Dialysis and column chromatography for biomass pyrolysis liquids separation.

In the current study, a novel approach for separating value-added chemicals from pine wood residues' pyrolysis liquids (bio-oil) was effectively carried out. It combined two separation techniques used for the first time in this field: dialysis with water, methanol and acetone, and column chromatography with Amberlite™ XAD7 resin. This strategy made it possible to separate bio-oil into four fractions: (1) pyrolytic lignin, which can be utilized in the synthesis of resins, foams, electrodes, asphalt, etc.

The effect of reactor scale on biochars and pyrolysis liquids from slow pyrolysis of coffee silverskin, grape pomace and olive mill waste, in auger reactors.

Several studies have addressed the potential biorefinery, through small-scale pyrolysis, of coffee silverskin (CSS), grape pomace (GP) and olive mill waste (OMW), which are respectively the main solid residues from coffee roasting, wine making and olive oil production processes. However, increasing the scale of reactor to bring these studies to an industrial level may affect the properties, and hence applications, of the resulting products. The aim of this study is therefore to perform pilot scale experiments to compare and verify the results of analytical study (TGA) and bench scale reactor runs, in order to understand the fundamental differences and create correlations between pyrolysis runs at different scales.

Production of antioxidants and other value-added compounds from coffee silverskin via pyrolysis under a biorefinery approach.

The coffee roasting industry produces about 0.4 Mt of coffee silverskin (CSS) per year, the only residue generated from the roasting process that is mostly disposed as industrial waste. The aim of this study is to convert CSS into value-added products by intermediate pyrolysis, transforming the waste into a resource within an integrated biorefinery perspective.

Amperometric biosensor for the determination of histamine in fish samples.

A bienzymatic biosensor employing diamine oxidase (DOx) and horseradish peroxidase (HRP) for the detection of histamine in fish samples has been developed and optimized in this work. These enzymes have been co-immobilized into a polysulfone/carbon nanotubes/ferrocene membrane by means of phase inversion technique onto screen-printed electrodes. The electrochemical measurements have been carried out in phosphate buffer solution at pH 8.

Amperometric bienzymatic biosensor for L-lactate analysis in wine and beer samples.

A novel amperometric bienzymatic biosensor has been developed based on the incorporation of Lactate Oxidase (LOx) and Horseradish Peroxidase (HRP) into a carbon nanotube/polysulfone membrane by the phase inversion technique onto screen-printed electrodes (SPEs). In order to improve the sensitivity and reduce the working potential, experimental conditions have been optimized and ferrocene has also been incorporated into the membrane as a redox mediator of the enzymatic reactions, which allows the reduction of H(2)O(2) at -100 mV. Measurements were carried out in phosphate buffer solution at pH 7.

Employing the metabolic "branch point effect" to generate an all-or-none, digital-like response in enzymatic outputs and enzyme-based sensors.

Here, we demonstrate a strategy to convert the graded Michaelis-Menten response typical of unregulated enzymes into a sharp, effectively all-or-none response. We do so using an approach analogous to the "branch point effect", a mechanism observed in naturally occurring metabolic networks in which two or more enzymes compete for the same substrate. As a model system, we used the enzymatic reaction of glucose oxidase (GOx) and coupled it to a second, nonsignaling reaction catalyzed by the higher affinity enzyme hexokinase (HK) such that, at low substrate concentrations, the second enzyme outcompetes the first, turning off the latter's response.

Detection of biomarkers with carbon nanotube-based immunosensors.

A facile and capable method of preparation of sensitive carbon nanotube (CNT)/polysulfone/RIgG immunosensor is discussed in this chapter. The immunosensor is based on the modification of disposable screen-printed electrodes by phase inversion method. CNT/polysulfone membrane acts as the reservoir of immunomolecules as well as a transducer.

The first isoform-selective protein biosensor: a metallothionein potentiometric electrode.

The construction of a biosensor membrane by embedding mammalian Zn(7)-MT1 complexes as ionophores in a polysulfone matrix resulted in precise, accurate and, significantly, selective electrodes for MT1 quantification, so that the presence of other mammalian MT isoforms did not interfere in MT1 measurement.

Carbon nanotube/polysulfone soft composites: preparation, characterization and application for electrochemical sensing of biomarkers.

Multi-walled carbon nanotube/polysulfone soft composites (MWCNT/PSf) prepared via phase inversion are a novel platform for electrochemical and electroanalytical purposes with practical applications in the design of screen-printed electrodes for electrochemical sensing. We present here a thorough characterization of the morphological, physical, chemical and electrochemical properties of this material. These composites constitute a robust mesoporous network with high specific surface area, which is beneficial for trapping bioanalytes and increasing the electrochemical sensitivity.

Novel potentiometric sensors based on polysulfone immobilized metallothioneins as metal-ionophores.

We show here the use of immobilized metal-binding biomolecules for metal analysis by using novel potentiometric sensors. To this end and as a model, Ag(+)-ISEs were developed using polysulfone matrix embedding metallothioneins as ionophores (mouse MT1 (P1) or sea urchin SpMTA (P2)). Polysulfone, a porous polymer that was not used until the present in potentiometric biosensors, has the advantage of being compatible with biological materials.

Electrochemical activation of carbon nanotube/polymer composites.

Electrochemical activation of carbon nanotube/polysulfone composite electrodes for enhanced heterogeneous electron transfer is studied. The physicochemical insight into the electrochemical activation of carbon nanotube/polymer composites was provided by transmission electron microscopy, Raman spectroscopy, electrochemical impedance spectroscopy, and cyclic voltammetry. Dopamine, ascorbic acid, NADH, and ferricyanide are used as a model redox system for evaluating the performance of activated carbon nanotube/polymer composite electrodes.

Toward a fast, easy, and versatile immobilization of biomolecules into carbon nanotube/polysulfone-based biosensors for the detection of hCG hormone.

The aim of this study was the fabrication and characterization of biomembranes by the phase inversion (PI) method followed by their subsequent casting onto screen-printed electrodes (SPE) for biomedical applications. The combination of multiwalled carbon nanotubes (MWCNT) as a transducer with polysulfone (PSf) polymer enables easy incorporation of biological moieties (hormones or antibodies), providing a 3D composite with high electrochemical response to corresponding analytes. Antibody/MWCNT/PSf biosensors were characterized by confocal scanning laser microscopy (CSLM), scanning electron microscopy (SEM), and electrochemical methods.

Sulfonated poly(ether ether ketone) as an alternative charged material to poly(vinyl chloride) in the design of ion-selective electrodes.

To date, poly(vinyl chloride) (PVC) is the most used polymer in the design of ion selective electrode (ISE) membranes. This paper is focused on the use of sulfonated poly(ether ether ketone) (SPEEK) as an alternative material to PVC for the design of ISEs. SPEEK of the desired degree of sulfonation is synthesized from poly(ether ether ketone) (PEEK).

Carbon nanotube/polysulfone screen-printed electrochemical immunosensor.

The simple and efficient method for preparing sensitive carbon nanotube/polysulfone/RIgG immunocomposite is described. The membrane of the modified disposable screen-printed electrochemical immunosensor is based on phase inversion method. Carbon nanotube/polysulfone membrane acts both as reservoir of immunological material and transducer while offering high surface area, high toughness and mechanical flexibility.

Evaluation of different mediator-modified screen-printed electrodes used in a flow system as amperometric sensors for NADH.

This work presents a comparative study between two different methods for the preparation of mediator-modified screen-printed electrodes, to be used as detectors in a reliable flow injection system for the determination of the nicotinamide adenine dinucleotide (NADH) coenzyme. The best strategy was selected for the final development of compact biosensors based on dehydrogenase enzymes. For the first immobilisation strategy, different redox mediators were electropolymerised onto the SPE surface.

Carbon nanotube/polysulfone composite screen-printed electrochemical enzyme biosensors.

The fabrication, evaluation and attractive performance of multiwall carbon nanotube(MWCNT)/polysulfone biocomposite membrane modified thick-film screen-printed electrochemical biosensors are reported. The fabricated carbon nanotube/polysulfone (CNT/PS) strips combine the attractive advantages of carbon nanotube materials, polysulfone matrix and disposable screen-printed electrodes. Such thick-film carbon nanotubes/polysulfone sensors have a well defined performance, are mechanically stable, and exhibit high electrochemical activity.

Evaluation of different strategies for the development of amperometric biosensors for L-lactate.

Two strategies were investigated for the development of lactate biosensors based on sol-gel matrixes and polysulfone composite films, both containing L-lactate dehydrogenase (LDH). Firstly, reagentless disposable screen-printed electrodes (SPE's) with Meldola's Blue (MB) and the cofactor NAD(+) inside a sol-gel matrix were prepared. These showed relatively low sensitivities (260 microA/M).

New antibodies immobilization system into a graphite-polysulfone membrane for amperometric immunosensors.

Polysulfone membrane is used for the first time for the preparation of electrochemical immunosensors. A disposable immunosensor based on a porous conductor polymer graphite-polysulfone-electrode has been developed using a phase inversion technique for the determination of anti-rabbit IgG (anti-RIgG) as a model analyte. To construct the sensor, a conductor membrane was deposited on the surface of working graphite-epoxy composite (GEC) electrode.

New redox mediator-modified polysulfone composite films for the development of dehydrogenase-based biosensors.

This work presents polysulfone membranes as new materials for the development of compact dehydrogenase-based biosensors. Composite films were prepared by mixing polysulfone with graphite and were deposited on epoxy-graphite composite electrodes. Redox mediators were successfully immobilized in the composite film leading to highly reproducible biosensors, without leakage of the immobilized species.

Comparative study of electron mediators used in the electrochemical oxidation of NADH.

A comparison of the behavior of six different redox mediators for the electrocatalysis of the oxidation of NADH, which are widely used in the construction of dehydrogenase-based biosensors, is reported. The redox mediators were, potassium hexacyanoferrate (II), Meldola's Blue (MB), dichlorophenolindophenol (DCPIP), p-benzoquinone (p-BQ), o-phenylenediamine (o-PDA) and 3,4-dihydroxybenzaldehyde (3,4-DHB). After incorporating each of them in the sensor system following four different strategies (in solution, entrapped in epoxy-composites, adsorbed or electropolymerized on the electrode surface), several aspects regarding repeatability and reproducibility were considered and compared.