“Dual microfluidic sensor system for enriched electrochemical profiling and identification of illicit drugs on-site”. Steijlen ASM, Parrilla M, Van Echelpoel R, De Wael K, Analytical chemistry 96, 590 (2024). http://doi.org/10.1021/ACS.ANALCHEM.3C05039
Abstract: Electrochemical sensors have emerged as a new analytical tool for illicit drug detection to facilitate ultrafast and accurate identification of suspicious compounds on-site. Drugs of abuse can be identified using their unique voltammetric fingerprint at a given pH. Today, the right buffer solution is manually selected based on drug appearance, and in some cases, a consecutive analysis in two different pH solutions is required. In this work, we present a disposable microfluidic multichannel sensor system that automatically records fingerprints in two pH solutions (e.g., pH 5 and pH 12). This system has two advantages. It will overcome the manual selection of a buffer solution at the right pH, decrease analysis time, and minimize the risk of human errors. Second, the combination of two fingerprints, the superfingerprint, contains more detailed information about the samples, which enhances the selectivity of the analytical technique. First, real-time pH measurements proved that the sample can be brought to the desired pH within a minute. Subsequently, an electrochemical study on the microfluidic platform with 1 mM illicit drug standards of MDMA, cocaine, heroin, and methamphetamine showed that the characteristic voltammetric fingerprints and peak potentials are reproducible, also in the presence of common cutting agents. Finally, the microfluidic concept was validated with real confiscated samples, showing promising results for the user-friendly identification of drugs of abuse. In short, this paper presents a successful proof-of-concept study of a multichannel microfluidic sensor system to enrich the fingerprints of illicit drugs at pH 5 and pH 12, thus providing a low-cost, portable, and rapid identification system of illicit drugs with minimal user intervention.
Keywords: A1 Journal article; Engineering sciences. Technology; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)
Impact Factor: 7.4
DOI: 10.1021/ACS.ANALCHEM.3C05039
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“Combined macro X-ray fluorescence (MA-XRF) and pulse phase thermography (PPT) imaging for the technical study of panel paintings”. Deleu N, Hillen M, Steenackers G, Borms G, Janssens K, Van der Stighelen K, Van der Snickt G, Talanta : the international journal of pure and applied analytical chemistry 270, 125533 (2024). http://doi.org/10.1016/J.TALANTA.2023.125533
Abstract: Museum staff usually relies on a proven combination of X-ray radiography (XRR) and infrared reflectography (IRR) to study paintings in a non-destructive manner. In the last decades, however, the research toolbox of heritage scientists has expanded considerably, with a prime example being macro X-ray fluorescence (MA-XRF), producing element-specific images. The goal of this article is to illustrate the added value of augmenting MA-XRF with pulse phase thermography (PPT), a variant of active infrared thermographic imaging (IRT), which is an innovative diagnostic method that is able to reveal variations between or in materials, based on a different response to minor fluctuations in temperature when irradiated with optical radiation. By examining three 16thand 17th-century panel paintings we assess the extent in which combined MA-XRF and PPT contributes to a better understanding of two commonly encountered interventions to panel paintings: (a) Anstuckungen (enlargement of the panel) or (b) substitutions (replacement of part of the panel). Yielding information from different depths of the painting, these two techniques proved highly complementary with IRR and XRR, expanding the understanding of the build-up, genesis, and material history of the paintings. While MA-XRF documented the interventions to the wooden substrate indirectly by revealing variations in painting materials, paint handling and/ or layer sequence between the original part and the extended or replaced planks, PPT proved beneficial for the study of the wooden support itself, by providing a clear image of the wood structure quasi-free of distortion by the superimposed paint or cradling. XRR, on the other hand, revealed other features from the wood structure, not visible with PPT, and allowed looking through the wooden panels, revealing e.g. the dowels used for joining the planks. Additionally, IRR visualised dissimilarities in the underdrawings. In this way, the results indicate that PPT has the potential to become an acknowledged add-on to the expanding set of imaging methods for paintings, especially when used in combination with MA-XRF, IRR and XRR.
Keywords: A1 Journal article; Art; Antwerp Cultural Heritage Sciences (ARCHES); Antwerp X-ray Imaging and Spectroscopy (AXIS)
Impact Factor: 6.1
DOI: 10.1016/J.TALANTA.2023.125533
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“Chemical mapping of the degradation of geranium lake in paint cross sections by MALDI-MSI”. Alvarez-Martin A, Quanico J, Scovacricchi T, Avranovich Clerici E, Baggerman G, Janssens K, Analytical chemistry 95, 18215 (2023). http://doi.org/10.1021/ACS.ANALCHEM.3C03992
Abstract: Matrix assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) has become a powerful method to extract spatially resolved chemical information in complex materials. This study provides the first use of MALDI-MSI to define spatial–temporal changes in oil paints. Due to the highly heterogeneous nature of oil paints, the sample preparation had to be optimized to prevent molecules from delocalizing. Here, we present a new protocol for the layer-specific analysis of oil paint cross sections achieving a lateral resolution of 10 μm and without losing ionization efficiency due to topographic effects. The efficacy of this method was investigated in oil paint samples containing a mixture of two historic organic pigments, geranium lake and lead white, a mixture often employed in the work of painter Vincent Van Gogh. This methodology not only allows for spatial visualization of the molecules responsible for the pink hue of the paint but also helps to elucidate the chemical changes behind the discoloration of paintings with this composition. The results demonstrate that this approach provides valuable molecular compositional information about the degradation pathways of pigments in specific paint layers and their interaction with the binding medium and other paint components and with light over time. Since a spatial correlation between molecular species and the visual pattern of the discoloration pattern can be made, we expect that mass spectrometry imaging will become highly relevant in future degradation studies of many more historical pigments and paints.
Keywords: A1 Journal article; Antwerp X-ray Imaging and Spectroscopy (AXIS); Ecosphere
Impact Factor: 7.4
DOI: 10.1021/ACS.ANALCHEM.3C03992
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“Investigating the electrochemical profile of methamphetamine to enable fast on-site detection in forensic analysis”. Drăgan A-M, Parrilla M, Sleegers N, Slosse A, Van Durme F, van Nuijs A, Oprean R, Cristea C, De Wael K, Talanta : the international journal of pure and applied analytical chemistry 255, 124208 (2023). http://doi.org/10.1016/J.TALANTA.2022.124208
Abstract: Methamphetamine (MA) is a synthetic psychoactive drug which is consumed both licitly and illicitly. In some countries it is prescribed for attention-deficit and hyperactivity disorder, and short-term treatment of obesity. More often though, it is abused for its psychostimulant properties. Unfortunately, the spread and abuse of this synthetic drug have increased globally, being reported as the most widely consumed synthetic psychoactive drug in the world in 2019. Attempting to overcome the shortcomings of the currently used on-site methods for MA detection in suspected cargos, the present study explores the potential of electrochemical identification of MA by means of square wave voltammetry on disposable graphite screen-printed electrodes. Hence, the analytical characterization of the method was evaluated under optimal conditions exhibiting a linear range between 50 mu M and 2.5 mM MA, a LOD of 16.7 mu M, a LOQ of 50.0 mu M and a sensitivity of 5.3 mu A mM-1. Interestingly, two zones in the potential window were identified for the detection of MA, depending on its concentration in solution. Furthermore, the oxidative pathway of MA was elucidated employing liquid chromatography – mass spectrometry to understand the change in the electrochemical profile. Thereafter, the selectivity of the method towards MA in mixtures with other drugs of abuse as well as common adulterants/cutting agents was evaluated. Finally, the described method was employed for the analysis of MA in confiscated samples and compared with forensic methods, displaying its potential as a fast and easy-to-use method for on-site analysis.
Keywords: A1 Journal article; Toxicological Centre; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)
Impact Factor: 6.1
DOI: 10.1016/J.TALANTA.2022.124208
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“Photoelectrochemical behavior of phthalocyanine-sensitized TiO₂, in the presence of electron-shuttling mediators”. Khan SU, Trashin S, Beltran V, Korostei YS, Pelmus M, Gorun SM, Dubinina T V, Verbruggen SW, De Wael K, Analytical chemistry 94, 12723 (2022). http://doi.org/10.1021/ACS.ANALCHEM.2C02210
Abstract: Dye-sensitized TiO(2 )has found many applications for dye sensitized solar cells (DSSC), solar-to-chemical energy conversion, water/air purification systems, and (electro)chemical sensors. We report an electrochemical system for testing dye-sensitized materials that can be utilized in photoelectrochemical (PEC) sensors and energy conversion. Unlike related systems, the reported system does not require a direct electron transfer from semiconductors to electrodes. Rather, it relies on electron shuttling by redox mediators. A range of model photocatalytic materials were prepared using three different TiO2 materials (P25, P90, and PC500) and three sterically hindered phthalocyanines (Pcs) with electron-rich tert-butyl substituents (t-Bu4PcZn, t-Bu4PcAlCl, and t-Bu4PcH2). The materials were compared with previously developed TiO(2 )modified by electron-deficient, also sterically hindered fluorinated phthalocyanine F64PcZn, a singlet oxygen (O-1(2)) producer, as well as its metal-free derivative, F64PcH2. The PEC activity depended on the redox mediator, as well as the type of TiO2 and Pc. By comparing the responses of one-electron shuttles, such as K4Fe(CN)(4), and O-1(2)-reactive electron shuttles, such as phenol, it is possible to reveal the action mechanism of the supported photosensitizers, while the overall activity can be assessed using hydroquinone. t-Bu4PcAlCl showed significantly lower blank responses and higher specific responses toward chlorophenols compared to t-Bu4PcZn due to the electron-withdrawing effect of the Al3+ metal center. The combination of reactivity insights and the need for only microgram amounts of sensing materials renders the reported system advantageous for practical applications.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL); Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)
Impact Factor: 7.4
DOI: 10.1021/ACS.ANALCHEM.2C02210
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“Wearable hollow microneedle sensing patches for the transdermal electrochemical monitoring of glucose”. Parrilla M, Detamornrat U, Domínguez-Robles J, Donnelly RF, De Wael K, Talanta : the international journal of pure and applied analytical chemistry 249, 123695 (2022). http://doi.org/10.1016/J.TALANTA.2022.123695
Abstract: According to the World Health Organization, about 422 million people worldwide have diabetes, with 1.5 million deaths directly attributed each year. Therefore, there is still a need to effectively monitor glucose in diabetic patients for proper management. Recently, wearable patches based on microneedle (MN) sensors provide minimally invasive analysis of glucose through the interstitial fluid (ISF) while exhibiting excellent correlation with blood glucose. Despite many advances in wearable electrochemical sensors, long-term stability and continuous monitoring remain unsolved challenges. Herein, we present a highly stable electrochemical biosensor based on a redox mediator bilayer consisting of Prussian blue and iron-nickel hexacyanoferrate to increase the long-term stability of the readout coupled with a hollow MN array as a sampling unit for ISF uptake. First, the enzymatic biosensor is developed by using affordable screen-printed electrodes (SPE) and optimized for long-term stability fitting the physiological range of glucose in ISF (i.e., 2.5–22.5 mM). In parallel, the MN array is assessed for minimally invasive piercing of the skin. Subsequently, the biosensor is integrated with the MN array leaving a microfluidic spacer that works as the electrochemical cell. Interestingly, a microfluidic channel connects the cell with an external syringe to actively and rapidly withdraw ISF toward the cell. Finally, the robust MN sensing patch is characterized during in vitro and ex vivo tests. Overall, affordable wearable MN-based patches for the continuous monitoring of glucose in ISF are providing an advent in wearable devices for rapid and life-threatening decision-making processes.
Keywords: A1 Journal article; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)
DOI: 10.1016/J.TALANTA.2022.123695
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“Direct sensing of superoxide and its relatives reactive oxygen and nitrogen species in phosphate buffers during cold atmospheric plasmas exposures”. Girard-Sahun F, Lefrancois P, Badets V, Arbault S, Clement F, Analytical Chemistry 94, 5555 (2022). http://doi.org/10.1021/ACS.ANALCHEM.1C04998
Abstract: This study aims at sensing in situ reactive oxygen and nitrogen species (RONS) and specifically superoxide anion (O-2(center dot-)) in aqueous buffer solutions exposed to cold atmospheric plasmas (CAPs). CAPs were generated by ionizing He gas shielded with variable N-2/O-2 mixtures. Thanks to ultramicroelectrodes protected against the high electric fields transported by the ionization waves of CAPs, the production of superoxide and several RONS was electrochemically directly detected in liquids during their plasma exposure. Complementarily, optical emissive spectroscopy (OES) was used to study the plasma phase composition and its correlation with the chemistry in the exposed liquid. The specific production of O-2(center dot-), a biologically reactive redox species, was analyzed by cyclic voltammetry (CV), in both alkaline (pH 11), where the species is fairly stable, and physiological (pH 7.4) conditions, where it is unstable. To understand its generation with respect to the plasma chemistry, we varied the shielding gas composition of CAPs to directly impact on the RONS composition at the plasma-liquid interface. We observed that the production and accumulation of RONS in liquids, including O(2)(center dot-)depends on the plasma composition, with N-2-based shieldings providing the highest superoxide concentrations (few 10s of micromolar at most) and of its derivatives (hundreds of micromolar). In situ spectroscopic and electrochemical analyses provide a high resolution kinetic and quantitative understanding of the interactions between CAPs and physiological solutions for biomedical applications.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.4
DOI: 10.1021/ACS.ANALCHEM.1C04998
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“Correlation between the fluorination degree of perfluorinated zinc phthalocyanines, their singlet oxygen generation ability, and their photoelectrochemical response for phenol sensing”. Neven L, Barich H, Ching HYV, Khan SU, Colomier C, Patel HH, Gorun SM, Verbruggen S, Van Doorslaer S, De Wael K, Analytical chemistry 94, 5221 (2022). http://doi.org/10.1021/ACS.ANALCHEM.1C04357
Abstract: Electron-withdrawing perfluoroalkyl peripheral groups grafted on phthalocyanine (Pc) macrocycles improve their single-site isolation, solubility, and resistance to self-oxidation, all beneficial features for catalytic applications. A high degree of fluorination also enhances the reducibility of Pcs and could alter their singlet oxygen (1O2) photoproduction. The ethanol/toluene 20:80 vol % solvent mixture was found to dissolve perfluorinated FnPcZn complexes, n = 16, 52, and 64, and minimize the aggregation of the sterically unencumbered F16PcZn. The 1O2 production ability of FnPcZn complexes was examined using 9,10-dimethylanthracene (DMA) and 2,2,6,6-tetramethylpiperidine (TEMP) in combination with UV–vis and electron paramagnetic resonance (EPR) spectroscopy, respectively. While the photoreduction of F52PcZn and F64PcZn in the presence of redox-active TEMP lowered 1O2 production, DMA was a suitable 1O2 trap for ranking the complexes. The solution reactivity was complemented by solid-state studies via the construction of photoelectrochemical sensors based on TiO2-supported FnPcZn, FnPcZn|TiO2. Phenol photo-oxidation by 1O2, followed by its electrochemical reduction, defines a redox cycle, the 1O2 production having been found to depend on the value of n and structural features of the supported complexes. Consistent with solution studies, F52PcZn was found to be the most efficient 1O2 generator. The insights on reactivity testing and structural–activity relationships obtained may be useful for designing efficient and robust sensors and for other 1O2-related applications of FnPcZn.
Keywords: A1 Journal article; Organic synthesis (ORSY); Sustainable Energy, Air and Water Technology (DuEL); Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)
Impact Factor: 7.4
DOI: 10.1021/ACS.ANALCHEM.1C04357
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“Micro to nano : multiscale IR analyses reveal zinc soap heterogeneity in a 19th-century painting by Corot”. Ma X, Pavlidis G, Dillon E, Beltran V, Schwartz JJ, Thoury M, Borondics F, Sandt C, Kjoller K, Berrie BH, Centrone A, Analytical chemistry 94, 3103 (2022). http://doi.org/10.1021/ACS.ANALCHEM.1C04182
Abstract: Formation and aggregation of metal carboxylates (metal soaps) can degrade the appearance and integrity of oil paints, challenging efforts to conserve painted works of art. Endeavors to understand the root cause of metal soap formation have been hampered by the limited spatial resolution of Fourier transform infrared microscopy (mu-FTIR). We overcome this limitation using optical photothermal infrared spectroscopy (O-PTIR) and photothermal-induced resonance (PTIR), two novel methods that provide IR spectra with approximate to 500 and approximate to 10 nm spatial resolutions, respectively. The distribution of chemical phases in thin sections from the top layer of a 19th-century painting is investigated at multiple scales (mu-FTIR approximate to 10(2) mu m(3), O-PTIR approximate to 10(-1) mu m(3), PTIR approximate to 10(-5) mu m(3)). The paint samples analyzed here are found to be mixtures of pigments (cobalt green, lead white), cured oil, and a rich array of intermixed, small (often << 0.1 mu m(3)) zinc soap domains. We identify Zn stearate and Zn oleate crystalline soaps with characteristic narrow IR peaks (approximate to 1530-1558 cm(-1)) and a heterogeneous, disordered, water-permeable, tetrahedral zinc soap phase, with a characteristic broad peak centered at approximate to 1596 cm(-1). We show that the high signal-to-noise ratio and spatial resolution afforded by O-PTIR are ideal for identifying phase-separated (or locally concentrated) species with low average concentration, while PTIR provides an unprecedented nanoscale view of distributions and associations of species in paint. This newly accessible nanocompositional information will advance our knowledge of chemical processes in oil paint and will stimulate new art conservation practices.
Keywords: A1 Journal article; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)
DOI: 10.1021/ACS.ANALCHEM.1C04182
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“Electrochemical identification of hazardous phenols and their complex mixtures in real samples using unmodified screen-printed electrodes”. Barich H, Cánovas R, De Wael K, Journal of electroanalytical chemistry : an international journal devoted to all aspects of electrode kynetics, interfacial structure, properties of electrolytes, colloid and biological electrochemistry. 904, 115878 (2022). http://doi.org/10.1016/J.JELECHEM.2021.115878
Abstract: The electrochemical behavior of some of the most relevant endocrine-disrupting phenols using unmodified carbon screen-printed electrodes (SPEs) is described for the first time. Experiments were made to assess the electrochemical behavior of phenol (PHOH), pentachlorophenol (PCP), 4-tert octylphenol (OP) and bisphenol A (BPA) and their determination in the most favorable conditions, using voltammetric methods such as cyclic voltammetry (CV), linear sweep voltammetry (LSV) and square wave voltammetry (SWV) in Britton Robinson (BR) buffer. Further, the usefulness of the electrochemical approach was validated with real samples from a local river and was compared to commercial phenols test kit, which is commonly used for on-site screening in industrial streams and wastewaters. Finally, the approach was compared with a lab-bench standard method using real samples, i.e., high-performance liquid chromatography with a photodiode array detector (HPLC-DAD).
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)
Impact Factor: 4.5
DOI: 10.1016/J.JELECHEM.2021.115878
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“High-resolution mass spectrometry and nontraditional mass defect analysis of brominated historical pigments”. Alvarez-Martin A, Newsome GA, Janssens K, Analytical Chemistry 93, 14851 (2021). http://doi.org/10.1021/ACS.ANALCHEM.1C03815
Abstract: The implementation of high-resolution mass spectrometry systems offers new possibilities for the analysis of complex art samples such as historical oil paintings. However, these multicomponent systems generate large and complex data sets that require advanced visualization tools to aid interpretation, especially when no chromatographic separation is performed. In the context of this research, it was crucial to propose a data analysis tool to identify the products generated during the synthesis, drying, and aging of historical pigments. This study reports for the first time a nontraditional mass defect analysis of oil paint samples containing a fugitive brominated-organic pigment, eosin or geranium lake, by using direct infusion electrospray ionization in combination with a high-resolution Orbitrap mass spectrometer. The use of nontraditional Kendrick mass defect plots is presented in this study as a processing and visualization tool to recognize brominated species based on their specific mass defect and isotope pattern. The results demonstrate that this approach could provide valuable molecular compositional information on the degradation pathways of this pigment. We anticipate that mass defect analysis will become highly relevant in future degradation studies of many more historical organic pigments.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp X-ray Imaging and Spectroscopy (AXIS)
Impact Factor: 6.32
DOI: 10.1021/ACS.ANALCHEM.1C03815
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“Voltammetric sensing using an array of modified SPCE coupled with machine learning strategies for the improved identification of opioids in presence of cutting agents”. Ortiz-Aguayo D, De Wael K, del Valle M, Journal Of Electroanalytical Chemistry 902, 115770 (2021). http://doi.org/10.1016/J.JELECHEM.2021.115770
Abstract: This work reports the use of modified screen-printed carbon electrodes (SPCEs) for the identification of three drugs of abuse and two habitual cutting agents, caffeine and paracetamol, combining voltammetric sensing and chemometrics. In order to achieve this goal, codeine, heroin and morphine were subjected to Square Wave Voltammetry (SWV) at pH 7, in order to elucidate their electrochemical fingerprints. The optimized SPCEs electrode array, which have a differentiated response for the three oxidizable compounds, was derived from Carbon, Prussian blue, Cobalt (II) phthalocyanine, Copper (II) oxide, Polypyrrole and Palladium nanoparticles ink-modified carbon electrodes. Finally, Principal Component Analysis (PCA) coupled with Silhouette parameter assessment was used to select the most suitable combination of sensors for identification of drugs of abuse in presence of cutting agents.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)
Impact Factor: 3.012
DOI: 10.1016/J.JELECHEM.2021.115770
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“Analytical techniques for the detection of amphetamine-type substances in different matrices : a comprehensive review”. Drăgan A-M, Parrilla M, Feier B, Oprean R, Cristea C, De Wael K, Trac-Trends In Analytical Chemistry 145, 116447 (2021). http://doi.org/10.1016/J.TRAC.2021.116447
Abstract: This current review focuses on contributions to amphetamine-type substances (ATS) analysis. This type of synthetic illicit drugs has been increasingly present worldwide reaching 5% of the market on illicit drugs in 2019. The increment of their production in many clandestine laboratories and easy distribution among society are two of the main concerns towards the battle against synthetic drugs. Therefore, the first part of this review details the classification and mechanism of action of ATS in the human body. Second, the pharmacological and toxicological effects of ATS on human health are described to motivate the need of early detection of ATS. Subsequently, the most used laboratory-based and portable methods are presented and critically discussed along the review. Finally, a careful discussion on the advantages and disadvantages of portable techniques employed on the field are addressed as potential tools for on-site ATS detection by law enforcement officers.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)
Impact Factor: 8.442
DOI: 10.1016/J.TRAC.2021.116447
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“Nanobody-based immunosensor detection enhanced by photocatalytic-electrochemical redox cycling”. Trashin S, Morales-Yánez F, Thiruvottriyur Shanmugam S, Paredis L, Carrión EN, Sariego I, Muyldermans S, Polman K, Gorun SM, De Wael K, Analytical Chemistry 93, 13606 (2021). http://doi.org/10.1021/ACS.ANALCHEM.1C02876
Abstract: Detection of antigenic biomarkers present in trace amounts is of crucial importance for medical diagnosis. A parasitic disease, human toxocariasis, lacks an adequate diagnostic method despite its worldwide occurrence. The currently used serology tests may stay positive even years after a possibly unnoticed infection, whereas the direct detection of a re-infection or a still active infection remains a diagnostic challenge due to the low concentration of circulating parasitic antigens. We report a time-efficient sandwich immunosensor using small recombinant single-domain antibodies (nanobodies) derived from camelid heavy-chain antibodies specific to Toxocara canis antigens. An enhanced sensitivity to pg/mL levels is achieved by using a redox cycle consisting of a photocatalytic oxidation and electrochemical reduction steps. The photocatalytic oxidation is achieved by a photosensitizer generating singlet oxygen (1O2) that, in turn, readily reacts with p-nitrophenol enzymatically produced under alkaline conditions. The photooxidation produces benzoquinone that is electrochemically reduced to hydroquinone, generating an amperometric response. The light-driven process could be easily separated from the background, thus making amperometric detection more reliable. The proposed method for detection of the toxocariasis antigen marker shows superior performances compared to other detection schemes with the same nanobodies and outperforms by at least two orders of magnitude the assays based on regular antibodies, thus suggesting new opportunities for electrochemical immunoassays of challenging low levels of antigens.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)
Impact Factor: 6.32
DOI: 10.1021/ACS.ANALCHEM.1C02876
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“Unraveling the effect of the aptamer complementary element on the performance of duplexed aptamers : a thermodynamic study”. Dillen A, Vandezande W, Daems D, Lammertyn J, Analytical And Bioanalytical Chemistry 413, 4739 (2021). http://doi.org/10.1007/S00216-021-03444-Y
Abstract: Duplexed aptamers (DAs) are widespread aptasensor formats that simultaneously recognize and signal the concentration of target molecules. They are composed of an aptamer and aptamer complementary element (ACE) which consists of a short oligonucleotide that partially inhibits the aptamer sequence. Although the design principles to engineer DAs are straightforward, the tailored development of DAs for a particular target is currently based on trial and error due to limited knowledge of how the ACE sequence affects the final performance of DA biosensors. Therefore, we have established a thermodynamic model describing the influence of the ACE on the performance of DAs applied in equilibrium assays and demonstrated that this relationship can be described by the binding strength between the aptamer and ACE. To validate our theoretical findings, the model was applied to the 29-mer anti-thrombin aptamer as a case study, and an experimental relation between the aptamer-ACE binding strength and performance of DAs was established. The obtained results indicated that our proposed model could accurately describe the effect of the ACE sequence on the performance of the established DAs for thrombin detection, applied for equilibrium assays. Furthermore, to characterize the binding strength between the aptamer and ACEs evaluated in this work, a set of fitting equations was derived which enables thermodynamic characterization of DNA-based interactions through thermal denaturation experiments, thereby overcoming the limitations of current predictive software and chemical denaturation experiments. Altogether, this work encourages the development, characterization, and use of DAs in the field of biosensing.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.431
DOI: 10.1007/S00216-021-03444-Y
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“Flowing Atmospheric Pressure Afterglow for Ambient Ionization: Reaction Pathways Revealed by Modeling”. Aghaei M, Bogaerts A, Analytical Chemistry 93, 6620 (2021). http://doi.org/10.1021/acs.analchem.0c04076
Abstract: We describe the plasma chemistry in a helium flowing atmospheric pressure afterglow (FAPA) used for analytical spectrometry, by means of a quasione-dimensional (1D) plasma chemical kinetics model. We study the effect of typical impurities present in the feed gas, as well as the afterglow in ambient humid air. The model provides the species density profiles in the discharge and afterglow regions and the chemical pathways. We demonstrate that H, N, and O atoms are formed in the discharge region, while the dominant reactive neutral species in the afterglow are O3 and NO. He* and He2* are responsible for Penning ionization of O2, N2, H2O, H2, and N, and especially O and H atoms. Besides, He2+ also contributes to ionization of N2, O2, H2O, and O through charge transfer reactions. From the pool of ions created in the discharge, NO+ and (H2O)3H+ are the dominant ions in the afterglow. Moreover, negatively charged clusters, such as NO3H2O− and NO2H2O−, are formed and their pathway is discussed as well. Our model predictions are in line with earlier observations in the literature about the important reagent ions and provide a comprehensive overview of the underlying pathways. The model explains in detail why helium provides a high analytical sensitivity because of high reagent ion formation by both Penning ionization and charge transfer. Such insights are very valuable for improving the analytical performance of this (and other) ambient desorption/ionization source(s).
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 6.32
DOI: 10.1021/acs.analchem.0c04076
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“Mapping the gaps in chemical analysis for the characterisation of aptamer-target interactions”. Daems E, Moro G, Campos R, De Wael K, Trac-Trends In Analytical Chemistry 142, 116311 (2021). http://doi.org/10.1016/J.TRAC.2021.116311
Abstract: Aptamers are promising biorecognition elements with a wide applicability from therapeutics to bio-sensing. However, to successfully use these biomolecules, a complete characterisation of their bindingperformance in the presence of the target is crucial. Several multi-analytical approaches have been re-ported including techniques to describe kinetic and thermodynamic aspects of the aptamer-targetinteraction, and techniques which allow an in-depth understanding of the aptamer-target structures.Recent literature shows the need of a critical data interpretation, a combination of characterisationtechniques and suggests the key role of the characterisation protocol design. Indeed, thefinal applicationof the aptamer should be considered before choosing the characterisation method. All the limitations andcapabilities of the analytical tools in use for aptamer characterisation should be taken into account. Here,we present a critical overview of the current methods and multi-analytical approaches to study aptamer-target binding, aiming to provide researchers with guidelines for the design of characterisation protocols.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 8.442
DOI: 10.1016/J.TRAC.2021.116311
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“Electrochemistry of intact versus degraded cephalosporin antibiotics facilitated by LC–MS analysis”. Sleegers N, van Nuijs ALN, van den Berg M, De Wael K, Analytical Chemistry 93, 2394 (2021). http://doi.org/10.1021/ACS.ANALCHEM.0C04286
Abstract: The electrochemical detection of cephalosporins is a promising approach for the monitoring of cephalosporin levels in process waters. However, this class of antibiotics, like penicillins, is composed of chemically active molecules and susceptible to hydrolysis and aminolysis of the four membered β-lactam ring present. In order to develop a smart monitoring strategy for cephalosporins, the influence of degradation (hydrolysis and aminolysis) on the electrochemical fingerprint has to be taken into account. Therefore, an investigation was carried out to understand the changes of the voltammetric fingerprints upon acidic and alkaline degradation. Changes in fingerprints were correlated to the degradation pathways through the combination of square wave voltammetry and liquid chromatography quadrupole time-of-flight analysis. The characteristic electrochemical signals of the β-lactam ring disappeared upon hydrolysis. Additional oxidation signals that appeared after degradation were elucidated and linked to different degradation products, and therefore, enrich the voltammetric fingerprints with information of the state of the cephalosporins. The applicability of the electrochemical monitoring system was explored by the analysis of the intact and degraded industrial process waters containing the key intermediate 7-aminodeacetoxycephalosporanic acid (7-ADCA). Clearly, the intact process samples exhibited the expected core signals of 7-ADCA and could be quantified, while the degraded samples only showed the newly formed degradation products.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Toxicological Centre
Impact Factor: 6.32
DOI: 10.1021/ACS.ANALCHEM.0C04286
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“Identifying Electrochemical Fingerprints of Ketamine with Voltammetry and Liquid Chromatography–Mass Spectrometry for Its Detection in Seized Samples”. Schram J, Parrilla M, Sleegers N, Samyn N, Bijvoets SM, Heerschop MWJ, van Nuijs ALN, De Wael K, Analytical Chemistry 92, 13485 (2020). http://doi.org/10.1021/acs.analchem.0c02810
Abstract: Herein, a straightforward electrochemical approach for the determination of ketamine in street samples and seizures is presented by employing screen-printed electrodes (SPE). Square wave voltammetry (SWV) is used to study the electrochemical behavior of the illicit drug, thus profiling the different oxidation states of the substance at different pHs. Besides, the oxidation pathway of ketamine on SPE is investigated for the first time with liquid chromatography–high-resolution mass spectrometry. Under the optimized conditions, the calibration curve of ketamine at buffer solution (pH 12) exhibits a sensitivity of 8.2 μA μM–1, a linear relationship between 50 and 2500 μM with excellent reproducibility (RSD = 2.2%, at 500 μM, n = 7), and a limit of detection (LOD) of 11.7 μM. Subsequently, binary mixtures of ketamine with adulterants and illicit drugs are analyzed with SWV to investigate the electrochemical fingerprint. Moreover, the profile overlapping between different substances is addressed by the introduction of an electrode pretreatment and the integration of a tailor-made script for data treatment. Finally, the approach is tested on street samples from forensic seizures. Overall, this system allows for the on-site identification of ketamine by law enforcement agents in an easy-to-use and rapid manner on cargos and seizures, thereby disrupting the distribution channel and avoiding the illicit drug reaching the end-user.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Toxicological Centre
Impact Factor: 7.4
DOI: 10.1021/acs.analchem.0c02810
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“Damages induced by synchrotron radiation-based X-ray microanalysis in chrome yellow paints and related Cr-compounds : assessment, quantification, and mitigation strategies”. Monico L, Cotte M, Vanmeert F, Amidani L, Janssens K, Nuyts G, Garrevoet J, Falkenberg G, Glatzel P, Romani A, Miliani C, Analytical Chemistry 92, 14164 (2020). http://doi.org/10.1021/ACS.ANALCHEM.0C03251
Abstract: Synchrotron radiation (SR)-based X-ray methods are powerful analytical tools for several purposes. They are widely used to probe the degradation mechanisms of inorganic artists' pigments in paintings, including chrome yellows (PbCr1-xSxO4; 0 <= x <= 0.8), a class of compounds often found in Van Gogh masterpieces. However, the high intensity and brightness of SR beams raise important issues regarding the potential damage inflicted on the analyzed samples. A thorough knowledge of the SR X-ray sensitivity of each class of pigment in the painting matrix is therefore required to find analytical strategies that seek to minimize the damage for preserving the integrity of the analyzed samples and to avoid data misinterpretation. Here, we employ a combination of Cr K-edge X-ray absorption near-edge structure spectroscopy, Cr-K-beta X-ray emission spectroscopy, and X-ray diffraction to monitor and quantify the effects of SR X-rays on the stability of chrome yellows and related Cr compounds and to define mitigation strategies. We found that the SR X-ray beam exposure induces changes in the oxidation state and local coordination environment of Cr ions and leads to a loss of the compound's crystalline structure. The extent of X-ray damage depends on some intrinsic properties of the samples (chemical composition of the pigment and the presence/absence and nature of the binder). It can be minimized by optimizing the overall fluence/dose released to the samples and by working in vacuum and under cryogenic conditions.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 7.4
DOI: 10.1021/ACS.ANALCHEM.0C03251
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“Epidermal patch with glucose biosensor : pH and temperature correction toward more accurate sweat analysis during sport practice”. Wiorek A, Parrilla M, Cuartero M, Crespo GA, Analytical Chemistry 92, 10153 (2020). http://doi.org/10.1021/ACS.ANALCHEM.0C02211
Abstract: We present an epidermal patch for glucose analysis in sweat incorporating for the first time pH and temperature correction according to local dynamic fluctuations in sweat during on-body tests. This sort of correction is indeed the main novelty of the paper, being crucial toward reliable measurements in every sensor based on an enzymatic element whose activity strongly depends on pH and temperature. The results herein reported for corrected glucose detection during on-body measurements are supported by a two-step validation protocol: with the biosensor operating off- and on-bodily, correlating the results with UV-vis spectrometry and/or ion chromatography. Importantly, the wearable device is a flexible skin patch that comprises a microfluidic cell designed with a sweat collection zone coupled to a fluidic channel in where the needed electrodes are placed: glucose biosensor, pH potentiometric electrode and a temperature sensor. The glucose biosensor presents a linear range of response within the expected physiological levels of glucose in sweat (10-200 mu M), and the calibration parameters are dynamically adjusted to any change in pH and temperature during the sport practice by means of a new “correction approach”. In addition, the sensor displays a fast response time, appropriate selectivity, and excellent reversibility. A total of 9 validated on-body tests are presented: the outcomes revealed a great potential of the wearable glucose sensor toward the provision of reliable physiological data linked to individuals during sport activity. In particular, the developed “correction approach” is expected to impact into the next generation of wearable devices that digitalize physiological activities through chemical information in a trustable manner for both sport and healthcare applications.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 7.4
DOI: 10.1021/ACS.ANALCHEM.0C02211
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“Unlocking the full power of electrochemical fingerprinting for on-site sensing applications”. Moro G, Barich H, Driesen K, Montiel NF, Neven L, Mendonca CD, Thiruvottriyur Shanmugam S, Daems E, De Wael K, Analytical And Bioanalytical Chemistry , 1 (2020). http://doi.org/10.1007/S00216-020-02584-X
Abstract: Electrochemical sensing for the semi-quantitative detection of biomarkers, drugs, environmental contaminants, food additives, etc. shows promising results in point-of-care diagnostics and on-site monitoring. More specifically, electrochemical fingerprint (EF)-based sensing strategies are considered an inviting approach for the on-site detection of low molecular weight molecules. The fast growth of electrochemical sensors requires defining the concept of direct electrochemical fingerprinting in sensing. The EF can be defined as the unique electrochemical signal or pattern, mostly recorded by voltammetric techniques, specific for a certain molecule that can be used for its quantitative or semi-quantitative identification in a given analytical context with specified circumstances. The performance of EF-based sensors can be enhanced by considering multiple features of the signal (i.e., oxidation or reduction patterns), in combination with statistical data analysis or sample pretreatments or by including electrode surface modifiers to enrich the EF. In this manuscript, some examples of EF-based sensors, strategies to improve their performances, and open challenges are discussed to unlock the full power of electrochemical fingerprinting for on-site sensing applications.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 4.3
Times cited: 3
DOI: 10.1007/S00216-020-02584-X
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“Modeling plasmas in analytical chemistry—an example of cross-fertilization”. Bogaerts A, Analytical And Bioanalytical Chemistry 412, 6059 (2020). http://doi.org/10.1007/s00216-020-02587-8
Abstract: This paper gives an overview of the modeling work developed in our group in the last 25 years for various plasmas used in analytical spectrochemistry, i.e., glow discharges (GDs), inductively coupled plasmas (ICPs), and laser ablation (LA) for sample introduction in the ICP and for laser-induced breakdown spectroscopy (LIBS). The modeling approaches are briefly presented, which are different for each case, and some characteristic results are illustrated. These plasmas are used not only in analytical chemistry but also in other applications, and the insights obtained in these other fields were quite helpful for us to develop models for the analytical plasmas. Likewise, there is now a huge interest in plasma–liquid interaction, atmospheric pressure glow discharges (APGDs), and dielectric barrier discharges (DBDs) for environmental, medical, and materials applications of plasmas. The insights obtained in these fields are also very relevant for ambient desorption/ionization sources and for liquid sampling, which are nowadays very popular in analytical chemistry, and they could be very helpful in developing models for these sources as well.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.3
DOI: 10.1007/s00216-020-02587-8
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“Interface for reproducible, multishot direct analysis of solid-phase microextraction samples”. Newsome GA, Kavich G, Alvarez-Martin A, Analytical Chemistry 92, 4182 (2020). http://doi.org/10.1021/ACS.ANALCHEM.9B05691
Abstract: An enclosed interface that joins a direct analysis in real time (DART) probe, solid-phase microextraction (SPME) fiber, and the inlet of a high-resolution mass spectrometer is described. Unlike other systems to couple SPME sampling to ambient mass spectrometry, the interface is able to perform discrete analyses on different areas of a single SPME fiber device for up to three technical replicate measurements of one sampling event. Inlet flow speed and desorption temperature are optimized, and reproducibility is demonstrated between replicate analyses on the same derivatized SPME fiber and with sequential fiber sampling events, yielding analyte measurement center of variance (CV) from 3 to 6%. Conditioning is also performed with the enclosed DART. The interface is a straightforward addition to commercially available technologies, and machine diagrams for custom components operated with SPME/DART/MS equipment are included.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 7.4
DOI: 10.1021/ACS.ANALCHEM.9B05691
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“Amperometric flow-injection analysis of phenols induced by reactive oxygen species generated under daylight irradiation of titania impregnated with horseradish peroxidase”. Rahemi V, Trashin S, Hafideddine Z, Van Doorslaer S, Meynen V, Gorton L, De Wael K, Analytical Chemistry 92, 3643 (2020). http://doi.org/10.1021/acs.analchem.9b04617
Abstract: Titanium dioxide (TiO2) is a unique material for biosensing applications due to its capability of hosting enzymes. For the first time, we show that TiO2 can accumulate reactive oxygen species (ROS) under daylight irradiation and can support the catalytic cycle of horseradish peroxidase (HRP) without the need of H2O2 to be present in the solution. Phenolic compounds, such as hydroquinone (HQ) and 4-aminophenol (4-AP), were detected amperometrically in flow-injection analysis (FIA) mode via the use of an electrode modified with TiO2 impregnated with HRP. In contrast to the conventional detection scheme, no H2O2 was added to the analyte solution. Basically, the inherited ability of TiO2 to generate reactive oxygen species is used as a strategy to avoid adding H2O2 in the solution during the detection of phenolic compounds. Electron paramagnetic resonance (EPR) spectroscopy indicates the presence of ROS on titania which, in interaction with HRP, initiate the electrocatalysis toward phenolic compounds. The amperometric response to 4-AP was linear in the concentration range between 0.05 and 2 μM. The sensitivity was 0.51 A M–1 cm–2, and the limit of detection (LOD) 26 nM. The proposed sensor design opens new opportunities for the detection of phenolic traces by HRP-based electrochemical biosensors, yet in a more straightforward and sensitive way following green chemistry principles of avoiding the use of reactive and harmful chemical, such as H2O2.
Keywords: A1 Journal article; Laboratory of adsorption and catalysis (LADCA); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 7.4
Times cited: 3
DOI: 10.1021/acs.analchem.9b04617
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“Thin-layer potentiometry for creatinine detection in undiluted human urine using ion-exchange membranes as barriers for charged interferences”. Liu Y, Cánovas R, Crespo GA, Cuartero M, Analytical Chemistry 92, 3315 (2020). http://doi.org/10.1021/ACS.ANALCHEM.9B05231
Abstract: Herein, thin-layer potentiometry combined with ion-exchange membranes as barriers for charged interferences is demonstrated for the analytical detection of creatinine (CRE) in undiluted human urine. Briefly, CRE diffuses through an anion-exchange membrane (AEM) from a sample contained in one fluidic compartment to a second reservoir, containing the enzyme CRE deiminase. There, CRE reacts with the enzyme, and the formation of ammonium is dynamically monitored by potentiometric ammonium-selective electrodes. This analytical concept is integrated into a lab-on-a-chip microfluidic cell that allows for a high sample throughput and the operation under stop-flow mode, which allows CRE to passively diffuse across the AEM. Conveniently, positively charged species (i.e., potassium, sodium, and ammonium, among others) are repelled by the AEM and never reach the ammonium-selective electrodes; thus, possible interference in the response can be avoided. As a result, the dynamic potential response of the electrodes is entirely ascribed to the stoichiometric formation of ammonium. The new CRE biosensor exhibits a Nernstian slope, within a linear range of response from 1 to 50 mM CRE concentration. As expected, the response time (15–60 min) primarily depends on the CRE diffusion across the AEM. CRE analysis in urine samples displayed excellent results, without requiring sample pretreatment (before the introduction of the sample in the microfluidic chip) and with high compatibility with development into a potential point-of-care clinical tool. In an attempt to decrease the analysis time, the presented analytical methodology for CRE detection is translated into an all-solid-state platform, in which the enzyme is immobilized on the surface of the ammonium-selective electrode and with the AEM on top. While more work is necessary in this direction, the CRE sensor appears to be promising for CRE analysis in both urine and blood.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 7.4
DOI: 10.1021/ACS.ANALCHEM.9B05231
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“Emerging halogenated flame retardants in the indoor environment”. Poma G, McGrath TJ, Christia C, Govindan M, Covaci A, Comprehensive analytical chemistry 88, 107 (2020). http://doi.org/10.1016/BS.COAC.2019.10.004
Abstract: Indoor environments are considered an important contributor to external human exposure to halogenated flame retardants (HFRs) due to the large amounts of chemicals currently incorporated in indoor equipment and the time humans spend every day in indoor environments. In this chapter, the presence and use of novel brominated flame retardants (NBFRs), dechlorane plus (DPs), chlorinated organophosphorus flame retardants (Cl-PFRs) and chlorinated paraffins (CPs) in indoor dust, air and consumer products collected from different indoor microenvironments (homes, public indoor spaces, and vehicles) are discussed. While data on the concentrations of HFRs in indoor dust and air are widely available, figures are still scarce for consumer products, such as textiles and foams, furnishings, flooring, electric and electronic products and building materials. This knowledge gaps still represents the biggest obstacle in linking eventual sources of contamination to the presence and chemical patterns in indoor dust and air.
Keywords: A1 Journal article; Pharmacology. Therapy; Electron microscopy for materials research (EMAT); Toxicological Centre
DOI: 10.1016/BS.COAC.2019.10.004
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“Unraveling the mechanisms behind the complete suppression of cocaine electrochemical signals by chlorpromazine, promethazine, procaine, and dextromethorphan”. De Jong M, Sleegers N, Florea A, Van Loon J, van Nuijs ALN, Samyn N, De Wael K, Analytical chemistry 91, 15453 (2019). http://doi.org/10.1021/ACS.ANALCHEM.9B03128
Abstract: The present work investigates the challenges accompanied by the electrochemical cocaine detection in physiological conditions (pH 7) in the presence of chlorpromazine, promethazine, procaine, and dextromethorphan, frequently used cutting agents in cocaine street samples. The problem translates into the absence of the cocaine oxidation signal (signal suppression) when in a mixture with one of these compounds, leading to false negative results. Although a solution to this problem was provided through earlier experiments of our group, the mechanisms behind the suppression are now fundamentally investigated via electrochemical and liquid chromatography quadrupole-time-of-flight mass spectrometry (LC-QTOF-MS) strategies. The latter was used to confirm the passivation of the electrodes due to their interaction with promethazine and chlorpromazine. Electron transfer mechanisms were further identified via linear sweep voltammetry. Next, adsorption experiments were performed on the graphite screen printed electrodes both with and without potential assistance in order to confirm if the suppression of the cocaine signals is due to passivation induced by the cutting agents or their oxidized products. The proposed strategies allowed us to identify the mechanisms of cocaine suppression for each cutting agent mentioned. Suppression due to procaine and dextromethorphan is caused by fouling of the electrode surface by their oxidized forms, while for chlorpromazine and promethazine the suppression of the cocaine signal is related to the strong adsorption of these (nonoxidized) cutting agents onto the graphite electrode surface. These findings provide fundamental insights in possible suppression and other interfering mechanisms using electrochemistry in general not only in the drug detection sector.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Toxicological Centre; Product development
Impact Factor: 6.32
DOI: 10.1021/ACS.ANALCHEM.9B03128
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“Fast one-step ultrasensitive detection of toxocara canis antigens by a nanobody-based electrochemical magnetosensor”. Morales-Yanez F, Trashin S, Hermy M, Sariego I, Polman K, Muyldermans S, De Wael K, Analytical chemistry 91, 11582 (2019). http://doi.org/10.1021/ACS.ANALCHEM.9B01687
Abstract: Human toxocariasis (HT) is a cosmopolitan zoonotic disease caused by the migration of the larval stage of the roundworm Toxocara canis. Current HT diagnostic methods do not discriminate between active and past infections. Here, we present a method to quantify Toxocara excretory/secretory antigen, aiming to identify active cases of HT. High specificity is achieved by employing nanobodies (Nbs), single domain antigen binding fragments from camelid heavy chain-only antibodies. High sensitivity is obtained by the design of an electrochemical magnetosensor with an amperometric read-out. Reliable detection of TES antigen at 10 and 30 pg/mL level was demonstrated in phosphate buffered saline and serum, respectively. Moreover, the assay showed no cross-reactivity with other nematode antigens. To our knowledge, this is the most sensitive method to quantify the TES antigen so far. It also has great potential to develop point of care diagnostic systems in other conditions where high sensitivity and specificity are required.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 6.32
Times cited: 2
DOI: 10.1021/ACS.ANALCHEM.9B01687
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“Rapid evaluation of the debromination mechanism of eosin in oil paint by direct analysis in real time and direct infusion-electrospray ionization mass spectrometry”. Alvarez-Martin A, Cleland TP, Kavich GM, Janssens K, Newsome GA, Analytical chemistry 91, 10856 (2019). http://doi.org/10.1021/ACS.ANALCHEM.9B02568
Abstract: Eosin is a synthetic organic colorant prone to fading under the influence of light. On the basis of the growing interest in the understanding of the discoloration mechanism of eosin-based lakes, this study compares the ability of two ultrafast and ultrasensitive mass spectrometry techniques to detect eosin derivatives in complex matrices, such as oil media without the use of conventional separation columns or additional sample preparation protocols. Direct analysis in real time mass spectrometry (DART-MS) and direct infusion electrospray ionization mass spectrometry (DI-ESI-MS) were used to characterize the degradation pathway of eosin in oil media. The analysis protocols developed in this study are applied to discern the degradation mechanism of the lake pigment eosin (comprising the molecule per se complexed to an inorganic substrate) dispersed in linseed oil to create an oil paint. The analysis of oil paints by high resolution MS without an extraction methodology that modifies the system chemistry allowed us to identify the degradation forms without causing any additional fragmentation. Both techniques revealed the primary photodegradation pathway of eosin in linseed oil, and DI-ESI-MS provided additional information on the native conformation of the lake.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 6.32
Times cited: 3
DOI: 10.1021/ACS.ANALCHEM.9B02568
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