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.

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 (β-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.

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.

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.

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.