a b s t r a c tNovel chitosan based polyelectrolyte complexes (PEC) were developed and optimized in order to obtain films possessing the optimal functional properties (flexibility, resistance, water vapour transmission rate and bioadhesion) to be applied on skin. The development was based on the combination of chitosan and two polyacrylic acid (PAA) polymers with different crosslinkers and crosslinking densities. The interaction between the polymers was maximized controlling the pH, and by forming the films at a pH value close to the pK a of the respective components as identified by potentiometric and turbidimetric titrations. The action of glycerol, PEG200, Hydrovance and trehalose upon the functional properties of the films was also evaluated. Glycerol was found to improve the film properties in terms of flexibility, resistance and water vapour transmission rate (WVTR) with a maximum effect at 30%. The application of a pressure sensitive adhesive (PSA) significantly improved bioadhesion with a negligible influence in the resistance and flexibility of the films.The optimized film, including adhesive, has shown very good properties for application in the skin and represents a very promising formulation for further incorporation of drugs for topical and transdermal administration.

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The effect of EuCl3 on the aggregation processes of sodium dodecyl sulfate was investigated. Electrical conductivity data, combined with Eu(III) luminescence measurements, suggest that the formation of micelles involving EuCl3 and SDS occurs at low SDS concentration; the formation of these mixed aggregates was also monitored by light scattering, which indicates that the addition of EuCl3 to SDS concentration at values below the critical micelle concentration of the pure surfactant results in a much higher light scattering than that found just with SDS micelles. It was also found that the Eu(III)/DS- complexes are formed with a binding ratio which varies between 20 and 4, depending on the initial concentration of Eu(III). As the concentration increases, turbidity occurs initially, but solutions become clear subsequently. In contrast to the behavior of SDS in the presence of aluminum(III), no flocculation was observed. From the analysis of electrical conductivity data and comparison with other systems, it is suggested that growth of aggregates happens, probably with formation of nonspherical systems. At the highest concentrations these may involve just Eu(III) and DS- ions. The effect of temperature on the SDS micellization process was studied. The calculated free energy of SDS micellization is not dependent on the initial EuCl3 but is dependent on the final balance between the presence of counterions in solution (ionic strength) and the temperature.

This work addresses the impact of pH variation on DNA-polyethylenimine (PEI) complex formation, in aqueous solution and at constant ionic strength. An initial potentiometric characterization of the acid-base behavior of PEI is carried out to measure the concentration of ionized species in the relevant systems. The characterization of the DNA-PEI complexes is performed by precipitation assays, agarose gel electrophoresis, photon correlation spectroscopy, and zeta potential analysis. It is observed that the variations on the electrophoretic mobility, size, and electrical properties of complexes display nonmonotonic, nontrivial trends with pH, if the same polycation/polyanion charge ratios are used for different values of pH. It is seen that both linear charge density and the relative number of chains of the condensing agent are important factors governing the condensation behavior. Complexes prepared at pH 4, for example, indicate strong binding and a large mean size, while those prepared at pH 8 are smaller, in a more uniform population. Finally, charge inversion was observed for all studied pH values (even below charge neutralization).

Water quality is currently a subject of increasing concern, especially because of the emerging pollutants contaminating aquatic environment. The aim of this study was to verify the presence of emerging pollutants in the Iguaçu River, from source to mouth, such as: pharmaceuticals, including acetylsalicylic acid (ASA), salicylic acid, ketoprofen (KET), naproxen (NAP), gemfibrozil and fenofibrate; female sex hormones, including estradiol (E1), ethinylestradiol (EET) and estrone (E2); UV filters, including 4‐methylbenzylidene camphor and octylmethoxycinnamate; and caffeine (CAF). The extracted pollutants were purified using solid phase extraction and then analyzed by liquid chromatography with diode array detection and gas chromatography‐tandem mass spectrometry. All analyzed compounds were detected in at least one site in one sample. The analysis revealed maximum concentrations of 27.0 μg L−1 CAF, 5.17 μg L−1 ASA, 0.34 μg L−1 NAP, 0.62 μg L−1 KET, 1.42 μg L−1 E1, 1.48 μg L−1 EET, and 0.94 μg L−1 E2. The results indicated that Iguaçu river water is contaminated with emerging pollutants and nutrients and that this may be due to domestic sewage and water from tributary rivers mixing with Iguaçu river water. Statistical analysis demonstrated that the study of emerging environmental contaminants is a useful tool to determine if contamination is due to domestic sewage input once traditional physical, chemical and spectroscopic analyses have been insufficient to prove an anthropogenic influence.

The successful use of nucleic acids in medicine requires efficient DNA condensation and protection, as well as a low cytotoxicity of the vector. In previous work, we have used a ternary DNA-PEI-Fe(III) complex and have shown that the addition of Fe(III) to the DNA-PEI complexes enhances DNA condensation, whereas allows an easier DNA release from the complexes, in the presence of a decompacting agent. The focus of the present work was to investigate the influence of the polycation architecture on the DNA-PEI-Fe(III) ternary system, and also to develop a potential gene delivery system with reduced toxicity. Herein, lPEI (2.5 and 25 kDa) and bPEI (1.2 and 10 kDa) were used in conjunction with Fe(III), and the complexes formed were physico-chemically characterized using precipitation and gel electrophoresis assays, and size and zeta potential determinations. It was observed that the addition of Fe(III) ions equalizes the charge ratios for the onset of DNA condensation irrespective of the PEI used, although a more pronounced condensation effect is still visible with the polycations with a lower M w . At low N/P ratios, the presence of Fe(III) caused the zeta potential to change from negative to positive values. Also, a reduction in polyplex size is visible before aggregation takes place. The hemolytic activity of the condensing agents was found to be dependent on the pH of the medium, but no perturbation of erythrocytes integrity was detected. Furthermore, the cytotoxicity of each condensing agent individually and of the complexes towards 3T3 fibroblast cell line and HeLa cell line was monitored using the MTT and LDH assays. The magnitude of the cytotoxic effects of the polycations and Fe(III) was found to be dependent on the concentration of the condensing agents, the molecular weight of the polycations, and the pH of the culture medium. The combination of Fe(III) with PEI determines higher IC 50 values than in the absence of the metal ion. Additionally, a lower cytotoxicity of DNA-PEI-Fe(III) complexes was observed, when compared to native PEI-DNA complexes, at the same degree of condensation and values of zeta potential. The results show that Fe(III) reinforces the DNA-PEI condensation in both PEI architectures. It allows the cytotoxicity of PEIs to be mitigated and the concentration of the latter needed to obtain stable polyplexes to be decreased.

We report on a multiscale polymer-within-polymer structure of the cationic conjugated polyelectrolyte poly{[9,9-bis(6′-N,N,N-trimethylammonium)hexyl]fluorene−phenylene} (HTMA-PFP) in aqueous poly(vinyl alcohol) (PVA) sol. Molecular dynamics simulations and small-angle neutron scattering (SANS) data show that HTMA-PFP forms aggregates in water but becomes entangled by PVA (with a 1:1 molar ratio of HTMA-PFP to PVA) and eventually immersed in PVA clusters (with the ratio 1:4). This is attributed to the hydrophobic−hydrophilic balance. Contrast variation data with regular and deuterated PVA support a rigid body model, where HTMA-PFP is confined as locally isolated, but closely located, chains within PVA clusters, which alter correlation distances within the system. These results are supported by enhanced photoluminescence (PL) and ionic conductivity which, together with a red-shift in UV/vis absorption spectra, indicate the breakup of HTMA-PFP aggregates upon PVA addition.

Introduction Transanal total mesorectal excision (TaTME) has rapidly emerged as a novel approach for rectal cancer surgery. Safety profiles are still emerging and more comparative data is urgently needed. This study aimed to compare indications and short‐term outcomes of TaTME, open, laparoscopic, and robotic TME internationally. Methods A pre‐planned analysis of the European Society of Coloproctology (ESCP) 2017 audit was performed. Patients undergoing elective total mesorectal excision (TME) for malignancy between 1 January 2017 and 15 March 2017 by any operative approach were included. The primary outcome measure was anastomotic leak. Results Of 2579 included patients, 76.2% (1966/2579) underwent TME with restorative anastomosis of which 19.9% (312/1966) had a minimally invasive approach (laparoscopic or robotic) which included a transanal component (TaTME). Overall, 9.0% (175/1951, 15 missing outcome data) of patients suffered an anastomotic leak. On univariate analysis both laparoscopic TaTME (OR 1.61, 1.02–2.48, P = 0.04) and robotic TaTME (OR 3.05, 1.10–7.34, P = 0.02) were associated with a higher risk of anastomotic leak than non‐transanal laparoscopic TME. However this association was lost in the mixed‐effects model controlling for patient and disease factors (OR 1.23, 0.77–1.97, P = 0.39 and OR 2.11, 0.79–5.62, P = 0.14 respectively), whilst low rectal anastomosis (OR 2.72, 1.55–4.77, P < 0.001) and male gender (OR 2.29, 1.52–3.44, P < 0.001) remained strongly associated. The overall positive circumferential margin resection rate was 4.0%, which varied between operative approaches: laparoscopic 3.2%, transanal 3.8%, open 4.7%, robotic 1%. Conclusion This contemporaneous international snapshot shows that uptake of the TaTME approach is widespread and is associated with surgically and pathologically acceptable results.