Enhanced label-free detection of proteins on Au nanoparticle micropatterns for surface-enhanced infrared absorption spectroscopy.

A label-free one-step lithographically masked deposition technique was implemented for the fabrication of gold nanoparticle (Au NP) micropatterns. These micropatterns serve as active substrates for surface-enhanced infrared absorption spectroscopy (SEIRAS) and exhibit a substantial increase in the IR signal upon adsorption of multiple proteins compared to untreated surfaces. Micro-FTIR chemical imaging was conducted to evaluate the efficacy of Au NP micropatterns as singular enhancers for SEIRAS across diverse IR-active substrates demonstrating a promising application for the detection of proteins at low concentrations within biological fluids.

Non-destructive molecular FTIR spectromicroscopy for real time assessment of redox metallodrugs.

Recent emergence of FTIR spectromicroscopy (micro-FTIR) as a dynamic spectroscopy for imaging to study biological chemistry has opened new possibilities for investigating in situ drug release, redox chemistry effects on biological molecules, DNA and drug interactions, membrane dynamics, and redox reactions with proteins at the single cell level. Micro-FTIR applied to metallodrugs has been playing an important role since the last decade because of its great potential to achieve more robust and controlled pharmacological effects against several diseases, including cancer. An important aspect in the development of these drugs is to understand their cellular properties, such as uptake, accumulation, activity, and toxicity. In this review, we present the potential application of micro-FTIR and its importance for studying metal-based drugs, highlighting the perspectives of chemistry of living cells. We also emphasise bioimaging, which is of high importance to localize the cellular processes, for a proper understanding of the mechanism of action.

On the Weak Binding and Spectroscopic Signature of SARS-CoV-2 nsp14 Interaction with RNA.

The SARS-CoV-2 non-structural protein 14 (nsp14), known as exoribonuclease is encoded from the large polyprotein of viral genome and is a major constituent of the transcription replication complex (TRC) machinery of the viral RNA synthesis. This protein is highly conserved among the coronaviruses and is a potential target for the development of a therapeutic drug. Here, we report the SARS-CoV-2 nsp14 expression, show its structural characterization, and ss-RNA exonuclease activity through vibrational and electronic spectroscopies. The deconvolution of amide-I band in the FTIR spectrum of the protein revealed a composition of 35 % α-helix and 25 % ß-sheets. The binding between protein and RNA is evidenced from the spectral changes in the amide-I region of the nsp14, showing protein conformational changes during the binding process. A value of 20.60±3.81 mol L-1 of the binding constant (KD ) is obtained for nsp14/RNA complex. The findings reported here can motivate further studies to develop structural models for better understanding the mechanism of exonuclease enzymes for correcting the viral genome and can help in the development of drugs against SARS-CoV-2.

Highly sensitive interfaces of graphene electrical-electrochemical vertical devices for on drop atto-molar DNA detection.

The development of novel high-sensitivity DNA-based biosensors is beneficial, as these devices have applications in the identification of genetic risk factors, medical diagnostics, and environmental monitoring. Herein, we report on the first robust device capable of detecting DNA on a microliter drop with a zepto-molar (10-21) concentration. To accomplish this, we engineered an electrical-electrochemical vertical device (EEVD) that comprises a novel drain and source terminal in a short-circuited configuration, paired with an ideal non-polarizable reference electrode. Vertical electron transfer occurs perpendicularly to the graphene plane, while the electronic current flows through the graphene van der Waals (vdW) heterojunctions. Ferrocene adsorbed on graphene was strategically chosen as the vdW heterojunction redox component. Charge carrier insertion into the graphene makes the EEVD 10 times more sensitive than traditional graphene field-effect transistors. Interfacial potential changes were measured for single-stranded DNA detection with an unprecedented zepto-molar limit of detection.

On the Challenges for the Diagnosis of SARS-CoV-2 Based on a Review of Current Methodologies.

Diagnosis of COVID-19 has been challenging owing to the need for mass testing and for combining distinct types of detection to cover the different stages of the infection. In this review, we have surveyed the most used methodologies for diagnosis of COVID-19, which can be basically categorized into genetic-material detection and immunoassays. Detection of genetic material with real-time polymerase chain reaction (RT-PCR) and similar techniques has been achieved with high accuracy, but these methods are expensive and require time-consuming protocols which are not widely available, especially in less developed countries. Immunoassays for detecting a few antibodies, on the other hand, have been used for rapid, less expensive tests, but their accuracy in diagnosing infected individuals has been limited. We have therefore discussed the strengths and limitations of all of these methodologies, particularly in light of the required combination of tests owing to the long incubation periods. We identified the bottlenecks that prevented mass testing in many countries, and proposed strategies for further action, which are mostly associated with materials science and chemistry. Of special relevance are the methodologies which can be integrated into point-of-care (POC) devices and the use of artificial intelligence that do not require products from a well-developed biotech industry.

Recognizing conductive islands in polymeric redox surfaces using electrochemical-coupled vibrational spectromicroscopy.

We introduce a set up by coupling multiplex FTIR microscopy to electrochemistry through a home-made spectroelectrochemical cell to observe real time changes in the electronic states of polymeric islands by monitoring the oxidation states of polyaniline (PANI). The resultant technique, called electrochemical-coupled vibrational spectromicroscopy (EVSM), enables the measurement of structural changes in the conductive islands of PANI with the spatial resolution as high as 2.5 µm. Unique 2D and 3D chemical maps obtained by the integration of the spectral bands in the subtractively normalized interfacial infrared (SNIFTIR) spectra reveal electrochemical heterogeneity, showing promising topological properties control for conducting polymer-based electronic devices.

Monitoring cellulose oxidation for protein immobilization in paper-based low-cost biosensors.

The oxidation of paper by periodate was investigated and systematically characterized by Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy, X-ray diffraction, goniometry, and dynamic mechanical analysis. For the first time, in situ FTIR microscopy analysis was performed, yielding chemical images of carbonyl groups on the cellulose fibers. The enhancement of protein immobilization on oxidized paper was quantified by a colorimetric assay with Ponceau dye, demonstrating that 0.5-h oxidation suffices to functionalize the paper-based devices. The oxidized paper was applied as a sensor for protein quantification in urine, a test able to detect levels of proteinuria and even microalbuminuria. The quantification was based on the capture of proteins through covalent bonds formed with the carbonyl groups on the oxidized paper followed by the staining of the region with Ponceau dye. There is a linear dependency between human serum albumin (HSA) concentration and the length of the stained blot from 0.1 to 3 mg mL-1. This method correlated linearly with a reference method showing a higher sensitivity (0.866 cm mL mg-1) than the latter. The limit of quantification was 0.1 mg mL-1, three times lower than that of the commercial strip. Graphical abstract Paper oxidation with periodate and extensive characterization, including microspectroscopy. The conversion of cellulose hydroxyl groups to aldehyde enhances covalent immobilization of protein on paper for application as analytical device. The oxidized paper determined protein in urine, suitable for proteinuria diagnosis.

A combined Far-FTIR, FTIR Spectromicroscopy, and DFT Study of the Effect of DNA Binding on the [4Fe4S] Cluster Site in EndoIII.

Endonuclease III (EndoIII) is a DNA glycosylase that contains the [4Fe4S] cluster, which is essential for the protein to bind to damaged DNA in a process called base excision repair (BER). Here we propose that the change in the covalency of Fe-S bonds of the [4Fe4S] cluster caused by double-stranded (ds)-DNA binding is accompanied by a change in their strength, which is due to alterations of the electronic structure of the cluster. Micro-FTIR spectroscopy in the mid-IR region and FTIR spectroscopy in the far IR (450 and 300 cm-1) were used independently to study the structural changes in EndoIII and the behavior of the [4Fe4S] cluster it contains, in the native form and upon its binding to ds-DNA. Structural changes in the DNA itself were also examined. The characteristics vibrational modes, corresponding to Fe-S (sulfide) and Fe-S (thiolate) bonds were identified in the cluster through far IR spectroscopy as well through quantum chemistry calculations. Based on the experimental results, these vibrational modes shift in their spectral positions caused by negatively charged DNA in the vicinity of the cluster. Modifications of the Fe-S bond lengths upon DNA binding, both of the Fe-S (sulfide) and Fe-S (thiolate) bonds in the [4Fe4S] cluster of EndoIII are responsible for the stabilization of the cluster towards higher oxidation state (3+), and hence its redox communication along the ds-DNA helix.

Assessing electron transfer reactions and catalysis in multicopper oxidases with operando X-ray absorption spectroscopy.

Here we propose an experimental setup based on operando X-ray absorption spectroscopy (XAS) to understand why copper-containing oxidoreductase enzymes show exceptional performance as catalysts for the oxygen reduction reaction (ORR). An electrode based on carbon nanoparticles organized in mesoporous structures with bilirubin oxidase (BOD) was developed to be used in a home-made operando XAS electrochemical cell, and we probed the electron transfer under ORR regime. In the presence of molecular oxygen, the BOD cofactor containing 4 copper ions require an overpotential about 150 mV to be reduced as compared to that in the absence of oxygen. A second electron transfer step, which occurs faster than the cofactor reduction, suggests that the cooper ions act as a tridimensional redox active electronic bridges for the electron transfer reaction.

Microwires of Au-Ag Nanocages Patterned via Magnetic Nanoadhesives for Investigating Proteins using Surface Enhanced Infrared Absorption Spectroscopy.

The controlled assembly of metal nanoparticles into ordered structures interacting with biological molecules is an emerging concept in surface science. Here, bare magnetite nanoparticles (Fe3O4-NPs) were employed as nanoadhesives to capture hollow metallic nanostructures (Au-Ag nanocages) from aqueous suspensions, and these coupled nanostructures were patterned onto various types of substrate via magnetolithography. Microwires of Au-Ag nanocages patterned onto an Au substrate behaved as optical antennas, providing a plasmonic enhancement exploited in surface-enhanced infrared absorption spectroscopy (SEIRAS) to investigate the proteins cytochrome c, bilirubin oxidase, alcohol dehydrogenase, bovine serum albumin, and glucose oxidase. Chemical maps containing more than 4000 spectra, acquired within only 2 min with a focal plane array detector, indicate that proteins were adsorbed along the microwires with their secondary structure preserved according to the spatial distribution of their amide groups. We believe there are significant practical aspects of the methodology proposed here to develop an alternative label-free assay for investigating biological molecules.

The structure-property relationship in LAPONITE® materials: from Wigner glasses to strong self-healing hydrogels formed by non-covalent interactions.

Rheology, small-angle X-ray scattering (SAXS), and dynamic light scattering (DLS) analysis, zeta potential measurement, scanning electron microscopy (SEM), and micro-FTIR and absorbance spectroscopy were used to enlighten the controversial literature about LAPONITE® materials. Our data suggest that pristine LAPONITE® in water does not form hydrogels induced by the so-called "house of cards" assembly, but rather forms Wigner glasses governed by repulsive forces. Ionic interactions between anisotropic LAPONITE® nanodiscs, sodium polyacrylate and inorganic salts afforded hydrogels that were transparent, self-standing, moldable, strong, and biocompatible with shear-thinning and self-healing behavior. An extensive study on the role of salts in the gelification process dictates a trend that relates the valence of cations with the viscoelastic properties of the bulk material (G' values follow the trend, monovalent < divalent < trivalent). These hydrogels present G' values up to 5.1 × 104 Pa, which are considered high values for non-covalent hydrogels. Hydrogels crosslinked with sodium phosphate salts are biocompatible, and might be valid candidates for injectable drug delivery systems due to their shear-thinning behavior with rapid self-healing after injection.

Nano-flocks of a bimetallic organic framework for efficient hydrogen evolution electrocatalysis.

Nano-flocks of a bimetallic organic framework (NiCo-MOF) were grown on a nickel mesh and covered with a graphene oxide aerosol skeleton by employing a nebulizer air compressor. The resulting material induces a high accessible active surface area and shows enhanced electrocatalytic activity towards the hydrogen evolution reaction with excellent stability in alkaline medium.

Activity and Stability of Dispersed Multi Metallic Pt-based Catalysts for CO Tolerance in Proton Exchange Membrane Fuel Cell Anodes.

Studies aiming at improving the activity and stability of dispersed W and Mo containing Pt catalysts for the CO tolerance in proton exchange membrane fuel cell (PEMFC) anodes are revised for the following catalyst systems: (1) a carbon supported PtMo electrocatalyst submitted to heat treatments; (2) Pt and PtMo nanoparticles deposited on carbon-supported molybdenum carbides (Mo2C/C); (3) ternary and quaternary materials formed by PtMoFe/C, PtMoRu/C and PtMoRuFe/C and; (4) Pt nanoparticles supported on tungsten carbide/carbon catalysts and its parallel evaluation with carbon supported PtW catalyst. The heat-treated (600 oC) Pt-Mo/C catalyst showed higher hydrogen oxidation activity in the absence and in the presence of CO and better stability, compared to all other Mo-containing catalysts. PtMoRuFe, PtMoFe, PtMoRu supported on carbon and Pt supported on Mo2C/C exhibited similar CO tolerances but better stability, as compared to as-prepared PtMo supported on carbon. Among the tungsten-based catalysts, tungsten carbide supported Pt catalyst showed reasonable performance and reliable stability in comparison to simple carbon supported PtW catalyst, though an uneven level of catalytic activity towards H2 oxidation in presence of CO is observed for the former as compared to Mo containing catalyst. However, a small dissolution of Mo, Ru, Fe and W from the anodes and their migration toward cathodes during the cell operation is observed. These results indicate that the fuel cell performance and stability has been improved but not yet totally resolved.

Activity and Stability of Dispersed Multi Metallic Pt-based Catalysts for CO Tolerance in Proton Exchange Membrane Fuel Cell Anodes

ABSTRACT Studies aiming at improving the activity and stability of dispersed W and Mo containing Pt catalysts for the CO tolerance in proton exchange membrane fuel cell (PEMFC) anodes are revised for the following catalyst systems: (1) a carbon supported PtMo electrocatalyst submitted to heat treatments; (2) Pt and PtMo nanoparticles deposited on carbon-supported molybdenum carbides (Mo2C/C); (3) ternary and quaternary materials formed by PtMoFe/C, PtMoRu/C and PtMoRuFe/C and; (4) Pt nanoparticles supported on tungsten carbide/carbon catalysts and its parallel evaluation with carbon supported PtW catalyst. The heat-treated (600 oC) Pt-Mo/C catalyst showed higher hydrogen oxidation activity in the absence and in the presence of CO and better stability, compared to all other Mo-containing catalysts. PtMoRuFe, PtMoFe, PtMoRu supported on carbon and Pt supported on Mo2C/C exhibited similar CO tolerances but better stability, as compared to as-prepared PtMo supported on carbon. Among the tungsten-based catalysts, tungsten carbide supported Pt catalyst showed reasonable performance and reliable stability in comparison to simple carbon supported PtW catalyst, though an uneven level of catalytic activity towards H2 oxidation in presence of CO is observed for the former as compared to Mo containing catalyst. However, a small dissolution of Mo, Ru, Fe and W from the anodes and their migration toward cathodes during the cell operation is observed. These results indicate that the fuel cell performance and stability has been improved but not yet totally resolved.

Influence of one week education program on the knowledge and approach of pharmacy students towards diabetes mellitus / Influencia del programa una semana de educación en el conocimiento y enfoque de los estudiantes de farmacia hacia la diabetes mellitus / Influência do programa uma semana de educação no conhecimento e enfoque dos estudantes de farmácia para o diabetes mellitus

The objective of this study was to assess the improvement in knowledge and attitude of Pharmacy student towards diabetes by implementing one week long education program. Study design: Study was conducted between April 25, 2011 to April 29, 2011 which engaged the 3rd professional year Pharm. D. students comprising two groups: experimental and control groups. Lectures and visual presentations on diabetic education and practice were conducted for five days. Three surveys were performed on two groups i.e. non intervened control, non- intervened experimental and intervened experimental surveys. Questionnaire was used as survey tool comprising of 46 questions under ten categories. Results: Scores in all diabetic knowledge aspect was increased after education intervention and was significantly (P<0.05) different from that of control group. Conclusion: The marked increase in knowledge about diabetes among pharmacy students illustrates the importance of educational intervention. Educational programs may markedly increase the educational skills, efficiency and confidence of pharmacy students as well as professionals.

El objetivo del estudio fue evaluar cómo mejorar el conocimiento y la actitud de los estudiantes de Farmacia hacia la diabetes, mediante la implementación de un programa de educación de una semana. Diseño: El estudio se realizó entre el 25 y el 29 de abril de 2011, entre estudiantes de 3er año de la carrera de Farmacia, conformados en dos grupos: uno experimental y otro de control. Se llevaron a cabo conferencias y presentaciones visuales en educación y práctica de la diabetes durante cinco días. Tres estudios se realizaron en dos grupos: el grupo control y experimental no intervenido y el de estudio experimental intervenido. Un cuestionario se utilizó como herramienta de estudio con 46 preguntas en diez categorías. Resultados: Las puntuaciones en el conocimiento sobre todo aspecto de la diabetes se incrementó después de la intervención educativa, lo que fue significativo (P <0,05) diferente de la de grupo de control. Conclusión: El marcado aumento en el conocimiento sobre la diabetes entre los estudiantes de farmacia ilustra la importancia de la intervención educativa. Los programas educativos pueden aumentar notablemente la capacidad educativa, la eficiencia y la confianza tanto en los estudiantes de farmacia, así como en los profesionales.

O objetivo do estudo foi avaliar como melhorar o conhecimento e a atitude dos estudantes de Farmácia para o diabetes, mediante a implementação de um programa de educação de uma semana. Projeto: O estudo se realizou entre 25 e 29 de abril de 2011, entre estudantes de 3º ano do curso de Farmácia, conformados em dois grupos: um experimental e outro de controle. Foram levadas a cabo conferências e apresentações visuais em educação e prática do diabetes durante cinco dias. Três estudos foram realizados em dois grupos: o grupo controle e experimental sem intervenção e o grupo de estudo experimental com intervenção. Um questionário foi utilizado como ferramenta de estudo com 46 perguntas em dez categorias. Resultados: As pontuações no conhecimento sobre todo aspecto do diabetes foi incrementado depois da intervenção educativa, o que foi significativamente (P <0,05) diferente das do grupo de controle. Conclusão: O marcado aumento no conhecimento sobre o diabetes entre os estudantes de farmácia ilustra a importância da intervenção educativa. Os programas educativos podem aumentar notavelmente a capacidade educativa, a eficiência e a confiança tanto nos estudantes de farmácia, bem como nos profissionais.