Ultimately Sensitive Organic Bioelectronic Transistor Sensors by Materials and Device Structure Design

Organic bioelectronic sensors are gaining momentum as they can combine high‐performance sensing level with flexible large‐area processable materials. This opens to potentially highly powerful sensing systems for point‐of‐care health monitoring and diagnostics at low cost. Prominent to detect biochemical recognition events, are electrolyte‐gated organic field‐effect transistors (EGOFETs) and organic electrochemical transistors (OECTs) as they are easily fabricated and operated. EGOFETs are recently shown to be capable of label‐free single‐molecule detections, even in serum. This progress report aims to provide a critical perspective through a selected overview of the literature on both EGOFET and OECT biosensors. Attention is paid to correctly attribute them to the potentiometric and amperometric biosensor categories, which is important to set the right conditions for quantification purposes. Moreover, to deepen the understanding of the sensing mechanisms, with the support of unpublished data, focus is put on two among the most critical aspects, namely, the capacitance interplay and the role of Faradaic currents. The final aim is to provide a rationale of the functional mechanisms encompassing both EGOFET and OECT sensors, to improve materials and devices' designs taking advantage of the processes that enhance the sensing response enabling the extremely high‐performance level resulting in ultimate sensitivity, selectivity, and fast response.     

Proteome analysis of biological fluids from autoimmune-rheumatological disorders

Autoimmune-rheumatological diseases are worldwide distributed disorders and represent a complex array of illnesses characterized by autoreactivity (reactivity against self-antigens) of T-B lymphocytes and by the synthesis of autoantibodies crucial for diagnosis (biomarkers). Yet, the effects of the autoimmune chronic inflammation on the infiltrated tissues and organs generally lead to profound tissue and organ damage with loss of function (i.e., lung, kidney, joints, exocrine glands). Although progresses have been made on the knowledge of these disorders, much still remains to be investigated on their pathogenesis and identification of new biomarkers useful in clinical practice. The rationale of using proteomics in autoimmune-rheumatological diseases has been the unmet need to collect, from biological fluids that are easily obtainable, a summary of the final biochemical events that represent the effects of the interplay between immune cells, mesenchymal cells and endothelial cells. Proteomic analysis of these fluids shows encouraging results and in this review, we addressed four major autoimmune-rheumatological diseases investigated through proteomic techniques and provide evidence-based data on the highlights obtained in systemic sclerosis, primary and secondary Sjogren's syndrome, systemic lupus erythematosus and rheumatoid arthritis.     

Chlorophyll concentration mapping with MIVIS data to assess crown discoloration in the Ticino Park oak forest

Airborne hyperspectral remote observations, characterized by high spatial and spectral resolution, allow the estimation of quantitative vegetation variables useful in forest condition assessment. In this research, total chlorophyll (a?+ b) concentration (C _ab), a biochemical variable describing crown discoloration rate, was mapped to assess oak (Quercus robur L.) condition in the Ticino Regional Park. A simulation experiment was conducted to evaluate the error in C _ab estimation due to ecological variables (i.e. canopy leaf area index and understorey characteristics) and to sun-sensor configurations when optical indices are used. Canopy reflectance was simulated by means of the PROSPECT leaf radiative transfer model (Jacquemoud and Baret 1990 Jacquemoud, S. and Baret, F. 1990. PROSPECT: a model of leaf optical-properties spectra. Remote Sensing of Environment, 34: 75–91. [Crossref], [Web of Science ®] , [Google Scholar]) coupled with the SAILH canopy radiative transfer model, a variation of the SAIL (Scattering by Arbitrarily Inclined Leaves) model modified to include the hot spot effect (Verhoef 1984 Verhoef, W. 1984. Light scattering by leaf layers with application to canopy reflectance modeling: The SAIL model. Remote Sensing of Environment, 16: 125–141. [Crossref], [Web of Science ®] , [Google Scholar], Kuusk 1991 Kuusk, A. 1991. “The hot-spot effect in plant canopy reflectance”. In Photon–Vegetation Interactions: Application in Optical Remote Sensing and Plant Ecology, Edited by: Mynemi, R. and Ross, J. 139–159. New York: Springer Verlag. [Crossref] , [Google Scholar]). The vegetation was modelled as a two layer medium with oak canopy as the top layer and the understorey as the bottom layer. Simulations were performed for varying leaf C _ab and canopy Leaf Area Index (LAI) of the top layer, θ_l (mean leaf inclination angle) and LAI of the bottom layer (LAI_u) and sun-sensor geometry. Optical indices were calculated and used in C _ab retrieval. Simulations demonstrated that errors in C _ab estimation were negligible when MTCI (MERIS Terrestrial Chlorophyll Index) was used, thus indicating that MTCI was the most reliable index in mapping C _ab in this forest environment. Empirical models based on optical indices were developed to map C _ab from Multispectral Infrared and Visible Imaging Spectrometer (MIVIS) images acquired by an airborne survey on the Park forested area. A regression analysis between C _ab concentration measured in leaves sampled in field and optical indices computed from hyperspectral MIVIS data was conducted. The MTCI index showed the highest performances and was therefore used to map C _ab concentration of the Ticino Park oak forest. The C _ab map was then used to assess crown discoloration level.     

Plasma enhanced-CVD of undoped and fluorine-doped Co3O4 nanosystems for novel gas sensors

Co₃O₄-based nanosystems were prepared on polycrystalline Al₂O₃ by plasma enhanced-chemical vapor deposition (PE-CVD), at temperatures ranging between 200 and 400 °C. The use of two different precursors, Co(dpm)₂ (dpm = 2,2,6,6-tetramethyl-3,5-heptanedionate) and Co(hfa)₂·TMEDA (hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA = N,N,N′,N′-tetramethylethylenediamine) enabled the synthesis of undoped and fluorine-doped Co₃O₄ specimens, respectively. A thorough characterization of their properties was performed by glancing incidence X-ray diffraction (GIXRD), atomic force microscopy (AFM), field emission-scanning electron microscopy (FE-SEM), secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS). For the first time, the gas sensing properties of such PE-CVD nanosystems were investigated in the detection of ethanol and acetone. The results show an appreciable response improvement upon doping and functional performances directly dependent on the fluorine content in the Co₃O₄ system.     

Distribution of arsenic compounds in Mytilus galloprovincialis of the Venice lagoon (Italy)

Samples of Mytilus galloprovincialis collected in different sites of the Venice lagoon (Italy) were investigated for total arsenic concentrations by ICP-AES and for single arsenic species by HPLC-ICP-MS. For this purpose, an analytical procedure for the sensitive and efficient speciation of the arsenic species As(III), As(V), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenobetaine (AB), arsenocholine (AC), and four arsenosugars was optimised. The total arsenic and the single arsenic species were determined in both the hepatopancreas (digestive gland) and the remaining soft tissues in order to verify the different arsenic accumulation in the body parts of mussels. Arsenic compounds were extracted from the mussels with a methanol/water mixture; the extracts were evaporated to dryness, redissolved in water, and chromatographed in an anion-exchange column, a Hamilton PRP-X100. Only small quantities or traces of inorganic arsenic were detected in the mussels. The majority of arsenic compounds detected in the extracts were organic species, with a predominance of arsenobetaine and of an arsenosugar. In addition, a greater arsenic accumulation in the digestive glands of mussels was observed.     

Synthesis of gold nanotubes by sputtering of gold into porous materials

Hollow 1-D gold nanostructures with controlled morphology could be readily obtained by RF-sputtering of gold into porous matrices (polycarbonate, polyester), used as scaffolds at low temperatures. Post-synthesis membrane etching by oxygen plasmas or in solution enabled the preparation of free-standing Au nanotubes maintaining the original morphology, that are attractive elements in device structures, such as biosensors for DNA chips or nanoelectrode ensembles. The present results appear extremely promising for the scale-up of different kinds of 1-D materials.     

Surface characterization of Ba-β-alumina

The surface properties of a Ba-β-alumina sample (Ba ∶ Al ratio 1∶ 12) very stable to sintering (15 m²/g after calcination at 1670 K for 10 h) have been investigated by FT-IR spectroscopy of adsorbed probe molecules (water, pyridine and CO₂) and by measuring the isoelectric point. The surface has a medium-strong basic character, justified by the preferential exposition of Ba-O-containing “mirror planes”, parallel to 0001 planes, on the surface of plate-like particles. This behavior has been associated to the resistance to sintering, typical of this material, possibly originated by the difficulty of the very big Ba²⁺ ions to migrate into the spinel-type alumina blocks. This should imply the blocking of the crystal growth along the crystallographicc axis.     

Sourdough derived strains of Saccharomyces cerevisiae and their potential for farmhouse ale brewing

The Finnish farmhouse ale sahti is unique in that it is fermented with baking, rather than brewing strains of Saccharomyces cerevisae. The custom of maintaining farmhouse yeast cultures is however no longer practiced in Finland, and much yeast derived diversity in sahti beers has presumably been lost as a consequence. Here, the brewing potential of a number of sourdough derived strains was tested with respect to a number of different fermentation traits. Seven strains originally isolated from Finnish or Italian sourdough cultures were used to ferment high gravity sahti wort (20°P), and fermentation performance together with production of volatile compounds were assessed and compared with a reference baking yeast. Strains differed in terms of fermentation rate, yield, yeast viability and beer flavour profile. All were maltotriose positive, but utilisation varied so that alcohol yield could be greater or lower than that of the reference strain, with values ranging from 6.6 to 7.9% (v/v). Production of aroma compounds was also variable so that it was possible to identify strains producing high levels of esters and those with lower production, which could be used to emphasise flavours originating from raw materials. All strains generated 4-vinyl guaiacol and so would be suitable for other beers where this is a part of the normal flavour profile. Results suggest that sourdough isolates of S. cerevisiae are suitable for sahti production, but could also be applied to other beer styles as a way to differentiate products. © 2020 The Authors. Journal of the Institute of Brewing published byJohn Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling