Multiresponsive spiropyran-based copolymer: synthesis and characterization

Photochromic copolymers carrying spiropyran side groups have attracted particular attention for potential applications in optical devices, photonic memory and photosensing, as well as, fluorescence imaging.[1] These materials allow overcoming many of the limitations inherent to traditional spiropyran doped polymers, such as, phase separation of the colorant and retardation of the decoloration of the open form.[2] The introduction of light sensitive moieties within responsive polymers has led to the development of sophisticated multiresponsive systems.[3] Block copolymers are important self-assembling systems that can assume a diversity of nanometer-scale morphologies due to the incompatibility and the connectivity constrains between the chemically distinct segments. Therefore, self-assembly of photochromic copolymers in the solid state or in solution allows the development of nanostructured materials. [4] The aim of this research study is the synthesis of a multiresponsive spiropyran-based copolymer, poly(styrene)- co-poly([1´,3´,3´-trimethyl-6-methacryloyloxyspiro(2H-1-benzopyran-2,2´-indoline)]4-vinylbenzoic acid) 2. The functionalized block copolymer poly(styrene)-block-poly(4-vinylbenzoic acid) (PSt-b-P4VBA) 1 synthesized by reversible addition fragmentation chain-transfer (RAFT) polymerization was coupled with 1,3,3-trimethyl-6- hydroxyspiro(2H-1-benzopyran-2,2-indoline). The link between the functionalized block copolymer and spiropyran was successfully obtained by Steglich esterification using DMAP/DCC as catalysts (Scheme 1).n-STeP ProjectNORTE-07-0124-FEDER-000039Programa Operacional Regional do Norte (ON.2)PEst-C/CTM/LA0025/2013 (Strategic Project - LA 25 - 2013-2014

Effect of clay mineral addition on properties of bio-based polymer blends

The effect of clay mineral addition to bio-based blends on morphology and physical properties of thermoplastic starch (TPS) and polypropylene grafted with maleic anhydride (PP-g-MA) was investigated. Blends and nanocomposites containing organoclay, Cloisite 30B, were prepared by melt mixing and characterized by several techniques. X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM, STEM) and dynamic mechanical analysis (DMA) demonstrate a very good dispersion of the clay mineral in the polymer matrix, an increase of polymer compatibility and an improvement of mechanical properties. Biodegradation studies performed in compost revealed that Cloisite 30B addition enhanced the matrix biodegradability. Therefore clay minerals, which can be obtained from natural resources, can be efficiently used to improve the properties of bio-based materials and contribute to sustainability.The authors acknowledge the n-STeP - Nanostructured systems for Tail, with reference NORTE-07-0124-FEDER-000039, supported by the Programa Operacional Regional do Norte (ON.2), PEst-C/CTM/LA0025/2013 (Strategic Project - LA 25 - 2013-2014)

Thermoplastic starch-polypropy/lene reinforced with clay

In this study, bio-based blends of thermoplastic starch (TPS) and polypropylene grafted with maleic anhydride (PP-g-MA) without and with organoclay, Cloisite 30B, were prepared in an internal mixer. A TPS-g-PP copolymer was successfully obtained in melt and its formation was confirmed by SEM. The establishment of this copolymer creates an interpenetrating network leading an intercalated/exfoliated clay nanocomposite. Several analytical, angle X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM, STEM) and dynamic mechanical analysis (DMA) were used to characterize the prepared materials. The nanocomposites mechanical properties were improved, showing an increase of about 11% for the nanocomposite when compared with the neat blend. Biodegradation studies performed in compost revealed good percentage of weight loss for the copolymer with clay addition

Development of silver and clay-starch bio-nanocomposites

Starch, among biopolymers is that had the lowest production cost, wide availability, fully biodegradability and is a renewable agriculture resource. Starch due to its sensitivity to humidity and poor mechanical properties cannot be used in many applications. For that, the dispersion of clays in this material improves their physical and mechanical properties, at very low filler loadings. On the other hand, the incorporation of silver nanoparticles into biocompatible and biodegradable matrices gives antimicrobial properties opening a new field for packaging applications. [...

The development of trust in therapeutic communities and its impact on treatment adherence

A confiança é reconhecida como um elemento essencial para o estabelecimento da relação terapêutica, com um importante impacto na adesão ao tratamento. No entanto, existem poucos estudos e modelos teóricos que permitam a sua conceptualização e mensuração neste contexto. A presente investigação tem como objectivo estudar o desenvolvimento da confiança nas Comunidades Terapêuticas e o seu impacto na adesão ao tratamento. Foi adoptada uma metodologia mista e participaram nesta investigação, 231 sujeitos distribuídos por nove Comunidades Terapêuticas. Os resultados mostram a existência de dois níveis de confiança (na relação dos residentes com os técnicos e com as instituições) e apresentam-na como um elemento fundamental para o desenvolvimento da relação terapêutica e para a adesão ao tratamento.Trust is recognized as an essential element for the establishment of therapeutic relationship and has a major impact on treatment adherence. However, there are few studies and theoretical models which allow its conceptualization and measurement within this context. This research aims to study the development of trust in Therapeutic Communities and its impact on treatment adherence. It was adopted a mixed methodology and 231 subjects spread over nine Therapeutic Communities participated of the study. The results show the existence of two levels of trust (with the technical staff and with the institutions) and present it as a key element for developing therapeutic relationship and treatment adherence

Sustained gene expression in the retina by improved episomal vectors

Gene and cellular therapies are nowadays part of therapeutic strategies for the treatment of diverse pathologies. The drawbacks associated with gene therapy-low levels of transgene expression, vector loss during mitosis, and gene silencing-need to be addressed. The pEPI-1 and pEPito family of vectors was developed to overcome these limitations. It contains a scaffold/matrix attachment region, which anchors its replication to cell division in eukaryotic cells while in an extrachromosomal state and is less prone to silencing, due to a lower number of CpG motifs. Recent success showed that ocular gene therapy is an important tool for the treatment of several diseases, pending the overcome of the aforementioned limitations. To achieve sustained gene delivery in the retina, we evaluated several vectors based on pEPito and pEPI-1 for their ability to sustain transgene expression in retinal cells. These vectors stably transfected and replicated in retinal pigment epithelial (RPE) cells. Expression levels were promoter dependent with constitutive promoters cytomegalovirus immediate early promoter (CMV) and human CMV enhancer/human elongation factor 1 alpha promoter yielding the highest levels of transgene expression compared with the retina-specific RPE65 promoter. When injected in C57Bl6 mice, transgene expression was sustained for at least 32 days. Furthermore, the retina-specific RPE65 promoter showed higher efficiency in vivo compared to in vitro. In this study, we demonstrate that by combining tissue-specific promoters with a mitotic stable system, less susceptible to epigenetic silencing such as pEPito-based plasmids, we can achieve prolonged gene expression and a sustained therapeutic effect.Fundacao para a Ciencia e Tecnologia, Portugal [PEst/OE/EQB-LA 0023/2013, SFRH/BD/76873/2011, SFRH/BD/70318/2010, PTDC/SAU/BEB/098475/2008]; European Union [PIRG-GA-2009-249314

Entrapment of CdTe quantum dots in polymeric micelles

Semiconductor quantum dots (QDs) have attracted increasing interest to their unique sizedependent optical and electronic properties. Some of the most promising applications are imaging and biological sensing, acting as fluorescent probes.[1] However, for these purposes QDs need to be attached to other species. Thus, amphiphilic polymers, displaying both hydrophobic and hydrophilic regions, are interesting systems to encapsulate QDs.[2] The entrapment of hydrophobic QDs into surfactant micelles results in the formation of fluorescent nanoparticles composed by a QD core and a surfactant shell. This results in improved QDs dispersion in biological environments, lowering their toxicity. The present work investigates the entrapment of CdTe QDs in micelles formed by poly(acrylic acid) macroRAFT (PAA), a new water soluble amphiphilic polymer. The results obtained indicate that the PAA/QDs ration plays an important role not only in the dispersion of the nanoparticles in aqueous systems but also in the optical properties of the QDs

Polymeric micellar drug carriers with fluorescent properties

Self-assembling polymeric surfactants, based on amphiphilic block copolymers into nanosized aggregates in aqueous solution, are of great interest in the biomedical fields as one class of promising carrier systems, for drug delivery, gene therapy and diagnostic biosensors.[1] The incorporation of fluorescent probes into polymeric micelles has been fulfilled either by physically encapsulation or chemically attachment of fluorophores. [2] These micelle-based fluorescent probes not only facilitate better dispersion of fluorophores in biological environments, but also reduce their cytotoxicity by avoiding direct contact with normal cells or tissues. In this work we present new water soluble amphiphilic polymers, poly(acrylic acid) macroRAFT (PAA) 1 and poly(acrylic acid)-block-poly(9-vinylanthracene) (PAA-b-P9VA) 2, for the production of the mixed fluorescent micelles. Fluorescence assays were performed to monitoring the effect of their ratio on the formation of mixed micelles and to determine 1’s critical micelle concentration (cmc). The cmc was also evaluated by surface tension measurements

Environmental risk assessment in a contaminated estuary: an integrated weight of evidence approach as a decision support tool

Environmental risk assessment of complex ecosystems such as estuaries is a challenge, where innovative and integrated approaches are needed. The present work aimed at developing an innovative integrative methodology to evaluate in an impacted estuary (the Sado, in Portugal, was taken as case study), the adverse effects onto both ecosystem and human health. For the purpose, new standardized lines of evidence based on multiple quantitative data were integrated into a weight of evidence according to a best expert judgment approach. The best professional judgment for a weight of evidence approach in the present study was based on the following lines of evidence: i) human contamination pathways; ii) human health effects: chronic disease; iii) human health effects: reproductive health; iv) human health effects: health care; v) human exposure through consumption of local agriculture produce; vi) exposure to contaminated of water wells and agriculture soils; vii) contamination of the estuarine sedimentary environment (metal and organic contaminants); viii) effects on benthic organisms with commercial value; and ix) genotoxic potential of sediments. Each line of evidence was then ordinally ranked by levels of ecological or human health risk, according to a tabular decision matrix and expert judgment. Fifteen experts scored two fishing areas of the Sado estuary and a control estuarine area, in a scale of increasing environmental risk and management actions to be taken. The integrated assessment allowed concluding that the estuary should not be regarded as impacted by a specific toxicant, such as metals and organic compounds hitherto measured, but by the cumulative risk of a complex mixture of contaminants. The proven adverse effects on species with commercial value may be used to witness the environmental quality of the estuarine ecosystem. This method argues in favor of expert judgment and qualitative assessment as a decision support tool to the integrative management of estuaries. Namely it allows communicating environmental risk and proposing mitigation measures to local authorities and population under a holistic perspective as an alternative to narrow single line of evidence approaches, which is mandatory to understand cause and effect relationships in complex areas like estuaries.info:eu-repo/semantics/publishedVersio