Santiago Esteban Herrera- PhD
- Researcher at University of Buenos Aires
Santiago Esteban Herrera
- PhD
- Researcher at University of Buenos Aires
About
33
Publications
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Introduction
Current institution
Publications
Publications (33)
This work reports the phase behavior and electro-chemical properties of liquid coacervates made of ferricyanide and poly(ethylenimine). In contrast to the typical polyanion/polycation pairs used in liquid coacervates, the ferricyanide/poly-(ethylenimine) system is highly asymmetric because poly-(ethylenimine) has approximately 170 charges per molec...
The assembly of polyelectrolytes and biomacromolecules (proteins, DNA) has attracted great attention in several fields related to medicine, molecular biology, and clinical chemistry. Here, a quick and easy multicomponent self-assembly is used to unite two species with the same charge to form an electroactive polyamine-enzyme assembly. Phosphate ion...
The complexation of polyelectrolytes with other oppositely charged structures gives rise to a great variety of functional materials with potential applications in a wide spectrum of technological fields. Depending on the assembly conditions, polyelectrolyte complexes can acquire different macroscopic configurations such as dense precipitates, nanos...
High-power density output in enzymatic fuel cells is a key feature to reduce the size of self-powered implantable medical devices. Electron transfer mediated through redox polyelectrolytes allows the transport of electrons from enzymes away from the electrode, improving the current output. It is known that doping ions in polyelectrolytes introduce...
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 bul...
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 hydr...
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. Th...
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 use of soft materials as building blocks in layer‐by‐layer (LbL) assemblies represent a very appealing and useful approach to enhance the loading capacity of thin films. Here, the capacity of positively charged polyamine‐salt aggregates (PSAs) based on ionically crosslinked poly(allylamine hydrochloride) (PAH) with phosphate anions (Pi) is expl...
A Gaussian distribution of tunneling distances due to different orientation populations in electrochemically active self-assembled monolayers comprised of alkane thiols of different length has been assumed in a model which leads to a Gaussian distribution of the logarithm of the electron transfer constants. The model has been validated with experim...
Metal nanoparticle mediated electron transfer (ET) across an insulator thin film containing nanoparticles with attached redox centers was studied using electrochemical impedance spectroscopy. Specifically, a gold spherical microelectrode was modified with 16-amino-1-hexa-decanethiol creating an insulator film. This was followed by the electrostatic...
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...
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 anio...
4,4´‐Dithiodipyridine was coordinated by the N atom to Iron(II) phthalocyanine(FePc) and then adsorbed from a benzene solution onto a Au(111) single crystal electrode with cleavage of the S‐S bond and formation of Au‐S bond. The coordination of PySSPy to FePc was monitored by UV‐Visible spectroscopy while the adsobed FePc anchored by PyS‐Au(111) wa...
4-Mercaptopyridine (4MPy) self-assembled on Au(111) has been studied by in-situ electro-chemical scanning tunneling microscopy (E-STM) in HCLO4, cyclic voltammetry, X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT). Samples prepared by varying the immersion time at constant concentration named short time (30 seconds) and lo...
The Back Cover picture illustrates advances in battery technology. Electrochemically generated soluble lithium superoxide in DMSO–TBAPF6 dismutates into insoluble lithium peroxide on Au upon addition of lithium ions to the solution, which offers progress in the area of lithium–air batteries. More information can be found in the Communication by E....
The dismutation of electrochemically generated soluble lithium superoxide with the formation of a lithium peroxide deposit on Au has been studied by addition of lithium ions and following the mass uptake detected by the electrochemical quartz crystal microbalance at the open-circuit potential and the surface morphology evolution by using atomic for...
The molecular and electronic structure of Os(II) complexes covalently bonded to self-assembled monolayers (SAMs) on Au(111) surfaces was studied by means of polarization modulation infrared reflection absorption spectroscopy, photoelectron spectroscopies, scanning tunneling microscopy, scanning tunneling spectroscopy, and density functional theory...
The O2/Li2O2 electrode reaction has been studied on low surface area Au electrodes in three solvent-electrolyte pairs (0.1M LiPF6/DMSO, LiPF6/ACN and LiBF4/ACN) using an electro-chemical cell coupled to UHV XPS spectrometer, EQCM, AFM and DEMS. The XPS spectra of the surfaces after treatment at selected electrode potentials for the O2 reduction and...
The electrochemical study of electron transport between Au electrodes and the redox molecule Os[(bpy)2(PyCH2 NH2CO-]ClO4 tethered to molecular linkers of different length (1.3 to 2.9 nm) to Au surfaces has shown an exponential decay of the rate constant kET0 with a slope β = 0.53 consistent with through bond tunneling to the redox center. Electroch...
Ru(II) bipyridyl complexes were covalently bonded to self-assembled monolayers (SAM) on Au surfaces. Their molecular and electronic structure was studied by means of polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), photoelectron spectroscopies, scanning tunneling microscopy (STM) and density functional theory (DFT) ca...
Ex situ atomic force microscopy (AFM) has been used to study the morphology of oxygen reduction products in the LiPF6-dimethyl sulfoxide (DMSO) electrolyte, i.e. Li2O2 on a highly oriented pyrolytic graphite (HOPG) surface. Both cyclic voltammetry and chronoamperometry have shown that at low cathodic polarization the initial deposits decorate the e...
The synthesis of atomic metal (gold and nickel) clusters by pulsed galvanostatic electrodeposition on nanoporous alumina is presented. The method allows the production of clusters with an average diameter of 0.7 nm for gold and 1.1 nm for nickel, while the size can be controlled through the current density applied. This strategy represents a simple...
Questions
Question (1)
I recently obtained a CR2032 coin cell pressing machine manufactured by the GELON lib group for the purpose of building Li-O2 batteries within an MBRAUN glovebox. However, I encountered an issue during the vacuum application in the antechamber, where a significant amount of oil was spilled. To address this problem, I attempted partial vacuum cycles followed by Ar filling within the antechamber. Unfortunately, this approach led to excessive water levels once the machine was inside the glovebox. If anyone has faced a similar challenge, I would greatly appreciate hearing about your experiences and any potential solutions you discovered. Thank you for your assistance.
