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1.
Mikrochim Acta ; 188(6): 185, 2021 05 11.
Artículo en Inglés | MEDLINE | ID: mdl-33977395

RESUMEN

An abdominal aortic aneurysm (AAA) is abnormal swelling in the abdominal aorta and a prevalent life-threatening disease. This research introduces a new interdigitated microelectrode (IDME)-sensing surface modified by iron oxide nanoworms (IONWs) for detecting the AAA biomarker insulin-like growth factor-1 (IGF1). A sandwich pattern was formulated with the IGF1 aptamer and IGFBP1 (IGF binding protein-1) on the IONW-constructed IDME hybrid to identify IGF1. The surface morphology of the IONWs revealed a uniform distribution of worm-like structures (80-100 nm) as confirmed by FESEM and FETEM analyses. Further, the presence of the major elements, Fe and O, was confirmed by EDX and XPS studies. The crystal planes that appeared in the IONW reflect cubic magnetite. IONW-modified IDME attained a limit of detection for IGF1 of 1 fM (3σ) with an aptamer-IGF1-IGFBP1 sandwich. This sandwich with IGFBP1 enhanced the current level at all concentrations of IGF1 and displayed linearity in the range 1 fM to 100 pM with a determination coefficient of R2 = 0.9373 [y = 3.38221x - 4.79]. Control experiments with complementary aptamer sequences, IGF2 and IGFBP3 did not show notable signal changes, indicating the specific detection of IGF1. This IONW constructed electrode helps to achieve the detection of low amounts of IGF1 and diagnose AAA at the stage prior to rupture.


Asunto(s)
Aneurisma de la Aorta Abdominal/diagnóstico , Factor I del Crecimiento Similar a la Insulina/análisis , Nanoestructuras/química , Aneurisma de la Aorta Abdominal/sangre , Aptámeros de Nucleótidos/química , Biomarcadores/sangre , Biomarcadores/química , Técnicas Biosensibles/instrumentación , Técnicas Biosensibles/métodos , Técnicas Electroquímicas/instrumentación , Técnicas Electroquímicas/métodos , Compuestos Ferrosos/química , Humanos , Ácidos Nucleicos Inmovilizados/química , Factor I del Crecimiento Similar a la Insulina/química , Límite de Detección , Microelectrodos
2.
Mikrochim Acta ; 188(4): 112, 2021 03 06.
Artículo en Inglés | MEDLINE | ID: mdl-33675442

RESUMEN

An electrochemical biosensor was prepared for nucleic acid-based hantavirus detection using a Cu-based metal-organic framework (CuMOF) as a signal tag. The CuMOF was synthesized by the solvothermal method and then covalently bonded with signal DNA (sDNA) probes. The Au nanoparticles and reduced graphene oxide composite were deposited on the electrode surface by electroreduction as support substrate and was then functionalized with capture DNA (cDNA) probes by self-assembly. Through the complementary base pairing, the target DNA (tDNA) fragment of hantavirus hybridized with the cDNA and the sDNA in a sandwich-type format. The tDNA was detected according to the current signal of the CuMOF catalyzed reaction using o-phenylenediamine as redox substrate. The peak current of the biosensor at - 0.55 V increased linearly in proportion to the logarithmic value of the tDNA concentration from 10-15 to 10-9 mol/L, with a detection limit of 0.74 × 10-15 mol/L. Moreover, the proposed biosensor was successfully applied to detect hantavirus and was able to distinguish hantavirus from other arboviruses.


Asunto(s)
Técnicas Biosensibles/métodos , ADN Viral/análisis , Técnicas Electroquímicas/métodos , Grafito/química , Nanopartículas del Metal/química , Orthohantavirus/química , Técnicas Biosensibles/instrumentación , Cobre/química , ADN Complementario/química , ADN Complementario/genética , ADN Viral/genética , Técnicas Electroquímicas/instrumentación , Electrodos , Oro/química , Límite de Detección , Estructuras Metalorgánicas/química , Hibridación de Ácido Nucleico
3.
Mikrochim Acta ; 188(4): 138, 2021 03 26.
Artículo en Inglés | MEDLINE | ID: mdl-33772377

RESUMEN

An electrochemical sensor-based phosphorus-doped microporous carbon spheroidal structures (P-MCSs) has been designed for selective adrenaline (ADR) signaling in human blood serum. The P-MCS electrode sensor is built with heterogeneous surface alignments including multiple porous sizes with open holes and meso-/macro-grooves, rough surface curvatures, and integral morphology with interconnected and conjugated microspheres. In addition, the P atom-doped graphitic carbon forms highly active centers, increases charge mobility on the electrode surface, creates abundant active centers with facile functionalization, and induces binding to ADR molecules. The designed P-MCS electrode exhibits ultrasensitive monitoring of ADR with a low detection limit of 0.002 µM and high sensitivity of 4330 µA µM-1 cm-2. In addition, two electrochemical techniques, namely, square wave voltammetry (SWV) and chronoamperometry (CA), were used; these techniques achieve high stability, fast response, and a wide linear range from 0.01 to 6 µM. The sensing assays based on P-MCSs provide evidence of the formation of active interfacial surface-to-ADR binding sites, high electron diffusion, and heavy target loads along with/without a plane of spheroids. Thus, P-MCSs can be used for the routine monitoring of ADR in human blood serum, providing a fast response, and requiring highly economical materials at extremely low concentrations. Electrode surface modulation based on P-doped carbon spheres (P-MCS) exhibits high electrochemical activity with fast charge transport, multi-diffusible active centers, high loading of ADR, and facile molecular/electron diffusion at its surface. The P-MCS sensitively and selectively detects the ADR in human fluids and can be used for clinical investigation of some neuronal diseases such as Alzheimer diseases.


Asunto(s)
Carbono/química , Técnicas Electroquímicas/métodos , Epinefrina/sangre , Adsorción , Técnicas Biosensibles/instrumentación , Técnicas Biosensibles/métodos , Técnicas Electroquímicas/instrumentación , Electrodos , Epinefrina/química , Humanos , Límite de Detección , Oxidación-Reducción , Fósforo/química , Porosidad , Reproducibilidad de los Resultados
4.
Mikrochim Acta ; 188(3): 85, 2021 02 15.
Artículo en Inglés | MEDLINE | ID: mdl-33587169

RESUMEN

A new covalent organic framework (COF) has been prepared with 1,3,6,8-tetra(4-formyl phenyl) pyrene (TFPPy) and 2,6-diaminopyridine (DP) as building units through a Schiff base reaction by a simple tube oven heating procedure and the structure of the COF has been characterized in detail. The obtained DP-Py COF is employed to fabricate a novel electrochemical sensing platform for sensitive and selective determination of theophylline (TP) and caffeine (CAF) simultaneously through compounding with AuNPs; the peak positions of TP and CAF are 0.95 V and 1.28 V, respectively. The synergistic effect between DP-Py COF and AuNPs effectively enhances the analytical sensitivity for the target analytes. Under the optimized experimental conditions, the electrochemical sensing platform shows a sensitive voltammetric response and wide linear range to both TP and CAF, and the detection limits are 0.19 µM and 0.076 µM (S/N = 3), respectively. This method has been successfully used for the determination of TP and CAF in compound paracetamol capsules and black tea samples. The recovery and relative standard deviations (RSD) of TP are 99.3~101% and 97.6~101% and 1.3~2.0% and 1.3~2.1%, respectively, and the recovery and RSD of CAF are 96.1~102% and 99.4~104% and 2.8~3.9% and 1.7~3.2%, respectively. Compared with traditional detection methods, the constructed sensing platform has better performance and is expected to be widely used also in other real sample analyses.


Asunto(s)
Cafeína/análisis , Técnicas Electroquímicas/métodos , Nanopartículas del Metal/química , Estructuras Metalorgánicas/química , Teofilina/análisis , Acetaminofén/análisis , Cápsulas/análisis , Contaminación de Medicamentos/prevención & control , Técnicas Electroquímicas/instrumentación , Electrodos , Oro/química , Límite de Detección , Reproducibilidad de los Resultados , Té/química
5.
Mikrochim Acta ; 188(3): 71, 2021 02 06.
Artículo en Inglés | MEDLINE | ID: mdl-33547976

RESUMEN

A glassy carbon electrode (GCE) was modified with magnetic molecularly imprinted polymers (mMIPs) using catechin as a template, reduced graphene oxide (rGO), and zeolitic imidazolate frameworks-8 (ZIF-8) for the sensitive detection of catechin (mMIPs/rGO-ZIF-8/GCE). The prepared rGO, ZIF-8, and mMIPs exhibited typical structures and properties determined by various characterizations. The mMIPs showed good selectivity for catechin among several structural analogs. The mMIPs/rGO-ZIF-8/GCE showed a higher maximum peak current for catechin than that of a single component modified GCE. After the optimization of the material ratio, coating amounts, pH, and scan rate, the mMIPs/rGO-ZIF-8/GCE exhibited good selectivity, good linearity, and a low detection limit (LOD) for catechin. The linear range was 0.01 nmol/L-10 µmol/L and the LOD was 0.003 nmol/L (S/N = 3). The relative standard deviations for reproducibility and stability tests (n = 6) were 5.2% and 6.1%, respectively. A recovery between 99.1 and 101.3% was obtained in the detection of catechin in spiked samples. Based on these findings, the proposed mMIPs/rGO-ZIF-8/GCE could be developed further, and future research could be conducted on alternate fabrication strategies and methods to create more portable and practical electrochemical sensors. Graphical Abstract.


Asunto(s)
Catequina/análisis , Grafito/química , Imidazoles/química , Polímeros Impresos Molecularmente/química , Nanocompuestos/química , Zeolitas/química , Adsorción , Catequina/química , Técnicas Electroquímicas/instrumentación , Técnicas Electroquímicas/métodos , Electrodos , Límite de Detección , Reproducibilidad de los Resultados , Té/química
6.
Anal Biochem ; 621: 114123, 2021 05 15.
Artículo en Inglés | MEDLINE | ID: mdl-33549546

RESUMEN

In the present study, a simple, cheaply and environmental friendly method was evaluated for the synthesis of silver nanoparticle via Cupressus sempervirens L. (CSPE) pollen extract as reducing and stabilizing agent. Various parameters such as volume of CSPE, temperature and reaction time on AgNPs formation were investigated spectrophotometrically to optimize reaction conditions. The electrochemical behavior of the biosynthesized AgNPs were investigated by cyclic voltammetry and square wave voltammetry techniques. An electrosensor based on AgNPs modified glassy carbon electrode were constructed and tested on electro reduction of hydrogen peroxide in phosphate buffer medium. The prepared electrosensor could detect the H2O2 in the range of 5.0 µM - 2.5 mM with a detection limit of 0.23 µM. In addition, the antioxidant activity of biosynthesized AgNPs were evaluated against DPPH free radical. Results obtained from the antioxidant study suggested that CSPE mediated AgNPs exhibit a good antioxidant effect.


Asunto(s)
Antioxidantes/análisis , Técnicas Electroquímicas/instrumentación , Nanopartículas del Metal/química , Extractos Vegetales/química , Polen/química , Plata/química , Cupressus/química , Técnicas Electroquímicas/métodos , Electrodos , Radicales Libres/análisis , Peróxido de Hidrógeno/análisis , Tamaño de la Partícula , Fitoquímicos/química , Reproducibilidad de los Resultados , Espectroscopía Infrarroja por Transformada de Fourier , Temperatura , Difracción de Rayos X
7.
Food Chem ; 340: 127919, 2021 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-32889210

RESUMEN

Non-enzymatic electrochemical sensors for the monitoring of reducing sugars in foods has great potential as a rapid in-situ detection method. This development involved the assembly of a nanoporous platinum structure on a screen-printed carbon electrode (SPCE). The modified electrode was then employed as an amperometric sensing element in a flow injection analysis (FIA) manifold. The system was successfully applied to the rapid detection of reducing sugars in potatoes, without the need for sample preparation. Optimal signals were achieved in phosphate buffer (pH 7.4) at a flow rate of 0.5 mL min-1 and an applied potential of 0.6 V. Experimental results demonstrated the sensor's long-term stability and high selectivity for reducing sugars. This method provides high sample throughput due to a rapid response time of less than five seconds. Reducing sugar values determined were in good agreement with those recorded using a commercially available enzymatic assay kit.


Asunto(s)
Técnicas Electroquímicas/métodos , Electrodos , Análisis de Inyección de Flujo/métodos , Análisis de los Alimentos/métodos , Solanum tuberosum/química , Azúcares/análisis , Carbono/química , Técnicas Electroquímicas/instrumentación , Análisis de Inyección de Flujo/instrumentación , Análisis de los Alimentos/instrumentación , Fructosa/análisis , Jugos de Frutas y Vegetales/análisis , Glucosa/análisis , Nanoestructuras/química , Platino (Metal)/química , Propiedades de Superficie
8.
Anal Bioanal Chem ; 413(1): 193-203, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33119785

RESUMEN

Herein, a photoelectrochemical (PEC) aptasensing platform was designed by integrating surface oxygen vacancy (OV) defects, Ti3+ self-doping, the heterojunction, and resonance energy transfer (RET) effect into one platform for the detection of diclofenac sodium (DCF). Briefly, OV defects were introduced on TiO2 nanospheres with simultaneous Ti3+ self-doping, followed by a well-separated deposition of FeVO4 nanoparticles on TiO2 to obtain a Ti3+-O-TiO2/FeVO4 heterojunction. The surface modification of OVs, Ti3+ doping, and deposition of FeVO4 were confirmed by SEM, XPS, EPR, DRS, and PEC measurements. The surface OVs and doping of Ti3+ species created a new donor (defect) energy level under the conduction band of TiO2, which minimized the bandgap and thereby improved the visible light absorption of TiO2. Moreover, the capture of photo-excited electrons by surface OVs could hinder the electron-hole recombination. Due to the intimate surface contact and perfect energy matching between TiO2 and FeVO4, the formation of heterojunction decreased the bandgap and facilitated the electron-hole separation of TiO2. All these above events contributed to the enhancement of the PEC signals, which were then quenched by the RET effect between Ti3+-O-TiO2/FeVO4 and Au nanoparticle (AuNP)-labeled cDNA that had been attached to its complementary DCF aptamer on Ti3+-O-TiO2/FeVO4|ITO. The addition of target-DCF detached AuNP-labeled cDNA from the electrode to recover the photocurrent, resulting in a "signal-on" PEC aptasensor that exhibited a 0.1-500-nM linear range and a detection limit of 0.069 nM for DCF, attributed to the excellent amplification of the proposed aptasensing platform.


Asunto(s)
Antiinflamatorios no Esteroideos/análisis , Diclofenaco/análisis , Técnicas Electroquímicas/instrumentación , Hierro/química , Procesos Fotoquímicos , Titanio/química , Vanadatos/química , Técnicas Biosensibles/instrumentación , Oro/química , Límite de Detección , Nanopartículas del Metal/química , Propiedades de Superficie
9.
Mikrochim Acta ; 187(11): 588, 2020 10 05.
Artículo en Inglés | MEDLINE | ID: mdl-33015730

RESUMEN

Nanofabricated gold nanoparticles (Au-NPs) on MoS2 nanosheets (Au-NPs/MoS2) in back-gated field-effect transistor (BG-FET) are presented, which acts as an efficient semiconductor device for detecting a low concentration of C-reactive protein (C-RP). The decorated nanomaterials lead to an enhanced electron conduction layer on a 100-µm-sized transducing channel. The sensing surface was characterized by Raman spectroscopy, ultraviolet-visible spectroscopy (UV-Vis), atomic force microscopy (AFM), scanning electron microscopy (SEM), and high-power microscopy (HPM). The BG-FET device exhibits an excellent limit of detection of 8.38 fg/mL and a sensitivity of 176 nA/g·mL-1. The current study with Au-NPs/MoS2 BG-FET displays a new potential biosensing technology; especially for integration into complementary metal oxide (CMOS) technology for hand-held future device application.


Asunto(s)
Proteína C-Reactiva/análisis , Nanopartículas del Metal/química , Nanocompuestos/química , Transistores Electrónicos , Anticuerpos Inmovilizados/inmunología , Técnicas Biosensibles/instrumentación , Técnicas Biosensibles/métodos , Proteína C-Reactiva/inmunología , Disulfuros/química , Conductividad Eléctrica , Técnicas Electroquímicas/instrumentación , Técnicas Electroquímicas/métodos , Oro/química , Humanos , Límite de Detección , Molibdeno/química , Reproducibilidad de los Resultados
10.
Mikrochim Acta ; 187(9): 517, 2020 08 26.
Artículo en Inglés | MEDLINE | ID: mdl-32851503

RESUMEN

For the first time a nickel foam electrode (NFE) is applied in the field of electrochemical vapor generation (EVG) to carry out the electrochemical vapor phase conversion of mercury. Systematical electrochemical and morphological research has demonstrated that the specific surface area of the NFE was several times larger than that of the metal/non-metal electrode with the same geometric size. At the same time, the 3D porous channel composed of multi-layer nickel wire ensures the full contact between reactant and interface. The evident enhancement of spectral signals on a Ni electrode (283%), compared with Pt (27%) and graphite (109%), confirmed that the NFE effectively enhances the yield of mercury reduction. The NFE exhibits low limit of detection (0.017 µg L-1) and a wide linear range (0.2-20 µg L-1) with recoveries of actual samples in the range 87.8-117% towards Hg2+. Although the NFE has no advantage in electronic transmission and catalytic performance, its excellent stability, especially anti-interference and other characteristics, is sufficient for the analysis of hazardous mercury in complex matrix including certified reference materials and real samples.


Asunto(s)
Técnicas Electroquímicas/métodos , Gases/análisis , Mercurio/análisis , Níquel/química , Técnicas Electroquímicas/instrumentación , Electrodos , Contaminación de Alimentos/análisis , Gases/química , Límite de Detección , Mercurio/química , Oryza/química , Oxidación-Reducción , Porosidad , Ríos/química , Té/química , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/química
11.
Mikrochim Acta ; 187(9): 500, 2020 08 16.
Artículo en Inglés | MEDLINE | ID: mdl-32803374

RESUMEN

A novel "signal-on" electrochemical aptasensor was developed for ultrasensitive and specific detection of BPA, using single-walled carbon nanotubes (SWCNT) as the electro-catalytic probe for further signal amplification. The multi-walled carbon nanotubes (MWCNT), amino-functionalized magnetite, and gold nanoparticles (NH2-Fe3O4/Au NPs) were applied first to modify the glassy carbon electrode (GCE) surface and to form a nanomaterial film with satisfactory conductive properties, stability, and biocompatibility. The BPA aptamer was then loaded onto the sensing platform by hybridization with complementary DNA (CDNA). In the presence of BPA it combines with the aptamer and the BPA-aptamer conjugate was released from the electrode;subsequently the added SWCNT and CDNA assembled quickly. Thus, the dual-amplification of the "signal-on" electrochemical aptasensor takes effect. The [Fe (CN)6]3-/4- redox probe signal (∆I) detected by DPV (differential pulse voltammetry) is proportional to the negative logarithm of BPA concentration between 10-19 M and 10-14 M. The detection limit is 0.08 aM. Importantly, the proposed biosensor represents a successful application for determination of BPA in human serum and lake water. Schematic representation of SWCNT-amplified "signal-on" electrochemical aptasensor for the detection of trace level of bisphenol A in human serum and lake water.


Asunto(s)
Aptámeros de Nucleótidos/química , Compuestos de Bencidrilo/sangre , Técnicas Biosensibles/métodos , Técnicas Electroquímicas/métodos , Nanotubos de Carbono/química , Fenoles/sangre , Secuencia de Bases , Técnicas Biosensibles/instrumentación , ADN/química , Técnicas Electroquímicas/instrumentación , Electrodos , Óxido Ferrosoférrico/química , Oro/química , Humanos , Ácidos Nucleicos Inmovilizados/química , Lagos/análisis , Límite de Detección , Nanopartículas del Metal/química , Reproducibilidad de los Resultados
12.
PLoS One ; 15(8): e0237583, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32804936

RESUMEN

Identification and quantification of plant flavonoids are critical to pharmacokinetic study and pharmaceutical quality control due to their distinct pharmacological functions. Here we report on a novel plant flavonoid electrochemical sensor for sensitive and selective detection of dihydromyricetin (DMY) based on double- layered membranes consisting of gold nanoparticles (Au) anchored on reduced graphene oxide (rGO) and molecularly imprinted polymers (MIPs) modified glassy carbon electrode (GCE). Both rGO-Au and MIPs membranes were directly formed on GCE via in-situ electrochemical reduction and polymerization processes step by step. The compositions, morphologies, and electrochemical properties of membranes were investigated with X-ray powder diffractometry (XRD), Fourier transform infrared spectrum (FTIR), Field emission scanning electron microscopy (FESEM) combined with various electrochemical methods. The fabricated electrochemical sensor labeled as GCE│rGO-Au/MIPs exhibited excellent performance in determining of DMY under optimal experimental conditions. A wide linear detection range (LDR) ranges from 2.0×10-8 to 1.0×10-4 M together with a low limit of detection (LOD) of 1.2×10-8 M (S/N = 3) were achieved. Moreover, the electrochemical sensor was employed to determine DMY in real samples with satisfactory results.


Asunto(s)
Carbono/química , Técnicas Electroquímicas/instrumentación , Flavonoides/análisis , Flavonoles/análisis , Grafito/química , Técnicas Biosensibles/métodos , Electrodos , Oro , Límite de Detección , Nanopartículas del Metal , Impresión Molecular , Extractos Vegetales/análisis , Polímeros/síntesis química , Polímeros/química , Espectroscopía Infrarroja por Transformada de Fourier , Difracción de Rayos X
13.
Nat Commun ; 11(1): 3743, 2020 07 27.
Artículo en Inglés | MEDLINE | ID: mdl-32719350

RESUMEN

Ions are ubiquitous biological regulators playing a key role for vital processes in animals and plants. The combined detection of ion concentration and real-time monitoring of small variations with respect to the resting conditions is a multiscale functionality providing important information on health states. This multiscale functionality is still an open challenge for current ion sensing approaches. Here we show multiscale real-time and high-sensitivity ion detection with complementary organic electrochemical transistors amplifiers. The ion-sensing amplifier integrates in the same device both selective ion-to-electron transduction and local signal amplification demonstrating a sensitivity larger than 2300 mV V-1 dec-1, which overcomes the fundamental limit. It provides both ion detection over a range of five orders of magnitude and real-time monitoring of variations two orders of magnitude lower than the detected concentration, viz. multiscale ion detection. The approach is generally applicable to several transistor technologies and opens opportunities for multifunctional enhanced bioelectronics.


Asunto(s)
Amplificadores Electrónicos , Sistemas de Computación , Técnicas Electroquímicas/instrumentación , Técnicas Electroquímicas/métodos , Iones/análisis , Compuestos Orgánicos/química , Transistores Electrónicos , Electricidad , Humanos , Iones/sangre , Potasio/análisis
14.
Biosens Bioelectron ; 162: 112273, 2020 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-32452396

RESUMEN

Cardiac arrhythmia and drug-induced cardiotoxicity seriously threaten the human life. To develop antiarrhythmic agents and prevent the drug-induced cardiotoxicity, it is demanded to explore the high-specificity and high-efficiency drug screening platforms for preclinical investigations. Here, a specific electromechanical integrated correlation (EMIC) model was established based on the synchronized signal recording of cardiomyocyte-based biosensing system. The cardiomyocyte-based biosensing system consists of an integrated electromechanical device and a synchronized recording instrument. By extracting the feature points and correlation information of both electrical and mechanical signals, the multi-parameters of EMIC are applied for the drug recognition, showing the good specificity to analyze the typical Na+, K+, Ca2+ channel blockers. Further, visualized analysis of EMIC parameters was performed using the extracted parameters of synchronized recording signals to present the drug specific recognition functions. By heat map, radar map, and principal component analysis (PCA), the specific features and patterns were intuitively displayed to achieve the drug recognition. We believe this high-content and high-specific drug recognition strategy will be a promising and alternative method for the preclinical screening of cardiac safety and drug development in biomedical fields.


Asunto(s)
Evaluación Preclínica de Medicamentos/instrumentación , Técnicas Electroquímicas/instrumentación , Canales Iónicos/antagonistas & inhibidores , Miocitos Cardíacos/efectos de los fármacos , Técnicas Biosensibles/instrumentación , Línea Celular , Diseño de Equipo , Humanos , Canales Iónicos/metabolismo , Miocitos Cardíacos/metabolismo
15.
Langmuir ; 36(16): 4272-4279, 2020 04 28.
Artículo en Inglés | MEDLINE | ID: mdl-32239946

RESUMEN

The available active surface area and the density of probes immobilized on this surface are responsible for achieving high specificity and sensitivity in electrochemical biosensors that detect biologically relevant molecules, including DNA. Here, we report the design of gold-coated, silicon micropillar-structured electrodes functionalized with modified poly-l-lysine (PLL) as an adhesion layer to concomitantly assess the increase in sensitivity with the increase of the electrochemical area and control over the probe density. By systematically reducing the center-to-center distance between the pillars (pitch), denser micropillar arrays were formed at the electrode, resulting in a larger sensing area. Azido-modified peptide nucleic acid (PNA) probes were click-reacted onto the electrode interface, exploiting PLL with appended oligo(ethylene glycol) (OEG) and dibenzocyclooctyne (DBCO) moieties (PLL-OEG-DBCO) for antifouling and probe binding properties, respectively. The selective electrochemical sandwich assay formation, composed of consecutive hybridization steps of the target complementary DNA (cDNA) and reporter DNA modified with the electroactive ferrocene functionality (rDNA-Fc), was monitored by quartz crystal microbalance. The DNA detection performance of micropillared electrodes with different pitches was evaluated by quantifying the cyclic voltammetric response of the surface-confined rDNA-Fc. By decrease of the pitch of the pillar array, the area of the electrode was enhanced by up to a factor 10.6. A comparison of the electrochemical data with the geometrical area of the pillared electrodes confirmed the validity of the increased sensitivity of the DNA detection by the design of the micropillar array.


Asunto(s)
ADN/análisis , Ácidos Nucleicos Inmovilizados/química , Ácidos Nucleicos de Péptidos/química , Técnicas Biosensibles/instrumentación , Técnicas Biosensibles/métodos , ADN/genética , Técnicas Electroquímicas/instrumentación , Técnicas Electroquímicas/métodos , Electrodos , Oro/química , Ácidos Nucleicos Inmovilizados/genética , Hibridación de Ácido Nucleico , Ácidos Nucleicos de Péptidos/genética , Polilisina/química , Silicio/química
16.
Anal Chim Acta ; 1108: 98-107, 2020 Apr 29.
Artículo en Inglés | MEDLINE | ID: mdl-32222249

RESUMEN

The electrocatalytic properties of tetra L-Methionine cobalt (II) phthalocyanine (CoTL-MethPc) and functionalized MWCNTs, decorated on glassy carbon electrode (GCE) was investigated. The synthesis of the CoTL-MethPc was confirmed using UV-Vis, FT-IR, XRD, TGA and MASS techniques. Successful modification of GCE with the CoTL-MethPc and their composite was also confirmed using cyclic voltammetry (CVs), differential pulse voltammetry (DPV) and chrono-amperometry (CA) techniques. CoTL-MethPc/MWCNTs/GCE was the best electrode towards nitrite and hydrogen peroxide (H2O2) detection with a very low detection limit (30 and 10 nmol L-1) by CVs method, which compared favorably with literature, good sensitivity, electrocatalytic oxidation of nitrite and hydrogen peroxide on CoTL-MethPc/MWCNTs/GCE electrode was diffusion controlled but characterized with some adsorption of electro-oxidation-reduction reaction intermediates products. The fabricated sensors are easy to prepare, cost-effective and can be applied for real sample analysis of nitrite in beetroot vegetable. The excellent electrocatalytic property of CoTL-MethPc/MWCNTs is high reproducibility, repeatability, selectivity.


Asunto(s)
Complejos de Coordinación/química , Peróxido de Hidrógeno/análisis , Nanotubos de Carbono/química , Nitritos/análisis , Beta vulgaris/química , Cobalto/química , Complejos de Coordinación/síntesis química , Técnicas Electroquímicas/instrumentación , Técnicas Electroquímicas/métodos , Electrodos , Peróxido de Hidrógeno/química , Indoles/síntesis química , Indoles/química , Isoindoles , Límite de Detección , Metionina/análogos & derivados , Metionina/síntesis química , Nitritos/química , Oxidación-Reducción , Reproducibilidad de los Resultados
17.
Food Chem ; 314: 126168, 2020 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-31951889

RESUMEN

In this work, a kinetic model for protein extraction from Camellia oleifera seed cake using high voltage electrical discharge extraction (HVED) was built with discharge energy inputs as primary variables. The results showed that both the equilibrium yields and the mass transfer coefficient of HVED were highly dependent on the HVED specific energy input per pulse (kJ/kg). After linear and nonlinear fitting with five different basic functions, the best model satisfied the power function relationship through optimizing the influence of specific energy input per pulse on the equilibrium yields and the mass transfer coefficients. Based on the observations, a predictive model that correlates the energy input, mass of raw material and kinetics of HVED extraction was proposed. The validity of the predictive model was verified, and the observed deviation was found to be less than 10%. This could provide a model basis for optimization of HVED at different processing capacities.


Asunto(s)
Camellia/química , Fraccionamiento Químico/métodos , Técnicas Electroquímicas/métodos , Extractos Vegetales/aislamiento & purificación , Fraccionamiento Químico/instrumentación , Técnicas Electroquímicas/instrumentación , Diseño de Equipo , Cinética , Modelos Teóricos , Extractos Vegetales/química , Proteínas de Plantas/aislamiento & purificación , Reproducibilidad de los Resultados , Semillas/química
18.
Anal Chim Acta ; 1095: 197-203, 2020 Jan 25.
Artículo en Inglés | MEDLINE | ID: mdl-31864622

RESUMEN

Black phosphorus (BP) has a high charge-carrier mobility (∼1000 cm2 V-1 s-1), but the bare BP degrades rapidly in the presence of oxygen and water which limits the application of the BP. In this study, a simple, non-covalent passivation strategy is developed by modifying of the BP with hexamethylendiamine (HA). The functionalized BP exhibits good stability over 4 weeks. The organic phase interdigital electrode which is constructed by stable HA/BP and tyrosinase displays lowest noise signal (0.025 nA) and relatively low detection limit (10 nmol L-1) for bisphenol A. This work provides a new strategy for construction of novel biofuel cell, bioelectronics and biosensors.


Asunto(s)
Compuestos de Bencidrilo/análisis , Técnicas Biosensibles/métodos , Disruptores Endocrinos/análisis , Monofenol Monooxigenasa/química , Fenoles/análisis , Fósforo/química , Compuestos de Bencidrilo/química , Benzoquinonas/química , Diaminas/química , Técnicas Electroquímicas/instrumentación , Técnicas Electroquímicas/métodos , Electrodos , Disruptores Endocrinos/química , Enzimas Inmovilizadas/química , Límite de Detección , Fenoles/química , Reproducibilidad de los Resultados
19.
Anal Chim Acta ; 1095: 61-70, 2020 Jan 25.
Artículo en Inglés | MEDLINE | ID: mdl-31864631

RESUMEN

Tuning the electrocatalytic properties of high surface area porous metallic frameworks like Nanoporous Gold (NPG) by tailoring the structure is a convenient strategy to design electrochemical sensors. Accordingly, an NPG-based sensitive, selective and robust electroanalytical platform was designed for the detection of ascorbic acid (AA) in acidic extracts of Aspergillus fumigatus fungus and Arabidopsis thaliana leaves. NPG films were electrodeposited on a gold microelectrode by potentiostatic electrodeposition and characterized by electron microscopy techniques, which confirmed the morphology and highly porous structure resembling nanowires-type pure gold fractals. The electrodeposition parameters, particularly deposition potential and time, were optimized to achieve large and selective amperometric detection of AA on the NPG modified electrodes. Faster electron transfer kinetics was manifested on the 0.3 V shift in overpotential and remarkable enhancement of the oxidation peak current as compared with bare gold electrode. Amperometric measurements were performed at 0.3 V vs. Ag/AgCl(sat. KCl) in the highly acidic electrolyte solution employed to extract ascorbate from biological samples and minimize its autoxidation. The sensitivity of conventional Au-microelectrodes was increased about one thousand-fold upon modification with NPG film, reaching 2 nA µmol-1 L-1. The detection limit for AA based on a linear current-concentration calibration plot was found to be 2 µmol L-1. The NPG-based microsensor was demonstrated to be selective, reproducible and stable, and was employed for determinations of AA concentration in highly acidic biological extracts.


Asunto(s)
Ácido Ascórbico/análisis , Técnicas Electroquímicas/métodos , Oro/química , Nanocables/química , Arabidopsis/química , Ácido Ascórbico/química , Aspergillus fumigatus/química , Técnicas Electroquímicas/instrumentación , Concentración de Iones de Hidrógeno , Límite de Detección , Microelectrodos , Nanoporos , Oxidación-Reducción , Extractos Vegetales/análisis , Hojas de la Planta/química , Porosidad , Reproducibilidad de los Resultados
20.
Anal Bioanal Chem ; 412(21): 5031-5041, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-31745609

RESUMEN

This paper reports a simple electrochemical strategy for the determination of microRNAs (miRNAs) using a commercial His-Tag-Zinc finger protein (His-Tag-ZFP) that binds preferably (but non-sequence specifically) RNA hybrids over ssRNAs, ssDNAs, and dsDNAs. The strategy involves the use of magnetic beads (His-Tag-Isolation-MBs) as solid support to capture the conjugate formed in homogenous solution between His-Tag-ZFP and the dsRNA homohybrid formed between the target miRNA (miR-21 selected as a model) and a biotinylated synthetic complementary RNA detector probe (b-RNA-Dp) further conjugated with a streptavidin-horseradish peroxidase (Strep-HRP) conjugate. The electrochemical detection is carried out by amperometry at disposable screen-printed carbon electrodes (SPCEs) (- 0.20 V vs Ag pseudo-reference electrode) upon magnetic capture of the resultant magnetic bioconjugates and H2O2 addition in the presence of hydroquinone (HQ). The as-prepared biosensor exhibits a dynamic concentration range from 3.0 to 100 nM and a detection limit (LOD) of 0.91 nM for miR-21 in just ~ 2 h. An acceptable discrimination was achieved between the target miRNA and other non-target nucleic acids (ssDNA, dsDNA, ssRNA, DNA-RNA, miR-122, miR-205, and single central- or terminal-base mismatched sequences). The biosensor was applied to the analysis of miR-21 from total RNA (RNAt) extracted from epithelial non-tumorigenic and adenocarcinoma breast cells without target amplification, pre-concentration, or reverse transcription steps. The versatility of the methodology due to the ZFP's non-sequence-specific binding behavior makes it easily extendable to determine any target RNA only by modifying the biotinylated detector probe.


Asunto(s)
Técnicas Biosensibles/instrumentación , Técnicas Electroquímicas/instrumentación , MicroARNs/análisis , Dedos de Zinc , Línea Celular , Línea Celular Tumoral , Humanos , Límite de Detección
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