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1.
Nat Commun ; 12(1): 1868, 2021 03 25.
Artículo en Inglés | MEDLINE | ID: mdl-33767166

RESUMEN

It is very attractive yet underexplored to synthesize heterocyclic moieties pertaining to biologically active molecules from biomass-based starting compounds. Herein, we report an electrocatalytic Achmatowicz reaction for the synthesis of hydropyranones from furfuryl alcohols, which can be readily produced from biomass-derived and industrially available furfural. Taking advantage of photo-induced polymerization of a bipyridyl ligand, we demonstrate the facile preparation of a heterogenized nickel electrocatalyst, which effectively drives the Achmatowicz reaction electrochemically. A suite of characterization techniques and density functional theory computations were performed to aid the understanding of the reaction mechanism. It is rationalized that the unsaturated coordination sphere of nickel sites in our electrocatalyst plays an important role at low applied potential, not only allowing the intimate interaction between the nickel center and furfuryl alcohol but also enabling the transfer of hydroxide from nickel to the bound furfuryl alcohol.


Asunto(s)
Técnicas Electroquímicas/métodos , Furanos/química , 2,2'-Dipiridil/química , Biomasa , Catálisis , Níquel/química
2.
Biosens Bioelectron ; 180: 113112, 2021 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-33706158

RESUMEN

Infectious diseases caused by viruses can elevate up to undesired pandemic conditions affecting the global population and normal life function. These in turn impact the established world economy, create jobless situations, physical, mental, emotional stress, and challenge the human survival. Therefore, timely detection, treatment, isolation and prevention of spreading the pandemic infectious diseases not beyond the originated town is critical to avoid global impairment of life (e.g., Corona virus disease - 2019, COVID-19). The objective of this review article is to emphasize the recent advancements in the electrochemical diagnostics of twelve life-threatening viruses namely - COVID-19, Middle east respiratory syndrome (MERS), Severe acute respiratory syndrome (SARS), Influenza, Hepatitis, Human immunodeficiency virus (HIV), Human papilloma virus (HPV), Zika virus, Herpes simplex virus, Chikungunya, Dengue, and Rotavirus. This review describes the design, principle, underlying rationale, receptor, and mechanistic aspects of sensor systems reported for such viruses. Electrochemical sensor systems which comprised either antibody or aptamers or direct/mediated electron transfer in the recognition matrix were explicitly segregated into separate sub-sections for critical comparison. This review emphasizes the current challenges involved in translating laboratory research to real-world device applications, future prospects and commercialization aspects of electrochemical diagnostic devices for virus detection. The background and overall progress provided in this review are expected to be insightful to the researchers in sensor field and facilitate the design and fabrication of electrochemical sensors for life-threatening viruses with broader applicability to any desired pathogens.


Asunto(s)
Técnicas Biosensibles/métodos , Técnicas Electroquímicas/métodos , Virosis/diagnóstico , Anticuerpos Antivirales/inmunología , Humanos , Técnicas Analíticas Microfluídicas , Técnica SELEX de Producción de Aptámeros
3.
Mikrochim Acta ; 188(3): 105, 2021 03 02.
Artículo en Inglés | MEDLINE | ID: mdl-33651173

RESUMEN

Severe acute respiratory syndrome SARS-CoV-2 has caused a global pandemic starting in 2020. Accordingly, testing is crucial for mitigating the economic and public health effects. In order to facilitate point-of-care diagnosis, this study aims at presenting a label-free electrochemical biosensor as a powerful nanobiodevice for SARS-CoV-2 spike protein detection. Utilizing the IgG anti-SARS-CoV-2 spike antibody onto the electrode surface as a specific platform in an ordered orientation through staphylococcal protein A (ProtA) is highly significant in fabricating the designed nanobiodevice. In this sense, the screen-printed carbon electrode modified with Cu2O nanocubes (Cu2O NCs), which provide a large surface area in a very small space, was applied in order to increase the ProtA loading on the electrode surface. Accordingly, the sensitivity and stability of the sensing platform significantly increased. The electrochemical evaluations proved that there is a very good linear relationship between the charge transfer resistance (Rct) and spike protein contents via a specific binding reaction in the range 0.25 fg mL-1 to 1 µg mL-1. Moreover, the assay when tested with influenza viruses 1 and 2 was performed in 20 min with a low detection limit of 0.04 fg mL-1 for spike protein without any cross-reactivity. The designed nanobiodevice exhibited an average satisfactory recovery rate of ~ 97-103% in different artificial sample matrices, i.e., saliva, artificial nasal, and universal transport medium (UTM), illustrating its high detection performance and practicability. The nanobiodevice was also tested using real patients and healthy samples, where the results had been already obtained using the standard polymerase chain reaction (PCR) procedure, and showed satisfactory results. Graphical abstract.


Asunto(s)
Técnicas Biosensibles/métodos , /diagnóstico , Cobre/química , Técnicas Electroquímicas/métodos , Nanoestructuras/química , Glicoproteína de la Espiga del Coronavirus/análisis , Anticuerpos Antivirales/metabolismo , Electrodos , Humanos , Inmunoensayo/métodos , Inmunoglobulina G/metabolismo , Unión Proteica , Sensibilidad y Especificidad , Proteína Estafilocócica A/química , Propiedades de Superficie
4.
Chem Commun (Camb) ; 57(30): 3704-3707, 2021 Apr 18.
Artículo en Inglés | MEDLINE | ID: mdl-33729260

RESUMEN

Accurate and rapid diagnostic tests are critical to reducing the impact of SARS-CoV-2. This study presents early, but promising measurements of SARS-CoV-2 using the ACE2 enzyme as the recognition element to achieve clinically relevant detection. The test provides a scalable route to sensitive, specific, rapid and low cost mass testing.


Asunto(s)
/química , Técnicas Biosensibles/métodos , Técnicas Electroquímicas/métodos , Enzimas Inmovilizadas/química , /aislamiento & purificación , /metabolismo , Técnicas Biosensibles/instrumentación , /instrumentación , Técnicas Electroquímicas/instrumentación , Electrodos , Enzimas Inmovilizadas/metabolismo , Fluorocarburos/química , Oro/química , Humanos , Límite de Detección , Glicoproteína de la Espiga del Coronavirus/metabolismo
5.
Food Chem ; 351: 129252, 2021 Jul 30.
Artículo en Inglés | MEDLINE | ID: mdl-33626469

RESUMEN

Herein, an innovative enzyme free electrochemiluminescence chlorpyrifos sensor was reported based on the incorporation of ternary nanocomposite (ruthenium nanobeads/silver nanoparticles/graphene oxide) on the surface of glassy carbon electrode. The silver nanoparticles as a robust signal enhancing agent were well deposited on the modified graphene oxide/glassy carbon electrode and exhibited supreme electrocatalytic proficiency. Then, Ru(bipy)32+ species in bead-like nanoparticles were uniformly anchored on the surface of the modified electrode with the help of chitosan, as a good crosslinking agent. Boron nitride quantum dots as a new coreactant species showed the excellent proficiency for signal enhancement of the fabricated electrode. The fabricated electrode was successfully used as an ultra-sensitive sensor for trace analysis of chlorpyrifos by ECL technique. The wide linear range and the low detection limit were obtained from 5.0 × 10-15 to 4.2 × 10-9 M and 6.5 × 10-16 M, respectively.


Asunto(s)
Cloropirifos/análisis , Técnicas Electroquímicas/métodos , Mediciones Luminiscentes/métodos , Nanocompuestos/química , Compuestos de Boro/química , Catálisis , Técnicas Electroquímicas/instrumentación , Electrodos , Grafito/química , Límite de Detección , Mediciones Luminiscentes/instrumentación , Nanopartículas del Metal/química , Puntos Cuánticos/química , Rutenio/química , Plata/química
6.
Anal Methods ; 13(7): 874-883, 2021 02 25.
Artículo en Inglés | MEDLINE | ID: mdl-33576354

RESUMEN

Using the children's toy, Shrinky-Dink©, we present an aptamer-based electrochemical (E-AB) assay that recognizes the spike protein of SARS-CoV-2 in saliva for viral infection detection. The low-cost electrodes are implementable at population scale and demonstrate detection down to 1 ag mL-1 of the S1 subunit of the spike protein.


Asunto(s)
Técnicas Biosensibles/métodos , Técnicas Electroquímicas/métodos , Poliestirenos/química , Saliva/química , Glicoproteína de la Espiga del Coronavirus/análisis , Aptámeros de Nucleótidos/química , Técnicas Electroquímicas/instrumentación , Electrodos , Oro/química , Humanos , Límite de Detección , Dominios Proteicos , Glicoproteína de la Espiga del Coronavirus/química
7.
Molecules ; 26(4)2021 Feb 10.
Artículo en Inglés | MEDLINE | ID: mdl-33578737

RESUMEN

Copper-doped zinc oxide nanoparticles (NPs) CuxZn1-xO (x = 0, 0.01, 0.02, 0.03, and 0.04) were synthesized via a sol-gel process and used as an active electrode material to fabricate a non-enzymatic electrochemical sensor for the detection of glucose. Their structure, composition, and chemical properties were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) and Raman spectroscopies, and zeta potential measurements. The electrochemical characterization of the sensors was studied using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). Cu doping was shown to improve the electrocatalytic activity for the oxidation of glucose, which resulted from the accelerated electron transfer and greatly improved electrochemical conductivity. The experimental conditions for the detection of glucose were optimized: a linear dependence between the glucose concentration and current intensity was established in the range from 1 nM to 100 µM with a limit of detection of 0.7 nM. The proposed sensor exhibited high selectivity for glucose in the presence of various interfering species. The developed sensor was also successfully tested for the detection of glucose in human serum samples.


Asunto(s)
Técnicas Biosensibles/métodos , Glucemia/análisis , Cobre/química , Técnicas Electroquímicas/métodos , Electrodos , Nanopartículas/química , Óxido de Zinc/química , Humanos , Oxidación-Reducción
8.
Nat Commun ; 12(1): 802, 2021 02 05.
Artículo en Inglés | MEDLINE | ID: mdl-33547323

RESUMEN

Coronavirus disease 2019 (COVID-19) is a highly contagious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Diagnosis of COVID-19 depends on quantitative reverse transcription PCR (qRT-PCR), which is time-consuming and requires expensive instrumentation. Here, we report an ultrasensitive electrochemical biosensor based on isothermal rolling circle amplification (RCA) for rapid detection of SARS-CoV-2. The assay involves the hybridization of the RCA amplicons with probes that were functionalized with redox active labels that are detectable by an electrochemical biosensor. The one-step sandwich hybridization assay could detect as low as 1 copy/µL of N and S genes, in less than 2 h. Sensor evaluation with 106 clinical samples, including 41 SARS-CoV-2 positive and 9 samples positive for other respiratory viruses, gave a 100% concordance result with qRT-PCR, with complete correlation between the biosensor current signals and quantitation cycle (Cq) values. In summary, this biosensor could be used as an on-site, real-time diagnostic test for COVID-19.


Asunto(s)
Técnicas Biosensibles/métodos , Técnicas Electroquímicas/métodos , /aislamiento & purificación , /virología , Humanos , Técnicas de Amplificación de Ácido Nucleico/métodos , ARN Viral/genética , /fisiología , Sensibilidad y Especificidad
9.
J Agric Food Chem ; 69(4): 1398-1404, 2021 Feb 03.
Artículo en Inglés | MEDLINE | ID: mdl-33433214

RESUMEN

As one of the most toxic forms of arsenic, inorganic As(III) is easy to accumulate in rice, leading to severe public health problems. Effective control of As(III) requires the development of fast analytical methods for its detection with high sensitivity and specificity. Toward this end, in this work, we report the fabrication of an As(III) electrochemical sensor based on a solution-gated graphene transistor (SGGT) platform with a novel sensing mechanism. The gold gate electrode of the SGGT was modified with DNA probes and then blocked with bovine serum albumin (BSA). The specific interaction between As(III) and gold disrupted the adsorption states of DNA probes, redistributing surface charges on the gate electrode, further leading to potential drop changes at the interfaces of the gate electrode and graphene active layer. This new mechanism based on DNA-charge-redistribution-induced SGGT current responses (denoted as "DNA-SGGT") was found to greatly improve the selectivity of the sensor: the response of DNA-SGGT to As(III) was effectively enhanced fourfold, while to other interfering cations, it was significantly reduced. The optimized sensor showed a detection limit as low as 5 nM with superior selectivity to As(III). The as-prepared DNA-SGGT-based sensor has also been successfully applied to the detection of As(III) in practical rice samples with a high recovery rate, showing great potential for heavy metal detection in many types of food samples.


Asunto(s)
Arsénico/análisis , ADN/química , Técnicas Electroquímicas/métodos , Grafito/química , Oryza/química , Técnicas Electroquímicas/instrumentación , Contaminación de Alimentos/análisis , Límite de Detección , Semillas/química
10.
J Mater Chem B ; 9(5): 1175-1188, 2021 02 07.
Artículo en Inglés | MEDLINE | ID: mdl-33458727

RESUMEN

The use of sensitive electrochemical sensors to detect biomarkers is an effective method for the early diagnosis of several neurodegenerative diseases (NDs), such as Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, etc. However, the commercialization of enzyme/aptamer-based sensors is still hampered owing to the historic drawbacks of biorecognition elements including high cost, poor stability, and complex integration technology. Non-enzymatic electrochemical sensors are more attractive compared to their traditional counterparts and can be widely harnessed owing to their low cost, high stability, sensitivity, and ease of miniaturization. This review summarizes recent research progress focusing on the construction of non-enzymatic electrochemical sensors and analyzes their present use in the early diagnosis of NDs. Additionally, this review addresses the limitations and challenges of the use of current non-enzymatic electrochemical sensor technologies for the diagnosis of NDs and highlights the possible directions for future research.


Asunto(s)
Técnicas Biosensibles/métodos , Técnicas Electroquímicas/métodos , Enfermedades Neurodegenerativas/diagnóstico , Humanos
11.
Food Chem ; 347: 128980, 2021 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-33465693

RESUMEN

In order to achieve accurate detection and evaluation of the freshness of fish samples, high sensitivity and selectivity of histamine sensors based on solution-gated graphene transistors (SGGT) have been successfully developed. By using graphene (Gra), multi-walled carbon nanotubes (MWNT) and gold nanoparticles (AuNP) to functionalize the gate electrode, the electrocatalytic performance of the device can be significantly improved. We have found that graphene, MWNT and AuNP modified SGGT sensors exhibit an ultra-low detection limit of 100 nM for histamine, a linear range of 3 µM-100 µM. We have also demonstrated that the SGGT-based histamine sensor has a high recovery rate and is capable of assessing the histamine content of actual fish samples in a fast and accurate manner. Considering the superior performance of the SGGT-based histamine sensor, it can be readily extended to histamine determination in many other real food samples for their freshness assessment.


Asunto(s)
Técnicas Electroquímicas/métodos , Histamina/análisis , Nanopartículas del Metal/química , Nanotubos de Carbono/química , Animales , Técnicas Electroquímicas/instrumentación , Electrodos , Peces/metabolismo , Oro/química , Grafito/química , Límite de Detección , Reproducibilidad de los Resultados , Transistores Electrónicos
12.
Artículo en Inglés | MEDLINE | ID: mdl-33499749

RESUMEN

In the present study, the electrocoagulation (EC) performance of a Mg-Mg system was applied for the industrial wastewater treatment, from an industrial park that covers different activities such as: food, automotive, pharmaceutical, chemistry and cosmetics, after primary clarification. The effects of major operating parameters such as pH, reaction time, and current density were investigated for chemical oxygen demand (COD), color, and turbidity removal efficiency. The batch system was found convenient, achieving 63.52% COD, 96% color, and 99.32% turbidity removal at optimized operating conditions of pH 7.12, reaction time of 75 min, and current density of 201.5 A/m2. On the other hand, for continuous EC, the process removed approximately 46.58%, 95.96%, and 87.19% of the COD, color, and turbidity respectively, at 90 min of retention time, current density 440 A/m2, and a rate of 20 mL/min. Additionally, concerning nutrient removal (N and P), the EC system with Mg electrodes was highly efficient; batch treatment removed 97% of total phosphorus and 67% of ammoniacal nitrogen, whereas the continuous treatment removed 98.5% of total phosphorus and 83% of ammoniacal nitrogen. The sludge characterization before and after EC treatment was made by SEM, EDS, Fluorescence spectroscopy, IR spectroscopy. Minerals such as chlorite, crossite, richterite, pyroaurite, langbeinite as weel as aliphatic and polysubstituted aromatics compounds, sulfates and phosphates inorganic ions, and organic phosphorus were reduced. The energy cost in the batch EC is US$0.05/m3. A numerical CFD model was used to estimate the velocity fields and guarantee the presence of turbulent kinetic energy within a continuous flow reactor.


Asunto(s)
Técnicas Electroquímicas/métodos , Magnesio/química , Eliminación de Residuos Líquidos/métodos , Purificación del Agua/métodos , Análisis de la Demanda Biológica de Oxígeno , Electrodos , Concentración de Iones de Hidrógeno , Residuos Industriales , Minerales , Nitrógeno , Compuestos Orgánicos , Fósforo , Contaminantes Químicos del Agua
13.
Int Rev Immunol ; 40(1-2): 126-142, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33448909

RESUMEN

Coronavirus disease (COVID-19) is an emerging and highly infectious disease making global public health concern and socio-economic burden. It is caused due to Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2). It has the tendency to spread rapidly through person-to-person. Currently, several molecular diagnostic platforms such as PCR, qRT-PCR, reverse transcription loop-mediated isothermal amplification (RT-LAMP), CRISPR are utilized for the diagnosis of SARS-CoV-2. These conventional techniques are costly, time consuming and require sophisticated instrumentation facility with well trained personnel for testing. Hence, it is tough to provide testing en-masse to the people in developing countries. On the other hand, several serological biosensors such as lateral flow immunosensor, optical, electrochemical, microfluidics integrated electrochemical/fluorescence is currently utilized for the diagnosis of SARS-CoV-2. In current pandemic situation, there is an urgent need of rapid and efficient diagnosis on mass scale of SARS-CoV-2 for early stage detection. Early monitoring of viral infections can help to control and prevent the spreading of infections in large chunk of population. In this review, the SARS-CoV-2 and their biomarkers in biological samples, collection of samples and recently reported potential electrochemical immunosensors for the rapid diagnosis of SARS-CoV-2 are discussed.


Asunto(s)
Técnicas Biosensibles/métodos , /diagnóstico , Técnicas Electroquímicas/métodos , /inmunología , /métodos , Humanos , Inmunoensayo/métodos , Técnicas de Diagnóstico Molecular/métodos , Sistemas de Atención de Punto , /genética
14.
ACS Appl Mater Interfaces ; 13(2): 3295-3302, 2021 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-33400479

RESUMEN

In this work, a nanocomposite of Zr-trimesic acid MOF (MOF-808) with carbon nanotube (CNT) was synthesized through an in situ formation of MOF-808 on the activated CNT. The synthesized materials were characterized by powder X-ray diffraction, transmission electron microscopy, X-ray photoluminescence spectroscopy, Brunauer-Emmett-Teller, Fourier transform infrared spectroscopy, and Raman spectroscopy. The protein compatible nature with high surface area and electrocatalytic ability of MOF-808 was utilized to construct an immunosensor for ultra low-level detection of the ovarian cancer biomarker, carbohydrate antigen 125 (CA 125). The mutual benefit of each constituent of the MOF-808/CNT composite was capable of producing highly enhanced electrochemical properties. A glassy carbon electrode modified with MOF-808/CNT was used as a platform to fabricate a label-free electrochemical immunosensor. The antibody binding sites of MOF-808/CNT were enriched by functionalization with streptavidin. The immunosensor exhibited two linear determination ranges of 0.001-0.1 and 0.1-30 ng·mL-1, and the calculated limit of detection was 0.5 pg·mL-1 (S/N 3). The immunosensor showed excellent reproducibility and selectivity. The patient serum sample analysis was cross-verified with the electrochemiluminescence method with a relative error of 105-110%.


Asunto(s)
Anticuerpos Inmovilizados/química , Técnicas Biosensibles/métodos , Antígeno Ca-125/sangre , Estructuras Metalorgánicas/química , Nanotubos de Carbono/química , Técnicas Electroquímicas/métodos , Electrodos , Humanos , Inmunoensayo/métodos , Límite de Detección , Neoplasias/sangre
15.
Food Chem ; 346: 128901, 2021 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-33450645

RESUMEN

An electrochemical deposition method was used to fabricate a gold nanoflower (AuNF) and carbon nanoparticle (CNP) modified carbon paper (CP) sensor (AuNFs-CNPs/CP) for the low-cost detection of 5-methyltetrahydrofolate (5-mTHF) in egg yolk. AuNF morphology and structures were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), revealing nanoflower sizes in the 50 to 200 nm range. AuNFs formed on the sensor were in the Au0. We evaluated 5-mTHF assay performance using cyclic voltammetry, differential pulse voltammetry and chronoamperometry. The AuNFs-CNPs/CP sensor detected 5-mTHF concentrations in the ranges from 1 to 5 mg L-1 and 1-20 µg L-1, with an excellent limit of detection of 1 µg L-1 and good selectivity toward 5-mTHF, when compared to other potentially interfering molecules in samples. The AuNFs-CNPs/CP sensor was also used to detect 5-mTHF in folate-rich, and was found to be twice than that of ordinary egg yolk.


Asunto(s)
Yema de Huevo/química , Técnicas Electroquímicas/métodos , Papel , Tetrahidrofolatos/análisis , Carbono/química , Yema de Huevo/metabolismo , Técnicas Electroquímicas/instrumentación , Electrodos , Oro/química , Límite de Detección , Nanoestructuras/química , Reproducibilidad de los Resultados
16.
Anal Chem ; 93(2): 812-819, 2021 01 19.
Artículo en Inglés | MEDLINE | ID: mdl-33395261

RESUMEN

Electrochemical impedance spectroscopy (EIS), an extremely sensitive analytical technique, is a widely used signal transduction method for the electrochemical detection of target analytes in a broad range of applications. The use of nucleic acids (aptamers) for sequence-specific or molecular detection in electrochemical biosensor development has been extensive, and the field continues to grow. Although nucleic acid-based sensors using EIS offer exceptional sensitivity, signal fidelity is often linked to the physical and chemical properties of the electrode-solution interface. Little emphasis has been placed on the stability of nucleic acid self-assembled monolayers (SAMs) over repeated voltammetric and impedimetric analyses. We have studied the stability and performance of electrochemical biosensors with mixed SAMs of varying length thiolated nucleic acids and short mercapto alcohols on gold surfaces under repeated electrochemical interrogation. This systematic study demonstrates that signal fidelity is linked to the stability of the SAM layer and nucleic acid structure and the packing density of the nucleic acid on the surface. A decrease in packing density and structural changes of nucleic acids significantly influence the signal change observed with EIS after routine voltammetric analysis. The goal of this article is to improve our understanding of the effect of multiple factors on EIS signal response and to optimize the experimental conditions for development of sensitive and reproducible sensors. Our data demonstrate a need for rigorous control experiments to ensure that the measured change in impedance is unequivocally a result of a specific interaction between the target analyte and nucleic recognition element.


Asunto(s)
Impedancia Eléctrica , Ácidos Nucleicos/química , Aptámeros de Nucleótidos/química , ADN , Espectroscopía Dieléctrica/métodos , Técnicas Electroquímicas/métodos , Electrodos , Oro/química , Transducción de Señal
17.
ACS Appl Mater Interfaces ; 13(3): 3653-3668, 2021 Jan 27.
Artículo en Inglés | MEDLINE | ID: mdl-33439005

RESUMEN

A thin layer of gold nanoparticles (Au NPs) sputtered on cadmium sulfide quantum dots (CdS QDs) decorated anodic titanium dioxide nanotubes (TNTs) (Au/CdS QDs/TNTs) was fabricated and explored for the nonenzymatic detection of cholesterol and hydrogen peroxide (H2O2). Morphological studies of the sensor revealed the formation of uniform nanotubes decorated with a homogeneously dispersed CdS QDs and Au NPs layer. The electrochemical measurements showed an enhanced electrocatalytic performance with a fast electron transfer (∼2 s) between the redox centers of each analyte and electrode surface. The hybrid nanostructure (Au/CdS QDs/TNTs) electrode exhibited about a 6-fold increase in sensitivity for both cholesterol (10,790 µA mM-1 cm-2) and H2O2 (78,833 µA mM-1 cm-2) in analyses compared to the pristine samples. The hybrid electrode utilized different operational potentials for both analytes, which may lead to a voltage-switchable dual-analyte biosensor with a higher selectivity. The biosensor also demonstrated a good reproducibility, thermal stability, and increased shelf life. In addition, the clinical significance of the biosensor was tested for cholesterol and H2O2 in real blood samples, which showed maximum relative standard deviations of 1.8 and 2.3%, respectively. These results indicate that a Au/CdS QDs/TNTs-based hybrid nanostructure is a promising choice for an enzyme-free biosensor due to its suitable band gap alignment and higher electrocatalytic activities.


Asunto(s)
Técnicas Biosensibles/métodos , Colesterol/sangre , Oro/química , Peróxido de Hidrógeno/sangre , Nanopartículas del Metal/química , Compuestos de Cadmio/química , Técnicas Electroquímicas/métodos , Humanos , Límite de Detección , Nanotubos/química , Puntos Cuánticos/química , Sulfuros/química , Titanio/química
18.
ACS Appl Mater Interfaces ; 13(4): 5795-5802, 2021 Feb 03.
Artículo en Inglés | MEDLINE | ID: mdl-33480669

RESUMEN

A novel ratiometric electrochemical (EC) sensing platform was established for sensitive immunoassay of target cytokeratin 19 fragment 21-1 (CYFRA21-1) biomarker by combining competitive immunoreaction and multisignal output. This immunosensor utilized Ag nanoparticles (NPs)-functionalized urchin-like Fe3O4@polydopamine (u-Fe3O4@PDA-Ag) as a matrix to immobilize CYFRA21-1 antigens and methylene blue (MB)-absorbed Ni3Si2O5(OH)4-Au nanotubes (NTs) to label the anti-CYFRA21-1 (Ab). During the competitive immunoreaction, square wave voltammetric (SWV) current changes of Ag NPs from u-Fe3O4@PDA-Ag indicator and MB from Ni3Si2O5(OH)4-Au/MB indicator are relevant to the dosage of CYFRA21-1-acquired Ni3Si2O5(OH)4-Au/MB/Ab. More importantly, numerous CYFRA21-1 loaded stably on u-Fe3O4@PDA-Ag exhibited strong competitive capacity toward the target-CYFRA21-1 to combine Ni3Si2O5(OH)4-Au/MB/Ab, causing sensitive changes in the ratio of two measured SWV currents. Prominently, "ΔI = ΔIMB + |ΔIAg NPs|" (ΔIMB and |ΔIAg NPs| represents the change values of the oxidation peak currents of MB and Ag NPs, respectively) could be regarded as significantly amplifying the signal response and ultimately improving the sensitivity of CYFRA21-1 detection, from which we derived a wide dynamic range from 500 fg/mL to 50 ng/mL and a low detection limit of 0.39 pg/mL (S/N = 3). This work may exert a profound impact on monitoring other biomarkers in early diagnosis of diseases.


Asunto(s)
Antígenos de Neoplasias/sangre , Óxido Ferrosoférrico/química , Oro/química , Queratina-19/sangre , Azul de Metileno/química , Nanotubos/química , Antígenos de Neoplasias/análisis , Técnicas Electroquímicas/métodos , Humanos , Inmunoensayo/métodos , Indoles/química , Queratina-19/análisis , Límite de Detección , Nanopartículas del Metal/química , Nanopartículas del Metal/ultraestructura , Nanotubos/ultraestructura , Polímeros/química , Compuestos de Silicona/química , Plata/química
19.
Molecules ; 26(3)2021 Jan 22.
Artículo en Inglés | MEDLINE | ID: mdl-33499217

RESUMEN

The current environmental situation requires taking actions regarding processes for energy production, thus promoting renewable energies, which must be complemented with the development of routes to reduce pollution, such as the capture and storage of CO2. Graphene materials have been chosen for their unique properties to be used either as electrocatalyst or as catalyst support (mainly for non-noble metals) that develop adequate efficiencies for this reaction. This review focuses on comparing experimental and theoretical results of the electrochemical reduction reaction of carbon dioxide (ECO2RR) described in the scientific literature to establish a correlation between them. This work aims to establish the state of the art on the electrochemical reduction of carbon dioxide on graphene-based catalysts.


Asunto(s)
Dióxido de Carbono/química , Técnicas Electroquímicas/métodos , Grafito/química , Catálisis , Electroquímica , Nanopartículas del Metal/química , Oxidación-Reducción , Puntos Cuánticos/química , Termodinámica
20.
Ecotoxicol Environ Saf ; 209: 111828, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33385681

RESUMEN

Herein, we fabricated a feasible and accurate sensing platform for the quantification of toxic organic pollutant 2-nitroaniline (2-NA) in water samples through electrocatalyst made up of bismuth molybdate (Bi2MoO6, BMO) functionalized carbon nanofiber (f-CNF) modified electrode. The preparation of BMO/f-CNF composite is of two methods, such as co-precipitation (C-BMO/f-CNF) and ultrasonication method (U-BMO/f-CNF). The physicochemical properties of the composites were characterized by XRD, FTIR, Raman, BET, FE-SEM, and HR-TEM techniques. At U-BMO/f-CNF, the charge transfer resistance was low (Rct = 12.47 Ω) compared to C-BMO/f-CNF because nanosized U-BMO particles correctly aim at the defective sites of the f-CNF surface wall. Further, the electrocatalytic activity of C&U-BMO/f-CNF composites was examined by cyclic voltammetry (CV) and differential pulse voltammetry techniques (DPV) for the electrochemical detection of 2-nitroaniline (2-NA). The U-BMO/f-CNF/GCE shows a higher cathodic current, wide dynamic linear range of 0.01-168.01 µM, and superior electrocatalytic activity with a low detection limit (0.0437 µM) and good sensitivity (0.6857 µA µM-1 cm-2). The excellent selectivity nature of U-BMO/f-CNF/GCE was observed in the presence of various organic pollutants and a few toxic metal cations. The practical applicability such as stability, repeatability towards 2-NA outcomes with accepted results. Besides, the practical viability of as proposed U-BMO/f-CNF sensor was investigated in soil and lake water samples delivers good recovery results. Hence from these analyses, we conclude that U-BMO/f-CNF/GCE potential for the determination of hazardous environmental pollutant 2-NA.


Asunto(s)
Bismuto , Técnicas Electroquímicas/métodos , Monitoreo del Ambiente/métodos , Contaminantes Ambientales/análisis , Molibdeno , Nanofibras/química , Compuestos de Anilina , Carbono/química , Electrodos , Suelo
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