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Cells Nov 2022Gaining structural information is a must to allow the unequivocal structural characterization of analytes from natural sources. In liquid state, NMR spectroscopy is... (Review)
Review
Gaining structural information is a must to allow the unequivocal structural characterization of analytes from natural sources. In liquid state, NMR spectroscopy is almost the only possible alternative to HPLC-MS and hyphenating the effluent of an analyte separation device to the probe head of an NMR spectrometer has therefore been pursued for more than three decades. The purpose of this review article was to demonstrate that, while it is possible to use mass spectrometry and similar methods to differentiate, group, and often assign the differentiating variables to entities that can be recognized as single molecules, the structural characterization of these putative biomarkers usually requires the use of NMR spectroscopy.
Topics: Molecular Structure; Magnetic Resonance Spectroscopy; Chromatography, High Pressure Liquid; Mass Spectrometry
PubMed: 36359922
DOI: 10.3390/cells11213526 -
Frontiers in Chemistry 2021Anodic stripping voltammetry (ASV) is a powerful electrochemical analytical technique that allows for the detection and quantification of a variety of metal ion species... (Review)
Review
Anodic stripping voltammetry (ASV) is a powerful electrochemical analytical technique that allows for the detection and quantification of a variety of metal ion species at very low concentrations in aqueous media. While early, traditional ASV measurements relied on macroscopic electrodes like Hg drop electrodes to provide surfaces suitable for plating/stripping, more recent work on the technique has replaced these electrodes with thin film metal electrodes generated . Such electrodes are plated alongside the analyte species onto the surface of a primary electrode, producing a composite metal electrode from which the analyte(s) can then be stripped, identified, and quantified. In this minireview, we will explore the development and use of these unique electrodes in a variety of different applications. A number of metals (e.g., Hg, Bi, Sn, etc.) have shown promise as thin film ASV electrodes in both acidic and alkaline media, and frequently multiple metals in addition to the analyte of interest are deposited together to optimize the plating/stripping behavior, improving sensitivity. Due to the relatively simple nature of the measurement and its suitability for a wide range of pH, it has been used broadly: To measure toxic metals in the environment, characterize battery materials, and enable biological assays, among other applications. We will discuss these applications in greater detail, as well as provide perspective on future development and uses of these thin film electrodes in ASV measurements.
PubMed: 35186893
DOI: 10.3389/fchem.2021.809535 -
Foods (Basel, Switzerland) Oct 2023Multi-analyte methods based on QuEChERS sample preparation and chromatography/mass spectrometry determination are indispensable in monitoring pesticide residues in the...
Multi-analyte methods based on QuEChERS sample preparation and chromatography/mass spectrometry determination are indispensable in monitoring pesticide residues in the feed and food chain. QuEChERS method, even though perceived as convenient and generic, can contribute to sample matrix constituents' introduction to the measuring system and possibly affect analytical results. In this study, matrix effects (ME) were investigated in four food matrices of plant origin (apples, grapes, spelt kernels, and sunflower seeds) during GC-MS/MS analysis of >200 pesticide residues using QuEChERS sample preparation. Data analysis revealed considerable analyte signal enhancement and suppression: strong enhancement was observed for the majority of analytes in two matrices within the commodity groups with high water content-apples, and high acid and water content-grapes (73.9% ME and 72.5% ME, and 77.7% ME and 74.9% ME, respectively), while strong suppression was observed for matrices within the commodity groups with high starch/protein content and low water and fat content-spelt kernels, and high oil content and very low water content-sunflower seeds (82.1% ME and 82.6% ME, and 65.2% ME and 70.0% ME, respectively). Although strong matrix effects were the most common for all investigated matrices, the use of matrix-matched calibration for each sample type enabled satisfactory method performance, i.e., recoveries for the majority of analytes (up to roughly 90%, depending on the fortification level and matrix type), which was also externally confirmed through participation in proficiency testing schemes for relevant food commodity groups with the achieved z-scores within acceptable range ≤ |2|.
PubMed: 37959112
DOI: 10.3390/foods12213991 -
ACS Sensors Oct 2021Potentiometric sensors induce a spontaneous voltage that indicates ion activity in real time. We present here an advanced self-powered potentiometric sensor with memory....
Potentiometric sensors induce a spontaneous voltage that indicates ion activity in real time. We present here an advanced self-powered potentiometric sensor with memory. Specifically, the approach allows for one to record a deviation from the analyte's original concentration or determine whether the analyte concentration has surpassed a threshold in a predefined time interval. The sensor achieves this by harvesting energy in a capacitor and preserving it with the help of a diode. While the analyte concentration is allowed to return to an original value following a perturbation over time, this may not influence the sensor readout. To achieve the diode function, the sensor utilizes an additional pair of driving electrodes to move the potentiometric signal to a sufficiently high base voltage that is required for operating the diode placed in series with the capacitor and between the sensing probes. A single voltage measurement across the capacitor at the end of a chosen time interval is sufficient to reveal any altered ion activity occurring during that period. We demonstrate the applicability of the sensor to identify incurred pH changes in a river water sample during an interval of 2 h. This approach is promising for achieving deployable sensors to monitor ion activity relative to a defined threshold during a time interval with minimal electronic components in a self-powered design.
Topics: Electrodes; Electronics; Potentiometry
PubMed: 34582164
DOI: 10.1021/acssensors.1c01273 -
Lab on a Chip Jan 2021The biophysical analysis of single-cells by microfluidic impedance cytometry is emerging as a label-free and high-throughput means to stratify the heterogeneity of...
The biophysical analysis of single-cells by microfluidic impedance cytometry is emerging as a label-free and high-throughput means to stratify the heterogeneity of cellular systems based on their electrophysiology. Emerging applications range from fundamental life-science and drug assessment research to point-of-care diagnostics and precision medicine. Recently, novel chip designs and data analytic strategies are laying the foundation for multiparametric cell characterization and subpopulation distinction, which are essential to understand biological function, follow disease progression and monitor cell behaviour in microsystems. In this tutorial review, we present a comparative survey of the approaches to elucidate cellular and subcellular features from impedance cytometry data, covering the related subjects of device design, data analytics (i.e., signal processing, dielectric modelling, population clustering), and phenotyping applications. We give special emphasis to the exciting recent developments of the technique (timeframe 2017-2020) and provide our perspective on future challenges and directions. Its synergistic application with microfluidic separation, sensor science and machine learning can form an essential toolkit for label-free quantification and isolation of subpopulations to stratify heterogeneous biosystems.
Topics: Data Science; Electric Impedance; Flow Cytometry; Microfluidic Analytical Techniques; Microfluidics; Phenotype
PubMed: 33331376
DOI: 10.1039/d0lc00840k -
The Journal of Physical Chemistry. C,... Aug 2022Diagnostic advancements require continuous developments of reliable analytical sensors, which can simultaneously fulfill many criteria, including high sensitivity and...
Diagnostic advancements require continuous developments of reliable analytical sensors, which can simultaneously fulfill many criteria, including high sensitivity and specificity for a broad range of target analytes. Incorporating the highly sensitive attributes of surface-enhanced Raman spectroscopy (SERS) combined with highly specific analyte recognition capabilities via molecular surface functionalization could address major challenges in molecular diagnostics and analytical spectroscopy fields. Herein, we have established a controllable molecular surface functionalization process for a series of textured gold surfaces. To create the molecularly surface-functionalized SERS platforms, self-assembled benzyl-terminated and benzoboroxole-terminated monolayers were used to compare which thicknesses and root-mean-square (RMS) roughness of planar gold produced the most sensitive and specific surfaces. Optimal functionalization was identified at 80 ± 8 nm thickness and 7.2 ± 1.0 nm RMS. These exhibited a considerably higher SERS signal (70-fold) and improved sensitivity for polysaccharides when analyzed using principal component analysis (PCA) and self-organizing maps (SOM). These findings lay the procedure for establishing the optimal substrate specifications as an essential prerequisite for future studies aiming at developing the feasibility of molecular imprinting for SERS diagnostic applications and the subsequent delivery of advanced, highly selective, and sensitive sensing devices and analytical platforms.
PubMed: 36017358
DOI: 10.1021/acs.jpcc.2c03524 -
Biosensors Sep 2021In the last 10 years, paper-based electrochemical biosensors have gathered attention from the scientific community for their unique advantages and sustainability vision.... (Review)
Review
In the last 10 years, paper-based electrochemical biosensors have gathered attention from the scientific community for their unique advantages and sustainability vision. The use of papers in the design the electrochemical biosensors confers to these analytical tools several interesting features such as the management of the solution flow without external equipment, the fabrication of reagent-free devices exploiting the porosity of the paper to store the reagents, and the unprecedented capability to detect the target analyte in gas phase without any sampling system. Furthermore, cost-effective fabrication using printing technologies, including wax and screen-printing, combined with the use of this eco-friendly substrate and the possibility of reducing waste management after measuring by the incineration of the sensor, designate these type of sensors as eco-designed analytical tools. Additionally, the foldability feature of the paper has been recently exploited to design and fabricate 3D multifarious biosensors, which are able to detect different target analytes by using enzymes, antibodies, DNA, molecularly imprinted polymers, and cells as biocomponents. Interestingly, the 3D structure has recently boosted the self-powered paper-based biosensors, opening new frontiers in origami devices. This review aims to give an overview of the current state origami paper-based biosensors, pointing out how the foldability of the paper allows for the development of sensitive, selective, and easy-to-use smart and sustainable analytical devices.
Topics: Biosensing Techniques; Electrochemical Techniques; Electrodes; Paper
PubMed: 34562920
DOI: 10.3390/bios11090328 -
Biomolecules Apr 2014Catalytically amplified sensors link an allosteric analyte binding site with a reactive site to catalytically convert substrate into colored or fluorescent product that... (Review)
Review
Catalytically amplified sensors link an allosteric analyte binding site with a reactive site to catalytically convert substrate into colored or fluorescent product that can be easily measured. Such an arrangement greatly improves a sensor's detection limit as illustrated by successful application of ELISA-based approaches. The ability to engineer synthetic catalytic sites into non-enzymatic proteins expands the repertoire of analytes as well as readout reactions. Here we review recent examples of small molecule sensors based on allosterically controlled enzymes and organometallic catalysts. The focus of this paper is on biocompatible, switchable enzymes regulated by small molecules to track analytes both in vivo and in the environment.
Topics: Biocatalysis; Biosensing Techniques; Chemistry Techniques, Analytical; Humans; Organometallic Compounds; Proteins
PubMed: 24970222
DOI: 10.3390/biom4020402 -
Sensors (Basel, Switzerland) Mar 2023On-site detection of chemical warfare agents (CWAs) can be performed by various analytical techniques. Devices using well-established techniques such as ion mobility... (Review)
Review
On-site detection of chemical warfare agents (CWAs) can be performed by various analytical techniques. Devices using well-established techniques such as ion mobility spectrometry, flame photometry, infrared and Raman spectroscopy or mass spectrometry (usually combined with gas chromatography) are quite complex and expensive to purchase and operate. For this reason, other solutions based on analytical techniques well suited to portable devices are still being sought. Analyzers based on simple semiconductor sensors may be a potential alternative to the currently used CWA field detectors. In sensors of this type, the conductivity of the semiconductor layer changes upon interaction with the analyte. Metal oxides (both in the form of polycrystalline powders and various nanostructures), organic semiconductors, carbon nanostructures, silicon and various composites that are a combination of these materials are used as a semiconductor material. The selectivity of a single oxide sensor can be adjusted to specific analytes within certain limits by using the appropriate semiconductor material and sensitizers. This review presents the current state of knowledge and achievements in the field of semiconductor sensors for CWA detection. The article describes the principles of operation of semiconductor sensors, discusses individual solutions used for CWA detection present in the scientific literature and makes a critical comparison of them. The prospects for the development and practical application of this analytical technique in CWA field analysis are also discussed.
PubMed: 36991985
DOI: 10.3390/s23063272 -
Free Radical Biology & Medicine Dec 1999Isolation and quantification of volatile breath biomarkers indicative of relevant alterations in clinical status has required development of new techniques and... (Review)
Review
Isolation and quantification of volatile breath biomarkers indicative of relevant alterations in clinical status has required development of new techniques and applications of existing analytical chemical methods. The most significant obstacles to successful application of this type of sample have been reduction in required sample volume permitting replicate analysis (an absolute requirement for all clinical studies), separation of the analyte(s) of interest from background molecules, water vapor and other molecules with similar physical properties, introduction of automation in analysis and the use of selective detection systems (electron impact mass spectrometry, flame photometric, thermionic detectors), and automated sample collection from the human subject. Advances in adsorption technology and trace gas analysis have permitted rapid progress in this area of clinical chemistry.
Topics: Animals; Antioxidants; Biomarkers; Breath Tests; Chromatography, Gas; Ethane; Humans; Oxidative Stress
PubMed: 10641709
DOI: 10.1016/s0891-5849(99)00212-9