1,720,971 research outputs found
Biological and technical factors affecting the point-of-care diagnostics in not-oncological chronic diseases
No full textInexpensive point-of-care (POC) analytical solutions have the potential to allow the implementation of large-scale screening campaigns aimed at identifying the initial stages of pathologies in the population, reducing morbidity, mortality and, indirectly, also the costs for the healthcare system. At global level, the most common preventive screening schemes address some cancer pathologies or are used to monitor the spread of some infective diseases. However, systematic testing might become decisive to improve the care response even in the case of chronic pathologies and, in this review, we analyzed the state-of-the-art of the POC diagnostics for Chronic Kidney Disease, Chronic Obstructive Pulmonary Disease and Multiple Sclerosis. The different technological options used to manufacture the biosensors and evaluate the produced data have been described and this information has been integrated with the present knowledge relatively to the biomarkers that have been proposed to monitor such diseases, namely their availability and reliability. Finally, the nature of the macromolecules used to capture the biomarkers has been discussed in relation to the biomarker nature
A novel strategy for fabrication, activation and cleaning of fully 3D printed flexible planar electrochemical platforms
Full text linkIn recent years, 3D printing of carbon-based conductive filaments has received growing attention for assembling electrodes to be used in a wide variety of electroanalytical devices and applications. Despite the large amount of work present in literature concerning the development of three-dimensional (3D) conductive structures, its potential as dry deposition method for assembling two-dimensional (2D) electrodes to be used in planar configuration is still largely unexplored. In fact, the possibility to rapidly change the geometry of the electrochemical circuits, associated with the reduction of waste and the absence of solvents, which are instead important components of ink and paste formulations, makes this strategy a valid green and efficient alternative to other deposition approaches such as screen-printing technology. We report here a rapid and solvent-free method for assembling fully 3D printed flexible planar electroanalytical platforms (3DEPs) to be used with microliters of liquid. At the same time, a novel protocol for the surface pre-treatment of 3D printed electrodes based on ultrasonication in aqueous NaOH solution followed by electrochemical activation using the same medium, is presented. In addition, the same procedure has proved to be efficient for cleaning the electrode surface after electrochemical passivation, thus confirming the validity of both time-efficient and environmentally-friendly assembling and activation/cleaning procedures developed which allow efficient and reusable electrodes to be produced. Finally, 3DEPs were tested by a proof-of-concept quantification of a commonly used food dye (Brilliant Blue, E-133) in commercial solutions used for homemade food coloring
A portable electrochemiluminescence aptasensor for β-lactoglobulin detection
Full text linkCow’s milk allergy is one of the most common food allergies in children with a prevalence of around 2.5%. Milk contains several allergens; the main ones are caseins and β-lactoglobulin (β-LG). At regulatory level, β-LG is not explicitly named, but milk is included in the list of substances or products causing allergies or intolerances. Hence, the presence of β-LG can be a useful marker for determining the presence of milk in food. In this work, we present an aptasensor based on electrochemiluminescence (ECL) for the quantification of β-LG in real food matrices displaying integrated advantages consisting of high specificity, good sensitivity, portability, and cost effectiveness. The performance and applicability of this sensor were tested by analyzing a sample of skimmed milk and an oat-based drink proposed as a vegetable substitute for milk of animal origin. We obtained a linear correlation between the intensity of the signal and the concentration of β-LG standard solutions (y = x * 0.00653 + 1.038, R2 = 0.99). The limit of detection (LOD) and the limit of quantification (LOQ) were found to be 1.36 and 4.55 μg L−1, respectively. Graphical abstract: [Figure not available: see fulltext.
Early stress detection in forest trees using a nanobody-functionalized electrochemical biosensor for ascorbate peroxidase
Full text linkForest environments are exposed to multiple stressful factors of both abiotic and biotic nature such as heavy metal contamination, drought, or pest infestations which may lead to their massive decline. We designed a comprehensive approach for isolating, producing and functionalizing reagents suitable for the affordable detection of forest plant stress biomarkers with the aim to provide quantitative data to assess plant stress fluctuation and, possibly, to design mitigation strategies. We first optimized a panning protocol to recover nanobodies targeting shared sequences that could cross-react with both Pisum sativum and Populus nigra ascorbate peroxidase (APX). After their production as recombinant constructs and their extensive biophysical and biochemical characterization, such reagents were exploited as the immunocapture element of an electrochemical biosensor conceived as a potential point-of-care device. Such biosensor could detect both pea and poplar APX in leaf extracts and could be used to clearly discriminate between control and heavy metal-stressed poplar plants based on their APX activity, even before the appearance of any phenotypic symptom. The combination of fast and inexpensive reagent production with the development of portable diagnostics opens the opportunity for large-scale, on-site surveys of forest trees
Amperometric sniffer for volatile amines based on paper-supported room-temperature ionic liquids enabling rapid assessment of fish spoilage
No full textA smartphone aptasensor for fipronil detection in honey samples
Full text linkIn this study, an electrochemical smartphone-based aptasensor for the determination of fipronil was developed by modifying a screen-printed carbon electrode (SPCE). Fipronil is a broad-spectrum insecticide that has been widely used in various applications such as agriculture, veterinary, and household pest control. Recently, its use has raised concerns over the potential impact on the environment and human health. The absence of effective methods for this purpose poses a significant obstacle. To tackle this problem, we have developed a cutting-edge aptamer-based portable sensor capable of rapidly and conveniently detecting fipronil in situ. Considering that the detection of small molecules, such as fipronil, can be a challenging task, a competitive replacement assay was set up based on the aptamer’s preference for the free form of fipronil over the immobilized one on the electrode. The analytical performance provided by the sensor on standard solutions of a known fipronil content made it possible to estimate a limit of detection (LOD) equal to 1.07 μg kg−1 and a limit of quantification (LOQ) of 3.21 μg kg−1. Selectivity tests were conducted using atrazine as a possible interferent. The use and performance of the developed portable aptasensor was assessed on honey samples, which were simultaneously analyzed using an HPLC–MS method. This aptasensor could be an affordable and effective tool for accurately quantifying fipronil not only in honey samples but also in other food products. Graphical abstract: [Figure not available: see fulltext.
Paper-based aptamer-antibody biosensor for gluten detection in a deep eutectic solvent (DES)
Full text linkPaper has been widely employed as cheap material for the development of a great number of sensors such as pregnancy tests, strips to measure blood sugar, and COVID-19 rapid tests. The need for new low-cost analytical devices is growing, and consequently the use of these platforms will be extended to different assays, both for the final consumer and within laboratories. This work describes a paper-based electrochemical sensing platform that uses a paper disc conveniently modified with recognition molecules and a screen-printed carbon electrode (SPCE) to achieve the detection of gluten in a deep eutectic solvent (DES). This is the first method coupling a paper biosensor based on aptamers and antibodies with the DES ethaline. Ethaline proved to be an excellent extraction medium allowing the determination of very low gluten concentrations. The biosensor is appropriate for the determination of gluten with a limit of detection (LOD) of 0.2 mg L−1 of sample; it can detect gluten extracted in DES with a dynamic range between 0.2 and 20 mg L−1 and an intra-assay coefficient of 10.69%. This approach can be of great interest for highly gluten-sensitive people, who suffer from ingestion of gluten quantities well below the legal limit, which is 20 parts per million in foods labeled gluten-free and for which highly sensitive devices are essential. Graphical abstract: [Figure not available: see fulltext.
An Effective Label-Free Electrochemical Aptasensor Based on Gold Nanoparticles for Gluten Detection
Full text linkNanomaterials can be used to modify electrodes and improve the conductivity and the performance of electrochemical sensors. Among various nanomaterials, gold-based nanostructures have been used as an anchoring platform for the functionalization of biosensor surfaces. One of the main advantages of using gold for the modification of electrodes is its great affinity for thiol-containing molecules, such as proteins, forming a strong Au-S bond. In this work, we present an impedimetric biosensor based on gold nanoparticles and a truncated aptamer for the quantification of gluten in hydrolyzed matrices such as beer and soy sauce. A good relationship between the Rct values and PWG-Gliadin concentration was found in the range between 0.1–1 mg L−1 of gliadin (corresponding to 0.2–2 mg L−1 of gluten) with a limit of detection of 0.05 mg L−1 of gliadin (corresponding to 0.1 mg L−1 of gluten). The label-free assay was also successfully applied for the determination of real food samples
Gas sensor for 4-ethylguaiacol detection based on tyrosinase enzymatic activity in a deep eutectic solvent
Full text linkThe use of environmentally friendly, cost-effective and biodegradable deep eutectic solvents (DESs) as nonaqueous solvents and electrolytes offers a promising avenue for enhancing enzymatic sensors and extending their applicability to the gas phase. In this study, an assembly is presented that includes a paper crown modified with tyrosinase enzyme, soaked in a DES and positioned on a disposable screen-printed carbon electrode. The paper crown contacts the outer edge of the carbon disk working electrode, as well as the peripheral counter and reference electrodes. This assembly yields a portable and disposable electrochemical platform, effortlessly immobilising DESs onto a porous and economical supporting material like paper. Moreover, the entire configuration resulted in a sensitive, rapidly responsive, membrane-free gas sensor whose response time depended exclusively on the enzymatic reaction. The electroanalytical capabilities of this setup were evaluated through voltammetric and amperometric determinations of phenols in synthetic and real wine samples. The proposed gas enzymatic sensor demonstrated excellent analytical performance for detecting phenolic compounds, offering fast measurement times, simple operation, high sensitivity, wide linear range and good repeatability
Transmittance measurements on paper soaked with deep eutectic solvents
No full textThis investigation was carried out with the aim of verifying whether transmittance detection modes on soaked paper, which is a simple and attractive determination approach for microfluidic paper-based analytical devices, can be improved by using deep eutectic solvents (DESs) as suitable media for minimizing reflection and refraction phenomena affecting these measurements. With this purpose, we tested two DESs such as ethaline and glyceline by checking that paper soaked with both two DESs displayed a quite higher transparency than that soaked with water (the absorbance decreased of about 25%). This result is particularly important in that DESs offer the appreciable advantage of being characterized by a negligible vapor pressure, unlike water or the majority of organic media, thus allowing long-term detections or analysis of very small samples to be conducted avoiding any problem caused by the solvent evaporation. As a proof of concept, we have then compared the detection of the patent blue V dye (E131) in ethaline solutions with that of the same dye dissolved in water. These determinations were performed on paper discs defined by a circular hydrophobic barrier which were installed into a plastic holder, which was constructed on purpose by the 3D technology to fit the cell housing of a Varian Cary 50 bio benchtop spectrophotometer adopted in our spectrophotometric measurements. The results found on paper discs soaked with ethaline were totally satisfactory in that they were characterized by a good repeatability and allowed a calibration plot to be constructed in a quite wide concentration range which allowed quite low concentrations to be detected (in the μM range) and was characterized by a good enough correlation coefficient. On the contrary, the results found on paper discs soaked with water were totally unsatisfactory since they were strongly affected by both the solvent evaporation and a more marked ripple present in the recorded spectra
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