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A new “off-on” switch for sensitive and selective fluorescence detection of biothiols[glutathione(GSH), cysteine(Cys) and homocysteine(Hcy)] was developed based on an anionic conjugated polyelectrolyte(CPE), pyridyl-functionalized poly(phenylene ethynylene)(P1). The fluorescence of P1 can be significantly quenched by Ag+ due to complexation-mediated interpolymer aggregation. Furthermore, biothiols can efficiently recover the fluorescence intensity of P1 as a result of the stronger binding between thiol group and Ag+, which dissociates P1 from the P1/Ag+ complex and disrupts interpolymer aggregation. Under optimum conditions, a good linear relationship in a range of 100–4200 nmol/L is obtained for GSH with a detection limit of 80 nmol/L(S/N=3). As a result of specific interaction between the thiol group and Ag+, the proposed method shows a high selectivity for biothiols. In addition, the CPE-based fluorescence “off-on” switch has been used to quantitatively detect total biothiols in cell lysates.

This Feature Article focuses on recent progress made in elucidating the intermolecular interactions between a novel class of synthetic phenylene ethynylene (PPE)-based conjugated polyelectrolyte polymers (CPEs) and oligomers (OPEs) and multiscale cellular targets that give rise to their remarkable broad spectrum biocidal activity. We first review the interactions and self-assembly behaviors of the CPEs and OPEs with a set of vital biomolecules, including lipids, proteins, and nucleic acids, that reveal the potential pathways by which synthetic biocidal agents could exert toxicity. An overview of the antimicrobial effects and mechanisms of the CPEs and OPEs on multiple clinically relevant pathogens is then presented, with an emphasis on the morphological damage induced by the biocidal compounds toward the pathogens. Finally, we discuss the cytotoxicity of these materials against mammalian cells and human tissues to explore the potential applications of the CPEs and OPEs as antiseptics. We also pose some unanswered questions about their antimicrobial mechanisms, which provide direction for a future study.

A specific fluorescent switch for anions was successfully constructed. The novel sensing switch is a two-component ensemble, which was combined using a water-soluble conjugated polyelectrolyte and a boronic acid functionalized pyridine salt. In the ensemble, the polyelectrolyte is used as a fluorescent signal unit, and the pyridine boronic acid acts as receptor and quencher. The two-component ensemble shows a fluorescence reversible “off–on” response toward cyanide and phosphate anions based on different binding ways. Furthermore, the facile design and construction of this ensemble presents a novel opportunity for obtaining an efficient and practical probe.

The water-soluble conjugated polyelectrolyte, poly[3-(1′-propyloxy-3′-sodium sulfonate) thiophene] (PTH-n3-SO3Na), was prepared. The interaction between the PTH-n3-SO3Na and bovine serum albumin (BSA) was investigated using UV-vis spectroscopy. It was found that the PTH-n3-SO3Na could be used as biosensor to detect BSA.

Among renewable energies, the sunlight has by far the highest theoretical potential to meet the worldwide need in energy. Photovoltaic devices are thus currently the subject of intense research for low-cost conversion of sunlight into electrical power. In particular, organic photovoltaics have emerged as an interesting alternative to produce electricity due to their low manufacturing cost compared to silicon solar cells, their mechanical flexibility and the versatility of the possible chemical structures. In this dissertation, we focused our research on the development of new organic pi-conjugated materials for organic solar cells applications. Two types of solar cells have been studied during this work: bulk heterojunction and dye-sensitized solar cells. The charge transfer leading to the photocurrent is usually based on (i) a polymer donor and a fullerene acceptor in BHJ solar cells, such as the widely studied poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) materials and (ii) a metal oxide (titanium oxide) sensitized with a dye and an electrolyte in DSSCs. Despite power conversion efficiencies have reached 5 and 13 % respectively for these two types of devices, they still display several drawbacks that limit their commercialization. P3HT displays a narrow absorption of the solar spectrum thus limiting the conversion efficiency. To overcome this limitation, we combined P3HT with chromophores, i.e. porphyrins, having an extending absorption. Then, to ensure better charge transfer and extraction within the device, a cathode interfacial layer based on cationic pi-conjugated polyelectrolytes was added. Finally, dyes extracted from the biomass (chlorophyll a derivatives) were synthesized to replace the expensive ruthenium dyes in DSSCs. Since liquid electrolytes are volatile and corrosive, which considerably limit the DSSCs stability, solid polymer electrolytes were also developed as an alternative., Le développement des énergies renouvelables est aujourd’hui devenu un enjeu mondial majeur comme alternative aux énergies fossiles dans la production d'énergie. Parmi elles, l’énergie solaire est considérée comme la source la plus prometteuse, permettant de couvrir l’ensemble des besoins énergétiques liés à l’activité humaine. Les cellules photovoltaïques les plus performantes aujourd’hui, entre 16 et 18 % en modules, sont composées de silicium, un semi-conducteur inorganique. Cependant, leur coût de production élevé a nécessité le développement de matériaux alternatifs moins couteux. Parmi les voies explorées, les cellules solaires organiques ont émergé comme une alternative prometteuse pour produire l’électricité à faible coût. Le sujet de cette thèse s’intègre dans ce contexte de recherche. Deux types de cellules solaires ont été étudiés : les cellules à hétérojonction en volume (BHJ) et sensibilisées au colorant (DSSCs). Le courant photogénéré repose généralement (i) dans les cellules BHJ, sur le transfert entre de charge entre un polymère donneur et un accepteur d’électrons (fullerène), tels que le couple poly(3-hexyl)thiophène (P3HT) et [6,6]-phényl-C61-butanoate de méthyle (PCBM), et (ii) dans les DSSCs, la sensibilisation de la surface d’un semi-conducteur inorganique tel que l’oxyde de titane par un colorant et la présence d’un électrolyte, jouant le rôle de médiateur redox. Bien qu’ayant atteint des rendements de photoconversion respectifs de 5 et 13 %, ces cellules nécessitent des améliorations pour une commercialisation à grande échelle. Tout d’abord, les performances des cellules BHJ à base de P3HT sont considérablement limitées par sa faible absorption, ne couvrant pas la globalité du spectre solaire. Afin de palier ce problème, nous avons combiné le P3HT avec des chromophores, i.e. des porphyrines, ayant une absorption plus étendue. Ensuite, pour assurer une meilleure extraction des charges au sein du dispositif, une couche interfaciale cathodique à base de polyélectrolytes pi-conjugués a été ajoutée. Enfin, des colorants extraits de la biomasse ont été préparés afin de remplacer les colorants coûteux à base de ruthénium. En outre, les électrolytes liquides étant volatils et corrosifs, ce qui limite considérablement la stabilité des DSSCs, des électrolytes solides à base de polymères ont été étudiés comme alternative.

This short review focuses on an extended study of synthetic oligomericphenyleneethynylene (OPE) electrolytes that have been investigated for both their antimicrobial activity and their fluorescence sensing properties. In both cases, interfaces between these synthetic electrolytes and naturally occurring materials such as proteins, lipids, nucleic acids and cells are critical to their function or activity. The review contains a general overview with a focus at the end on three recent examples including biological and chemical sensing, induction of spore germination and fluorescent detection of amyloid protein aggregates.

We report the "light switch" effect of [Ru(bpy)2(dppz)](2+) (where bpy = 2,2'-bipyridine and dppz = dipyrido[3,2-a:2',3'-c] phenazine, Ru-dppz) in the presence of anionic conjugated polyelectrolyte dendrimers (CPDs). The metal-to-ligand charge-transfer luminescence from Ru-dppz is efficient in the presence of CPD because the complex is shielded from water by binding to the hydrophobic dendrimer core.

Texto completo: acesso restrito. p. 420–426 Submitted by Edileide Reis (leyde-landy@hotmail.com) on 2014-08-05T12:39:01Z No. of bitstreams: 1 D. Cerqueira.pdf: 911156 bytes, checksum: 1132457170d737323a3b8d200af7af3b (MD5) Approved for entry into archive by Rodrigo Meirelles (rodrigomei@ufba.br) on 2015-10-09T18:47:38Z (GMT) No. of bitstreams: 1 D. Cerqueira.pdf: 911156 bytes, checksum: 1132457170d737323a3b8d200af7af3b (MD5) Made available in DSpace on 2015-10-09T18:47:38Z (GMT). No. of bitstreams: 1 D. Cerqueira.pdf: 911156 bytes, checksum: 1132457170d737323a3b8d200af7af3b (MD5) Previous issue date: 2012 The preparation of cellulose acetate-poly-(9,9-bis(6′-N,N,N trimethylammonium)-hexyl-fluorene phenylene) bromide (HTMA-PFP) blend films by solvent casting from a dispersion is reported. Films were characterized by UV–visible spectroscopy, SEM, electrical conductivity, TGA and DSC. It was found that morphological and physical chemical properties of blends were dependent both on the solvent and the degree of polymerization of cellulose acetate. The fluorescence properties of different blends were evaluated by fluorescence microscopy and it was shown that they are dependent on the structural properties of the blend as well as the aggregation level of the polyfluorene. Release kinetics of HTMA-PFP, incorporated into blend films, in SDS aqueous solutions have been studied and are discussed on the basis of the Korsmeyer–Peppas equation.

This review deals with the emerging field of fluorescent conjugated polymers for the development of chemical and/or biochemical sensors. As a result of their amplified physical properties due to a “molecular wire effect”, these materials offer excellent characteristics to develop different sensing schemes (e.g., employing direct superquenching or relying on development of fluorescence-resonance-energy-transfer formats). The versatility of their synthesis procedures allows us to introduce the desired functional groups to achieve analytically useful interactions with analytes [e.g., from transition-metal ions to explosives, or even, in recent years, relevant biomolecules (e.g., proteins or DNA, where conformational changes play a decisive role in detection)].

We demonstrate herein a method for chemically modifying cotton fibers and cotton-containing fabric with a light-activated, cationic phenylene-ethynylene (PPE-DABCO) conjugated polyelectrolyte biocide. When challenged with Pseudomonas aeruginosa and Bacillus atropheaus vegetative cells from liquid suspension, light-activated PPE-DABCO effects 1.2 and 8 log, respectively, losses in viability of the exposed bacteria. These results suggest that conjugated polyelectrolytes retain their activity when grafted to fabrics, showing promise for use in settings where antimicrobial textiles are needed.

Conjugated polyelectrolytes (CPEs), with electron-delocalized backbones and charged ionic side chains, are unique sensory materials for the construction of optical biosensors. In this feature article, CPE-based visual detection of heparin is summarized. Three CPE-based heparin probes, including ratiometric, light-up and colormetric probes, are discussed in terms of molecular design, detection selectivity and quantification capability. The work summarized here provides fundamental guidelines for CPE-based label-free visual sensing.

A phalloidin-functionalized hyperbranched conjugated polyelectrolyte (HCPE-phalloidin) is synthesized and used for direct filamentous actin (F-actin) imaging in living Hela cells. Different from co...

Fluorescent nanoparticles were prepared via adsorption of the conjugated polyelectrolyte poly[5-methoxy-2-(3-sulfopropoxy)-1,4-phenylenevinylene] (MPS-PPV) onto 50 and 100 nm aminosilane functionalized silica beads. The particles were investigated via ensemble and single-molecule or -particle spectroscopy techniques to quantify the effect of the silica bead core on the exciton migration efficiency within the polymer. Ensemble emission spectra and ensemble fluorescence quenching studies with methyl viologen are consistent with good exciton migration along the polymer in the polymer-coated bead. The silica nanobead scaffolding preserves the sensitivity of the free polymer and provides a controllable architecture that minimizes nonspecific interactions. Single-particle spectroscopy studies were conducted on particles immobilized onto the positively charged surface of glass cover slips. Particle immobilization enabled us to monitor the effect of oxygen scavenger solutions on individual particles by changing the surrounding solution. The intensity–time trajectories of individual beads provide a mechanism of signal transduction with potential applications in multiplexing studies. Hundreds of individual beads can be imaged in a rapid parallel fashion.

Fluorescent conjugated polyelectrolytes (CPEs) have attracted considerable interest over the past decade as novel materials for developing biosensing schemes and sensing devices for biomolecules. This interest stems from the exquisite polymer sensitivity to the presence of fluorescence quenchers, enabling amplified sensing of molecules of interest. Efficient energy transport along the polymer backbone is critical to their sensing capabilities. Considerable research efforts have thus gone into understanding and controlling energy transport along the polymer backbone. In particular, it has been shown that interactions between CPEs with either surfactants or lipid molecules may significantly reduce energy transport along the polymer backbone that in turn may provide for unique biosensing opportunities. In the first half of this review, we give a historical overview on energy transport in conjugated polymers and polyelectrolytes. In the second half, we summarize the most recent work on the interaction of CPEs with surfactants with an emphasis on our own work elucidating electronic energy transport in CPEs encapsulated into lipid vesicles or embedded within the membrane of lipid vesicles.

This review focuses on novel fluorescent sensing systems for rapid, sensitive, reliable and cost-effective DNA detection in clinical diagnostics. Several materials, including conjugated polyelectrolytes, nanomaterials and molecular beacons, which exhibit attractive properties, are involved to stabilize and to amplify the signal. We describe and evaluate these different DNA analytical methods and give some pointers as to the likely directions of future developments.

Conjugated polyelectrolytes (CPEs) have become one of the most utilized materials in chemo- and bio-sensory systems. Useful properties of CPEs, such as amplified quenching effects and aggregation behavior, are illustrated in detail in order to provide guidelines for underlying concepts of CPE-based sensors. Well established sensing mechanisms, such as conformational changes and fluorescence resonance energy transfer, are reviewed with representative examples. Target species include small ions, small biomolecules, proteins, enzymatic activities, and DNA. New and unique mechanisms for CPE-based sensing are also described.

The conjugated polyelectrolyte (CPE) poly{9,9'-bis[6 ''-(N,N,N-trimethylammonium)-hexylfluorene-alt-co-phenylene] dibromide} (PFPN+Br-) demonstrates a high solubility in methanol in comparison to o ...

Conjugated polyelectrolytes comprise an electronically delocalized backbone with pendant groups bearing ionic functionalities. Important new developments regarding their use to improve charge injection from metallic electrodes into organic semiconductors, a key requirement in emissive devices, have recently appeared. This article provides an overview of recent studies concerning the basic properties of conjugated polyelectrolytes as a function of molecular structure, and of optoelectronic devices with conjugated polyelectrolytes as essential functional components. Processes where more insightful mechanistic understanding is needed and areas of opportunity are discussed.

A fluorescence based assay for human serum-derived phospholipase activity has been developed in which cationic conjugated polyelectrolytes are supported on silica microspheres. The polymer-coated beads are overcoated with an anionic phospholipid (1,2-dimyristoyl-sn-glycero-3-[phospho- rac-(1-glycerol)) (DMPG) to provide "lipobeads" that serve as a sensor for PLA2. The lipid serves a dual role as a substrate for PLA2 and an agent to attenuate quenching of the polymer fluorescence by the external electron transfer quencher 9,10-anthraquinone-2,6-disulfonic acid (AQS). In this case quenching of the polymer fluorescence by AQS increases as the PLA2 digests the lipid. The lipid can also be used itself as a quencher and substrate by employing a small amount of energy transfer quencher substituted lipid in the DMPG. In this case the fluorescence of the polymer is quenched when the lipid layer is intact; as the enzyme digests the lipid, the fluorescence of the polymer is restored. The sensing of PLA2 activity has been studied both by monitoring fluorescence changes in a multiwell plate reader and by flow cytometry. The assay exhibits good sensitivity with EC50 values in the nanomolar range.

International audience; Interfacial engineering is poised to play a key role in delivering solution-processable organic solar cells that simultaneously feature low cost and high efficiency. Here, we report the strategic design, synthesis and characterisation of phosphonium-functionalised polythiophene homo- (P3HTPMe3) and diblock (P3HT-b-P3HTPMe3) conjugated polyelectrolytes (CPEs) coupled with either bromide (Br-) or dodecylsulfate (DS-) surfactant counterions, for application as cathodic interlayers in polymer solar cells. The counterion is shown to have a pronounced effect on the properties of the CPEs in solution. Optical studies revealed that the bulkier DS- counterion hinders interchain interactions more effectively, leading to a moderate blue-shift in the absorption and emission maxima. Similarly, small-angle neutron scattering (SANS) studies also indicated that the solution structures, solvent content, and therefore hydrophobicity, were extremely dependent on both the CPE structure and counterion. The effect of the CPE structure on the thermal properties of the CPE-surfactant complexes was also investigated by Rapid Heat–Cool calorimetry (RHC) measurements. CPE-DS complexes were subsequently employed as cathodic interfacial layers and shown to boost the efficiency of PBDTTPD:PC71BM solar cells, leading to enhanced power conversion efficiencies of 8.65% and 8.78% (on average) for P3HTPMe3,DS and P3HT-b-P3HTPMe3,DS, respectively. These values are siginificantly higher (~20%) than those for the corresponding device incorporating a Ca interfacial layer (7.18%), which is attributed to an increase in short-circuit current density. Atomic force microscopy studies revealed distinctions in the adhesion efficiencies of the CPE-DS complexes to the photoactive layer, which is attributed to differences in the relative hydrophobicity of the CPEs in the deposition solution.

Polymer solar cells have been spotlighted due to their potential for low-cost manufacturing but their efficiency is still less than required for commercial application as lightweight/flexible modules. Forming a dipole layer at the electron-collecting interface has been suggested as one of the more attractive approaches for efficiency enhancement. However, only a few dipole layer material types have been reported so far, including only one non-ionic (charge neutral) polymer. Here we show that a further neutral polymer, namely poly(2-ethyl-2-oxazoline) (PEOz) can be successfully used as a dipole layer. Inclusion of a PEOz layer, in particular with a nanodot morphology, increases the effective work function at the electron-collecting interface within inverted solar cells and thermal annealing of PEOz layer leads to a state-of-the-art 10.74% efficiency for single-stack bulk heterojunction blend structures comprising poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-alt-3-fluorothieno[3,4-b]thiophene-2-carboxylate] as donor and [6,6]-phenyl-C71-butyric acid methyl ester as acceptor., Forming a dipole layer at the electron-collecting interface is a proposed method of efficiency enhancement in solar cells. Here, Nam et al. report the use of PEOz as a dipole layer, which increases the work function at the electron-collecting interface within the polymer solar cell leading to an efficiency of 10.7%.

We use steady-state and nanosecond time-resolved photoluminescence spectroscopy to investigate the evolution of packing interactions in dilute solutions of a sulfonated poly(diphenylenevinylene) lithium salt and its cyclodextrin-threaded polyrotaxanes as a function of the threading ratio (TR) when increasing the temperature from 10 to 40 °C. Contrary to the expectation of a temperature-induced increase of packing and aggregation, supported by previous Raman studies identifying a temperature-induced reduction in the inter-phenyl torsion angles, we find clear spectral (photoluminescence blue-shift and narrowing) and dynamic (shorter lifetimes and reduced weight of the long-lived components) signatures of a reduction of interchain interactions for the polyelectrolytes at higher temperatures with TR up to 1.3.

Despite the recent unprecedented increase in the power conversion efficiencies (PCEs) of small-area devices (≤0.1 cm2 ), the PCEs deteriorate drastically for PSCs of larger areas because of the incomplete film coverage caused by the dewetting of the hydrophilic perovskite precursor solutions on the hydrophobic organic charge-transport layers (CTLs). Here, an innovative method of fabricating scalable PSCs on all types of organic CTLs is reported. By introducing an amphiphilic conjugated polyelectrolyte as an interfacial compatibilizer, fabricating uniform perovskite films on large-area substrates (18.4 cm2 ) and PSCs with the total active area of 6 cm2 (1 cm2 × 6 unit cells) via a single-turn solution process is successfully demonstrated. All of the unit cells exhibit highly uniform PCEs of 16.1 ± 0.9% (best PCE of 17%), which is the highest value for printable PSCs with a total active area larger than 1 cm2 .

Organic–inorganic hybrid perovskite materials offer the potential for realization of low-cost and flexible next-generation solar cells fabricated by low-temperature solution processing. Although efficiencies of perovskite solar cells have dramatically improved up to 19% within the past 5 years, there is still considerable room for further improvement in device efficiency and stability through development of novel materials and device architectures. Here we demonstrate that inverted-type perovskite solar cells with pH-neutral and low-temperature solution-processable conjugated polyelectrolyte as the hole transport layer (instead of acidic PEDOT:PSS) exhibit a device efficiency of over 12% and improved device stability in air. As an alternative to PEDOT:PSS, this work is the first report on the use of an organic hole transport material that enables the formation of uniform perovskite films with complete surface coverage and the demonstration of efficient, stable perovskite/fullerene planar heterojunction solar cells., There is intensive research underway into the development of hole transport layers for perovskite solar cells. Here, the authors report an inverted-type perovskite solar cell with low-temperature solution-processable conjugated polyelectrolyte as the hole transport layer, which exhibits an efficiency of over 12%.

A highly sensitive and selective detection of thrombin is accomplished using an emission color-tunable conjugated polyelectrolyte. An implementation of a combined logic gate was realized upon emission modulation of the system including the polymer, fibrinogen, thrombin, and heparin.

Water-soluble conducting polymers are of interest to enable more versatile processing in aqueous media as well as to facilitate interactions with biomolecules. Here, we report a substituted poly(3,4-ethylenedioxythiophene) derivative (PEDOT-S:H) that is fully water-soluble and self-doped. When electrochemically oxidizing a PEDOT-S:H thin film, the film detaches from the underlying electrode. The oxidation of PEDOT-S:H starts with an initial phase of swelling followed by cracking before it finally disrupts into small flakes and detaches from the electrode. We investigated the detachment mechanism and found that parameters such as the size, charge, and concentration of ions in the electrolyte, the temperature, and also the pH influence the characteristics of detachment. When oxidizing PEDOT-S:H, the positively charged polymer backbone is balanced by anions from the electrolyte solution and also by the sulfonate groups on the side chains (more self-doping). From our experiments, we conclude that detachment of the PEDOT-S:H film upon oxidation occurs in part due to swelling caused by an inflow of solvated anions and associated water and in part due to chain rearrangements within the film, caused by more self-doping. We believe that PEDOT-S:H detachment can be of interest in a number of different applications, including addressed and active control of the release of materials such as biomolecules and cell cultures.