Oscar E. Pérez

Universidad de Buenos Aires | UBA · Institute of Biological Chemistry of the Faculty of Natural Sciences (IQUIBICEN)

Poly(amide-triazole) and poly(ester-triazole) synthesized from d-galactose as a renewable resource were applied for the synthesis of nanoparticles (NPs) by the emulsification/solvent evaporation method. The NPs were characterized as stable, spherical particles, and none of their components, including the stabilizer poly(vinyl alcohol), were cytotox...

Probiotics have been shown to be effective against infectious diseases in clinical trials, with either intestinal or extraintestinal health benefits. Even though probiotic effects are strain-specific, some “widespread effects” include: pathogen inhibition, enhancement of barrier integrity and regulation of immune responses. The mechanisms involved...

Chitosan-based nanocarriers (CS-NC) show a promising role in improving drugs and bioactive compounds delivery for therapy. However, the effects exerted by CS-NC at the cellular level, including their recognition and uptake, have not been fully investigated yet. Many factors, including size, shape, concentration, and surface chemistry of CS-NC, play...

The design of vehicles for the insulin hormone (INS) was explored in this chapter. Such vehicles were based on a high molecular weight chitosan (CS), which is a biodegradable, biocompatible, and mucoadhesive polysaccharide. It is intended as a new type of INS administration, offering an alternative to the traditional one (pulmonary or nasal route)...

Dr. Alaimo and Dr. Pérez are both corresponding authors. Plant-based polyphenols are natural compounds, present in fruits and vegetables. During recent years, polyphenols have gained special attention due to their nutraceutical and pharmacological activities for the prevention and treatment of human diseases. Nevertheless, their photosensitivity an...

The search for the exploitation and recycling of biomaterials is increasing for reducing the use of non-renewable resources and minimizing environmental pollution caused by synthetic materials. In this context, Chitosan (CS) being a naturally occurring biopolymer becomes relevant. The aim of the present work was to explore the effects of High Molec...

BACKGROUND: Dark-skin berries constitute a polyphenol-rich source of interest for the development of functional ingredients. OBJECTIVE: To develop an elderberry powder, addressing technological aspects for maximum bioactive recovery, including physical quality and bioaccesibility of the antioxidant compounds. METHODS: An optimization of the combine...

(*) BUOSI F.S. and ALAIMO A. CONTRIBUTED EQUALLY. Resveratrol High molecular weight chitosan Nanogels Ocular diseases Retinal pigment epithelium Cellular uptake ABSTRACT Oxidative stress and inflammation play a pivotal role in ocular diseases. Resveratrol (RSV) is a natural bioactive that has recently attracted attention due to it potent antioxida...

The objective of this work was to explore the complexation of a whey protein (β-lactoglobulin, β-lg) and a whey protein isolate (WPI) with folic acid (FA) at pH 3.0. Complexes were formed through non-covalent interactions, mainly electrostatic, as showed by ƺ-potential determination. Whey protein aggregation induced by the FA linkage was achieved,...

The objective of this work was to obtain Chitosan (CS) based particles for Insulin (INS) encapsulation, via nanospray drying of a feeding solution containing equal amounts of both components (0.1% w/v total solids content). The process was performed at pH 3 which is out of the range for electrostatic interactions to occur. The analysis involved the...

Baicalin (BAI) is a flavonoid of natural origin, obtained from the roots of Scutellaria baicalensis. Its medicinal use has been part of traditional Chinese forms of therapy for ancient times. It has antioxidant, antimicrobial and antitumor effects. BAI is a labile compound at alkaline pH. The healing of complex wounds involves the combined action...

Mammalian cells lines were treated with High Molecular Weight Chitosan (HMWC) and recombinant Platelet-derived Growth Factor (PDGF). Specifically, we studied cellular responses known to be involved in tissue regeneration, such as proliferation, cell migration and tubulogenesis. We also analysed changes in mitochondrial dynamics that could be associ...

Un grupo de investigadoras e investigadores argentinos intentan desarrollar un tratamiento novedoso para prevenir la degeneración macular relacionada con la edad, que es la principal causa de pérdida de visión en las personas mayores. ARTICULO: https://nexciencia.exactas.uba.ar/degeneracion-macular-ceguera-ojos-resveratrol-agustina-alaimo-oscar-per...

Bacterial eVs have been related to inter-kingdom communication between probiotic/pathogenic bacteria and their hosts. our aim was to investigate the transcytosis process of B. subtilis eVs using an in vitro intestinal epithelial cell model. In this study, using Confocal Laser Scanning Microscopy, we report that uptake and internalization of cfSe-la...

Electronic supplementary material Below is the link to the electronic supplementary material. Fig.S1. NMR Identification of trans- RSV. (A) Chemical structure of trans-resveratrol. (B) RVS was identified by NMR as (E)-isomer. 1H and 13C spectra in methanol-d4 displayed the characteristic peaks for unequivocal structure of trans-resveratrol. (TIF 1...

Age-related macular degeneration (AMD) is a late-onset retinal disease and the leading cause of central vision loss in the elderly. Degeneration of retinal pigment epithelial cells (RPE) is a crucial contributing factor responsible for the onset and progression of AMD. The toxic fluorophore N-retinyl-N-retinylidene ethanolamine (A2E), a major lipof...

Protein-polysaccharide complexes constructed via self-assembly method are often used to develop novel biomaterials for a wide range of applications in biomedicine, food and biotechnology. The objective of this work was to investigate theoretically and to demonstrate via constant-pH Monte Carlo simulations that the complexation phenomenon between IN...

The aim of this work was to analyze changes in some cellular responses induced by recombinant PDGF-AA and PDGF-BB when free chitosan is added to culture media. Standard in vitro culture of 3T3 and EAhy926 cell lines was performed and known concentrations of PDGF and chitosan were mixed as a media additive. Here, we analyze possible cytotoxic effect...

Organizers: Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA, CONICET) - Partner Institute of the Max Plack Society Max Planck Society Germany FOCEM - Mercosur http://www.ibioba-conicet.gob.ar/biociencias_2018.php

Organizers: Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA, CONICET) - Partner Institute of the Max Plack Society Max Planck Society Germany FOCEM - Mercosur http://www.ibioba-conicet.gob.ar/biociencias_2018.php

The objective of the present contribution was to design and characterize betanin (Bt) loaded 11S quinoa seed protein nanovehicles. 11S was isolated from quinoa seed floor. Protein purification was performed by Size-Exclusion Chromatography. MALDI-TOF (Matrix-Assisted Laser Desorption/Ionization-Time-Of- Flight) analysis confirmed the identity of 11...

Background: Core-shell micro and nanoparticles can be used to encapsulate bioactive or functional components and to replace fat content also, since they are able to mimic the organoleptic characteristics of the fat globules. Objective: The aim of this study was to investigate the effect of replacing milk fat matter by core-shell microparticles in...

Isolated 7S and 11S globulins obtained from defeated soy flour were complexated with folic acid (FA) in order to generate nano-carriers for this important vitamin in human nutrition. Fluorescence spectroscopy and dynamic light scattering were applied to follow the nano-complexes formation and for their characterization. Fluorescence experimental da...

Isolated 7S and 11S globulins obtained from defeated soy flour were complexated with folic acid (FA) in order to generate nano-carriers for this important vitamin in human nutrition. Fluorescence spectroscopy and dynamic light scattering were applied to follow the nano-complexes formation and for their characterization. Fluorescence experimental da...

The objective of this contribution was to propose a model that would explain the nanocomplexes formation between Human Recombinant Insulin (I) and a polydisperse Chitosan (CS). Such an objective implied exploring I and CS concentration conditions that allowed the formation of complexes with defined and reproducible submicronic dimensions. I-CS comp...

Atomic force microscopy (AFM) topography of negative control.

Archaea, bacteria, and eukarya secrete membrane microvesicles (MVs) as a mechanism for intercellular communication. We report the isolation and characterization of MVs from the probiotic strain Lactobacillus casei BL23. MVs were characterized using analytical high performance techniques, DLS, AFM and TEM. Similar to what has been described for othe...

The aim of this study was to investigate the rheological properties and storage stability of submicron O/W emulsions formulated with dried skim milk and vegetable oil at neutral pH, and to analyse the impact of their inclusion into starch suspension. Sunflower oil droplets were pre-emulsified in skim milk suspension by a rotor-stator homogenizer an...

Abstract The ability of egg white (EW) nanoparticles to bind folic acid (FA) and protect it through the gastrointestinal tract and the resulting properties of the mixtures as functional ingredient was investigated. Two kinds of EW nanoparticles (USN and TSN) were mixed with FA to generate nanocarriers (USF and TSF). The particle size distribution o...

Magnetic CoFe2O4 nanotubes, nanorods and nanowires were synthesized by the template method. The materials are highly crystalline and formed by compactly packed ceramic particles whose equivalent size diameter depends on the nanostructure type. Nanotubes and nanorods present the remarkable characteristic of having very large coercive fields (1000–11...

The objective of this work was to develop egg white (EW) nanoparticles by application of high intensity ultrasound (HIUS) at different solution pHs and treatment temperatures. At pH 7 HIUS without heating decreased the particle size. In contrast, the use of thermosonication (TS) increased the particle size. At pH 3, the application of both HIUS and...

Structured elastomer films (100–150 µm) presenting piezo and magneto resistance are described. The films are composites of filler particles, which are both electrically conductive and magnetic, dispersed in an elastomeric matrix. The particles consist of magnetite (6 nm) grouped in silver-coated aggregates (Fe3O4@Ag). The matrix is styrene–butadien...

Microencapsulation of hydrophobic flavors is of great importance in the flavoring and food industries, since solid or liquid microencapsulated food flavors exhibit good chemical stability and a controlled release. Spray drying is generally used to produce flavor powders in a short time (Gharsallaoui et al. 2010). As an initial step for drying, oil...

The static (film structure and elasticity) and dynamic features (surface dilatational properties) of whey protein concentrate (WPC) spread films at the air–water interface, as influenced by three commercial hidroxypropylmethycelluloses (HPMC), i.e., E4M, E50LV and F4M, were studied, at 20 °C, pH 7 and I = 0.05 M. To this end a fully automated Wilhe...

The performance of formulations for citral encapsulation by spray drying was assessed. Focus was put on the emulsions properties and stability. Formulations contained sucrose or trehalose with or without maltodextrin and a modified starch as emulsifier. Viscosity, molecular mobility, microstructure, droplet size distribution, and stability were ana...

The aim of this work was to build, to isolate and to characterize, core–shell microparticles composed of a core of thermally aggregated β-lactoglobulin (β-lg) covered by a shell of carboxymethylcellulose (CMC). The core–shell particles were obtained by mixing (β-lg)n and CMC solutions at pH 7 and finally, decreasing the pH up to 4, promoting the ad...

Nickel (Ni) based nanoparticles and nanochains were incorporated as fillers in polydimethylsiloxane (PDMS) elastomers and then these mixtures were thermally cured in the presence of a uniform magnetic field. In this way, macroscopically structured-anisotropic PDMS-Ni based magnetorheological composites were obtained with the formation of pseudo-cha...

An anisotropic magnetorheological composite formed by dispersions of silver-covered magnetite microparticles (Fe3O4@Ag) in polydimethylsiloxane (PDMS) displaying electrical conduction only in one preferred direction is presented. A set-up for applying and detecting electrical conduction through the composite is described and applied to characterize...

We have synthesized magnetic Fe2−xCoSmxO4 nanoparticles (NPs) by means of the coprecipitation method, varying Sm content from x=0 to x=0.5. Energy-dispersive X-ray spectroscopy showed agreement between the metal proportion of the obtained nanoparticles and the stoichiometric mixture of cations used for the synthesis. Part of the particles were heat...

The goal of this contribution was to determine the impact of HIUS on the thermal aggregation, gelation, foaming and emulsifying properties of egg white (EW) proteins.EW solutions were sonicated for 20 min using an ultrasonic processor Vibra Cell Sonics, model VCX 750 (frequency: 20 kHz; amplitude: 20%). The following properties were determined: par...

Magnetorheological elastomers, MREs, based on elastic organic matrices displaying anisotropic magnetoresistance and piezoresistivity at room temperature were prepared and characterized. These materials are dispersions of superparamagnetic magnetite forming cores of aggregated nanoparticles inside silver microparticles that are dispersed in an elast...

Magnetic elastic structured composites were prepared by using CoFe2O4 ferromagnetic and superparamagnetic nanoparticles as fillers in polydimethylsiloxane (PDMS) matrixes, which were cured in the presence of a uniform magnetic field. Cobalt-iron oxide nanoparticles of three different average sizes (between 2 and 12 nm) were synthesized and characte...

This work constitutes a study of the impact of phase separation behaviour on the gels properties of a low viscosity hydroxypropylmethylcellulose and whey protein concentrate (WPC) mixed system. The phase separation was characterized by drawing the limit of thermodynamic compatibility, i.e. binodal curve, at pH 6.5 and room temperature (25°C). Gelli...

A model for the dependence of the electrical conductance, G , with the strain induced by external mechanical stress in conducting particles-polymer composites is presented. The model assumes that the percolation probability between neighboring particles must depart from a scale-invariant behavior but saturate at moderated-high strains, reaching per...

The surface behaviour of hydroxypropylmethylcelluloses (HPMC) was studied at the air–water (A/W) and oil–water (O/W) interfaces. At the A/W interface, the π-C isotherms were sigmoidal and presented inflexions as the HPMC bulk concentration increases, related with different structural patterns adopted by the biopolymer segments. The behaviour of the...

In this work we have studied the impact of the competitive adsorption of a whey protein concentrate (WPC) and three well characterized hydroxypropyl-methyl-cellulose (HPMCs), commercially known as E4 M, E50LV and F4 M, on the surface dilatational properties (surface dilatational modulus, E, surface dilatational elasticity, Ed, and loss angle tangen...

The application of high-intensity ultrasound (HIUS) to modify biopolymers is increasingly been studied. Because of cavitation, HIUS can modify the structure of some proteins and polysaccharides. The objective of this study was to evaluate the effect of high-intensity ultrasound on the particle size of hydroxypropylmethylcellulose (HPMC) with differ...

The aim of this research is to quantify the competitive adsorption of a whey protein concentrate (WPC) and hydroxypropyl-methyl-cellulose (HPMC so called E4M, E50LV and F4M) at the air-water interface by means of dynamic surface tensiometry and Brewster angle microscopy (BAM). These biopolymers are often used together in many food applications. The...

Surface dynamic properties (surface pressure and surface dilatational properties) of three commercial hydroxypropyl methylcellulose (HPMC) adsorbed at the air–water interface are presented in this paper as a function of adsorption time. Experiments were performed at constant temperature (20 °C), pH 7, and ionic strength 0.05 M. The dynamics of adso...

Thermostability and gelation of the main proteins of whey, α-lactalbumin (α-lac) and β-lactoglobulin (β-lg) recovered by selective complexation with carboxymethylcellulose (CMC) was studied to evaluate its functionality in food systems. Their behavior was compared to the non-complexed proteins. Both complexes showed a maximum stability at pH 4, tha...

In this work the competitive behaviour of whey protein concentrate (WPC) and three well-characterized hydroxypropyl–methyl–celluloses (HPMCs), so-called E4M, E50LV and F4M, with different interfacial properties, were studied by measurement of the dynamics of adsorption and surface pressure isotherms. Such differences may be attributed to difference...

The influence of hydroxypropylmethycellulose (HPMC) on whey protein (WPC) gelling properties was studied under thermodynamic incompatibility conditions at neutral pH and room temperature. The binodal curve characterizing phase separation was determined. Thermal transitions of mixed systems above the binodal curve showed two endothermic peaks corrob...

Pasting properties, thermal properties and microstructure of starch from ground corn steeped at 52degreesC in sulfurous acid solution (0.20%) for 8, 16, 24, 32 or 40 h were investigated. The isolated starch obtained by wet milling was analysed for pasting properties using a rapid visco analyser (RVA), for retrogradation enthalpy by DSC and for gran...

Surface pressure isotherms and structural and surface dilatational properties of three hydroxypropylmethycelluloses (HPMCs, called E4M, E50LV, and F4M) adsorbed films at the air-water interface were determined. In this work we present evidence that HPMC molecules are able to diffuse and saturate the air-water interface at very low concentrations in...