushes provide a new perspective from which to consider the development of hybrid materials and devices with improved functionalities. The aim of this review is therefore to focus on what polymer brush-based solutions can offer and to show how the practical use of surface-grafted polymer layers can improve the performance and efficiency of fuel cells, lithium-ion batteries, organic radical batteries, supercapacitors, photoelectrochemical cells and photovoltaic devices.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c8cs00705eDOI Listing
February 2019