Molecularly imprinted polymers for per- and polyfluoroalkyl substances enrichment and detection.

Per- and polyfluoroalkyl substances (PFAS) are highly toxic pollutants of significant concern as they are being detected in water, air, fish and soil. They are extremely persistent and accumulate in plant and animal tissues. Traditional methods of detection and removal of these substances use specialised instrumentation and require a trained technical resource for operation. Molecularly imprinted polymers (MIPs), polymeric materials with predetermined selectivity for a target molecule, have recently begun to be exploited in technologies for the selective removal and monitoring of PFAS in environmental waters. This review offers a comprehensive overview of recent developments in MIPs, both as adsorbents for PFAS removal and sensors that selectively detect PFAS at environmentally-relevant concentrations. PFAS-MIP adsorbents are classified according to their method of preparation (e.g., bulk or precipitation polymerization, surface imprinting), while PFAS-MIP sensing materials are described and discussed according to the transduction methods used (e.g., electrochemical, optical). This review aims to comprehensively discuss the PFAS-MIP research field. The efficacy and challenges facing the different applications of these materials in environmental water applications are discussed, as well as a perspective on challenges for this field that need to be overcome before exploitation of the technology can be fully realised.

Influence of Sharklet-Inspired Micropatterned Polymers on Spatio-Temporal Variations of Marine Biofouling.

This article aims to show the influence of surface characteristics (microtopography, chemistry, mechanical properties) and seawater parameters on the settlement of marine micro- and macroorganisms. Polymers with nine microtopographies, three distinct mechanical properties, and wetting characteristics are immersed for one month into two contrasting coastal sites (Toulon and Kristineberg Center) and seasons (Winter and Summer). Influence of microtopography and chemistry on wetting is assessed through static contact angle and captive air bubble measurements over 3-weeks immersion in artificial seawater. Microscopic analysis, quantitative flow cytometry, metabarcoding based on the ribulose biphosphate carboxylase (rbcL) gene amplification, and sequencing are performed to characterize the settled microorganisms. Quantification of macrofoulers is done by evaluating the surface coverage and the type of organism. It is found that for long static in situ immersion, mechanical properties and non-evolutive wettability have no major influence on both abundance and diversity of biofouling assemblages, regardless of the type of organisms. The apparent contradiction with previous results, based on model organisms, may be due to the huge diversity of marine environments, both in terms of taxa and their size. Evolutive wetting properties with wetting switching back and forth over time have shown to strongly reduce the colonization by macrofoulers.

Detection of Bisphenol A in aqueous medium by screen printed carbon electrodes incorporating electrochemical molecularly imprinted polymers.

Electrochemical molecularly imprinted polymers (e-MIPs) were for the first time introduced in screen-printed carbon electrodes (SPCE) as the sensing element for the detection of an organic pollutant. To play this sensing role, a redox tracer was incorporated inside the binding cavities of a cross-linked MIP, as a functional monomer during the synthesis step. Ferrocenylmethyl methacrylate was used for this purpose. It was associated with 4-vinylpyridine as a co-functional monomer and ethylene glycol dimethacrylate as cross-linker for the recognition of the endocrine disruptor, Bisphenol A (BPA), as a target. Microbeads of e-MIP and e-NIP (corresponding non-imprinted polymer) were obtained via precipitation polymerization in acetonitrile. The presence of ferrocene inside the polymers was assessed via FTIR and elemental analysis and the polymers microstructure was characterized by SEM and nitrogen adsorption/desorption experiments. Binding isotherms and batch selectivity experiments evidenced the presence of binding cavities inside the e-MIP and its high affinity for BPA compared to carbamazepine and ketoprofen. e-MIP (and e-NIP) microbeads were then incorporated in a graphite-hydroxyethylcellulose composite paste to prepare SPCE. Electrochemical properties of e-MIP-SPCE revealed a high sensitivity in the presence of BPA in aqueous medium compared to e-NIP-SPCE with a limit of detection (LOD) of 0.06 nM. Selectivity towards carbamazepine and ketoprofen was also observed with the e-MIP-SPCE.

96X Screen-Printed Gold Electrode Platform to Evaluate Electroactive Polymers as Marine Antifouling Coatings.

Several alternatives are currently investigated to prevent and control the natural process of colonization of any seawater submerged surfaces by marine organisms. Since few years we develop an approach based on addressable electroactive coatings containing conducting polymers or polymers with lateral redox groups. In this article we describe the use of a screen-printed plate formed by 96 three-electrode electrochemical cells to assess the potential of these electroactive coatings to prevent the adhesion of marine bacteria. This novel platform is intended to control and record the redox properties of the electroactive coating in each well during the bioassay (15 h) and to allow screening its antiadhesion activity with enough replicates to support significant conclusions. Validation of this platform was carried out with poly(ethylenedioxythiophene) (PEDOT) as electroactive coating obtained by electropolymerization of EDOT monomer in artificial seawater electrolyte on the working electrode of each electrochemical cell of the 96-well microplate.

Bacterial anti-adhesion activity based on the electrochemical properties of polymethacrylates bearing ferrocenyl pendant groups.

Much current research is focused on preventing and controlling the natural process of colonization by marine organisms of surfaces submerged in seawater. Previously, the authors' laboratory has reported the synthesis and the full physico-chemical characterization of homopolymers obtained from 1-ferrocenylmethyl methacrylate (FMMA), 2-(ferrocenylmethoxy)ethyl methacrylate (FMOEMA), and 3-(ferrocenylmethoxy)propyl methacrylate (FMOPMA). Here, the bacterial anti-adhesion activity of these homopolymers (pFMMA, pFMOEMA and pFMOPMA) is reported when stimulated in 96-well microplates containing a printed electrochemical cell in each well. Polymers were deposited on the printed carbon working electrode of each well in two columns each comprising eight wells. Their electrochemical anti-adhesion properties were evaluated by inoculating a marine biofilm forming bacterial strain, Pseudoalteramonas lipolytica, in each well and then applying recurrent scans for 15 h. The results revealed an intrinsic anti-adhesion activity of all the polymers. This activity was amplified by a factor of 10 when potential recurrent scans were applied.

Assessment and modelling of Ni(II) retention by an ion-imprinted polymer: application in natural samples.

Three novel Ni(II)-Ion-Imprinted Polymer (IIP) were synthesized by precipitation polymerization of ethylene glycol dimethacrylate (crosslinker) with a complex of nickel(II) and vinylbenzyl iminodiacetic acid (VbIDA). The three IIPs were prepared with various mixtures of porogen solvents: methanol, methanol/2-methoxyethanol and methanol/acetonitrile (IIP1, IIP2 and IIP3, respectively). Non-Imprinted Polymers (NIP1, NIP2 and NIP3) were prepared as control polymers in similar conditions but with pure VbIDA instead of VbIDA-Ni. These polymers were characterized by FTIR, BET, SEM and tested for their efficiency and selectivity in Ni(II) retention. The most efficient (IIP1, around 12 mg g(-1) of nickel) was then positively checked for Ni(II) retention in presence of some competing species over a wide range of concentration. Finally Ni(II) retention by IIP1 was successfully demonstrated in natural samples. The modelling of the different experiments (Langmuir, Freundlich but also PROSECE and WHAM VII, frequently used in environmental studies) allowed demonstrating the presence of completely different binding sites when considering the ion-imprinted polymer and the non-imprinted one, and therefore led to a better understanding of what the imprinting effect is.

Effect of template ion-ligand complex stoichiometry on selectivity of ion-imprinted polymers.

In order to highlight the importance of the complex stoichiometry during ion imprinted polymer (IIP) synthesis, we investigated the effect of the complex structure on IIPs selectivity by adjusting the complex stoichiometry before polymerization. 2-(aminomethyl)pyridine monomer (amp) was chosen as a functionalized ligand for nickel(II) ions and a polymerizable vinylbenzyl derivative (Vbamp) was prepared. Complex formation was studied by varying the nickel/Vbamp ratio and recording absorption spectra of the complexes at the polymerization conditions. Using a least-squares minimization scheme, the complex species distribution was successfully established. From these results, it was possible to choose the metal/ligand stoichiometry in the complex (1:1; 1:2 or 1:3) by adjusting the initial metal/ligand ratio. IIPs were then prepared by inverse suspension copolymerization of Vbamp with ethyleneglycol dimethacrylate (EDMA). Highly porous particles with good nickel binding capacity and good Ni/Zn selectivity even at acidic conditions were obtained. Equilibrium uptake of Ni(II) at pH 7 ranged from 0.12 to 0.2 mmol g(-1) and relative selective coefficient was as high as 260 for the IIP prepared using the Ni(Vbamp)2 complex.

A versatile electrochemical sensing receptor based on a molecularly imprinted polymer.

Electrochemical molecularly imprinted polymers (e-MIPs) are reported for the first time. Their elaboration is based on the introduction of a redox tracer (vinylferrocene) inside the binding cavities of a cross-linked MIP. Determination of the analyte (benzo[a]pyrene) can be simply performed by measuring the redox tracer signal.

Highly specific and reversible fluoride sensor based on an organic semiconductor.

A novel sulfonamide-conjugated benzo-[2,1-b:3,4-b']bithiophene semiconductor has been designed and synthetized in order to develop a probe for specific detection of anions both in the homogeneous (solution) and heterogeneous phase. Its photophysical and electrochemical data were reported in this study. On the basis of the optical and NMR titrations analysis, the chelator was found to be highly selective for fluoride compared to others anions (Ka = 1.6 × 10(4) M(-1) in dimethyl sulfoxide (DMSO)). In addition, from an intricate sample, the novel chelator shows exceptional specificity toward fluoride and reveals a complete reversibility after addition of trifluoroacetic acid (TFA). Sensing films were obtained by electrochemical polymerization of the probe on an electrode surface, which clearly show effective detection of fluoride.

Co-grafting of porphyrins and fullerenes on ZnO nanorods: towards supramolecular donor-acceptor assembly.

This work presents the synthesis and physico-chemical characterization of a novel artificial photosynthetic design, using anisotropic semiconducting nanorods as scaffolds to assemble organic donor-acceptor complexes on their surface. These hierarchical hybrid D-A assemblies were obtained by the co-grafting of porphyrins and fullerenes on the ZnO nanorods. Polarity of the solvent and porphyrin to fullerene ratios were investigated to be markedly influencing the donor-acceptor interaction under the co-grafted conditions on ZnO nanorods. Fourier transform infrared spectroscopy, cyclic voltammetry, electronic absorption and fluorescence spectroscopic techniques were used to characterize the formation and investigate the optoelectronic properties of porphyrin-fullerene complexes on the surface of ZnO. To the best of our knowledge, this is the first example of highly interacting porphyrin-fullerene complexes on ZnO nanorods, which may allow generating efficient nanosystems for artificial photosynthesis and harvesting of solar energy.

Acetylenic spacers in phenylene end-substituted oligothiophene core for highly air-stable organic field-effect transistors.

Two thiophene-phenylene semiconductors, bis(2-phenylethynyl) end-substituted oligothiophenes (diPhAc-nTs, n = 2, 3), were synthesized and studied with respect to their optical, electrochemical, structural and electrical properties. The optical and electrochemical properties of the oligomers in solution were investigated by UV-vis absorption and photoluminescence spectroscopies, and cyclic voltammetry. High vacuum evaporated thin films were investigated by optical absorption, X-ray diffraction and AFM, and implemented as p-type semiconducting layers into organic thin-film transistors (OTFTs). A comparative study in solution and in the solid state with distyryl-oligothiophenes (DSnTs, n = 2, 3) reveals the great influence of acetylenic (-C[triple bond]C-) vs. olefinic (-C=C-) spacers in thiophene-phenylene derivatives on electronic structure, physical properties, and device efficiencies. Substituting olefinic for acetylenic pi-spacers in terthiophene-based conjugated semiconductors leads to one of incontrovertible attributes of OTFTs for low cost applications, a high mobility at low substrate temperature (T(sub)) i.e. typically 25 degrees C. Fine-tuning in the HOMO/LUMO levels by reducing the HOMO level introduces increased air-oxidation strength of thin films where OTFTs provide exactly the same hole mobility value after 100 days in air. All the results suggested that introduction of carbon-carbon triple bonds provided an efficient route to highly air-stable organic thin film transistors.

Internally referenced analysis of charge-transfer reactions in a new ferrocenyl bithiophenic conducting polymer through cyclic voltammetry.

A new ferrocenyl bithiophenic polymer has enabled the first demonstration of internally referenced quantitative analysis of charge-transfer reactions, which may enable better understanding and applications of conducting polymers in e.g. supercapacitors.

A "kite" shaped styryl end-capped benzo[2,1-b:3,4-b']dithiophene with high electrical performances in organic thin film transistors.

The bridging of distyryl-bithiophene leads to a kite shape of the conjugated system. This twist is not like twistacenes or twist deformation in alpha-oligothiophenes but a curvature such as in bowl shaped systems. Initially perceived to be undesirable, this new semiconductor in OTFT devices provides excellent performances in air, mu = 0.1 cm(2)/V.s, I(on)/I(off) > 10(6), S < 4 V/decade, higher by a factor of 5 to the parent unbridged coplanar analogue.

Efficient synthesis of substituted dihydrotetraazapentacenes.

We describe a versatile and very efficient synthesis of previously unknown substituted 5,14-dihydro-5,7,12,14-tetraazapentacenes (DHTAPs). A structural study by NMR spectroscopy showed that the conjugated pi-system of the pentacyclic skeleton rearranges depending on the electronic effect of the substituent(s).

The first automated synthesis of ferrocene-labelled phosphorothioate DNA probe: a new potential tool for the fabrication of DNA microarrays.

We report the synthesis and the characterisation of the first electroactive ferrocene-labelled oligonucleotide phosphorothioate (ODN-Fc-Ps) probe obtained by automated synthesis. The grafting of ODN-Fc-Ps probe on gold electrode resulted in the appearance of the ferrocene redox couple in cyclic voltammetry confirming the effectiveness of the ODN grafting. The electrochemical response of the modified electrode was analysed in aqueous media before and after hybridisation with ODN target. The hybridisation with ODN target induces a large conformational change in the surface-confined DNA structure monitored by cyclic voltammetry of the ferrocene marker which confirms the potential of ferrocene-labelled oligonucleotide phosphorothioate to develop electrochemical DNA chips.

Alpha,omega-distyryl oligothiophenes: high mobility semiconductors for environmentally stable organic thin film transistors.

Critical to the development of organic electronics is the design and synthesis of new organic semiconductors with improved electrical performance and enhanced environmental stability. We present in this communication the synthesis of a series of simple oligothiophene derivatives that bear the styryl unit as terminal substituent. Thin film field-effect transistors incorporating these compounds show high electrical performance, such as mobilities as high as 0.1 cm2/Vs, along with exceptional stability under ambient conditions. Especially, the longer oligomer, DS-4T, containing the quaterthiophene core gives rise to devices that show no decrease in performance after more than 17 months of storage and under continuous operation. Such stability features are unprecedented in the oligothiophene series.

Automated synthesis of new ferrocenyl-modified oligonucleotides: study of their properties in solution.

We have developed new ferrocenyl-modified oligonucleotide (ODN) probes for electrochemical DNA sensors. A monofunctional ferrocene containing phosphoramidite group has been prepared, and a new bisfunctional ferrocene containing phosphoramidite and dimethoxytrityl (DMT) groups has been developed. These ferrocenyl-phosphoramidites have been directly employed in an automated solid-phase DNA synthesizer using phosphoramidite chemistry. The advantages of this method are that it allows a non-specialist in nucleotide chemistry to access labeled ODNs and that it has demonstrated good results. ODNs modified at the 3' and/or 5' extremities have been prepared, with the incorporation of the ferrocenyl group into the chain. The 5' position appears to be more important due to its particular behavior. The thermal stability and electrochemical properties of these new ODN ferrocenes were analyzed before and after hybridization with different ODNs. The feasibility of using these new ferrocenyl-labeled ODNs in DNA sensors has been demonstrated.

Supported synthesis of ferrocene modified oligonucleotides as new electroactive DNA probes.

The use of 1-[3-O-(2-cyanoethyl-N,N-diisopropylphosphor amidityl)propyl]ferrocene and 1-[3-O-dimethoxytrityl propyl]-1'-[3'-O-(2-cyanoethyl-N,N-diisopropylphosphoramidityl) propyl] ferrocene as reactive synthons for DNA/RNA synthesizer allows to generate ferrocene-labelled oligonucleotides with remarkable DNA detection properties.

Bridged Dithienylethylenes as Precursors of Small Bandgap Electrogenerated Conjugated Polymers.

Bridged dithienylethylenes (DTEs) bearing solubilizing alkyl chains at various positions (2-5) have been synthesized by McMurry dimerization of cyclopenta[b]thiophen-6-ones. In order to introduce alkyl substituents at different positions of the DTE molecule, the precursor ketones have been prepared by different strategies based on a combination of Mannich or Wittig-Horner reaction and Friedel-Craft intramolecular cyclization. The position and the length of the alkyl substituents exert a strong effect on the ability of the precursor to undergo electrochemical polymerization. Thus, whereas substitution at the alpha-position of the ethylene linkage (3) results in a rapid inhibition of electropolymerization, introduction of alkyl chains at the beta-position (4, 5) greatly improves the efficiency of the polymerization process. The analysis of the electrochemical and optical properties of the polymers shows that rigidification of the DTE molecule leads to a significant decrease of the oxidation potential and bandgap. A comparative analysis of DTE and its bridged analogues by means of X-ray diffraction reveals, in agreement with experimental and theoretical results, that the observed reduction of both the HOMO-LUMO gap of the precursor and the bandgap of the corresponding polymers are related to a relaxation of bond length alternation in the DTE moiety.