Sorption and release process of polybrominated diphenyl ethers (PBDEs) from different composition microplastics in aqueous medium: Solubility parameter approach.

Microplastics represent a growing environmental concern in the aquatic environment due to its size resemblance to microplankton in addition to its ability to act as concentrators of persistent organic pollutants (POPs). Among them, polybrominated diphenyl ethers (PBDEs) stand out as POPs with dangerous levels in the aquatic environment. In this paper we have developed a methodology for studying the sorption and extraction process of twelve congeners of PBDE from four microplastics: polyethylene terephthalate (PET), polypropylene (PP), low density polyethylene (LDPE) and polystyrene (PS). We have proved that there is a dependence between the polymer composition and the solvent used for the extraction of the analytes. The extraction is function of the ability of the solvent to partially or totally dissolve the plastic that will allow the analyte to have a greater capacity to be released from the polymer structure. The solution of the polymer is achieved by making the free energy (ΔG, or Gibbs potential) of the system negative making the process occurs spontaneously, this will depend on the solubility parameter (∂), specific of both, solvent and polymer. Therefore, this study helps to determine which methodology to be applied for the extraction of pollutants before the start of the analysis. This approach has been applied to microplastic samples collected in different locations in the four oceans and collected from the Barcelona World Race (BWR) 2014-2015 sailing race.

Unraveling Polymeric Nanoparticles Cell Uptake Pathways: Two Decades Working to Understand Nanoparticles Journey to Improve Gene Therapy.

Polymeric nanoparticles have aroused an increasing interest in the last decades as novel advanced delivery systems to improve the treatment of many diseases. Hard work has been performed worldwide designing and developing polymeric nanoparticles using different building blocks, which target specific cell types, trying to avoid bioaccumulation and degradation pathways. The main handicap of the design is to understand the final fate and the journey that the nanoparticle will follow, which is intimately ligated with the chemical and physical properties of the nanoparticles themselves and specific factors of the targeted cells. Although the huge number of published scientific articles regarding polymeric nanoparticles for biomedical applications, their use in clinics is still limited. This fact could be explained by the limited data reporting the interaction of the huge diversity of polymeric nanoparticles with cells. This knowledge is essential to understand nanoparticle uptake and trafficking inside cells to the subcellular target structure.In this chapter, we aim to contribute to this field of knowledge by: (1) summarizing the polymeric nanoparticles properties and cellular factors that influence nanoparticle endocytosis and (2) reviewing the endocytic pathways classified as a function of nanoparticle size and as a function of the receptor playing a role. The revision of previously reported endocytic pathways for particular polymeric nanoparticles could facilitate scientist involved in this field to easily delineate efficient delivery systems based on polymeric nanoparticles.

Development of an optimized freeze-drying protocol for OM-PBAE nucleic acid polyplexes.

Long-term stability of polyplexes used for biomedical purposes is an objective envisaged by any research group developing this kind of nanoformulations. However, since biodegradable polymers such as oligopeptide end-modified poly (ß-aminoester) (OM-PBAE) are frequently used to ensure safety, and formulations are produced as aqueous dispersions, the stability of the nanoformulations is usually compromised. In this context, freeze-drying has aroused as a promising storage alternative to obtain solid nanoformulations with enhanced stability over time. Lyophilization is a challenging step that usually produces aggregation. Although some studies already achieved freeze-dried PBAE nanoparticles, none of them detailed the parameters that are critical for the success of this process. Moreover, due to the specific composition of each formulation, the critical parameters for the correct freeze-drying process need to be adjusted for each polyplex developed. In this paper, we have studied the variables that have a direct influence on the manufacturing and lyophilization of OM-PBAE nanoparticles with the aim to develop a versatile and robust freeze-drying receipt that properly preserves the library of polyplexes designed in our group, which have different pKa depending on the modification applied.

Double-targeted polymersomes and liposomes for multiple barrier crossing.

In order to treat metastasis in the brain, drug delivery systems must overcome multiple physical barriers between the point of administration and the target, such as the Blood-brain barrier, that hinder their free access across them. Multiple targeting approaches arise as a promising alternative to this barrier and target certain tissues inside the brain at a time. Herein, two surface modification methods are presented to obtain dual-targeted vesicle-like carriers functionalized with an MCF-7-specific phage protein and a BBB-specific peptide, providing the system the ability to cross a BBB model, target breast cancer cells and deliver its payload. The aim of this study was to compare new designed polymersomes with liposomes, a well-established delivery vehicle, in terms of drug loading, targeting, release and tumor cell killing. The bilayer structure of both systems allowed the conjugation with different ligands both by insertion and covalent binding. Different behaviour was observed in release, uptake and tumor cell killing corresponding to differences in membrane permeability of both vehicles and type of targeting and ligands' combination. Preliminary results showed that both formulations were able to cross the BBB monolayer without harming it, showing cytotoxic activity in the abluminal compartment.

Simultaneous monitoring of Staphylococcus aureus growth in a multi-parametric microfluidic platform using microscopy and impedance spectroscopy.

We describe the design, construction, and characterization of a scalable microfluidic platform that allows continuous monitoring of biofilm proliferation under shear stress conditions. Compared to other previous end-point assay studies, our platform offers the advantages of integration into multiple environments allowing simultaneous optical microscopy and impedance spectroscopy measurements. In this work we report a multi-parametric sensor that can monitor the growth and activity of a biofilm. This was possible by combining two interdigitated microelectrodes (IDuEs), and punctual electrodes to measure dissolved oxygen, K+, Na+ and pH. The IDuE has been optimized to permit sensitive and reliable impedance monitoring of Staphylococcus aureus V329 growth with two- and four-electrode measurements. We distinguished structural and morphological changes on intact cellular specimens using four-electrode data modeling. We also detected antibiotic mediated effects using impedance. Results were confirmed by scanning electrode microscopy and fluorescence microscopy after live/dead cell staining. The bacitracin mediated effects detected with impedance prove that the approach described can be used for guiding the development of novel anti-biofilm agents to better address bacterial infection.

Surface reactivity of pulsed-plasma polymerized pentafluorophenyl methacrylate (PFM) toward amines and proteins in solution.

Pulsed-plasma polymerization has been used to deposit ultrathin layers of pentafluorophenyl methacrylate by using low duty cycles and low power input. The monomer structure can be retained such that the chemical reactivity of the active ester group could be studied using the reaction with a simple amine. The film properties in aqueous phosphate buffer have been investigated using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and real time surface plasmon resonance spectroscopy. The films react readily with diaminohexane and immunoglobulin (IgG), yet the reactivity shows a dependence on the extent of hydrolysis of the ester group.

Fabrication of a three-dimensional nanostructured biomaterial for tissue engineering of bone.

A plasma process for the surface modification of HA powders has been developed. Acrylic acid and acrylic acid/octadiene plasma deposited films onto HA particles have demonstrated to interact with SBF allowing the calcium dissolution-precipitation mechanism. Therefore, a nanostructured composite between HA and a self-assembling peptide scaffold (RAD16-I) has been developed. The differentiation of mESC in this scaffold has been studied, in order to test the osteogenic capacity of the new composite material. We have observed that the mESC can be induced to produce Ca salts (mineralization) in a 3D-microenvironment and moreover, this activity can be enhanced by the presence of HA particles into the nanofiber scaffold.

New methodology to follow the evolution of squalene by-products during model compound vulcanization studies.

In this work, a new analytical methodology is proposed to separate squalene from its by-products after vulcanization, using reverse phase liquid chromatography. Regarding previous methods described in literature, the separation between reaction products and their detection have been clearly improved. A light scattering detector has been coupled to the HPLC equipment substituting the traditionally used UV detector. With these modifications is possible to detect a larger number of compounds along the reaction in only one-shot analysis. It is even possible to discern between cross-linked squalenes bonded with different sulfur chain lengths whose structures have been elucidated by mass spectrometry. Results obtained working with this methodology helped to gain more insight into the natural rubber accelerated vulcanization process.

Simple PVC-PPy electrode for pH measurement and titrations.

Cobaltabis(dicarbollide) [3,3'-Co(1,2-C2B9H11)](-)-doped polypyrrole (PPy) films have been prepared galvanostatically on glassy carbon electrodes in acetonitrile solution. The potential response behavior of the film of this new material has been investigated in some common pH buffers and in acid-base titrations. The potentiometric characteristics of the resulting films are indicative of a quasi-Nernstian response (approximately 50 mV/pH unit), a linearity range from pH 12 to 3 and correlation coefficients (r2) of approximately 0.98. The electrode is suitable for pH measurements and for monoprotic titrations of strong alkalis with strong acids, and weak bases with strong acids, but the long response time hinders the use of this electrode for multiprotic titrations. The time response has been dramatically improved by reducing the film thickness by using the template effect of a non-conducting polymer (PVC) cast over the graphite surface before PPy deposition. PPy polymerization occurs in the free channels of PVC leading to the formation of PPy wires. The morphological change of PPy does not affect the slope or linearity range. The response of the PVC-PPy electrochemical sensor is rapid and the sensor is easy to prepare, at low cost, and its performance is comparable with that of commercial glass electrodes.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis of some conducting polymers.

The application of laser desorption/ionization and matrix-assisted laser desorption/ionization mass spectrometry to the study of the structure of some conducting polymers was investigated. A methodology was developed and the experimental conditions for the characterization of these polymers were established. The parameters chosen to be changed for the method optimization are the matrix material (seven different matrices were tested depending on the polymer studied) and the solvent used in the preparation of the samples. The method seems to be suitable for the study of the structure of two oxidation states of polyaniline: emeraldine and pernigraniline. The analysis of the polymers derived from m-aminophenylbenzothiazole, benzothiazole and tetrathiopentalenes was also performed.} Copyright 2000 John Wiley & Sons, Ltd.

Quantification of sterols, 5alpha- and 5beta-stanols in sewage sludge, manure and soils amended with these both potential fertilizers.

A method for the quantitative determination of sterols, 5alpha- and 5beta-stanols is proposed to characterize the lipid fraction of two potential organic fertilizers, like sewage sludge and manure, as well as soils amended by them. It was possible to determine the kind of fertilizer added to the soil. Further studies were conducted to determine the accumulative effects of steroids in soils treated with manure and different doses of sewage sludge.