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Grapes’ infection with the fungi Botrytis cinerea is one of the major causes of economic loss in the winemaking sector worldwide. The laccase activity of grapes is considered an appropriate indicator of this type of fungal infection, and enzymatic activity higher than 3 U/mL indicates a high risk of irreversibly damaged grape must due to enzymatic browning. This work describes a fast test for the measurement of laccase activity based on a dual optical and electrochemical detection method. A paper sensor impregnated with the enzymatic substrate dye 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) provides a semi-quantitative optical measurement. While the paper sensor can be used independently, when combined with a screen-printed electrode and amperometry measurements, it enables the quantitative detection of laccase activities down to 0.4 U/mL in only 5 min. The method was applied for monitoring the artificial infection of white, rosé, and red grapes with different strains of Botrytis cinerea. The results were confirmed by parallel analysis using the spectrophotometric method of laccase activity determination based on syringaldazine. The influence of the fungal strain and type of grape on laccase activity levels is reported. The demonstrated robustness, simplicity, and versatility of the developed method make it ideal for application on-site in the vineyard or at grape processing points. Financial support provided by the Romanian Executive Agency for Higher Education, Research, Development and Innovation (UEFISCDI), ERANET-MANUNET-III-WINBIOTOOL-2, contract 151/9.03.2020 grant (for A.V), contract150/9.03.2020 (for P.E) and contract 152/9.03.2020 (for C.P. (Catalina Pantazi), E.B., and M.I.); the Romanian Academy grant RO1567-IBB05/2021 (for R.R. and C.P. (Cristina Purcarea)); the Basque Government and the European Union through the European regional development fund 2014–2020 (FEDER) (ZL-2020/00532 and ZL-2021/00340); and the Diputación Foral de Álava (ALAVA INNOVA program—INNOEM-2020/00045) for Bodegas de los Herederos del Marqués de Riscal; and the Diputación Foral de Álava (ALAVA INNOVA program— INNOEM-2020/00045) for Bodegas de los Herederos del Marqués de Risca is gratefully acknowledged.

Dithiocarbamate fungicides (DTFs) are widely used to control various fungal diseases in crops and ornamental plants. Maximum residual limits in the order of ppb-ppm are currently imposed by legislation to prevent toxicity problems associated with excessive use of DTFs. The specific analytical determination of DTFs is complicated by their low solubility in water and organic solvents. This review summarizes the current analytical procedures used for the analysis of DTF, including chromatography, spectroscopy, and sensor-based methods and discusses the challenges related to selectivity, sensitivity, and sample preparation. Biosensors based on enzymatic inhibition demonstrated potential as analytical tools for DTFs and warrant further research, considering novel enzymes from extremophilic sources. Meanwhile, Raman spectroscopy and various sensors appear very promising, provided the selectivity issues are solved.

This minireview appraises the chemical sensors and biosensors with the bio/sensitive active films obtained by matrix assisted laser evaporation (MAPLE). An overall presentation and examples of the materials utilized thus far introduce the discussion of sensing applications, where the following categories of biosensors are critically appraised: optical sensors (surface plasmon resonance, fluorescence microscopy, long period grating fiber); surface acoustic wave sensors; and electrochemical sensors. The deposition of active layers of biomolecules, potentially useful as sensing interfaces, is discussed in relation to the experimental parameters of MAPLE deposition, with emphasis on the preservation of structure and activity of biomolecules. Additionally, chemoselective layers, temperature responsive and antifouling coatings are also reviewed, as these be can be combined with the active layers to obtain advanced sensing interfaces, showing the versatility of MAPLE. The review concludes with future developments and perspectives.

This work proposes a novel method for determining the composition of mixtures of natural polyphenolic compounds: caffeic acid, gallic acid, ellagic acid, rosmarinic acid and quercitrin in plants. T...

Current advancements in the development of functional nanomaterials and precisely designed nanostructures have created new opportunities for the fabrication of practical biosensors for field analysis. Two-dimensional (2D) and three-dimensional (3D) nanomaterials provide unique hierarchical structures, high surface area, and layered configurations with multiple length scales and porosity, and the possibility to create functionalities for targeted recognition at their surface. Such hierarchical structures offer prospects to tune the characteristics of materials—e.g., the electronic properties, performance, and mechanical flexibility—and they provide additional functions such as structural color, organized morphological features, and the ability to recognize and respond to external stimuli. Combining these unique features of the different types of nanostructures and using them as support for bimolecular assemblies can provide biosensing platforms with targeted recognition and transduction properties, and increased robustness, sensitivity, and selectivity for detection of a variety of analytes that can positively impact many fields. Herein, we first provide an overview of the recently developed 2D nanostructures focusing on the characteristics that are most relevant for the design of practical biosensors. Then, we discuss the integration of these materials with bio-elements such as bacteriophages, antibodies, nucleic acids, enzymes, and proteins, and we provide examples of applications in the environmental, food, and clinical fields. We conclude with a discussion of the manufacturing challenges of these devices and opportunities for the future development and exploration of these nanomaterials to design field-deployable biosensors.

Proteins are utilized across many biomedical and pharmaceutical industries; therefore, methods for rapid and accurate monitoring of protein aggregation are needed to ensure proper product quality. Although these processes have been previously studied, it is difficult to comprehensively evaluate protein folding and aggregation by traditional characterization techniques such as atomic force microscopy (AFM), electron microscopy, or X-ray diffraction, which require sample pre-treatment and do not represent native state proteins in solution. Herein, we report early tracking of lysozyme (Lyz) aggregation states by using single-particle collision electrochemistry (SPCE) of silver nanoparticle (AgNP) redox probes. The method relies on monitoring the rapid interaction of Lyz with AgNPs, which decreases the number of single AgNPs available for collisions and ultimately the frequency of oxidative impacts in the chronoamperometric profile. When Lyz is in a non-aggregated monomeric form, the protein forms a homogeneous coverage onto the surface of AgNPs, stabilizing the particles. When Lyz is aggregated, part of the AgNP surface remains uncoated, promoting the agglomeration of Lyz-AgNP conjugates. The frequency of AgNP impacts decreases with increasing aggregation time, providing a metric to track protein aggregation. Visualizations of integrated oxidation charge-transfer data displayed significant differences between the charge transfer per impact for AgNP samples alone and in the presence of non-aggregated and aggregated Lyz with 99% confidence using parametric ANOVA tests. Electrochemical results revealed meaningful associations with UV-vis, circular dichroism, and AFM, demonstrating that SPCE can be used as an alternative method for studying protein aggregation. This electrochemical technique could serve as a powerful tool to indirectly evaluate protein stability and screen protein samples for formation of aggregates.

International audience; Carbon nanofibers (CNF) are efficient electrode modifiers in electrochemical biosensors that enhance the electrochemical active area, induce electrocatalytic effect toward the oxidation of the enzymatic cofactor nicotinamide adenine dinucleotide (reduced form, NADH), and enable the quantitative immobilization of enzymes. Combining CNF with efficient and stable mediators radically augments the speed of electron transfer between NADH and solid electrodes and leads to electrochemical sensors characterized by high sensitivity and stability. The main aim of this work was to investigate the performance of a novel mediator for NADH with advantageously low solubility in an electrochemical detector based on a screen-printed CNF electrode as well as its potential in biosensing. Using a mediator, prepared from Meldola Blue and Ni hexamine chloride, a stable and sensitive electrochemical NADH sensor is provided with a detection limit of 0.5 μmol L−1. Further on, covalent immobilization of a recently described aldehyde dehydrogenase from the Antarctic Flavobacterium PL002 strain on the surface of the mediator-modified electrode produced a stable biosensor for the detection of aldehydes. When integrated in a flow injection analysis (FIA) setup with amperometric detection at 0.1 V vs. Ag/AgCl, the measurement of benzaldehyde with a detection limit of 10 μmol L−1 over a linear range of 30–300 μmol L−1 is possible. Determination of trace benzaldehyde impurities in a pharmaceutical excipient was also demonstrated and results compared with a chromatographic method.

The development of sensors that mimic the natural smell sensing mechanism and selectively recognizes the odorants remains highly challenging. Electrochemical based sensing approaches aiming at monitoring molecular recognition events between surface receptors and analytes in solution or in the gas phase, are one possible transduction platforms among others for the construction of an artificial nose. The principle of electrochemical detection lies on the shift of the potential/current during the recognition event, which is proportional to the concentration of the analyte, in our case the odorant. A tremendous amount of efforts has been put into making electrochemical sensors sensitive and selective to the analyte of interest through the use of nanomaterials, development of different detection schemes and application of innovative receptor ligands for selective detection of the analyte. There have been significant advances in electrochemical based odorant sensing by using odorant binding proteins (OBP) as surface receptors, small soluble proteins present in nasal mucus at millimolar concentrations where the hydrophobic binding pocket gives the ability to reversibly bind odorant molecules. As OBPs are robust and easy to produce receptors, they are good candidates for the design of biosensors. In this chapter, we focus on the progress made on the detection of odorant molecules using OBPs as a bioreceptor and electrochemistry as a transduction method.

The development of sensors that mimic the natural smell sensing mechanism and selectively recognizes the odorants remains highly challenging. Electrochemical based sensing approaches aiming at monitoring molecular recognition events between surface receptors and analytes in solution or in the gas phase, are one possible transduction platforms among others for the construction of an artificial nose. The principle of electrochemical detection lies on the shift of the potential/current during the recognition event, which is proportional to the concentration of the analyte, in our case the odorant. A tremendous amount of efforts has been put into making electrochemical sensors sensitive and selective to the analyte of interest through the use of nanomaterials, development of different detection schemes and application of innovative receptor ligands for selective detection of the analyte. There have been significant advances in electrochemical based odorant sensing by using odorant binding proteins (OBP) as surface receptors, small soluble proteins present in nasal mucus at millimolar concentrations where the hydrophobic binding pocket gives the ability to reversibly bind odorant molecules. As OBPs are robust and easy to produce receptors, they are good candidates for the design of biosensors. In this chapter, we focus on the progress made on the detection of odorant molecules using OBPs as a bioreceptor and electrochemistry as a transduction method.

Lysozyme, also called “muramidase”, is an antimicrobial enzyme with antibacterial activity with importance in medicine, food industry, protein studies and enzymology. Lysozyme is also a model analyte in the biosensing field. Optical biosensors have been proposed as alternative analytical tools to the standard detection of lysozyme by ELISA, chromatographic methods or capillary electrophoresis. These biosensors combine specific recognition via antibodies, aptamers, peptides, Micrococcus lysodeikticus bacteria and molecularly imprinted polymers (MIPs) with sensitive detection based on luminescence, surface plasmon resonance (SPR), surface enhanced Raman spectroscopy (SERS), colorimetry etc. To deliver shorter response time, a better sensitivity, but also a lower cost, many of the sensing schemes included nanomaterial and enzyme-enabled amplification. Several biological and food matrices were explored for the potential applications of optical biosensors. The review presents the bioreceptors used and provides illustrative details on the sensing schemes, discussed in relation to the method of detection. Challenges for real samples applications and perspectives of optical biosensors for lysozyme are also presented.

In part 1 (A. Vasilescu et al., Porous reduced graphene oxide modified electrodes for the analysis of protein aggregation. Part 1: Lysozyme aggregation at pH 2 and 7.4 Electrochem. Acta, 254 (2017) 375–383) we proposed porous reduced graphene oxide coated glassy carbon electrode (GC/prGO) in combination with differential pulse voltammetry as a new analytical tool for aggregation studies of proteins. Lysozyme was used as a model to follow its aggregation by electrochemical means at pH 2 and pH 7.4, leading to the formation of amyloid and amorphous aggregates, respectively. Part 2 of this work widens the scope of this approach by investigating a biopharmaceutical product, as the aggregation of peptide based drugs affects their therapeutic activity and can induce allergic reactions in patients. The salmon polypeptide calcitonin (sCT) was chosen as an example of a bioactive peptide with limited pharmaceutical potential due to a tendency to form cytotoxic aggregates and amyloid fibrils. For practical applications, screen printed electrodes (SPE) and flexible electrodes (FE) modified with polydiallyldimethylammonium (PDDA) and prGO by using the layer-by-layer deposition technique have been developed for the detection of sCT. The results indicate that these electrodes can differentiate between formation of amyloid aggregates of calcitonin (2 mg mL−1) in citrate buffer to no aggregation in acetate buffer. It was further demonstrated that these electrodes are able to analyze a pharmaceutical drug product of low potency, Miacalcic (8.3 μg mL−1), where no aggregation was observed.

Electrochemistry provides an array of methods to investigate protein aggregation and determine biomarkers of neurodenenerative diseases. Biosensors detecting monomeric or oligomeric biomarkers of Alzheimer's disease and Parkinson's disease evolved toward femtomolar, multiplexed detection in blood and biological fluids for less invasive diagnosis. The biosensors also serve as complementary tools in studies investigating putative biomarkers for the assessment of patient's cognitive decline. The study of protein aggregation via the direct electrochemical oxidation focused recently on enhanced sensitivity and on establishing correlations between protein structure and aggregation propensity. Departing from classic approaches, nanopore resistive pulse sensing and single-particle collision electrochemistry enable studying aggregates in solution. Growing applications converge toward accurate evaluation of aggregate populations and method adoption beyond proof of principle.

The combination between the specific recognition abilities of aptamers and the catalytic power of enzymes represents a powerful tool in bioanalysis to achieve the highly selective and sensitive detection of various molecules. Enzymes attached to biomolecules and nanomaterials facilitate the highly amplified detection of electroactive compounds. Meanwhile DNAzymes, small DNA strands showing enzyme-like activity are increasingly used as replacements of natural enzymes in electrochemical aptasensors. Moreover, nucleic acid catalysts have been integrated together with aptamer domains in aptazymes, where the aptamer-ligand interaction acts as a switch for the enzyme-like activity. The review discusses enzyme and DNAzyme based amplification, as the preferred approaches in electrochemical aptasensors. DNA and nanomaterial based signal enhancement is briefly mentioned, while a larger discussion is dedicated to aptasensors for the measurement of enzymatic activity and for the development of “universal” detection tools based on the aptamer-enzyme combination. This includes assays combining aptamers with glucometers for the detection of various molecules and promising “aptameric enzyme subunits”-yet to be integrated with electrochemical detection. The outlooks of the electrochemical biosensors coupling aptamers and enzymes are presented.

Protein instability due to misfolding and aggregation is of big concern for protein based therapeutics because it impacts the bioavailability and immunogenicity of such drugs. The development of simple and cost-effective methods for the analysis of pharmaceutical formulations, indicating the presence or absence of protein aggregates, is consequently of high importance. This work proposes a novel electrochemical interface based on porous reduced graphene oxide coated glassy carbon electrode (GC/prGO) allowing for the early and sensitive identification of protein aggregation by following the change in the oxidative current of the proteins. The novelty of this work lies in the exploration of the ability of GC/prGO interfaces to capture different aggregation behaviors. Lysozyme is used as a model to follow by electrochemistry its aggregation at two pH values, pH 2 and pH 7.4, leading to the formation of amyloid and amorphous aggregates, respectively. Comparing the oxidation peak of lysozyme by differential pulse voltammetry (DPV) for different electrode architectures allowed validating the higher sensitivity of the GC/prGO interface versus bare glassy electrodes or electrodes coated with non-porous reduced graphene oxide. Parallel experiments were performed by fluorescence with thioflavin T, size exclusion chromatography and Atomic Force Microscopy (AFM) imaging. These tests further highlighted the usefulness of GC/prGO electrode to visualize in a fast and reliable manner the changes in the protein structure and the differences between the processes occurring at pH 2 and pH 7.4. In particular, the ability to emphasize changes related to the first steps in aggregation that could be indicative of the aggregation course, recommend the GC/prGO electrode in combination with DPV as a new analytical tool for aggregation studies of biopharmaceuticals. Part 2 of this work will demonstrate later the utility of this approach for the analysis of a fast acting injectable human insulin formulation, Humulin R, used for diabetes treatment as well as for calcitonin.

Electrochemical aptasensors appear as promising tools in food analysis, able to provide sensitive, fast and cost-effective analysis, with the added advantage of portability. Carbon nanomaterials and in particular carbon nanotubes and graphene are among the nanomaterials most often used to build electrochemical aptasensors due to their good electrical conductivity, large surface area and multiple functionalisation possibilities. This review aims to give an overview of the types of carbon nanomaterials and their composites which have been used to enhance the performance of electrochemical aptasensors. Examples are detailed for the biosensors which were tested with real food samples. In these aptasensors, carbon nanomaterials have played different roles, from facilitating the immobilization of high amounts of aptamer and enhancing the electroactive area of the sensors to roles as nanocarrier for signaling probes in amplification schemes or even as electroactive probes generating the output signal. The survey of recent literature shows a positive evolution towards increased aptasensor testing with food samples. However, many challenges remain related to the better characterization of nanomaterials used, clarifying the roles of specific components in multi-component nanocomposites and widening the types of food matrices and analytes tested with the aptasensors. Although we are still far from knowing when these novel tools will replace classic analytical methods in food analysis, carbon nanomaterials will certainly continue to play an important role in the design of future electrochemical aptasensors for food analysis.

Electrophoretic deposition (EPD) of reduced graphene oxide nanosheets (rGO) offers several advantages over other surface coating approaches, including process simplicity, uniformity of the deposited films, and good control of the film thickness. The EPD conditions might also be of interest for the reduction of diazonium salts, which upon the release of N2 molecules and generation of radicals, can form covalent bonds with the sp2 hybridized carbon lattice atoms of rGO films. In this work, we report on the coating of gold electrodes in one step with rGO/polyethylenimine (PEI) thin films and their simultaneous modification using different phenyl (Ph) diazonium salt precursors bearing various functionalities such as −B(OH)2, −COOH, and −C≡CH. We show further the interest of such interfaces for designing highly sensitive sensing platforms. Azide-terminated lysozyme aptamers were clicked onto the rGO/PEI/Ph-alkynyl matrix and used for the sensing of lysozyme levels in patients suffering from inflammatory bowel ...

Lysozyme is an enzyme found in biological fluids, which is upregulated in leukemia, renal diseases as well as in a number of inflammatory gastrointestinal diseases. We present here the development of a novel lysozyme sensing concept based on the use of Micrococcus lysodeikticus whole cells adsorbed on graphene oxide (GO)-coated Surface Plasmon Resonance (SPR) interfaces. M. lysodeikticus is a typical enzymatic substrate for lysozyme. Unlike previously reported sensors which are based on the detection of lysozyme through bioaffinity interactions, the bioactivity of lysozyme will be used here for sensing purposes. Upon exposure to lysozyme containing serum, the integrity of the bacterial cell wall is affected and the cells detach from the GO based interfaces, causing a characteristic decrease in the SPR signal. This allows sensing the presence of clinically relevant concentrations of lysozyme in undiluted serum samples.

Peroxynitrite (PON for short) is a powerful nitrating, nitrosating and oxidative agent for cellular constituents. In vivo, PON is formed through the diffusion-controlled reaction between superoxide radical (O2•-) and nitric oxide (•NO). This critical review (with 67 refs.) covers the state of the art in nanomaterial-based (a) detection and imaging of PON inside cells and (b) monitoring of cellular events such as cellular oxidative burst by using optical or electrochemical methods. It starts with the formation, fate and pathophysiology of PON in vivo. The next part summarizes nanomaterial based electrochemical microsensors featuring nanofilms and nanostructured electrodes, nanospheres, 3D nanostructures and graphene-supported catalysts. A following chapter covers techniques based on optical nanoprobes, starting with nanomaterials used in optical detection of PON (including quantum dots, carbon dots, fluorescent organic polymer dots, rare earth nanocrystals including upconversion nanoparticles, iron oxide nanoparticles, gold nanoparticles, and fluorophore-modified nanoporous silicon). This is followed by subsections on strategies for optical detection of PON (including color changes, fluorescence quenching, activation and recovery), and on schemes for optimized spatial and temporal resolution, for improving sensitivity, selectivity, and (photo)stability. We then address critical issues related to biocompatibility, pharmacokinetics, give a number of representative practical applications and discuss challenges related to PON detection. The review concludes with a discussion of latest developments and future perspectives.

Biosensors enable specific analytical opportunities compared to the currently used devices for food allergens detection and intelligent packaging. This chapter summarizes the latest advances of biosensors and the trends in their development with regard to food allergens and intelligent packaging. While the focus is on commercial biosensors, for which the innovative elements, figures of merit, and applications reported for far are detailed, some analytical devices in early development stage are briefly presented as well. The limiting factors for the emergence of biosensors are discussed in the context of a commercial landscape dominated by chemical and physical sensors and indicators for intelligent packaging and by the standard immunoassay and DNA-based allergen detection kits, respectively. Increased impact of biosensor-based devices on people's life and notable contributions of these analytical tools to food safety are anticipated.

Stilbenes represent a class of compounds with a common 1,2-diphenylethylene backbone that have shown extraordinary potential in the biomedical field. As the most well-known example, resveratrol proved to have anti-aging effects and significant potential in the fight against cardiovascular diseases and some types of cancer. Mass spectrometry is an analytical method of critical importance in all studies related to stilbenes that are important in the biomedical field. From the discovery of new natural compounds and mapping the grape metabolome up to advanced investigations of stilbenes' potential for the protection of human health in clinical studies, mass spectrometry has provided critical analytical information. In this review we focus on various approaches related to mass spectrometry for the detection of stilbenes-such as coupling with chromatographic separation methods and direct infusion-with presentation of some illustrative applications. Clearly, the potential of mass spectrometry for assisting in the discovery of new stilbenes of biomedical importance, elucidating their mechanisms of action and quantifying minute quantities in complex matrices is far from being exhausted.

This goal of this minireview is to introduce the reader to the area of research concerned with exhaled breath analysis for the purpose of detecting abnormal levels of physiologically-relevant chemical markers reflective of respiratory diseases. Two main two groups of sensing methods are reviewed: mass spectrometry and (bio)sensors. The discussion focuses on biosensor applications for EB and EBC analyses, which are presented in detail. The review finishes with conclusions and future perspectives, including recommendations for future near-term and long-term development of EBC biomarker sensing.

Incidences of food allergies are on the rise, which can greatly affect the well-being of children as well as adults. Intolerance to gluten, a protein composite of gliadin and glutenin, present in wheat, barley, and rye and several cereals, can be the causative agent of celiac disease (CD) and other allergic reactions. A gluten-free diet has become essential for people affected by CD, and consequently, the amount of gluten in food products needs to be strictly controlled. In this paper, we report an electrochemical label-free immunosensor for ultrasensitive and specific detection of gliadin. The sensor takes advantage of the specific properties of porous reduced graphene oxide (prGO) covalently functionalized with anti-gliadin antibodies using 1-pyrenecarboxylic acid as linker molecule. Using differential pulse voltammetry (DPV) and [Fe(CN)6]3-/4- as a redox probe, a decrease of current is linked to the presence of gliadin. The sensor achieved a detection limit of 1.2 ng mL–1 over a 1.2–34 ng mL–1 linear r...

We report the development and characterization of a disposable single use electrochemical sensor based on the oxidase-like activity of nanoceria particles for the detection of phenolic antioxidants. The use of nanoceria in the sensor design enables oxidation of phenolic compounds, particularly those with ortho-dihydroxybenzene functionality, to their corresponding quinones at the surface of a screen printed carbon electrode. Detection is carried out by electrochemical reduction of the resulting quinone at a low applied potential of -0.1V vs the Ag/AgCl electrode. The sensor was optimized and characterized with respect to particle loading, applied potential, response time, detection limit, linear concentration range and sensitivity. The method enabled rapid detection of common phenolic antioxidants including caffeic acid, gallic acid and quercetin in the µM concentration range, and demonstrated good functionality for the analysis of antioxidant content in several wine samples. The intrinsic oxidase-like activity of nanoceria shows promise as a robust tool for sensitive and cost effective analysis of antioxidants using electrochemical detection.

Development of highly sensitive analytical procedures for food contaminants is one of the critical points in addressing new challenges related to food safety worldwide. Electrochemical aptamer-based sensors have been intensively investigated as potential analytical tools providing the desired portability, fast response, sensitivity and specificity in addition to lower cost and simplicity versus classical methods. The paper summarizes the aptasensors reported in the literature in the last 3 years, that have been used in applications related to food safety. New trends pertaining to increasing the sensitivity of detection by using nanomaterials and engineering of new aptamers are briefly discussed. With the recent development of new aptamers and following the lead of aptasensors devoted to biomedical field, the next years will witness an avalanche of new exciting electrochemical aptasensors for food safety.

The number of patients suffering from inflammatory bowel disease (IBD) is increasing worldwide. The development of noninvasive tests that are rapid, sensitive, specific, and simple would allow preventing patient discomfort, delay in diagnosis, and the follow-up of the status of the disease. Herein, we show the interest of vertically aligned nitrogen-doped carbon nanotube (VA-NCNT) electrodes for the required sensitive electrochemical detection of lysozyme in serum, a protein that is up-regulated in IBD. To achieve selective lysozyme detection, biotinylated lysozyme aptamers were covalently immobilized onto the VA-NCNTs. Detection of lysozyme in serum was achieved by measuring the decrease in the peak current of the Fe(CN)6(3-/4-) redox couple by differential pulse voltammetry upon addition of the analyte. We achieved a detection limit as low as 100 fM with a linear range up to 7 pM, in line with the required demands for the determination of lysozyme level in patients suffering from IBD. We attained the sensitive detection of biomarkers in clinical samples of healthy patients and individuals suffering from IBD and compared the results to a classical turbidimetric assay. The results clearly indicate that the newly developed sensor allows for a reliable and efficient analysis of lysozyme in serum.

Fundamental knowledge about protein aggregation is critical for the understanding of many neurodegenerative diseases. Protein aggregation can be difficult to comprehensively study by traditional characterization techniques which may require sample pretreatment and alter the native state of the samples being studied. There is a great need for native state "in solution" measurements of protein monitoring in the biomedical field. We have utilized single-particle collision electrochemistry (SPCE) for the early tracking of lysozyme (Lyz) aggregation states by electrochemically analyzing lysozyme modified silver nanoparticle (Lyz-AgNPs) and their oxidation currents. When the modified nanoparticles collide with a microelectrode at a high enough potential, they can be oxidized at the surface of the electrode. Information can be extrapolated from the electrochemical data and help aid in the determination of particle stability and coverage. Our electrochemical determination method was compared to other measurements from UV-Vis spectroscopy, circular dichroism (CD) and atomic force microscopy (AFM) to validate our findings and determine the strutural changes of lysozyme protein on the surface of silver nanoparticles. This work demonstrates that this electrochemical technique could potentially be used to screen protein samples for formation of aggregates.

Stilbenes represent a class of compounds with a common 1,2-diphenylethylene backbone that have shown extraordinary potential in the biomedical field. As the most well-known example, resveratrol proved to have anti-aging effects and significant potential in the fight against cardiovascular diseases and some types of cancer. Mass spectrometry is an analytical method of critical importance in all studies related to stilbenes that are important in the biomedical field. From the discovery of new natural compounds and mapping the grape metabolome up to advanced investigations of stilbenes’ potential for the protection of human health in clinical studies, mass spectrometry has provided critical analytical information. In this review we focus on various approaches related to mass spectrometry for the detection of stilbenes—such as coupling with chromatographic separation methods and direct infusion—with presentation of some illustrative applications. Clearly, the potential of mass spectrometry for assisting in the discovery of new stilbenes of biomedical importance, elucidating their mechanisms of action, and quantifying minute quantities in complex matrices is far from being exhausted.

Extremophilic microorganisms are equipped with enzymes able to catalyze various reactions under extreme conditions of temperature, salinity, pH, hydrostatic pressure, radiation, etc. The particular characteristics of these enzymes, also known as extremozymes, represent valuable assets for advanced industrial applications. Most recently, extremophiles were used for the “green” and cost-effective production of high-quality nanomaterials on a large scale. The eco-friendly production of metallic nanoparticles and reduced graphene oxide using extremozymes, discussed here, represents an important breakthrough for various applications. Further benefits of extremozymes immobilized on a variety of nanomaterials, resulting in highly effective biohybrids including light-harvesting devices, biofuel cells, and biosensors, are also discussed. For biosensor development, the dual strategy for improving their stability and sensitivity is based on utilization of extremozymes as biocatalyst and of nanomaterials as high-loading support with role also in signal transduction. While a low assortment of such biosensors was developed so far, a largely unexploited applicative potential of combined use of extremozymes and nanomaterials in biosensing is anticipated due to their already demonstrated industrial benefits.

This review provides a brief overview of the fabrication and properties of screen-printed electrodes and details the different opportunities to apply them for the detection of antibiotics, detection of bacteria and antibiotic susceptibility. Among the alternative approaches to costly chromatographic or ELISA methods for antibiotics detection and to lengthy culture methods for bacteria detection, electrochemical biosensors based on screen-printed electrodes present some distinctive advantages. Chemical and (bio)sensors for the detection of antibiotics and assays coupling detection with screen-printed electrodes with immunomagnetic separation are described. With regards to detection of bacteria, the emphasis is placed on applications targeting viable bacterial cells. While the electrochemical sensors and biosensors face many challenges before replacing standard analysis methods, the potential of screen-printed electrodes is increasingly exploited and more applications are anticipated to advance towards commercial analytical tools.

The challenges related to the detection of an increasingly wider range of environmental pollutants are currently met by developing fast, sensitive, and specific analytical methods, that ideally also respond to the need of device portability, simplicity, and low cost. Aptasensors made by combining an aptamer with highly sensitive transducers-optical, electrochemical, mass-sensitive, etc. can achieve these objectives and their performance can moreover be significantly increased by including various nanomaterials. In aptasensors, metal nanoparticles assist in various roles, from support for biomolecule immobilization to signaling probes or for signal amplification. This chapter reviews the advances in the field of aptasensors for the detection of emerging pollutants, focusing specifically on metal nanomaterial-assisted devices. The synthesis, properties, and role of metallic nanomaterials in aptasensing are presented first, followed by a discussion of aptamers and the properties which make them attractive in biosensors, in particular their combination with metal nanoparticles aimed at maximizing the analytical performances. Details on the application of metal nanoparticles in aptasensing platforms for pollutants monitoring are given in terms of sensitivity, design, and detection principles of various aptasensors. The focus is on pesticides, heavy metals, pharmaceutical compounds, phthalates, bisphenol A (BPA), and other pollutants including pathogenic bacteria, polychlorobiphenyls (PCBs), and 17-β-estradiol. Based on the summarized advantages and limitations, it can be concluded that while many challenges lie ahead, particularly related to the insufficient characterization of metal nanomaterials, the potential of metal nanomaterial-assisted aptasensors for the detection of emerging pollutants is only beginning to be discovered.