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1.
J Phys Chem Lett ; 12(32): 7854-7858, 2021 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-34380316

RESUMO

This work uses electrochemical quartz crystal microbalance methods to demonstrate the enantiospecific interaction between a magnetized surface and a chiral amino acid. The enantiospecific adsorption of chiral molecules (cysteine is used as a model) on a ferromagnetic surface is shown to arise from the kinetics of adsorption and not from a thermodynamic stabilization. Measurements of the Gibbs free energy of adsorption for different chiral forms of cysteine and different electrode magnetization states show no significant differences, whereas measurements of the adsorption and desorption kinetics reveal a strong dependence on the magnetization state of the electrode surface. In addition, the enantioselectivity is shown to depend sensitively on the solution pH and the charge state of the chiral adsorbate.


Assuntos
Cisteína/química , Imãs/química , Adsorção , Técnicas Eletroquímicas/instrumentação , Eletrodos , Cinética , Níquel/química , Técnicas de Microbalança de Cristal de Quartzo/instrumentação , Estereoisomerismo , Termodinâmica
2.
Molecules ; 26(16)2021 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-34443475

RESUMO

Different parts of a plant (seeds, fruits, flower, leaves, stem, and roots) contain numerous biologically active compounds called "phytoconstituents" that consist of phenolics, minerals, amino acids, and vitamins. The conventional techniques applied to extract these phytoconstituents have several drawbacks including poor performance, low yields, more solvent use, long processing time, and thermally degrading by-products. In contrast, modern and advanced extraction nonthermal technologies such as pulsed electric field (PEF) assist in easier and efficient identification, characterization, and analysis of bioactive ingredients. Other advantages of PEF include cost-efficacy, less time, and solvent consumption with improved yields. This review covers the applications of PEF to obtain bioactive components, essential oils, proteins, pectin, and other important materials from various parts of the plant. Numerous studies compiled in the current evaluation concluded PEF as the best solution to extract phytoconstituents used in the food and pharmaceutical industries. PEF-assisted extraction leads to a higher yield, utilizes less solvents and energy, and it saves a lot of time compared to traditional extraction methods. PEF extraction design should be safe and efficient enough to prevent the degradation of phytoconstituents and oils.


Assuntos
Fracionamento Químico/instrumentação , Fracionamento Químico/métodos , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Compostos Fitoquímicos , Indústria de Processamento de Alimentos , Solventes/química , Tecnologia Farmacêutica
3.
Molecules ; 26(11)2021 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-34198893

RESUMO

In this work, a low-cost and rapid electrochemical resistive DNA biosensor based on the current relaxation method is described. A DNA probe, complementary to the specific human papillomavirus type 16 (HPV-16) sequence, was immobilized onto a screen-printed gold electrode. DNA hybridization was detected by applying a potential step of 30 mV to the system, composed of an external capacitor and the modified electrode DNA/gold, for 750 µs and then relaxed back to the OCP, at which point the voltage and current discharging curves are registered for 25 ms. From the discharging curves, the potential and current relaxation were evaluated, and by using Ohm's law, the charge transfer resistance through the DNA-modified electrode was calculated. The presence of a complementary sequence was detected by the change in resistance when the ssDNA is transformed in dsDNA due to the hybridization event. The target DNA concentration was detected in the range of 5 to 20 nM. The results showed a good fit to the regression equation ΔRtotal(Ω)=2.99 × [DNA]+81.55, and a detection limit of 2.39 nM was obtained. As the sensing approach uses a direct current, the electronic architecture of the biosensor is simple and allows for the separation of faradic and nonfaradaic contributions. The simple electrochemical resistive biosensor reported here is a good candidate for the point-of-care diagnosis of HPV at a low cost and in a short detection time.


Assuntos
Técnicas Biossensoriais/instrumentação , DNA Viral/análise , Papillomavirus Humano 16/isolamento & purificação , Infecções por Papillomavirus/diagnóstico , Técnicas Eletroquímicas/instrumentação , Eletrodos , Ouro/química , Papillomavirus Humano 16/genética , Humanos , Limite de Detecção , Testes Imediatos
4.
Methods Mol Biol ; 2352: 201-226, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34324189

RESUMO

The detection of neurotransmitter release from reprogrammed human cell is an important demonstration of their functionality. Electrochemistry has the distinct advantages over alternative methods that it allows for the measuring of the analyte of interest at a high temporal resolution. This is necessary for fast events, such as neurotransmitter release and reuptake, which happen in the order of milliseconds to seconds. The precise description of these kinetic events can lead to insights into the function of cells in health and disease and allows for the exploration of events that might be missed using methods that look at absolute concentration values or methods that have a slower sampling rate. In the present chapter, we describe the use of constant potential amperometry and enzyme-coated multielectrode arrays for the detection of glutamate in vitro. These biosensors have the distinct advantage of "self-referencing," a method providing high selectivity while retaining outstanding temporal resolution. Here, we provide a step-by-step user guide for a commercially available system and its application for in vitro systems such as reprogrammed cells.


Assuntos
Reprogramação Celular , Técnicas Eletroquímicas , Neurotransmissores/biossíntese , Transmissão Sináptica , Técnicas de Cultura de Células , Reprogramação Celular/genética , Análise de Dados , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Eletroquímica/instrumentação , Eletroquímica/métodos , Software
5.
ACS Appl Mater Interfaces ; 13(24): 27868-27879, 2021 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-34110781

RESUMO

We demonstrate that a novel functionalized interface, where molecularly imprinted polymer nanoparticles (nanoMIPs) are attached to screen-printed graphite electrodes (SPEs), can be utilized for the thermal detection of the cardiac biomarker troponin I (cTnI). The ultrasensitive detection of the unique protein cTnI can be utilized for the early diagnosis of myocardial infraction (i.e., heart attacks), resulting in considerably lower patient mortality and morbidity. Our developed platform presents an innovative route to develop accurate, low-cost, and disposable sensors for the diagnosis of cardiovascular diseases, specifically myocardial infraction. A reproducible and advantageous solid-phase approach was utilized to synthesize high-affinity nanoMIPs (average size = 71 nm) for cTnI, which served as synthetic receptors in a thermal sensing platform. To assess the performance and commercial potential of the sensor platform, various approaches were used to immobilize nanoMIPs onto thermocouples or SPEs: dip coating, drop casting, and a covalent approach relying on electrografting with an organic coupling reaction. Characterization of the nanoMIP-functionalized surfaces was performed with electrochemical impedance spectroscopy, atomic force microscopy, and scanning electron microscopy. Measurements from an in-house designed thermal setup revealed that covalent functionalization of nanoMIPs onto SPEs led to the most reproducible sensing capabilities. The proof of application was provided by measuring buffered solutions spiked with cTnI, which demonstrated that through monitoring changes in heat transfer at the solid-liquid interface, we can measure concentrations as low as 10 pg L-1, resulting in the most sensitive test of this type. Furthermore, preliminary data are presented for a prototype platform, which can detect cTnI with shorter measurement times and smaller sample volumes. The excellent sensor performance, versatility of the nanoMIPs, and reproducible and low-cost nature of the SPEs demonstrate that this sensor platform technology has a clear commercial route with high potential to contribute to sustainable healthcare.


Assuntos
Polímeros Molecularmente Impressos/química , Nanopartículas/química , Troponina I/análise , Biomarcadores/análise , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Eletrodos , Grafite/química , Temperatura
6.
Food Chem ; 362: 130219, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34091170

RESUMO

The use of artificial colorants in food is highly regulated due to their potential to harm human health. Thus, it is crucial to detect these substances effectively to ensure conformance with industrial standards. In this work, we prepared a photomultiplier tube (PMT)-based electrochemiluminescence (ECL) sensor and a charged coupled device (CCD)-based ECL sensor and compared their merits in the detection of sunset yellow (SY) dye. The sensors used C,N quantum dot-embedded g-C3N4 nanosheets (QDs@NSs) as the ECL agent and K2S2O8 as the coreactant. SY was analyzed on the basis of amplification in the QDs@NHs-K2S2O8 ECL system. The PMT-based sensor realized ultrasensitive detection using a single electrode, especially at low concentrations of SY. A CCD-based sensor imaged the ECL phenomenon of an electrode array and provided the advantages of high throughput and time savings. Under optimized conditions, both sensors exhibited high specificity, reproducibility and stability; detection limits of 20 nM with PMT detection and 5 µM with CCD detection were determined for SY, with detection ranging over at least two decades. The practical feasibilities of these systems were confirmed by satisfactory detection of SY in real drink samples.


Assuntos
Compostos Azo/análise , Bebidas Gaseificadas/análise , Técnicas Eletroquímicas/instrumentação , Corantes de Alimentos/análise , Compostos Azo/química , Técnicas Eletroquímicas/métodos , Eletrodos , Corantes de Alimentos/química , Limite de Detecção , Medições Luminescentes/instrumentação , Medições Luminescentes/métodos , Nanoestruturas , Pontos Quânticos , Reprodutibilidade dos Testes
7.
Molecules ; 26(10)2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-34063344

RESUMO

Safety and quality are key issues for the food industry. Consequently, there is growing demand to preserve the food chain and products against substances toxic, harmful to human health, such as contaminants, allergens, toxins, or pathogens. For this reason, it is mandatory to develop highly sensitive, reliable, rapid, and cost-effective sensing systems/devices, such as electrochemical sensors/biosensors. Generally, conventional techniques are limited by long analyses, expensive and complex procedures, and skilled personnel. Therefore, developing performant electrochemical biosensors can significantly support the screening of food chains and products. Here, we report some of the recent developments in this area and analyze the contributions produced by electrochemical biosensors in food screening and their challenges.


Assuntos
Técnicas Biossensoriais/instrumentação , Técnicas Eletroquímicas/instrumentação , Inocuidade dos Alimentos/métodos , Antibacterianos/análise , Cadeia Alimentar , Humanos , Praguicidas/análise , Toxinas Biológicas/análise
8.
Molecules ; 26(10)2021 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-34065709

RESUMO

A simple and highly sensitive electrochemical sensor was developed for adsorptive cathodic stripping voltammetry of alprazolam. Based on an electrochemically pretreated glassy carbon electrode, the sensor demonstrated good adsorption and electrochemical reduction of alprazolam. The morphology of the glassy carbon electrode and the electrochemically pretreated glassy carbon electrode were characterized by scanning electron microscopy/energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. The electrochemical behaviors of alprazolam were determined by cyclic voltammetry, and the analytical measurements were studied by adsorptive cathodic stripping voltammetry. Optimized operational conditions included the concentration and deposition time of sulfuric acid in the electrochemical pretreatment, preconcentration potential, and preconcentration time. Under optimal conditions, the developed alprazolam sensor displayed a quantification limit of 0.1 mg L-1, a detection limit of 0.03 mg L-1, a sensitivity of 67 µA mg-1 L cm-2 and two linear ranges: 0.1 to 4 and 4 to 20 mg L-1. Sensor selectivity was excellent, and repeatability (%RSD < 4.24%) and recovery (82.0 ± 0.2 to 109.0 ± 0.3%) were good. The results of determining alprazolam in beverages with the developed system were in good agreement with results from the gas chromatography-mass spectrometric method.


Assuntos
Alprazolam/análise , Bebidas/análise , Técnicas Eletroquímicas/instrumentação , Adsorção , Espectroscopia Dielétrica , Eletrodos , Limite de Detecção , Microscopia Eletrônica de Varredura , Espectroscopia de Infravermelho com Transformada de Fourier
9.
Biosensors (Basel) ; 11(6)2021 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-34073756

RESUMO

Despite collaborative efforts from all countries, coronavirus disease 2019 (COVID-19) pandemic has been continuing to spread globally, forcing the world into social distancing period, making a special challenge for public healthcare system. Before vaccine widely available, the best approach to manage severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is to achieve highest diagnostic accuracy by improving biosensor efficacy. For SARS-CoV-2 diagnostics, intensive attempts have been made by many scientists to ameliorate the drawback of current biosensors of SARS-CoV-2 in clinical diagnosis to offer benefits related to platform proposal, systematic analytical methods, system combination, and miniaturization. This review assesses ongoing research efforts aimed at developing integrated diagnostic tools to detect RNA viruses and their biomarkers for clinical diagnostics of SARS-CoV-2 infection and further highlights promising technology for SARS-CoV-2 specific diagnosis. The comparisons of SARS-CoV-2 biomarkers as well as their applicable biosensors in the field of clinical diagnosis were summarized to give scientists an advantage to develop superior diagnostic platforms. Furthermore, this review describes the prospects for this rapidly growing field of diagnostic research, raising further interest in analytical technology and strategic plan for future pandemics.


Assuntos
Técnicas Biossensoriais/instrumentação , Teste para COVID-19/instrumentação , SARS-CoV-2/isolamento & purificação , Animais , Técnicas Biossensoriais/métodos , Teste para COVID-19/métodos , Colorimetria/instrumentação , Colorimetria/métodos , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Ensaio de Imunoadsorção Enzimática/instrumentação , Ensaio de Imunoadsorção Enzimática/métodos , Desenho de Equipamento , Humanos , Técnicas de Amplificação de Ácido Nucleico/instrumentação , Técnicas de Amplificação de Ácido Nucleico/métodos , Testes Imediatos
10.
J Phys Chem Lett ; 12(23): 5443-5447, 2021 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-34081461

RESUMO

Enzymes encapsulated in metal-organic frameworks (enzyme@MOFs), as a promising immobilized enzyme, were investigated for intrinsic catalytic activities at the single entity level via a stochastic collision electrochemical technique. Zeolitic imidazolate frameworks with amorphous (aZIF-8) and crystalline (ZIF-8) structures were chosen as model MOFs to encapsulate glucose oxidase (GOx). We carried out single enzyme@MOF nanoparticle (NP) collision experiments using the carbon ultramicroelectrode (CUME), which demonstrated that the catalytic activity of GOx@ZIF-8 NPs was much less than GOx@aZIF-8 NPs. Meanwhile, the kcat and TON per GOx in aZIF-8 NPs were obtained, revealing the intrinsic catalytic activity of GOx in aZIF-8 NPs at the single entity level. This strategy is the first approach for investigating enzyme@MOFs at a single entity level, which can not only broaden the horizons of single entity electrochemistry (SEE) but also provide further insights into research on electrochemistry, catalysis, and nanocomposites.


Assuntos
Técnicas Eletroquímicas/métodos , Enzimas Imobilizadas/química , Estruturas Metalorgânicas/química , Nanocompostos/química , Nanopartículas/química , Catálise , Técnicas Eletroquímicas/instrumentação , Enzimas Imobilizadas/análise , Estruturas Metalorgânicas/análise , Nanocompostos/análise , Nanopartículas/análise , Processos Estocásticos
11.
Food Chem ; 361: 130162, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34051600

RESUMO

Fabrication of temperature-influenced nanoparticles over the superficial region of glassy carbon electrode (GCE) stimulates the electrocatalytic activity owing to their morphology, defective sites, and higher active surface area, etc. In this regard, we have fabricated annealed magnesium stannate nanoparticles (Mg2SnO4 NPs) on GCE for nanomolar level detection of hazardous flavoring and pharmaceutical compound Rutin (RT). To analyze the impact of temperature, we have compared annealed Mg2SnO4 NPs with unannealed magnesium stannate hydrate (MgSnO3·3H2O) particles. The physicochemical properties of synthesized materials were characterized with different microscopic and spectroscopic techniques. From these studies, annealed Mg2SnO4 NPs formed purely without any flith and existence of water molecules as compared to unannealed MgSnO3·3H2O. Moreover as fabricated, Mg2SnO4 NPs/GCE outcomes with higher redox behavior compared to other electrodes in presence of RT at optimized working buffer (pH = 7.0). Interestingly, the electrode successfully established a dual wider linear response (0.062-34.8 & 34.8-346.8 µM) with a nanomolar detection limit (1 nM) and higher sensitivity. The practicability analysis of the proposed sensor also affords excellent selectivity, reproducibility, repeatability, reversibility, and storage stability. Furthermore, the real sample analysis was carried out in blood and orange samples fallout with better recovery results.


Assuntos
Técnicas Eletroquímicas/métodos , Compostos de Magnésio/síntese química , Nanopartículas Metálicas/química , Rutina/análise , Carbono/química , Citrus sinensis/química , Técnicas Eletroquímicas/instrumentação , Eletrodos , Análise de Alimentos/métodos , Humanos , Concentração de Íons de Hidrogênio , Limite de Detecção , Reprodutibilidade dos Testes , Rutina/sangue , Sensibilidade e Especificidade , Temperatura
12.
J Mater Chem B ; 9(23): 4608-4619, 2021 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-34013310

RESUMO

Worldwide infections and fatalities caused by the SARS-CoV-2 virus and its variants responsible for COVID-19 have significantly impeded the economic growth of many nations. People in many nations have lost their livelihoods, it has severely impacted international relations and, most importantly, health infrastructures across the world have been tormented. This pandemic has already left footprints on human psychology, traits, and priorities and is certainly going to lead towards a new world order in the future. As always, science and technology have come to the rescue of the human race. The prevention of infection by instant and repeated cleaning of surfaces that are most likely to be touched in daily life and sanitization drives using medically prescribed sanitizers and UV irradiation of textiles are the first steps to breaking the chain of transmission. However, the real challenge is to develop and uplift medical infrastructure, such as diagnostic tools capable of prompt diagnosis and instant and economic medical treatment that is available to the masses. Two-dimensional (2D) materials, such as graphene, are atomic sheets that have been in the news for quite some time due to their unprecedented electronic mobilities, high thermal conductivity, appreciable thermal stability, excellent anchoring capabilities, optical transparency, mechanical flexibility, and a unique capability to integrate with arbitrary surfaces. These attributes of 2D materials make them lucrative for use as an active material platform for authentic and prompt (within minutes) disease diagnosis via electrical or optical diagnostic tools or via electrochemical diagnosis. We present the opportunities provided by 2D materials as a platform for SARS-CoV-2 diagnosis.


Assuntos
Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Teste para COVID-19/instrumentação , Teste para COVID-19/métodos , COVID-19/diagnóstico , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , SARS-CoV-2/isolamento & purificação , COVID-19/mortalidade , Humanos , Análise Espectral Raman , Transistores Eletrônicos
13.
Chem Asian J ; 16(13): 1820-1831, 2021 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-34014032

RESUMO

In this investigation, a melamine electrochemical sensor has been developed by using wet-chemically synthesized low-dimensional aggregated nanoparticles (NPs) of ZnO-doped Co3 O4 as sensing substrate that were decorated onto flat glassy carbon electrode (GCE). The characterization of NPs such as UV-Vis, FTIR, XRD, XPS, EDS, and FESEM was done for detailed investigations in optical, functional, structural, elemental, and morphological analyses. The ZnO-doped Co3 O4 NPs decorated GCE was used as a sensing probe to analyze the target chemical melamine in a phosphate buffer at pH 5.7 by applying differential pulse voltammetry (DPV). It exhibited good performances in terms of sensor analytical parameters such as large linear dynamic range (LDR; 0.15-1.35 mM) of melamine detection, high sensitivity (80.6 µA mM-1 cm-2 ), low limit of detection (LOD; 0.118±0.005 mM), low limit of quantification (LOQ; 0.393 mM), and fast response time (30 s). Besides this, the good reproducibility (in several hours) and repeatability were investigated under identical conditions. Moreover, it was implemented to measure the long-time stability, electron mobility, less charge-transfer resistance, and analyzed diffusion-controlled process for the oxidation reaction of the NPs assembled working GCE electrode, which showed outstanding chemical sensor performances. For validation, real environmental samples were collected from various water sources and investigated successfully with regard to the reliability of the selective melamine detection with prepared NPs coated sensor probe. Therefore, this approach might be introduced as an alternative route in the sensor technology to detect selectively unsafe chemicals by an electrochemical method with nanostructure-doped materials for the safety of environmental, ecological, healthcare fields in a broad scale.


Assuntos
Carbono/química , Cobalto/química , Nanopartículas Metálicas/química , Óxidos/química , Triazinas/química , Água/química , Óxido de Zinco/química , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Eletrodos , Monitoramento Ambiental , Reprodutibilidade dos Testes , Poluentes Químicos da Água/química
14.
Anal Bioanal Chem ; 413(15): 3861-3872, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34021369

RESUMO

Aptamers are short single-stranded oligonucleotides (either DNA or RNA) that can fold into well-defined three-dimensional (3D) spatial structures which enable them to capture their specific target by complementary shape interactions. Aptamers are selected from large random libraries through the SELEX process and only a small fraction of the sequence is involved in direct docking with the target. In this paper, we describe the possible truncation variants of zearalenone (ZEA) aptamer which might be an effective binding region for the target. The originally selected zearalenone (ZEA) aptamer was 80-mer in length and shown to bind the target with a high affinity (Kd = 41 ± 5 nM). Herein, computational docking simulation was performed with 15 truncated variants to determine the predicted binding energy and responsible binding site of the aptamer-analyte complex. The results revealed that 5 truncated variants had binding energy lower than - 7.0 kcal/mol. Circular dichroism analysis was performed on the shortlisted aptamer and the conformational change of aptamers was observed with the presence of an analyte. Aptamer Z3IN (29-mer) was chosen as the most enhanced affinity for its target with a dissociation constant of 11.77 ± 1.44 nM. The aptamer was further applied in the electrochemical aptasensor of ZEA based on an indirect competitive format. The results demonstrated that the truncated aptamer leads to an enhancement of the sensitivity of the biosensor.


Assuntos
Aptâmeros de Nucleotídeos/análise , Técnicas Eletroquímicas/instrumentação , Zearalenona/análise , Aptâmeros de Nucleotídeos/química , Sequência de Bases , Técnicas Biossensoriais/métodos , Dicroísmo Circular , Espectroscopia Dielétrica , Limite de Detecção , Simulação de Acoplamento Molecular
15.
Anal Bioanal Chem ; 413(16): 4277-4287, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34057556

RESUMO

A novel smartphone-based electrochemical cell sensor was developed to evaluate the toxicity of heavy metal ions, such as cadmium (Cd2+), lead (Pb2+), and mercury (Hg2+) ions on Hep G2 cells. The cell sensor was fabricated with reduced graphene oxide (RGO)/molybdenum sulfide (MoS2) composites to greatly improve the biological adaptability and amplify the electrochemical signals. Differential pulse voltammetry (DPV) was employed to measure the electrical signals induced by the toxicity of heavy metal ions. The results showed that Cd2+, Hg2+, and Pb2+ significantly reduced the viability of Hep G2 cells in a dose-dependent manner. The IC50 values obtained by this method were 49.83, 36.94, and 733.90 µM, respectively. A synergistic effect was observed between Cd2+ and Pb2+ and between Hg2+ and Pb2+, and an antagonistic effect was observed between Cd2+ and Hg2+, and an antagonistic effect at low doses and an additive effect at high doses were found in the ternary mixtures of Cd2+, Hg2+, and Pb2+. These electrochemical results were confirmed via MTT assay, SEM and TEM observation, and flow cytometry. Therefore, this new electrochemical cell sensor provided a more convenient, sensitive, and flexible toxicity assessment strategy than traditional cytotoxicity assessment methods.


Assuntos
Técnicas Biossensoriais/instrumentação , Cádmio/toxicidade , Chumbo/toxicidade , Mercúrio/toxicidade , Oryza/efeitos dos fármacos , Cádmio/análise , Sobrevivência Celular/efeitos dos fármacos , Técnicas Eletroquímicas/instrumentação , Células Hep G2 , Humanos , Chumbo/análise , Mercúrio/análise , Oryza/citologia , Smartphone , Testes de Toxicidade/instrumentação
16.
Nat Biomed Eng ; 5(7): 759-771, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34045731

RESUMO

Evaluating the biomechanics of soft tissues at depths well below their surface, and at high precision and in real time, would open up diagnostic opportunities. Here, we report the development and application of miniaturized electromagnetic devices, each integrating a vibratory actuator and a soft strain-sensing sheet, for dynamically measuring the Young's modulus of skin and of other soft tissues at depths of approximately 1-8 mm, depending on the particular design of the sensor. We experimentally and computationally established the operational principles of the devices and evaluated their performance with a range of synthetic and biological materials and with human skin in healthy volunteers. Arrays of devices can be used to spatially map elastic moduli and to profile the modulus depth-wise. As an example of practical medical utility, we show that the devices can be used to accurately locate lesions associated with psoriasis. Compact electronic devices for the rapid and precise mechanical characterization of living tissues could be used to monitor and diagnose a range of health disorders.


Assuntos
Técnicas Eletroquímicas/métodos , Pele/química , Adulto , Idoso , Animais , Fenômenos Biomecânicos , Módulo de Elasticidade , Técnicas Eletroquímicas/instrumentação , Humanos , Hidrogéis/química , Pessoa de Meia-Idade , Miniaturização , Pele/metabolismo , Suínos , Vibração , Adulto Jovem
17.
Mikrochim Acta ; 188(6): 199, 2021 05 26.
Artigo em Inglês | MEDLINE | ID: mdl-34041585

RESUMO

Since the COVID-19 disease caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS- CoV-2) was declared a pandemic, it has spread rapidly, causing one of the most serious outbreaks in the last century. Reliable and rapid diagnostic tests for COVID-19 are crucial to control and manage the outbreak. Here, a label-free square wave voltammetry-based biosensing platform for the detection of SARS-CoV-2 in nasopharyngeal samples is reported. The sensor was constructed on screen-printed carbon electrodes coated with gold nanoparticles. The electrodes were functionalized using 11-mercaptoundecanoic acid (MUA) which was used for the immobilization of an antibody against SARS-CoV-2 nucleocapsid protein (N protein). The binding of the immunosensor with the N protein caused a change in the electrochemical signal. The detection was realised by measuring the change in reduction peak current of a redox couple using square wave voltammetry at 0.04 V versus Ag ref. electrode on the immunosensor upon binding with the N protein. The electrochemical immunosensor showed high sensitivity with a linear range from 1.0 pg.mL-1 to 100 ng.mL-1 and a limit of detection of 0.4 pg.mL-1 for the N protein in PBS buffer pH 7.4. Moreover, the immunosensor did not exhibit significant response with other viruses such as HCoV, MERS-CoV, Flu A and Flu B, indicating the high selectivity of the sensor for SARS-CoV-2. However, cross reactivity of the biosensor with SARS-CoV is indicated, which gives ability of the sensor to detect both SARS-CoV and SARS-CoV-2. The biosensor was successfully applied to detect the SARS-CoV-2 virus in clinical samples showing good correlation between the biosensor response and the RT-PCR cycle threshold values. We believe that the capability of miniaturization, low-cost and fast response of the proposed label-free electrochemical immunosensor will facilitate the point-of-care diagnosis of COVID 19 and help prevent further spread of infection.


Assuntos
Teste para COVID-19/métodos , COVID-19/diagnóstico , Proteínas do Nucleocapsídeo de Coronavírus/análise , Técnicas Eletroquímicas/métodos , Imunoensaio/métodos , SARS-CoV-2/química , Anticorpos Imobilizados/imunologia , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Teste para COVID-19/instrumentação , Carbono/química , Proteínas do Nucleocapsídeo de Coronavírus/imunologia , Técnicas Eletroquímicas/instrumentação , Eletrodos , Ácidos Graxos/química , Ouro/química , Humanos , Imunoensaio/instrumentação , Limite de Detecção , Nanopartículas Metálicas/química , Nasofaringe/virologia , Fosfoproteínas/análise , Fosfoproteínas/imunologia , Compostos de Sulfidrila/química
18.
Food Chem ; 358: 129763, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34000688

RESUMO

This work reports the electrochemical detection of bisphenol A (BPA) using a novel and sensitive electrochemical sensor based on the Cu functionalized SBA-15 like periodic mesoporous organosilica-ionic liquid composite modified glassy carbon electrode (Cu@TU-PMO/IL/GCE). The structural morphology of Cu@TU-PMO is characterized by X-ray powder diffraction (XRD), energy dispersive X-ray analysis (EDX), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), Field emission scanning electron microscopy (FE-SEM), and Brunauer-Emmett-Teller (BET). The catalytic activity of the modified electrode toward oxidation of BPA was interrogated with cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in phosphate buffer solution (pH 7.0) using the fabricated sensor. The electrochemical detection of the analyte was carried out at a neutral pH and the scan rate studies revealed that the sensor was stable. Under the optimal conditions, a linear range from 5.0 nM to 2.0 µM and 4.0 to 500 µM for detecting BPA was observed with a detection limit of 1.5 nM (S/N = 3). The sensor was applied to detect BPA in tap and seawater samples, and the accuracy of the results was validated by high-performance liquid chromatography (HPLC). The proposed method provides a powerful tool for the rapid and sensitive detection of BPA in environmental samples.


Assuntos
Compostos Benzidrílicos/análise , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Fenóis/análise , Tampões (Química) , Carbono/química , Cobre/química , Eletrodos , Concentração de Íons de Hidrogênio , Líquidos Iônicos/química , Limite de Detecção , Microscopia Eletrônica de Transmissão , Oxirredução , Fosfatos/química , Dióxido de Silício , Espectroscopia de Infravermelho com Transformada de Fourier , Poluentes Químicos da Água/análise , Difração de Raios X
19.
ACS Appl Mater Interfaces ; 13(14): 16155-16165, 2021 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-33792285

RESUMO

Breathomics is a widely emerging tool for noninvasive disease diagnosis and focuses on the detection of various levels of volatile organic compounds and inorganic gases present in human breath. One of the rapid, easy-to-use, and noninvasive detection methods being investigated is a system that can measure exhaled breath ammonia levels and can be correlated to the functional state of protein metabolic pathways and the renal functioning system. In this work, we have demonstrated the development of an electrochemical nose system using ferrocene encapsulated into zeolitic imidazole framework, Fc@ZIF-8, which can be successfully used for the detection of ammonia levels in breath. This is the first report of an electrochemical gas sensor platform that uses a faradaic probe (that is ferrocene) encapsulated into a metal-organic framework cavity used for disease diagnosis by monitoring the levels of the target gas and can be used for breathomics applications. This work demonstrates that low levels of ammonia gas (up to 400 ppb) can be detected with high sensitivity and specificity. The morphological and structural characterization of the novel, synthesized Fc@ZIF-8 nanocomposite has been performed using powder X-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared, ultraviolet-visible spectroscopy, and dynamic light scattering. Electrochemical characterization of the material has been performed using a standard glassy carbon electrode, and further application of the material has been shown using the in-house designed and reported spiral electrochemical notification coupled electrode, used for ammonia gas sensing. Cross-reactivity studies have also been performed to demonstrate sensor specificity toward the target gas. We demonstrate the first of its kind electrochemical bifunctional probe platform that can be used for sensing ammonia levels in breath, with high sensitivity and specificity, due to the hybrid material system-zinc-imidazole framework 8 (having excellent physisorption properties) and ferrocene (acting as a redox mediator). We envision that such a sensing system will allow noninvasive and early diagnosis of chronic kidney disease, thus leading to early treatment and a decrease in the mortality rate.


Assuntos
Amônia/análise , Técnicas Eletroquímicas/instrumentação , Nariz Eletrônico , Testes Respiratórios , Estruturas Metalorgânicas/química , Microscopia Eletrônica de Varredura , Difração de Pó , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral/métodos
20.
ACS Appl Mater Interfaces ; 13(17): 19793-19802, 2021 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-33886262

RESUMO

In this work, a self-circulation oxygen-hydrogen peroxide-oxygen (O2-H2O2-O2) system with photogenerated electrons as fuel and highly active hemin monomers as operators was engineered for ultrasensitive cathode photoelectrochemical bioassay of microRNA-141 (miRNA-141) using a stacked sealed paper device. During the circulation, the photogenerated electrons from BiVO4/Cu2O photosensitive structures assembled on a reduced graphene oxide paper electrode first reduced the electron acceptors (dissolved O2) to H2O2, which was then catalytically decomposed by hemin monomers to generate O2 again. The regenerated O2 continued to be reduced, which made O2 and H2O2 stuck in the infinite loop of O2-H2O2-O2 accompanied by the fast consumption of photogenerated electrons, generating an amplified photocurrent signal. When a target existed, a duplex-specific nuclease-induced target recycling reaction with dual trigger DNA probes as the output was performed to initiate the assembly of bridge-like DNA nanostructures, which endowed the self-circulation system with dual destruction functions as follows. (i) Reduced fuel supply: the assembled DNA bridges acting as a negatively charged barrier prevented the photogenerated electrons from participating in the O2 reduction to H2O2. (ii) Incapacitation of operators: DNA bridging induced the dimerization of hemin monomers linked on the DNA hairpins to catalytically inactive hemin dimers, leading to the abortive regeneration of O2. These destruction functions resulted in the circulation interruption and a remarkably decreased photocurrent signal. Thus, the developed cathode photoelectrochemical biosensing platform achieved ultrasensitive miRNA-141 detection with a linear range of 0.25 fM to 1 nM and a detection limit of 83 aM, and it also exhibited high accuracy, selectivity, and practicability.


Assuntos
Bioensaio/métodos , Técnicas Eletroquímicas/métodos , Eletrodos , Peróxido de Hidrogênio/química , MicroRNAs/análise , Oxigênio/química , Papel , Processos Fotoquímicos , Técnicas Eletroquímicas/instrumentação , Desenho de Equipamento , Limite de Detecção
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