Biogenic porous silica and silicon sourced from Mexican Giant Horsetail (Equisetum myriochaetum) and their application as supports for enzyme immobilization

Porous silica-based materials are attractive for biomedical applications due to their biocompatibility and biodegradable character. In addition, inorganic supports such as porous silicon are being developed due to integrated circuit chip compatibility and tunable properties leading to a wide range of multidisciplinary applications. In this contribution, biosilica extracted from a rarely studied plant material (Equisetum Myriochaetum), its conversion to silicon and the potential for both materials to be used as supports for enzyme immobilization are investigated. E. myriochaetum was subject to conventional acid digestion to extract biogenic silica with a % yield remarkably higher (up to 3 times) than for other Equisetum sp. (i.e. E. Arvense). The surface area of the isolated silica was ∼400 m2/g, suitable for biotechnological applications. Biogenic silicon was obtained by magnesiothermic reduction. The materials were characterized by SEM-EDX, XRD, FT-IR, ICP-OES, TGA and BET analysis and did not contain significant levels of class 1 heavy elements (such as Pb, Cd, Hg and As). Two commercial peroxidases, horseradish peroxidase (HRP) and Coprinus cinereus peroxidase (CiP) were immobilized onto the biogenic materials using three different functionalization routes: (A) carbodiimide, (B) amine + glutaraldehyde and (C) amine + carbodiimide. Although both biogenic silica and porous silicon could be used as supports differences in behaviour were observed for the two enzymes. For HRP, loading onto biogenic silica via the glutaraldehyde immobilization technique (route B) was most effective. The loading of CiP showed a much higher peroxidase activity onto porous silicon than silica functionalized by the carbodiimide method (route A). From the properties of the extracted materials obtained from Equisetum Myriochaetum and the immobilization results observed, these materials appear to be promising for industrial and biomedical applications

The role of the Chaperone BiP/Kar2p in Sec61-mediated protein translocation and integration

Eine Hauptfunktion des Endoplasmatischen Retikulums (ER) ist der Transport von ribosomal synthetisierten Membranproteinen durch und in die ER Membran, wobei dies co- oder post-translational erfolgen kann. Beide Varianten nutzen dazu den gleichen hydrophilen Kanal, der sogenannte Translokationskanal. In Eukaryoten wird er von dem heterotrimeren Proteinkomplex Sec61 geformt. Sec61 kann vertikal und lateral zur Membran geöffnet werden. Die laterale Öffnung ermöglicht es dem Polypeptid die Membran zu passieren, während eine laterale Öffnung den Austritt von Transmembrandomänen in die Membran ermöglicht. Auf der luminalen Seite des Kanals wird das ER Chaperon BiP durch Sec63 aktiviert und bindet an das translozierende Polypeptid. BiP wirkt vermutlich während der post-translationalen Translocation als eine treibende Kraft für den Transport der Peptidkette in das Lumen. Eine ähnliche Rolle wird für die co-translationale Translokation vermutet. ^Ziel der Studie war es, die Rolle von BiP in der co-translationalen Translokation zu charakterisieren. Um die Hydrophobizitäts-Schwelle der Membranintegration zu bestimmen wurden verschiedene Konstrukte erstellt. Bei dem translozierenden Segment, auf das ein hydrophobes Segment folgt, handelt es sich um eine Sequenz die BiP sehr gut oder schlecht bindet oder sehr flexible und hydrophile ist. Die Proteine wurden in Hefe exprimiert, mit Methionin radioaktiv markiert und via Immunpräzipitation, Gelelektrophorese, und Autoradiografie analysiert. Integration und Translokation wurde anhand des Glykosylierungsmusters bestimmt. Wir konnten zeigen, dass die Bindung von BiP die Entscheidung des hydrophoben Segments ob es transloziert oder integriert beeinflusst, wobei es die Membranintegration fördert. Modelproteine mit hoch flexiblen und hydrophilen Segment wiesen eine defiziente Translokation auf. ^Zusammenfassend lässt sich sagen, dass BiP eine wichtige Rolle in co-translationaler Translokation und Proteintopologie spielt.One of the major function of the endoplasmic reticulum (ER) is the translocation and integration of ribosomally synthesized membrane proteins. The translocation of proteins occurs co- or post-translational but both pathways use a channel with a hydrophilic interior, the so-called translocon. This channel is formed by a heterotrimeric protein complex termed Sec61 in eukaryotes. The translocon can open into two directions: vertical opening allows the polypeptide chain to pass through the membrane, whereas lateral opening allows the exit of transmembrane domains into the membrane. On the luminal side of the translocon the ER chaperone BiP is activated by its co-chaperone Sec63 and binds to the translocating polypeptide. Therefore, BiP may provide a driving force in post-translation translocation and act as molecular ratchet. A similar role is suggested for co-translational translocation. The aim of this study was to characterize the role of BiP in co-translation translocation. Therefore, different constructs were designed to determine the hydrophobicity threshold of membrane integration. The translocating segment prior to a hydrophobic segment was designed to either be efficiently or poorly recognized by BiP or consisted of a highly flexible hydrophilic and soluble sequence. The proteins were expressed in yeast, labeled with radioactive methionine and analyzed by immunoprecipitation, gel electrophoresis, and autoradiography. Integration and translocation was deduced from the glycosylation patterns. We could show, that binding of BiP affects the decision of a hydrophobic segment to translocate or integrate, surprisingly by facilitating membrane integration. Whereas, model proteins containing highly flexible and hydrophilic segments were defective in translocation. Taken together this study shows that BiP/Kar2p plays an important role in co-translational translocation and protein topogenesis.Anna Brunauer, BSczusammenfassungen in Deutsch und EnglischKarl-Franzens-Universität Graz, Masterarbeit, 2018(VLID)244815

Efficient integration of transmembrane domains depends on the folding properties of the upstream sequences

The topology of most membrane proteins is defined by the successive integration of α-helical transmembrane domains at the Sec61 translocon. The translocon provides a pore for the transfer of polypeptide segments across the membrane while giving them lateral access to the lipid. For each polypeptide segment of ∼20 residues, the combined hydrophobicities of its constituent amino acids were previously shown to define the extent of membrane integration. Here, we discovered that different sequences preceding a potential transmembrane domain substantially affect its hydrophobicity requirement for integration. Rapidly folding domains, sequences that are intrinsically disordered or very short or capable of binding chaperones with high affinity, allow for efficient transmembrane integration with low-hydrophobicity thresholds for both orientations in the membrane. In contrast, long protein fragments, folding-deficient mutant domains, and artificial sequences not binding chaperones interfered with membrane integration, requiring higher hydrophobicity. We propose that the latter sequences, as they compact on their hydrophobic residues, partially folded but unable to reach a native state, expose hydrophobic surfaces that compete with the translocon for the emerging transmembrane segment, reducing integration efficiency. The results suggest that rapid folding or strong chaperone binding is required for efficient transmembrane integration

Rapid detection of pathogens in wound exudate via nucleic acid lateral flow immunoassay

The rapid detection of pathogens in infected wounds can significantly improve the clinical outcome. Wound exudate, which can be collected in a non-invasive way, offers an attractive sample material for the detection of pathogens at the point-of-care (POC). Here, we report the development of a nucleic acid lateral flow immunoassay for direct detection of isothermally amplified DNA combined with fast sample preparation. The streamlined protocol was evaluated using human wound exudate spiked with the opportunistic pathogen Pseudomonas aeruginosa that cause severe health issues upon wound colonization. A detection limit of 2.1 × 105 CFU per mL of wound fluid was achieved, and no cross-reaction with other pathogens was observed. Furthermore, we integrated an internal amplification control that excludes false negative results and, in combination with the flow control, ensures the validity of the test result. The paper-based approach with only three simple hands-on steps has a turn-around time of less than 30 min and covers the complete analytical process chain from sample to answer. This newly developed workflow for wound fluid diagnostics has tremendous potential for reliable pathogen POC testing and subsequent target-oriented therapy

Integrated Devices for Non-Invasive Diagnostics

“Sample-in-answer-out” type integrated diagnostic devices have been widely recognized as the ultimate solution to simplify testing across healthcare systems. Such systems are equipped with advanced fluidic, mechanical, chemical, biological, and electronic components to handle patient samples without any manual steps therefore have the potential to accelerate intervention and improve patient outcomes. In this regard, the combination of integrated devices and non-invasive sampling has gained a substantial interest to further improve the comfort and safety of patients. In this Review, the pioneering developments in integrated diagnostics are covered and their potential in non-invasive sampling is discussed. The key properties of possible sample types are highlighted by addressing their relevance for the clinical practice. Last, the factors affecting the transition of integrated devices from academia to the market are identified by analyzing the technology readiness levels of selected examples and alternative remedies are explored to increase the rate of survival during this transition.This research has been partially funded by the German Research Foundation (DFG) under grant numbers 404478562, 421356369 and 397660978. F.G. acknowledges Imperial College Centre for Processible Electronics and Agri-Futures Lab. A.M. thanks funding by the CERCA programme/Generalitat de Catalunya and the Severo Ochoa Centres of Excellence programme and by the Spanish Research Agency (AEI, grant no. SEV-2017-0706) given to ICN2 as well as Financial support obtained under the MINECO Project MAT2017-87202-P. The authors thank Dr. Cihan Ates for his contributions to the conceptualization of the TOC image

Effect of Post-Synthesis Treatments on the Properties of ZnS Nanoparticles: An Experimental and Computational Study

This work deals with the characterization of ZnS NanoParticles (NP), prepared by precipitation employing thioacetamide as sulfur source at different reaction time length. The attention is focused on the modification induced on structural, surface and electronic properties of ZnS NP by post-synthesis treatments. These were aimed at removing from the samples surface adsorbed reactants, by washing or thermal treatments, both in air or vacuum. The effect of these parameters is followed by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Fourier Transform InfraRed (FTIR), gas-volumetric and ThermoGravimetric Analysis (TGA). Moreover, the effect of nanostructuration on the semiconducting material band gap is evaluated by Diffuse Reflectance UV-Vis (DR UV-Vis) spectroscopy. Density Functional Theory (DFT) calculations have been employed to clarify the role of the adsorbed reactants on the surface stability and to assess the relationship between particle size and band gap value

Bimetallic Fe/Mo–SiO2 aerogel catalysts for catalytic carbon vapour deposition production of carbon nanotubes

Abstract Highly porous nanocomposite aerogels based on bimetallic Fe and Mo nanoparticles with a variable Fe:Mo weight ratio ranging from 5:1; 3:1; and 0.7:1 dispersed on amorphous silica were obtained. N2 physisorption, X-ray diffraction, and transmission electron microscopy indicate that the Fe/Mo–SiO2 nanocomposite aerogels as obtained by a co-gelation sol–gel route followed by supercritical drying and reduction treatment under H2 exhibit Fe and Mo nanocrystals with size in the range 4–10 and 15 nm, respectively, supported on highly porous silica. The catalytic performance of the Fe/Mo–SiO2 aerogels for the synthesis of multi wall carbon nanotubes (MWCNT) by catalytic chemical vapour deposition (CCVD) was evaluated in terms of amount and quality of the produced CNTs as assessed by gravimetric results, thermal analysis, and TEM. The effect of catalyst composition and CCVD temperature was investigated, pointing out that high reaction temperatures (800 ?C) favor the formation of MWCNTs with high quality in elevated yield, the highest C uptake value being[400 %. Catalyst composition and CCVD temperature were also found to affect the homogeneity of CNT morphology, the best MWCNT quality (with outer diameter 23–25 nm) being achieved at 800 ?C with the catalyst having the largest Mo content

Modified and unmodified low-cost iron-containing solid wastes as adsorbents for efficient removal of As(III) and As(V) from mine water

© 2016 Elsevier LtdSulphate tailings and iron sand – industrial solid wastes containing iron oxide/hydroxides – were investigated as potential adsorbents for arsenic removal from water. Two effective methods of surface modification by NaOH treatment and atomic layer deposition of TiO2 and Al2O3 thin films were used for increasing As(III) and As(V) removal capacities of both adsorbents. The structure and surface area of the materials were characterised by scanning electron microscopy, middle infrared region spectroscopy, energy dispersive X-ray spectroscopy, and nitrogen adsorption. The iron sand waste was capable of binding significant amounts of As(III) and As(V) from synthetic solutions and wastewater. The sulphate tailings also showed a high adsorption capacity. Adsorption kinetics showed that equilibrium was reached within 240 min and fit to a pseudo second-order model with correlation coefficients greater than 0.99. Adsorption capacity was at the highest value at a solution pH range of 6–8. The Langmuir and Toth models can be used to fit the adsorption isotherms. The research showed that the proposed solid wastes can be successfully used for the adsorption of As(III) and As(V)