Ion-selective membrane plasticizer leakage in all-solid-state electrodes - an unobvious way to improve potential reading stability in time.

The effect of leakage of the plasticizer from the ion-selective membrane into the ion-to-electron transducer of all-solid-state potentiometric sensors is considered for the first time. The plasticizer can be transferred to the transducer phase, either during ion-selective membrane application or later; in both cases, its presence can affect the performance of the sensors. Clearly, this effect is most pronounced if the transducer is dispersible in the plasticizer. Towards this end, it is shown that application as the transducer of plasticizer dispersable poly(3-hexylthiophene) compared to typically used (non-dispersible) poly(3-octylthiophene) results in sensors offering higher reproducibility of recorded potentials equal to ±1.4 mV and ±2.5 mV, respectively (within-day test, n = 6). Although poly(3-hexylthiophene) was also found in the membrane in the solvent dispersed, neutral emission active form, the analytical parameters of poly(3-hexylthiophene) based sensors including selectivity were improved or comparable to those of classical poly(3-octylthiophene) transducer sensors.

A potentiometric sensor based on modified electrospun PVDF nanofibers - towards 2D ion-selective membranes.

Core-shell modified nanofiber mats were used as ion-selective membranes for the first time. Keeping the overall macroscopic size of the sensing element the same as for classical plasticized poly(vinyl chloride) membranes, herein the proposed nanofiber based systems resulted in ultrathin (<10 nm) recognition layers with the total area nearly 3 orders of magnitude larger and the surface to volume ratio close to 7.5 × 107. Thus, for the first time close to 2D potentiometric receptors were obtained. Formation of thin and continuous liquid recognition layers on nanofibers was confirmed by XPS studies. The nanofiber based ion-selective mats used in the classical internal-solution arrangement were characterized with analytical parameters - the slope and detection limit well comparable to those for classical plasticized poly(vinyl chloride) based membranes. Despite the novel arrangement of the ion-selective layer and its nanometric thickness, the reproducibility of the recorded potentials, studied for more than 30 days, was high. Using confocal microscopy it was shown that electrolyte transport through porous nanofibers' mat phase is the rate limiting step in conditioning of the receptor layer. The estimated electrolyte diffusion coefficients for the nanofiber phase are close to 10-10 cm2 s-1, and thus are orders of magnitude lower compared to values characterizing ion transport through classical poly(vinyl chloride) based membranes. The truly nanostructural character of nanofiber ion-selective mats is visible in chronoamperometric experiments. It was shown that a core-shell nanofiber mat behaves as an array of nanoelectrodes - individual nanofibers. Thus, the novel nanofiber based architecture of ion-selective mats brings also a new quality to the current based electrochemistry of ion-selective sensors.

Self-Powered Cascade Bipolar Electrodes with Fluorimetric Readout.

Bipolar electrodes working in a self-powered mode are a basis for the development of easy to use electrochemical-optical sensors, these systems are very promising due to their simplicity and no need of external polarization. However, the self-powered mode can be used only in cases when the redox potential difference of reactions occurring at opposite poles of the electrode is sufficiently high. To overcome this limitation, we propose the development of a system working spontaneously, but involving two bipolar electrodes, forming a cascade system. One of electrodes ("driving" electrode) works in self-powered mode and triggers charge transfer processes in the second ("sensing") bipolar electrode. For the sensing electrode, an electrochemical process of an analyte occurs at one pole, accompanied by a complementary process at the second pole, inducing an optical (fluorimetric) analytical signal. This concept was successfully tested on a model system of a sensing bipolar electrode with a platinum electrode participating in oxidation of an analyte, l-ascorbic acid, connected with electrode coated by poly(3-octylthiophene), where reduction of the polymer results in formation of fluorimetrically active neutral form. As the driving system, bipolar electrodes with zinc wire as one pole, characterized by a low redox potential, were used.

Multiwalled Carbon Nanotubes-Poly(3-octylthiophene-2,5-diyl) Nanocomposite Transducer for Ion-Selective Electrodes: Raman Spectroscopy Insight into the Transducer/Membrane Interface.

An approach to overcome drawbacks of well-established transducer materials for all-solid-state ion-selective electrodes is proposed; it is based on the formulation of the nanocomposite of multiwalled carbon nanotubes (MWCNTs) and poly(3-octylthiophene-2,5-diyl) (POT), in which the polymer is used as a dispersing agent for carbon nanotubes. Thus, the obtained material is characterized with unique properties that are important for its application as solid contact in ion-selective electrodes, including high: electronic conductivity, capacitance, and lipophilicity. Performance of the obtained all-solid-state electrodes was studied using a standard approach as well as Raman spectroscopy to allow insight into distribution of the transducer material within the sensor phases: the membrane and the transducer. Application of the composite prevents unwanted partition of POT to the membrane phase, thus eliminating the risk of alteration of the sensor performance due to uncontrolled change in the membrane composition.

Ambient Processed, Water-Stable, Aqueous-Gated sub 1 V n-type Carbon Nanotube Field Effect Transistor.

In this paper we report for the first time an n-type carbon nanotube field effect transistor which is air- and water-stable, a necessary requirement for electrolyte gated CMOS circuit operation. The device is obtained through a simple process, where the native p-type transistor is converted to an n-type. This conversion is achieved by applying a tailor composed lipophilic membrane containing ion exchanger on the active channel area of the transistor. To demonstrate the use of this transistor in sensing applications, a pH sensor is fabricated. An electrolyte gated CMOS inverter using the herein proposed novel n-type transistor and a classical p-type transistor is demonstrated.

Fate of Poly(3-octylthiophene) Transducer in Solid Contact Ion-Selective Electrodes.

An experimental approach allowing visualization and quantification of the underestimated spontaneous process of partition of conducting polymer transducer material to the ion-selective membrane phase is proposed. The approach proposed is based on optical properties of the transducer material applied, using polythiophene as a model system. It is shown that this process occurs not only during the sensor preparation step but also during pretreatment of the sensor before use. As shown, this uncontrolled partition of the transducer to the receptor leads to conducting polymer contents in the membrane phase reaching 0.5% w/w; this process is accompanied by a partial spontaneous change of the oxidation state of polythiophene. The conducting polymer present in the membrane participates to some extent in the overall response of the sensor, which can be observed as a change in the polythiophene optical emission spectra. Fluorescence microscopic images obtained clearly show that the conducting polymer is distributed throughout the membrane thickness, being present also at the membrane/solution interface. The experimental results presented were obtained for K+-selective sensors using poly(3-octylthiophene) as a model transducer; however, the proposed approach is also applicable for other systems.

Introducing Cobalt(II) Porphyrin/Cobalt(III) Corrole Containing Transducers for Improved Potential Reproducibility and Performance of All-Solid-State Ion-Selective Electrodes.

A novel solid contact type for all-solid-state ion-selective electrodes is introduced, yielding high stability and reproducibility of potential readings between sensors as well as improved analytical performance. The transducer phase herein proposed takes advantage of the presence of porphyrinoids containing the same metal ion at different oxidation states. In contrast to the traditional approach, the compounds of choice are not a redox pair; although they have different oxidation states, they cannot be electrochemically driven one to another. The compounds of choice were cobalt(II) porphyrin and cobalt(III) corrole-both characterized by a high stability of the coordinated metal ions in their respective redox states and electrical neutrality, as well as relatively high lipophilicity. The porphyrinoids were used together with carbon nanotubes to yield transducer layers for ion-selective electrodes. As a result, we obtained a high stability of potential readings of the resulting ion-selective electrodes together with good reproducibility between different sensor batches. Moreover, advantageously the presence of porphyrinoids in the transducer phase results in improvement of the analytical performance of the sensors: linear response range and selectivity due to interactions with membrane components, resulting in tailoring of ion fluxes through the membrane phase. Thus, carbon nanotubes with the cobalt(II) porphyrin/cobalt(III) corrole system are promising alternatives for existing transducer systems for potentiometric sensors.

Local GABAergic signaling within sensory ganglia controls peripheral nociceptive transmission.

The integration of somatosensory information is generally assumed to be a function of the central nervous system (CNS). Here we describe fully functional GABAergic communication within rodent peripheral sensory ganglia and show that it can modulate transmission of pain-related signals from the peripheral sensory nerves to the CNS. We found that sensory neurons express major proteins necessary for GABA synthesis and release and that sensory neurons released GABA in response to depolarization. In vivo focal infusion of GABA or GABA reuptake inhibitor to sensory ganglia dramatically reduced acute peripherally induced nociception and alleviated neuropathic and inflammatory pain. In addition, focal application of GABA receptor antagonists to sensory ganglia triggered or exacerbated peripherally induced nociception. We also demonstrated that chemogenetic or optogenetic depolarization of GABAergic dorsal root ganglion neurons in vivo reduced acute and chronic peripherally induced nociception. Mechanistically, GABA depolarized the majority of sensory neuron somata, yet produced a net inhibitory effect on the nociceptive transmission due to the filtering effect at nociceptive fiber T-junctions. Our findings indicate that peripheral somatosensory ganglia represent a hitherto underappreciated site of somatosensory signal integration and offer a potential target for therapeutic intervention.

MPL W515L expression induces TGFß secretion and leads to an increase in chemokinesis via phosphorylation of THOC5.

The thrombopoietin receptor (MPL) has been shown to be mutated (MPL W515L) in myelofibrosis and thrombocytosis yet new approaches to treat this disorder are still required. We have previously shown that transcriptome and proteomic effects do not correlate well in oncogene-mediated leukemogenesis. We therefore investigated the effects of MPL W515L using proteomics. The consequences of MPL W515L expression on over 3300 nuclear and 3500 cytoplasmic proteins were assessed using relative quantification mass spectrometry. We demonstrate that MPL W515L expression markedly modulates the CXCL12/CXCR4/CD45 pathway associated with stem and progenitor cell chemotactic movement. We also demonstrated that MPL W515L expressing cells displayed increased chemokinesis which required the MPL W515L-mediated dysregulation of MYC expression via phosphorylation of the RNA transport protein THOC5 on tyrosine 225. In addition MPL W515L expression induced TGFß secretion which is linked to sphingosine 1-phosphate production and the increased chemokinesis. These studies identify several pathways which offer potential targets for therapeutic intervention in the treatment of MPL W515L-driven malignancy. We validate our approach by showing that CD34+ cells from MPL W515L positive patients display increased chemokinesis and that treatment with a combination of MYC and sphingosine kinase inhibitors leads to the preferential killing of MPL W515L expressing cells.

Synthesis of conducting polymer nanospheres of high electrochemical activity.

We propose a novel approach to obtain conducting polymer nanoparticles with high electrochemical activity and a narrow size distribution. The method - templateless and seedless - uses polyacrylate microspheres to deliver the monomer for the polymerization reaction. Thus the obtained nanostructures have an active - unblocked - surface allowing fast charge/ion-exchange and the formation of stable suspensions in water. The obtained nanostructures have the potential to be applied in different fields ranging from conductive coatings and additives for increasing electronic conductivity, to electrochemical sensors.

Application of Tensegrity Massage to Relive Complications After Mastectomy--Case Report.

PURPOSE: The case study was to determine the effectiveness of tensegrity massage in a patient after mastectomy. DESIGN: Tensegrity massage was performed in a 50-year-old woman after mastectomy. The purpose of the massage was to normalize the tension of musculo-ligamento-fascial system in the chest, shoulder girdle, and back. METHODS: The patient was subjected to a series of six massage sessions, 45 minutes each, twice a week. FINDINGS: The applied massage therapy contributed to the reduction of the postoperative scar tenderness and painfulness, to the relaxation of the muscular tone within the shoulder girdle, and to the improvement of the patient's general feeling. CONCLUSIONS: Tensegrity massage is an effective therapy in the elimination of pain and abnormal tissue tension induced by extensive scarring after mastectomy. CLINICAL RELEVANCE: The presented massage procedure had a positive effect immediately after the therapy and after 1-month follow-up.

Spray-coated all-solid-state potentiometric sensors.

A novel fully spray coating-based method of the preparation of all-solid-state ion-selective electrodes of simplified construction is proposed. This method is an alternative for screen-printed electrodes used sometimes in potentiometric applications. The benefits of the herein-proposed approach include fully automatic sensor preparation and minimized use of chemicals allowing for the production of low-cost sensors that can be applied as disposables. A layer of spray-coated carbon nanotubes on an inert support was used both as an electrical lead and as a transducer, to simplify sensor layout and to avoid the possible problems of changing in-time composition of this layer, as previously observed in the case of screen-printed supporting electrodes in potentiometric applications. The ion-selective poly(vinyl chloride)-based membrane and the insulator layer were also spray-coated. The obtained sensors, as the model system potassium-selective sensors were prepared and characterized with analytical parameters well comparable with that of conventional, all-solid-state, ion-selective electrodes. In addition, the applicability of the herein-proposed approach to prepare other ion-selective electrodes was tested on examples of H(+) and Cl(-) sensors.

A specific PTPRC/CD45 phosphorylation event governed by stem cell chemokine CXCL12 regulates primitive hematopoietic cell motility.

CXCL12 governs cellular motility, a process deregulated by hematopoietic stem cell oncogenes such as p210-BCR-ABL. A phosphoproteomics approach to the analysis of a hematopoietic progenitor cell line treated with CXCL12 and the Rac 1 and 2 inhibitor NSC23766 has been employed to objectively discover novel mechanisms for regulation of stem cells in normal and malignant hematopoiesis. The proteomic data sets identified new aspects of CXCL12-mediated signaling and novel features of stem cell regulation. We also identified a novel phosphorylation event in hematopoietic progenitor cells that correlated with motile response and governed by the chemotactic factor CXCL12. The novel phosphorylation site on PTPRC/CD45; a protein tyrosine phosphatase, was validated by raising an antibody to the site and also using a mass spectrometry absolute quantification strategy. Site directed mutagenesis and inhibitor studies demonstrated that this single phosphorylation site governs hematopoietic progenitor cell and lymphoid cell motility, lies downstream from Rac proteins and potentiates Src signaling. We have also demonstrated that PTPRC/CD45 is down-regulated in leukemogenic tyrosine kinase expressing cells. The use of discovery proteomics has enabled further understanding of the regulation of PTPRC/CD45 and its important role in cellular motility in progenitor cells.

Simple and disposable potentiometric sensors based on graphene or multi-walled carbon nanotubes--carbon-plastic potentiometric sensors.

A simple procedure leading to disposable potentiometric sensors using as a supporting electrode - electrical lead and transducer - a layer of carbon nanostructured material, either graphene or multi-walled nanotubes, is proposed, and the effect of the material used on the properties of the sensor is discussed. The obtained layers were partially covered with a conventional poly(vinyl chloride) (PVC) based ion-selective membrane to result in simple, planar, and disposable potentiometric sensors. The analytical performance of the thus obtained electrodes was compared with that of classical macroscopic all-solid-state ion-selective electrodes (e.g. employing poly(octylthiophene) as a solid contact and a similar ion-selective membrane). It was superior (taking into account detection limits or selectivity towards Na(+) ions) compared to that of other disposable sensors proposed recently. The observed excellent analytical performance was attributed to the applied method of preparation of carbon nanostructured materials, which does not require addition of a surfactant to obtain a stable suspension (ink) used to prepare the electrical lead and the transducer of the sensor. Although the proposed sensors are predominantly intended for disposable use, pronounced stability of potential readings was obtained in within-day experiments. Moreover, due to their high conductivity carbon-plastic electrodes can be also applied in polarized potentiometric measurements.

Critical assessment of graphene as ion-to-electron transducer for all-solid-state potentiometric sensors.

Carboxy-functionalized graphene was used as a solid contact for potassium ion-selective electrodes with poly(vinyl chloride) based membrane. Transducer layers were obtained simply by application of a dispersion of graphene derivative in water. Analytical performance of thus obtained sensors was compared with that of all-solid-state sensors with typical transducer materials: poly(octylthiophene) applied as chloroform solution, conducting polymers available as aqueous dispersions of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) ions or polyaniline. It was found that all sensors tested were characterized with similar analytical parameters. Carboxy-functionalized graphene contact layer was in some respect similar to polyaniline one, what most probably results from the presence of pH sensitive groups in both materials.

Identification of nuclear protein targets for six leukemogenic tyrosine kinases governed by post-translational regulation.

Mutated tyrosine kinases are associated with a number of different haematological malignancies including myeloproliferative disorders, lymphoma and acute myeloid leukaemia. The potential commonalities in the action of six of these leukemogenic proteins on nuclear proteins were investigated using systematic proteomic analysis. The effects on over 3600 nuclear proteins and 1500 phosphopeptide sites were relatively quantified in seven isogenic cell lines. The effects of the kinases were diverse although some commonalities were found. Comparison of the nuclear proteomic data with transcriptome data and cytoplasmic proteomic data indicated that the major changes are due to post-translational mechanisms rather than changes in mRNA or protein distribution. Analysis of the promoter regions of genes whose protein levels changed in response to the kinases showed the most common binding site found was that for NFκB whilst other sites such as those for the glucocorticoid receptor were also found. Glucocorticoid receptor levels and phosphorylation were decreased by all 6 PTKs. Whilst Glucocorticoid receptor action can potentiate NFκB action those proteins where genes have NFκB binding sites were in often regulated post-translationally. However all 6 PTKs showed evidence of NFkB pathway modulation via activation via altered IkB and NFKB levels. Validation of a common change was also undertaken with PMS2, a DNA mismatch repair protein. PMS2 nuclear levels were decreased in response to the expression of all 6 kinases, with no concomitant change in mRNA level or cytosolic protein level. Response to thioguanine, that requires the mismatch repair pathway, was modulated by all 6 oncogenic kinases. In summary common targets for 6 oncogenic PTKs have been found that are regulated by post-translational mechanisms. They represent potential new avenues for therapies but also demonstrate the post-translational regulation is a key target of leukaemogenic kinases.

Non-covalently functionalized graphene for the potentiometric sensing of zinc ions.

The possibility of the application of non-covalently functionalized graphene as a sensing membrane for the potentiometric determination of zinc ions was examined. A graphene carboxylic derivative was functionalized with 1-(2-pyridylazo)-2-naphthol, the Zn(2+) ions complexing ligand, simply by adsorption of ligand molecules due to π-π interactions. This approach has resulted in a potentiometric sensor characterized with significant selectivity for Zn(2+) ions present in solution.

Gold nanoparticles solid contact for ion-selective electrodes of highly stable potential readings.

Internal solution free ion-selective electrodes were prepared applying for the first time gold nanoparticles as a solid contact layer. The presence of a layer of gold nanoparticles stabilized with aliphatic thiols at the back side of the membrane resulted in highly stable potentiometric responses of the sensors, good selectivities and close to Nernstian slopes. Electrochemical studies have confirmed that the applied material is effectively working as capacitive solid contact, yielding high stability sensors.

Lowering the resistivity of polyacrylate ion-selective membranes by platinum nanoparticles addition.

The effect of platinum nanoparticles introduction into polyacrylate membranes was examined. Platinum nanoparticles were added to the membrane cocktail before photopolymerization of the poly(n-butyl acrylate) based ion-selective membranes. Thus obtained sensors were characterized with significantly lowered electrical resistance and increased stability of potential readings compared to classical poly(n-butyl acrylate) membranes. The analytical parameters of platinum nanoparticle containing membranes were well comparable with those of classical membranes.

Assessment of downstream effectors of BCR/ABL protein tyrosine kinase using combined proteomic approaches.

Leukaemic transformation is frequently associated with the aberrant activity of a protein tyrosine kinase (PTK). As such it is of clinical relevance to be able to map the effects of these leukaemogenic PTKs on haemopoietic cells at the level of phosphorylation modulation. In this paradigm study we have employed a range of proteomic approaches to analyse the effects of one such PTK, BCR/ABL. We have employed phosphoproteome enrichment techniques allied to peptide and protein quantification to identify proteins and pathways involved in cellular transformation. Amongst the proteins shown to be regulated at the post-translational level were cofilin, an actin-severing protein thus linked to altered motility and Cbl an E3 ubiquitin ligase integrally linked to the control of tyrosine kinase signalling (regulated by 5 and 6 PTKs respectively). The major class of proteins identified however were molecular chaperones. We also showed that HSP90 phosphorylation is altered by BCR/ABL action and that HSP90 plays a crucial role in oncogene stability. Further investigation with another six leukaemogenic PTKs demonstrates that this HSP90 role in oncogene stability appears to be a common phenomenon in a range of leukaemias. This opens up the potential opportunity to treat different leukaemias with HSP90 inhibitors.