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1.
Mikrochim Acta ; 190(12): 493, 2023 11 30.
Article in English | MEDLINE | ID: mdl-38032374

ABSTRACT

Water-soluble, stable, and monodisperse palladium nanoclusters (PdNCs) were synthesized using NaBH4 as a reductant and lipoic acid as a ligand. PdNCs, measured by high-resolution transmission electron microscopy, showed a round shape and a diameter of 2.49 ± 0.02 nm. It was found that each PdNC contains 550 Pd atoms on average. These PdNCs offer high amplification as a label of biochemical reactions when inductively coupled plasma-mass spectrometry (ICP-MS) is used as a detector. In addition, PdNCs have catalytic activity on electrochemical reactions, allowing detection by linear sweep voltammetry (LSV). As a proof of applicability, a competitive immunoassay based on PdNC labels was developed for the determination of glial fibrillary acidic protein (GFAP) in human serum, comparing ICP-MS and LSV detection. GFAP is a biomarker for differentiating between patients with ischemic stroke (IS) and hemorrhagic stroke (HS). The limit of detection (LoD), corresponding to IC10 (4-parameter logistic curve), was 0.03 pM of GFAP, both by ICP-MS and LSV, being lower than the 0.31 pM LoD provided by the ELISA commercial kit. Using the error profile method, 0.03 pM and 0.11 pM LoDs were obtained respectively by ICP-MS and LSV: LoD is lower by ICP-MS due to the better precision of the measurements. The analyses of human serum samples from IS, HS, and control (CT) donors using PdNC labels and detection by ICP-MS and LSV were validated with a commercial ELISA kit (for CT donors only ICP-MS provided enough sensitivity). Results point out toward the future use of PdNCs as a label in other immunoprobes for the determination of specific proteins requiring very low LoDs as well as the development of electrochemical decentralized methodologies.


Subject(s)
Palladium , Stroke , Humans , Glial Fibrillary Acidic Protein , Stroke/diagnosis , Enzyme-Linked Immunosorbent Assay , Mass Spectrometry
2.
Cerebrovasc Dis ; 2023 Oct 25.
Article in English | MEDLINE | ID: mdl-37879303

ABSTRACT

INTRODUCTION: Differential diagnosis between ischemic stroke (IS) and intracerebral hemorrhage (ICH) is a great challenge. Recently, the discovery of cerebral lymphatic drainage towards the nostrils suggested nasal exudate (NE) as a new source for measure biomarkers from neural damage. We sought to confirm whether glial fibrillary acidic protein (GFAP) levels in NE could identify ICH. METHODS: GFAP in nasal exudate (nGFAP) was studied in 5 IS and 5 ICH patients. All patients underwent neurological examination, brain computed tomography, laboratory tests and measurement of nGFAP and serum GFAP. RESULTS: We found higher concentrations in ICH patients (p=0.02). The area under the ROC curve for IS/ICH discrimination was 0.840, with a cut-off point of 0.06 pg/mg for 100% sensitivity and 80% specificity Conclusions: These findings suggest that nGFAP could be a useful biomarker for differential diagnosis between IS and ICH and opens a potential field of study for other biomarkers in NE in neurological disorders.

3.
Adv Healthc Mater ; 12(12): e2202972, 2023 05.
Article in English | MEDLINE | ID: mdl-36715339

ABSTRACT

Quantitative polymerase chain reaction (qPCR) is considered the gold standard for pathogen detection. However, improvement is still required, especially regarding the possibilities of decentralization. Apart from other reasons, infectious diseases demand on-site analysis to avoid pathogen spreading and increase treatment efficacy. In this paper, the detection of SARS-CoV-2 is carried out by reverse transcription loop-mediated isothermal amplification, which has the advantage of requiring simple equipment, easily adaptable to decentralized analysis. It is proposed, for the first time, the use of palladium nanoclusters (PdNCs) as indicators of the amplification reaction at end point. The pH of the medium decreases during the reaction and, in turn, a variation in the catalytic activity of PdNCs on the oxygen reduction reaction (ORR) can be electrochemically observed. For the detection, flexible and small-size screen-printed electrodes can be premodified with PdNCs, which together with the use of a simple and small electrochemical equipment would greatly facilitates their integration in field-deployable devices. This would allow a faster detection of SARS-CoV-2 as well as of other future microbial threats after an easy adaptation.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , SARS-CoV-2/genetics , COVID-19/diagnosis , Reverse Transcription , Palladium , Clinical Laboratory Techniques , COVID-19 Testing , Sensitivity and Specificity , Molecular Diagnostic Techniques , Nucleic Acid Amplification Techniques , Biological Assay
4.
Anal Chem ; 94(38): 13061-13067, 2022 09 27.
Article in English | MEDLINE | ID: mdl-36106671

ABSTRACT

A highly sensitive electrochemical methodology for end-point detection of loop-mediated isothermal nucleic acid amplification reactions was developed. It is based on the oxidation process of phenol red (PR), commonly used as a visual indicator. The dependence of its redox process on pH, which changes during amplification, allows performing quantitative measurements. Thus, the change in the oxidation potential of PR during the amplification is used, for the first time, as the analytical signal that correlates with the number of initial DNA copies. As a proof-of-concept, the amplification of the pneumolysin gene from Streptococcus pneumoniae, one of the main pathogens causing community-acquired pneumonia, is performed. Combination of isothermal amplification with electrochemical detection, performed on small-size flexible electrodes, allows easy decentralization. Adaptation to the detection of other pathogens causing infectious diseases would be very useful in the prevention of future epidemics.


Subject(s)
Phenolsulfonphthalein , Streptococcus pneumoniae , Bacterial Proteins , DNA , Electrochemical Techniques , Nucleic Acid Amplification Techniques/methods , Oxidation-Reduction , Streptococcus pneumoniae/genetics , Streptolysins
5.
Sensors (Basel) ; 22(16)2022 Aug 19.
Article in English | MEDLINE | ID: mdl-36015999

ABSTRACT

The general objective of Analytical Chemistry, nowadays, is to obtain best-quality information in the shortest time to contribute to the resolution of real problems. In this regard, electrochemical biosensors are interesting alternatives to conventional methods thanks to their great characteristics, both those intrinsically analytical (precision, sensitivity, selectivity, etc.) and those more related to productivity (simplicity, low costs, and fast response, among others). For many years, the scientific community has made continuous progress in improving glucose biosensors, being this analyte the most important in the biosensor market, due to the large amount of people who suffer from diabetes mellitus. The sensitivity of the electrochemical techniques combined with the selectivity of the enzymatic methodologies have positioned electrochemical enzymatic sensors as the first option. This review, focusing on the electrochemical determination of glucose using paper-based analytical devices, shows recent approaches in the use of paper as a substrate for low-cost biosensing. General considerations on the principles of enzymatic detection and the design of paper-based analytical devices are given. Finally, the use of paper in enzymatic electrochemical biosensors for glucose detection, including analytical characteristics of the methodologies reported in relevant articles over the last years, is also covered.


Subject(s)
Biosensing Techniques , Glucose , Biosensing Techniques/methods , Electrochemical Techniques/methods , Humans
6.
Food Chem ; 396: 133659, 2022 Dec 01.
Article in English | MEDLINE | ID: mdl-35839727

ABSTRACT

Regulations of the EU obliges the indication of the presence of allergens on food labels. This work reports the development of an electrochemical immunosensor to determine tropomyosin (TPM) - a major shellfish allergen - prevailing in the muscles of crustacean species. Two linear ranges between the signal and TPM concentration were obtained: between 2.5 and 20 ng mL-1 and between 30 and 200 ng mL-1, with a lowest limit of detection of 0.47 ng mL-1. The selectivity of the optimized immunoassay, tested with other food allergens (e.g., Cyp c 1, a fish allergen), assures the effective detection of TPM, enabling successful control of foodstuff labelling. Several (12) foods, containing high and low TPM concentrations and TPM-free samples, were analysed using the sensor. A conventional ELISA kit and recovery assays were used to evaluate the accuracy of the results.


Subject(s)
Biosensing Techniques , Food Hypersensitivity , Allergens/analysis , Animals , Biosensing Techniques/methods , Food Analysis/methods , Immunoassay/methods , Tropomyosin/analysis
7.
Biosensors (Basel) ; 11(2)2021 Feb 16.
Article in English | MEDLINE | ID: mdl-33669316

ABSTRACT

Screen-printed technology has helped considerably to the development of portable electrochemical sensors since it provides miniaturized but robust and user-friendly electrodes. Moreover, this technology allows to obtain very versatile transducers, not only regarding their design, but also their ease of modification. Therefore, in the last decades, the use of screen-printed electrodes (SPEs) has exponentially increased, with ceramic as the main substrate. However, with the growing interest in the use of cheap and widely available materials as the basis of analytical devices, paper or other low-cost flat materials have become common substrates for SPEs. Thus, in this revision, a comprehensive overview on paper-based SPEs used for analytical proposes is provided. A great variety of designs is reported, together with several examples to illustrate the main applications.


Subject(s)
Electrodes , Paper , Electrodes/economics , Printing, Three-Dimensional
8.
Talanta ; 224: 121732, 2021 Mar 01.
Article in English | MEDLINE | ID: mdl-33379002

ABSTRACT

Miniaturization is one of the main requirements in the design of portable devices that allow in-field analysis. This is especially interesting in environmental monitoring, where the time of the sample-to-result process could be decreased considerably by approaching the analytical platforms to the sampling point. We employed traditional mass-produced and low-cost elements (micropipette tips and pins) in an out-of-box application to generate an innovative and cost-effective platform for analytical purposes. We have designed simple and easy-to-use electrochemical cells inside polypropylene micropipette tips with three stainless-steel pins acting as the working, reference and counter electrodes of a potentiostatic system. The pin acting as working electrode was previously coated with carbon ink, meanwhile the rest were used unmodified. In this way, electrochemical in-the-tip measurements were done directly using low volumes (µL) of sample. The devices showed good reproducibility, with a relative standard deviation of 7% (n = 5) for five different tip-based complete electrochemical cells. As a proof-of-concept, its utility has been probed by the determination of an anionic surfactant (sodium dodecyl sulphate, SDS) in water through its interaction with methylene blue (MB). Two different alternatives were presented based on the: 1) increase in the current intensity of the cathodic peak of MB due to the presence of SDS; 2) electrochemical determination of the MB remaining in the aqueous phase after extraction of the pair SDS-MB to an organic medium.

9.
Biosens Bioelectron ; 172: 112719, 2021 Jan 15.
Article in English | MEDLINE | ID: mdl-33166805

ABSTRACT

The ever-increasing presence of contaminants in environmental waters is an alarming issue, not only because of their harmful effects in the environment but also because of their risk to human health. Pharmaceuticals and pesticides, among other compounds of daily use, such as personal care products or plasticisers, are being released into water bodies. This release mainly occurs through wastewater since the treatments applied in many wastewater treatment plants are not able to completely remove these substances. Therefore, the analysis of these contaminants is essential but this is difficult due to the great variety of contaminating substances. Facing this analytical challenge, electrochemical sensing based on molecularly imprinted polymers (MIPs) has become an interesting field for environmental monitoring. Benefiting from their superior chemical and physical stability, low-cost production, high selectivity and rapid response, MIPs combined with miniaturized electrochemical transducers offer the possibility to detect target analytes in-situ. In most reports, the construction of these sensors include nanomaterials to improve their analytical characteristics, especially their sensitivity. Moreover, these sensors have been successfully applied in real water samples without the need of laborious pre-treatment steps. This review provides a general overview of electrochemical MIP-based sensors that have been reported for the detection of pharmaceuticals, pesticides, heavy metals and other contaminants in water samples in the past decade. Special attention is given to the construction of the sensors, including different functional monomers, sensing platforms and materials employed to achieve the best sensitivity. Additionally, several parameters, such as the limit of detection, the linear concentration range and the type of water samples that were analysed are compiled.


Subject(s)
Biosensing Techniques , Molecular Imprinting , Environmental Monitoring , Humans , Molecularly Imprinted Polymers , Polymers
10.
Biosensors (Basel) ; 10(10)2020 Sep 30.
Article in English | MEDLINE | ID: mdl-33008005

ABSTRACT

Food spoilage is caused by the development of microorganisms, biogenic amines, and other harmful substances, which, when consumed, can lead to different health problems. Foodborne diseases can be avoided by assessing the safety and freshness of food along the production and supply chains. The routine methods for food analysis usually involve long analysis times and complex instrumentation and are performed in centralized laboratories. In this context, sensors based on screen-printed electrodes (SPEs) have gained increasing importance because of their advantageous characteristics, such as ease of use and portability, which allow fast analysis in point-of-need scenarios. This review provides a comprehensive overview of SPE-based sensors for the evaluation of food safety and freshness, focusing on the determination of bacteria and biogenic amines. After discussing the characteristics of SPEs as transducers, the main bacteria, and biogenic amines responsible for important and common foodborne diseases are described. Then, SPE-based sensors for the analysis of these bacteria and biogenic amines in food samples are discussed, comparing several parameters, such as limit of detection, analysis time, and sample type.


Subject(s)
Bacteria , Biogenic Amines/analysis , Biosensing Techniques , Food Analysis/methods , Electrodes , Food , Food Safety , Humans
11.
Anal Chim Acta ; 1093: 28-34, 2020 Jan 06.
Article in English | MEDLINE | ID: mdl-31735212

ABSTRACT

Alzheimer's disease is one of the most common causes of dementia nowadays, and its prevalence increases over time. Because of this and the difficulty of its diagnosis, accurate methods for the analysis of specific biomarkers for an early diagnosis of this disease are much needed. Recently, the levels of unfolded isoform of the multifunctional protein p53 in plasma have been proved to increase selectively in Alzheimer's Disease patients in comparison with healthy subjects, thus entering the list of biomarkers that can be used for the diagnosis of this illness. We present here the development of an electrochemical immunosensor based on nanostructured screen-printed carbon electrodes for the quantification of unfolded p53 in plasma samples. The sensor shows a suitable linear range (from 2 to 50 nM) for its application in real blood samples and a very low limit of detection (0.05 nM). The concentration of unfolded p53 has been accurately detected in plasma of elderly people in healthy conditions, subjects with mild cognitive impairment (MCI) and Alzheimer's Disease (AD) subjects, obtaining results with no significant differences to those provided by an ELISA assay. These results support the possibility of measuring unfolded p53 levels with a cheap, simple and miniaturized device with a promising future for point-of-care applications in the early diagnosis of Alzheimer's dementia.


Subject(s)
Alzheimer Disease/diagnosis , Biosensing Techniques/methods , Immunoassay/methods , Intrinsically Disordered Proteins/blood , Tumor Suppressor Protein p53/blood , Alzheimer Disease/blood , Antibodies/immunology , Biomarkers/blood , Carbon/chemistry , Electrochemical Techniques/instrumentation , Electrochemical Techniques/methods , Electrodes , Gold/chemistry , Humans , Intrinsically Disordered Proteins/immunology , Limit of Detection , Metal Nanoparticles/chemistry , Protein Isoforms/blood , Protein Isoforms/immunology , Reproducibility of Results , Tumor Suppressor Protein p53/immunology
12.
Adv Mater ; 31(30): e1806739, 2019 Jul.
Article in English | MEDLINE | ID: mdl-31094032

ABSTRACT

Disposable sensors are low-cost and easy-to-use sensing devices intended for short-term or rapid single-point measurements. The growing demand for fast, accessible, and reliable information in a vastly connected world makes disposable sensors increasingly important. The areas of application for such devices are numerous, ranging from pharmaceutical, agricultural, environmental, forensic, and food sciences to wearables and clinical diagnostics, especially in resource-limited settings. The capabilities of disposable sensors can extend beyond measuring traditional physical quantities (for example, temperature or pressure); they can provide critical chemical and biological information (chemo- and biosensors) that can be digitized and made available to users and centralized/decentralized facilities for data storage, remotely. These features could pave the way for new classes of low-cost systems for health, food, and environmental monitoring that can democratize sensing across the globe. Here, a brief insight into the materials and basics of sensors (methods of transduction, molecular recognition, and amplification) is provided followed by a comprehensive and critical overview of the disposable sensors currently used for medical diagnostics, food, and environmental analysis. Finally, views on how the field of disposable sensing devices will continue its evolution are discussed, including the future trends, challenges, and opportunities.


Subject(s)
Biosensing Techniques/instrumentation , Diagnostic Techniques and Procedures/instrumentation , Disposable Equipment , Environmental Monitoring/instrumentation , Food Analysis/instrumentation , Animals , Electrochemical Techniques/methods , Equipment Design , Glass/chemistry , Humans , Membranes, Artificial , Nanostructures/chemistry , Optics and Photonics/methods , Polymers/chemistry
13.
Talanta ; 201: 211-216, 2019 Aug 15.
Article in English | MEDLINE | ID: mdl-31122413

ABSTRACT

Specific monitoring of cystatin C (CysC) levels in biological fluids is critical for diagnosis, treatment and mechanistic understanding of a spectrum of diseases, particularly chronic kidney disease (CKD). Despite evidences that CysC correlates with the high risk and/or progression of CKD, its use in clinical practice is still scarce. In this context, we report the development of a simple and sensitive immunosensor for the detection of CysC. The biosensor combines the technology of cost-effective screen-printed electrodes with the high specificity of a sandwich immunoassay. Optimized conditions showed that the sensor operates in a linear range between 10 and 100 ng mL-1, with a detection limit and a sensitivity of 6.0 ng mL-1 and 6.4 ±â€¯0.3 µA ng mL-1 cm-2, respectively. Moreover, the sensor provided precise results (RSD ≤ 6.2%) and the quantification of CysC in CKD serum samples revealed to be in agreement with the values obtained by a particle-enhanced nephelometric immunoassay. In this light, the proposed immunosensor qualifies for clinical application, constituting a step forward in the development of fast, sensitive and cost-effective diagnostic tools that can improve the current medical care settings of CKD patients.


Subject(s)
Cystatin C/urine , Electrochemical Techniques/methods , Immunoassay/methods , Animals , Antibodies, Monoclonal, Murine-Derived/immunology , Biomarkers/urine , Carbon/chemistry , Cystatin C/immunology , Electrochemical Techniques/instrumentation , Electrodes , Gold/chemistry , Humans , Limit of Detection , Metal Nanoparticles/chemistry , Mice , Renal Insufficiency, Chronic/urine
14.
Anal Chim Acta ; 728: 69-76, 2012 May 30.
Article in English | MEDLINE | ID: mdl-22560283

ABSTRACT

Different very simple single-use alcohol enzyme sensors were developed using alcohol oxidase (AOX) from three different yeast, Hansenula sp., Pichia pastoris and Candida boidinii, and employing three different commercial mediator-based Screen-Printed Carbon Electrodes as transducers. The mediators tested, Prussian Blue, Ferrocyanide and Co-phthalocyanine were included into the ink of the working electrode. The procedure to obtain these sensors consists of the immobilization of the enzyme on the electrode surface by adsorption. For the immobilization, an AOX solution is deposited on the working electrode and left until dried (1h) at room temperature. The best results were obtained with the biosensor using Screen-Printed Co-phthalocyanine/Carbon Electrode and AOX from Hansenula sp. The reduced cobalt-phthalocyanine form is amperometrically detected at +0.4V (vs. Ag pseudo reference electrode). This sensor shows good sensitivity (1211 nA mM(-1)), high precision (2.1% RSD value for the slope value of the calibration plot) and wide linear response (0.05-1.00 mM) for ethanol determination. The sensor provides also accurate results for ethanol quantification in alcoholic drinks.


Subject(s)
Alcoholic Beverages/analysis , Biosensing Techniques/methods , Candida/enzymology , Carbon/chemistry , Ethanol/analysis , Pichia/enzymology , Alcohol Oxidoreductases , Electrodes , Enzymes, Immobilized/metabolism , Ethanol/metabolism , Ferrocyanides/chemistry , Indoles/chemistry , Organometallic Compounds/chemistry , Oxidation-Reduction , Sensitivity and Specificity
15.
Talanta ; 88: 432-8, 2012 Jan 15.
Article in English | MEDLINE | ID: mdl-22265522

ABSTRACT

The first fructose sensor using a commercial screen-printed ferrocyanide/carbon electrodes (SPFCE) is reported here. The ferrocyanide is included in the carbon ink of the commercial screen-printed carbon electrode. The immobilization of enzyme d-fructose dehydrogenase (FDH) was carried out in an easy way. An aliquot of 10µL FDH was deposited on the electrode surface and left there until dried (approximately 1h) at room temperature. The sensor, so constructed, shows a good sensitivity to fructose (1.25µA/mM) with a slope deviation of ±0.02µA/mM and a linear range comprised between 0.1 and 1mM of fructose, with a limit of detection of 0.05mM. These sensors show good intersensors reproducibility after a previous pretreatment and a high stability. Fructose was determined in real samples as honey, Cola, fruit juices (orange, tomato, apple and pineapple), red wine, red and white grapes, musts and liquor of peach with a good accuracy.


Subject(s)
Biosensing Techniques , Carbohydrate Dehydrogenases , Ferrocyanides/chemistry , Fructose/analysis , Calibration , Carbon/chemistry , Electrochemistry , Electrodes , Enzymes, Immobilized , Fruit/chemistry , Honey/analysis , Hydrogen-Ion Concentration , Kinetics , Limit of Detection , Reproducibility of Results , Signal-To-Noise Ratio , Wine/analysis
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