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Lignins released in the black liquors of kraft pulp mills are an underutilised source of aromatics. Due to their phenol oxidase activity, laccases from ligninolytic fungi are suitable biocatalysts to depolymerise kraft lignins, which are characterised by their elevated phenolic content. However, the alkaline conditions necessary to solubilise kraft lignins make it difficult to use fungal laccases whose activity is inherently acidic. We recently developed through enzyme-directed evolution high-redox potential laccases active and stable at pH 10. Here, the ability of these tailor-made alkaliphilic fungal laccases to oxidise, demethylate, and depolymerise eucalyptus kraft lignin at pH 10 is evidenced by the increment in the content of phenolic hydroxyl and carbonyl groups, the methanol released, and the appearance of lower molecular weight moieties after laccase treatment. Nonetheless, in a second assay carried out with higher enzyme and lignin concentrations, these changes were accompanied by a strong increase in the molecular weight and content of β–O–4 and β–5 linkages of the main lignin fraction, indicating that repolymerisation of the oxidised products prevails in one-pot reactions. To prevent it, we finally conducted the enzymatic reaction in a bench-scale reactor coupled to a membrane separation system and were able to prove the depolymerisation of kraft lignin by high-redox alkaliphilic laccase. [ABSTRACT FROM AUTHOR]

Xylanases can boost pulp bleachability in Elemental Chlorine Free (ECF) processes, but their industrial implementation for producing bleached kraft pulps is not straightforward. It requires enzymes to be active and stable at the extreme conditions of alkalinity and high temperature typical of this industrial process; most commercial enzymes are unable to withstand these conditions. In this work, a novel highly thermo and alkaline-tolerant xylanase from Pseudothermotoga thermarum was overproduced in E. coli and tested as a bleaching booster of hardwood kraft pulps to save chlorine dioxide (ClO2) during ECF bleaching. The extremozyme-stage (EXZ) was carried out at 90 °C and pH 10.5 and optimised at lab scale on an industrial oxygen-delignified eucalyptus pulp, enabling us to save 15% ClO2 to reach the mill brightness, and with no detrimental effect on paper properties. Then, the EXZ-assisted bleaching sequence was validated at pilot scale under industrial conditions, achieving 25% ClO2 savings and reducing the generation of organochlorinated compounds (AOX) by 18%, while maintaining pulp quality and papermaking properties. Technology reproducibility was confirmed with another industrial kraft pulp from a mix of hardwoods. The new enzymatic technology constitutes a realistic step towards environmentally friendly production of kraft pulps through industrial integration of biotechnology. [ABSTRACT FROM AUTHOR]

The nonlinear optical and structural properties of both x-type and y-type Langmuir-Blodgett films of nonracemic thiohelicenebisquinone are investigated. The overall properties are found to be independent of the film thickness and deposition type, but depend on the susceptibility tensor components which are associated with chirality.

Electrochemiluminescence (ECL) of aromatic Tb(III) chelates at thin insulating film-coated electrodes provides a means for extremely sensitive detection of Tb(III) chelates and also of biologically interesting compounds if these chelates are used as labels in bioaffinity assays. The suitability of silicon electrodes coated with thermally grown silicon dioxide film as disposable working electrodes in sensitive time-resolved ECL measurements is demonstrated, and a rapid electrochemiluminoimmunoassay (ECLIA) of human C-reactive protein (hCRP) is described. Tb(III) chelate labels can be detected almost down to picomolar level, and the calibration curve of these labels covers more than 6 orders of magnitude of chelate concentration. The calibration curve of the present immunometric hCRP assay was found to be linear over a wide range, ~4 orders of magnitude of hCRP concentration, the detection limit of the protein being 0.3 ng m[L.sup.-1] (mean background + 2SD) on CV values of about 10-30%, depending on the immunoassay incubation time. In the ECLIA measurements, different incubation times were tested from 15 min (giving above-mentioned performance) to as short as only 2 min, which still gave successful results with ~20 000 times better detection limit levels than traditional commercial assay methods. During the ECLIA process, also the Si electrode surface morphology was also investigated by atomic force microscope monitoring.

Scanning probe microscopy (SPM) was utilized to study the thermal behavior of latex films dried under different conditions. Using the SPM probe resonance frequency method, the resonance frequency (ω) of the oscillating probe above the sample surface was followed as a function of temperature (T). Two different approaches for detecting thermal transitions were used and compared. In the heating-by-the-sample approach, the SPM probe acts as a thermal sensor detecting the heat dissipated by the heated sample. In the heating-by-the-probe approach, the SPM probe is utilized simultaneously as an actuator and a sensor: the heated probe both dissipates heat and detects the heat reflected from the sample surface. Thermal transitions in the polymer films could be observed in the Δω-T curves. The results were consistent with those observed by differential scanning calorimetry, but also additional information about the characteristics of the transitions was obtained. The heating-by-the-probe method showed higher surface sensitivity and more localized effects than the other approach. Furthermore, the progress of the latex film formation and the effect of the different drying conditions on film topography were studied by SPM imaging and roughness analysis. Skewness and local surface curvature are demonstrated to serve as useful numerical measures with which to distinguish different levels of particle deformation and the formation of a continuous film. Preannealing of the samples at high temperature influenced not only the topography (roughness) but also the characteristics of the thermal transitions. [ABSTRACT FROM AUTHOR]

Unsymmetrical diynes containing N -arylcarbamate groups in the hydrophobic part and hydroxymethylene groups in the hydrophilic part of the molecules were synthesized and studied. The Langmuir monolayer formation process was followed by Brewster angle microscopy (BAM). The Langmuir-Schaefer monolayer films, transferred on solid substrates (quartz or Si), were investigated by absorption spectroscopy and atomic force microscopy (AFM). Four substances had 2 methylene groups in the hydrophilic part of the molecule (n) and 4 or 5 of these groups in the hydrophobic part (m). At the same time the aryl substituent had a hydrogen atom or a MeO group in the p -position of the benzene ring. After 20 min of UV irradiation the initially colorless monomeric films of all four compounds turned into stable blue phase polymeric films. The blue phase is unusual for alcoholic diacetylene derivatives. The BAM and AFM measurements demonstrated higher homogeneity of the films with a MeO group in the aryl substituent in comparison to the molecules with a hydrogen atom. The reasons for these different structural organizations as well as potential applications of stable blue phase polydiacetylene thin films are discussed. [ABSTRACT FROM AUTHOR]

Solid topochemical photopolymerization (STP) of Langmuir-Schaefer films of a new class of unsymmetrical diynes, containing N -arylcarbamate groups in the hydrophobic part and hydroxymethylene groups in the hydrophilic part of the molecules was examined. In addition, the monomeric Langmuir monolayer formation was studied by Brewster angle microscopy and the surface morphology of monomer and polymer films on solid substrates were studied by scanning electron microscopy and atomic force microscopy. Three phases of polydiacetylene (PDA) (red, purple and blue) were observed after UV-light polymerization of above-mentioned films of alcohol diacetylene (DA) derivatives. The substitution of MeO group in the aryl ring substituent by hydrogen atom and the variation of the methylene group number in the hydrophobic part from 5 to 6 changed significantly the result of STP: instead of blue phase PDA observed for diynes with MeO group, the red phase PDA was observed for DA with H-atom from the very beginning of diyne film UV irradiation. For two other diynilic N -arylcarbamates of identical chemical structures except of the substituents in the aryl ring of hydrophobic parts of the molecules, no changes in the efficiency of polymerization or the position and shape of absorption bands were observed. This indicated the formation of the purple phase PDA. For these molecules, the number of methylene groups in hydrophobic and hydrophilic parts of the molecules was 9 and 2, respectively. [ABSTRACT FROM AUTHOR]

The integration of flexible electronic sensors in clinical diagnostics is visioned to significantly reduce the cost of many diagnostic tests and ultimately make healthcare more accessible. This study concentrates on the characterisation of inkjet-printed bio-functionalised polythiophene films on paper-based ultrathin gold film (UTGF) electrodes and their possible application as biorecognition layers. Physicochemical surface properties (topography, chemistry, and wetting) and electrochemical characteristics of water-soluble regioirregular tetraethylene-glycol polythiophene (TEGPT) and biotin-functionalised TEGPT (b-TEGPT) films were examined and compared. In addition, their specificity towards streptavidin protein was tested. The results show that stable supramolecular biorecognition layers of insulating b-TEGPT and streptavidin were successfully fabricated on a paper-based UTGF by inkjet-printing. Good adhesion of thiophene to UTGF can be attributed to covalent linkage between sulphur and gold, whereas the stability of the streptavidin layer is due to the high affinity between biotin and streptavidin. The device introduced can be utilised in the development of biosensors for clinically relevant analytes e.g. for detecting complementary DNA oligomers or antibody–antigen complexes. [ABSTRACT FROM AUTHOR]

Different length scale alterations in topography, surface texture, and symmetry are known to evoke diverse cell behavior, including adhesion, orientation, motility, cytoskeletal condensation, and modulation of intracellular signaling pathways. In this work, self-supported latex films with well-defined isotropic/anisotropic surface features and hierarchical morphologies were fabricated by a peel-off process from different template surfaces. In addition, the latex films were used as substrates for evaporated ultrathin gold films with nominal thicknesses of 10 and 20 nm. Optical properties and topography of the samples were characterized using UV–vis spectroscopy and Atomic Force Microscopy (AFM) measurements, respectively. The latex films showed high-level transmittance of visible light, enabling the fabrication of semi-transparent gold electrodes. Electrochemical impedance spectroscopy (EIS) measurements were carried out for a number of days to investigate the long-term stability of the electrodes. The effect of 1-octadecanethiol (ODT) and HS(CH 2 ) 11 OH (MuOH) thiolation and protein (human serum albumin, HSA) adsorption on the impedance and capacitance was studied. In addition, cyclic voltammetry (CV) measurements were carried out to determine active medicinal components, i.e., caffeic acid with interesting biological activities and poorly water-soluble anti-inflammatory drug, piroxicam. The results show that the fabrication procedure presented in this study enables the formation of platforms with hierarchical morphologies for multimodal (optical and electrical) real-time monitoring of length-scale-dependent biomaterial-surface interactions. [ABSTRACT FROM AUTHOR]

Appropriate and fine-tuned treatments of amorphous carbon (AC) involving aqua regia or concentrated HNO3 lead to oxidised carbon materials (oAC) which are able to catalyse 2,2'- and 3,3'- homocouplings of various functionalised indoles with outstanding activity. This newly developed carbocatalysed Csp²-Csp² bond formation can be achieved under mild thermal conditions. The study on the scope of the reaction revealed that the reaction can be extended to the homocoupling of other substrates of high synthetic interest such as 2-naphthol, 2-functionalised benzofurans and benzothiofurans. The characterisation of oAC with XPS together with ad hoc experiments aimed at blocking the active site revealed that the presence and distribution of C=O functionalities is critical and correlates well with the catalytic activity. Such experiments provide solid support for elucidation of the mechanism, suggesting a quinone nature of the active C= O groups, which are spontaneously regenerated by oxygen. This is confirmed by the fact that 2,3-dichloro- 5,6-dicyano-1,4-benzoquinone (DDQ) is able to promote the coupling in a stoichiometric fashion. [ABSTRACT FROM AUTHOR]

A roll-to-roll compatible fabrication process of porous silicon (pSi) based sensing elements for a real-time humidity monitoring is described. The sensing elements, consisting of printed interdigitated silver electrodes and a spray-coated pSi layer, were fabricated on a coated paper substrate by a two-step process. Capacitive and resistive responses of the sensing elements were examined under different concentrations of humidity. More than a three orders of magnitude reproducible decrease in resistance was measured when the relative humidity (RH) was increased from 0% to 90%. A relatively fast recovery without the need of any refreshing methods was observed with a change in RH. Humidity background signal and hysteresis arising from the paper substrate were dependent on the thickness of sensing pSi layer. Hysteresis in most optimal sensing element setup (a thick pSi layer) was still noticeable but not detrimental for the sensing. In addition to electrical characterization of sensing elements, thermal degradation and moisture adsorption properties of the paper substrate were examined in connection to the fabrication process of the silver electrodes and the moisture sensitivity of the paper. The results pave the way towards the development of low-cost humidity sensors which could be utilized, for example, in smart packaging applications or in smart cities to monitor the environment. [ABSTRACT FROM AUTHOR]

ABSTRACT Patterning of functionalized polymeric surfaces enables the adjustment of their characteristics and use in novel applications. We prepared breath figure (BF) films from three semifluorinated diblock copolymers, which all are composed of a polystyrene block and a semifluorinated one to compare their surface properties. 'Click' chemistry was employed to one of the polymers, containing a poly(pentafluorostyrene) block to incorporate hydrophilic sugar or carboxylic acid moieties. The structure of the polymer alters the obtained porous morphology of the films. Contact angle (CA) analyses of the BF films reveals that the surface porosity increases water CAs compared with solvent cast films, and, in the case of hydrophobic polymers, leads to significant increase in the CAs of dodecane. The hydrophobicity of the BF films is further amplified by the removal of the topmost layer which leads in some cases to superhydrophobic surfaces. BF films containing glucose units are hydrophilic exhibiting water CAs below 90°. These glycosylated porous surfaces are shown to bind lectin Con A-FITC or can be labelled with isothiocyanate marker. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41225. [ABSTRACT FROM AUTHOR]

Controlling the nanostructure of polymeric films using cost-effective deposition methods, like inkjet printing, has proven challenging due to the relative low resolution of such techniques. In this study, we combine inkjet printing with the use of nanopatterned substrates composed of TiO2 thin films on top of silicon wafers (NP-TiO2) for the preparation of polymeric films with similar surface morphologies. First, the evaporation induced self-assembly (EISA) process was used in the presence of a block co-polymer (polybutadiene-b-polyethyleneoxide) to prepare the NP-TiO2 substrates. The TiO2 ridges can be selectively modified with a hydrophobic perfluorinated phosphate, Zonyl FSE (ZFNP-TiO2). Conducting polymers (biotinylated polythiophene and polyaniline) were inkjet-printed both onto NP-TiO2 and ZFNP-TiO2 substrates, resulting either in continuous polymeric thin films or matrixes with separate droplets, respectively. The high surface energy determined for the NP-TiO2 substrate deemed it more suitable for the deposition of uniform and nanometer thin polymer layers. In fact, atomic force microscopy demonstrates that the deposited polymers are evenly distributed over the substrate surface while the nanopatterned structure is maintained. We conclude that the combination of inkjet printing and nanotemplating is a simple and cost-efficient way to fabricate nanopatterned polymer films with high potential in biosensing and electrical devices. [ABSTRACT FROM AUTHOR]

In this study, two different supramolecular recognition architectures for impedimetric detection of DNA hybridization have been formed on disposable paper-supported inkjet-printed gold electrodes. The gold electrodes were fabricated using a gold nanoparticle based ink. The first recognition architecture consists of subsequent layers of biotinylated self-assembly monolayer (SAM), streptavidin and biotinylated DNA probe. The other recognition architecture is constructed by immobilization of thiol-functionalized DNA probe (HS-DNA) and subsequent backfill with 11-mercapto-1-undecanol (MUOH) SAM. The binding capacity and selectivity of the recognition architectures were examined by surface plasmon resonance (SPR) measurements. SPR results showed that the HS-DNA/MUOH system had a higher binding capacity for the complementary DNA target. Electrochemical impedance spectroscopy (EIS) measurements showed that the hybridization can be detected with impedimetric spectroscopy in picomol range for both systems. EIS signal indicated a good selectivity for both recognition architectures, whereas SPR showed very high unspecific binding for the HS-DNA/MUOH system. The factors affecting the impedance signal were interpreted in terms of the complexity of the supramolecular architecture. The more complex architecture acts as a less ideal capacitive sensor and the impedance signal is dominated by the resistive elements. [ABSTRACT FROM AUTHOR]

Abstract: Background: Cheap, reliable, point-of-care diagnostics is a necessity for the growing and aging population of the world. Paper substrate and printing method, combined together, are the cheapest possible method for generating high-volume diagnostic sensor platforms. Electrical transduction tools also minimize the cost and enhance the simplicity of the devices. Methods: Standard surface characterization techniques, namely contact angle measurements, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were used to analyze the growth of the organic thiol layers on top of the printed metal electrodes on paper substrates. The results were compared with those obtained by impedimetric electrical characterization method. Results: This article reports the fabrication and characterization of printed metal electrodes and their functionalization by organic layers on paper and plastic substrates for biosensing and diagnostic applications. Impedimetric measurement is proposed as a simple, yet elegant, method of characterization of the organic layer growth. Conclusions: Very good correlation was observed between the results of organic layer growth from different measurement methods, justifying the use of paper as a substrate, printing as a method for fabricating metal and organic layers and impedance as a suitable measurement method for hand-held diagnostic devices. General significance: This result paves the way for the fabrication of more advanced bio-recognition layers for bio-affinity sensors using a printing technology that is compatible with flexible and cheap paper substrates. This article is part of a Special Issue entitled Organic Bioelectronics — Novel Applications in Biomedicine. [Copyright &y& Elsevier]

In this article, we report on the formation and mode-of-operation of an affinity biosensor, where alternate layers of biotin/streptavidin/biotinylated-CRP-antigen/anti-CRP antibody are grown on printed gold electrodes on disposable paper-substrates. We have successfully demonstrated and detected the formation of consecutive layers of supra-molecular protein assembly using an electrical (impedimetric) technique. The formation process is also supplemented and verified using conventional surface plasmon resonance (SPR) measurements and surface sensitive characterization techniques, such as X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The article provides a possible biosensor development scheme, where--(1) fabrication of paper substrate (2) synthesis of gold nanoparticle inks (3) inkjet printing of gold electrodes on paper (4) formation of the biorecognition layers on the gold electrodes and (5) electrical (impedimetric) analysis of growth--all are coupled together to form a test-structure for a recyclable and inexpensive point-of-care diagnostic platform. [ABSTRACT FROM AUTHOR]

Thin and narrow conductive patterns of metal (silver)and organicpolymer (polyaniline) were printed on various coated paper samples.A detailed characterization of the physical properties (i.e., shortlength scale roughness, surface energy, and air permeability) of thepaper samples was conducted. These properties were correlated withprint quality (print resolution and edge waviness) and electricalperformance (resistance) of the printed wires. A plastic film wasused as a reference substrate. The print resolution and the magnitudeof the edge waviness were affected by the complex interplay of differentphysical properties of both the substrate and the ink. On the otherhand, the resistance of the printed wires was found to correlate linearlywith the short length scale roughness of the print substrate. Theelectrical performance of the paper substrates showing the highestconductivity for the printed patterns was comparable to that of theplastic film. The paper substrate on which the printed wires showedthe best electrical performance was used as a substrate for fabricationof an organic transistor with low operating voltage. [ABSTRACT FROM AUTHOR]

Abstract: In this study, torsional harmonic atomic force microscopy (TH-AFM, HarmoniX mode) was applied for surface mapping of the mechanical properties of pigment-latex coated paper samples. In addition, topographic images and force maps of adhesive tip-sample interactions were captured concurrently. The spatial distribution of latex binder on the composite surface was distinguished with high resolution. The latex was found to dominate the surface chemistry of the composite coating, despite the fact that latex is a minor component in the coating color formulation. The latex resided as a thick layer between the pigments and as a thin layer on the individual pigments. In addition, the tip-sample thermodynamic work of adhesion of the composite materials on the coated surface was compared to the surface energy values obtained by contact angle measurements. A high tip-sample work of adhesion correlated to high surface energy. [ABSTRACT FROM AUTHOR]

Photoinduced intra- and intermolecular electron transfer (ET) in thin films of porphyrin–fullerene dyad (P–F) and perylenetetracarboxidiimide (PTCDI) was studied by means of photoelectrical and spectroscopic methods. Films consisting of smooth 100 mol% layers of P–Fand PTCDIwere prepared by the Langmuir–Schäfer (LS) technique and thermal evaporation, respectively. The time-resolved Maxwell displacement charge (TRMDC) and laser flash-photolysis methods were utilized to demonstrate photoinduced ET from P–Fto PTCDIregardless of which chromophore is photoexcited. Finally, the information about the electron movement in the respective thin films was used to build a layered organic solar cell, whose internal quantum yield (ΦI) of collected charges was 13%. [ABSTRACT FROM AUTHOR]

Abstract: Wetting and printing properties of recently developed smooth multilayer coated papers suitable for printed functionality have been investigated. Spreading of a semiconducting polymer poly(3-hexylthiophene) (P3HT) dissolved in ortho-dichlorobenzene (o-DCB) was studied both by contact angle measurements (macro-scale drop) and inkjet printing experiments (micro-scale droplet). In addition, film formation and final print quality of inkjetted P3HT was analyzed by topographical, chemical and optical characterization. Results were compared to reference substrates, poly(ethylene terephthalate) (PET) plastic and atomically flat mica. Wetting rate of the macro-scale drop was strongly influenced by the magnitude of surface extremes (asperties). Maximal spreading of inkjet droplets was affected by roughness, surface energy, pore volume and geometry of the substrate. Both the film formation of successive printings and the final film quality were comparable for the paper substrates and the PET film. Therefore the multilayer coated paper can be used instead of plastic films to reduce environmental impact. For example, low-cost disposable electronics can thus be made recyclable. [ABSTRACT FROM AUTHOR]

The article presents a study on the thermal characteristics of latex films with blends of two styrene-butadiene copolymers with different glass transition temperatures using scanning probe microscopy (SPM). The results showed the high sensitivity of SPM in detecting thermal transitions even though glass transitions are linked with a very small change in heat capacity. It was also found that thermal annealing in an oven had no effect on the transition associated with the change in heat capacity.

The relative thermodynamic stabilities of 4,7-dihydro-1,3-dioxepin (4,6-dioxacycloheptene, 1a) and 4,5-dihydro-1,3-dioxepin (3,5-dioxacycloheptene, 1b), and of a number of their 2-substituted derivatives, have been determined by base-catalyzed chemical equilibration in DMSO solution. Without exception, the 4,5-dihydro isomer is the dominating species at thermodynamic equilibrium. The relative stability of the b form is promoted by the presence of a single alkyl group on C-2, whereas two alkyl groups on C-2 have an opposite effect. In general, the thermodynamic parameters Δ H and Δ, of isomerization vary unexpectedly with the pattern of substitution at C-2. These trends appear to be derived from significant substituent-induced conformational changes in the b isomer, as suggested by 13C and 17O NMR chemical shift data. [ABSTRACT FROM AUTHOR]