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1.
Small ; 18(10): e2105880, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34989480

RESUMO

Glyconanoparticles (GNPs) made by self-assembly of carbohydrate-based polystyrene-block-ß-cyclodextrin copolymer are used as a building block for the design of nanostructured biomaterials of electrode. The firm immobilization of GNPs is carried out on electrochemically generated polymer, poly(pyrrole-adamantane), and copolymer, poly(pyrrole-adamantane)/poly(pyrrole-lactobionamide) via host-guest interactions between adamantane and ß-cyclodextrin. The ability of GNPs for the specific anchoring of biological macromolecules is investigated using glucose oxidase enzyme modified by adamantane groups as a protein model (GOx-Ad). The immobilization of GOx-Ad is carried out by incubation of an aqueous enzyme solution on a coating of GNPs adsorbed on a platinum electrode. The presence of immobilized GOx-Ad is evaluated in aqueous glucose solution by potentiostating the underlying platinum electrode at 0.7 V/SCE for the electro-oxidation of H2 O2 generated by the enzyme. The analytical performance of the bioelectrodes for the detection of glucose is compared to control electrodes prepared without GNPs or without electropolymerized films. The better permeability of copolymer compared to polymer and the possibility to elaborate two alternating layers of GNPs and GOx-Ad are clearly observed. The best amperometric response is recorded with a multilayered bioelectrode displaying a wide linear range linear range of the calibration curve: 68 µmol L-1 to 0.1 mol L-1 .


Assuntos
Técnicas Biossensoriais , Nanopartículas , beta-Ciclodextrinas , Eletrodos , Enzimas Imobilizadas/química , Glucose/química , Glucose Oxidase/química , Nanopartículas/química , Pirróis/química , beta-Ciclodextrinas/química
2.
Anal Chim Acta ; 1221: 340095, 2022 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-35934344

RESUMO

This work designs a competitive consumption strategy of surface electron donor and light absorption for quenching the photocurrent of ZnSnO3 nanocubes/BiOI nanoarrays/polydopamine (ZnSnO3 NCs/BiOI NAs/PDA) as a photoactive material. This material can be formed on electrode surface by successive coating and deposition to provide a substrate for immobilization of capture antibody, and producing strong photocurrent in the presence of ascorbate acid as a surface electron donor due to the well matching structure of band gaps between ZnSnO3 NCs and BiOI NAs, the excellent light absorption ability and high photo-electron conversion efficiency of BiOI NAs and PDA, and the accelerated electron transfer. Using ascorbate oxidase loaded dopamine-melanin nanosphere (DAM-AAO) as a label of the signal (secondary) antibody, the sandwich-type immunoreaction leads to dual photocurrent quenching of the label through the competitive consumption of ascorbate acid with enzymatic oxidation and the light absorption by DAM nanosphere. Thus, a sensitive "On-Off" photoelectrochemical (PEC) immunosensing method is constructed for the analysis of neuron specific enolase (NSE). The proposed method shows a detection range of 0.1 pg/mL -50 ng/mL and a detection limit of 0.03 pg/mL. The excellent performance and the recovery text demonstrated the practicability of the designed strategy and label in immunoassay of different protein biomarkers.


Assuntos
Técnicas Biossensoriais , Técnicas Eletroquímicas , Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas/métodos , Eletrodos , Elétrons , Imunoensaio/métodos , Limite de Detecção
3.
Anal Chim Acta ; 1221: 340168, 2022 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-35934387

RESUMO

Targeting the long-term monitoring of biological carbohydrate metabolism, we developed a one-step screen-printing method to fabricate electrochemical sensors using an enzyme microparticle hybrid ink. Most enzymes have low stability in high temperatures and organic solvents, making conventional enzyme modification a bottom-up procedure to be performed after electrode fabrication, resulting in inactivation and detachment in long-term work. Enzyme-loaded microparticles prepared by manganese carbonate co-precipitation had higher stability than free enzymes, which could to be mixed directly with carbon paste for direct screen-printing. Due to the co-printing immobilization and the local hydration environment in enzyme particles, the prepared electrodes exhibited higher long-term operational stability than the conventional multi-step cross-linking method. In the sensing applications, we prepared microparticles loaded with single enzyme (glucose oxidase) and dual enzymes (ß-galactosidase and glucose oxidase) for glucose and lactose monitoring, respectively. Both electrodes can accurately measure the consumption of the corresponding carbohydrates throughout the cell or bacterial culture period thus providing a sensing platform for bio-metabolic monitoring and drug screening.


Assuntos
Técnicas Biossensoriais , Glucose Oxidase , Técnicas Biossensoriais/métodos , Eletrodos , Glucose , Glucose Oxidase/metabolismo , Tinta
4.
Anal Chim Acta ; 1221: 340173, 2022 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-35934389

RESUMO

The sequential enzyme biosensors hold significant importance in measuring species which are usually hard to process with single-enzyme-based biosensors. However, sequential enzyme electrodes experience critical issues such as low catalytic efficiency, insensitivity and poor reproducibility. In this work, yeast surface co-displaying sequential enzymes of glucoamylase (GA) and glucose oxidase (GOx) with controllable ratios through the specific cohesion-dockerin protein interaction was explored, by which starch hydrolyzing by GA into glucose is the rate-limiting step. The modified electrodes were prepared by immobilizing yeast-GA&GOx whole-cell and reduced graphene oxide (RGO) on glassy carbon electrode (GCE), for which the direct electron transfer between the electrode and recombinant GOx was arrived. Interestingly, the current responses of sensors to starch and glucose are dependent on the displayed enzyme composition, of which the yeast-GA&GOx (2:1) exhibited the highest current. Thereafter, sequential enzyme sensor of yeast-GA&GOx (2:1)/RGO/GCE was developed. Based on reduction detection at negative potential without interference, the sensor is stable and capable of assaying glucose (linear range: 2.0-100 mg/L) or starch (linear range, 50-3500 mg/L), separately. Coupled with yeast-GOx/RGO/GCE glucose sensor, both glucose and starch in real samples can be detected satisfactorily. This work provides new ideas for the development of other sequential enzyme electrodes for potential applications.


Assuntos
Técnicas Biossensoriais , Glucose Oxidase , Carbono/química , Técnicas Eletroquímicas , Eletrodos , Enzimas Imobilizadas/química , Glucana 1,4-alfa-Glucosidase/metabolismo , Glucose/metabolismo , Glucose Oxidase/química , Reprodutibilidade dos Testes , Saccharomyces cerevisiae , Amido
5.
Anal Chim Acta ; 1221: 340118, 2022 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-35934401

RESUMO

Considering the complexities and speed of modern food chains, there is an increasing demand for point-of-need detection of food contaminants, particularly highly regulated chemicals and carcinogens such as aflatoxin B1. We report a user-friendly smartphone-based magneto-immunosensor on carbon black modified electrodes for point-of-need detection of aflatoxin B1 in cereals. For buffered analyte solutions and a corn extract sample, the assay demonstrated a low limit of detection of 13 and 24 pg/mL, respectively. The assay was also highly reproducible, exhibiting mean relative standard deviations of 3.7% and 4.0% for the buffered analyte and corn extract samples. The applicability of the assay was validated on the basis of EU guidelines and the detection capability was lower than or equal to 2 µg/kg, which is the EU maximum residue limit for aflatoxin B1 in cereals. False-positive and false-negative rates were less than 5%. Additionally, an open-source android application, AflaESense, was designed to provide a simple interface that displays the result in a traffic-light-type format, thus minimizing user training and time for data analysis. AflaESense was used for smartphone-based screening of spiked corn samples containing aflatoxin B1 (0.1, 2, and 10 ng/mL), and naturally contaminated corn containing 0.15 ng aflatoxin B1/mL. The measured values were in close agreement with spiked concentrations (r2 = 0.99), with recovery values ranging between 80 and 120%. Finally, contaminated samples correctly triggered a red alert while the non-contaminated samples led to the display of a green color of AflaESense. To the best of our knowledge, this is the first smartphone-based electrochemical system effective for screening samples for contamination with aflatoxin B1.


Assuntos
Aflatoxina B1 , Técnicas Biossensoriais , Aflatoxina B1/análise , Grão Comestível/química , Eletrodos , Contaminação de Alimentos/análise , Imunoensaio , Extratos Vegetais/análise , Smartphone , Fuligem
6.
PLoS One ; 17(8): e0272586, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35925927

RESUMO

Control fabrication of metal-oxide nanocatalysts for electrochemical reactions has received considerable research attention. Here, manganese oxide (Mn3O4) nanorods modified indium tin oxide (ITO) electrodes were prepared based on the in-situ one-step hydrothermal methods. The nanorods were well characterized using field emission scanning electron microscopy, Fourier transform infrared, and X-ray diffraction spectroscopy. The results showed the formation of pure crystalline Mn3O4 nanorods with a length of approximately 1.4 µm and a thickness of approximately 100 ± 30 nm. The Mn3O4 nanorod-modified ITO electrodes were used for accelerating urea electrochemical oxidation at room temperature using cyclic and square wave voltammetry techniques. The results indicated that the modified electrode demonstrated excellent electrocatalytic performance toward urea electrooxidation in an alkaline medium over concentrations ranging from 0.2 to 4 mol/L. The modified electrode showed high durability, attaining more than 88% of its baseline performance after 150 cycles; furthermore, the chronoamperometry technique demonstrated high stability. Thus, the Mn3O4 nanorod-modified ITO electrode is a promising anode for direct urea fuel cell applications.


Assuntos
Técnicas Biossensoriais , Nanotubos , Eletrodos , Compostos de Manganês , Óxidos , Compostos de Estanho , Ureia
7.
Sci Rep ; 12(1): 13400, 2022 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-35927324

RESUMO

4-Methylcoumarin-7-yloxy-N-phenyl acetamide and 4-methylcoumarin-7-yloxy-N-4-nitrophenyl acetamide were synthesized and used as new ionophores in the carbon paste matrix to produce two novel potentiometric modified electrodes. The selectivity of the electrode changed from copper (II) to chromium (III) with the addition of a nitro group to the phenyl ring of the ionophore. The ionophores' tendency to ions was confirmed by UV-visible spectrophotometry. Both electrodes were modified by multi-walled carbon nanotubes (MWCNTs) as an excellent modifier of carbon paste electrode (CPE). The best sensor response in the case of copper (II) selective CPE was obtained by 5% ionophore, 65% graphite powder, 5% MWCNT, and 25% paraffin oil. In addition, in the case of chromium (III) selective CPE, these conditions are 20% ionophore, 50% graphite powder, 5% MWCNT, and 25% paraffin oil. The copper (II) selective CPE showed a Nernstian slope of 32.15 mV/decade within the concentration range of 1.0 × 10-10-1.0 × 10-1 mol L-1, while chromium (III) selective CPE showed a Nernstian slope of 19.28 mV/decade over the concentration range of 1.0 × 10-10-7.0 × 10-3 mol L-1. The electrodes have short response time of less than 5 s and were used successfully to determine copper (II) in wastewater and to speciation of chromium (III) and chromium (VI).


Assuntos
Grafite , Nanotubos de Carbono , Acetamidas , Cromo , Cobre , Eletrodos , Concentração de Íons de Hidrogênio , Ionóforos , Pós
8.
Neural Plast ; 2022: 7790730, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35941932

RESUMO

Transcranial direct current stimulation (tDCS) provides a way to modulate the cortical activity and promote motor rehabilitation following stroke. However, evidence indicates that the response to tDCS is highly variable. This study was aimed at exploring rhythmic response of Electroencephalography (EEG) to three tDCS protocols in stroke subjects. We hypothesize that tDCS protocols may interact with stoke characteristics, and electrode placement may affect cortical activity which could be reflected by the EEG rhythm. 32 subjects with unilateral stroke were recruited to a single-blinded, randomized, and controlled crossover experiment. All of the subjects underwent four tDCS protocols (anodal (atDCS), cathodal (ctDCS), and bilateral tDCS (bi-tDCS) and sham) with an interval of at least 1 week. Resting-state EEG was acquired before and after the stimulation. We tested the change of EEG spectral power after tDCS and the difference of change among four protocols using the paired-sample t-test and repeated measures analysis of variance. Then, we investigated the clinical factors affecting the above changes using the linear and quadratic regression model. According to the results, EEG responded to atDCS and bi-tDCS protocols on alpha and beta rhythm and subjects with a left lesion had higher response than those with the right lesion. Besides that, the change of alpha and beta power after atDCS and of beta power after bi-tDCS showed association with clinical characteristics only in subjects with the left lesion. In conclusion, the study found varied EEG response with different protocols, lesion hemispheres, and other clinical characteristics supporting the individualized cortical oscillatory effect induced by tDCS.


Assuntos
Reabilitação do Acidente Vascular Cerebral , Acidente Vascular Cerebral , Estimulação Transcraniana por Corrente Contínua , Estudos Cross-Over , Eletrodos , Eletroencefalografia/métodos , Humanos , Acidente Vascular Cerebral/terapia , Estimulação Transcraniana por Corrente Contínua/métodos , Extremidade Superior
9.
Anal Chim Acta ; 1221: 340120, 2022 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-35934402

RESUMO

Early and accurate diagnosis of SARS-CoV-2 was crucial for COVID-19 control and urgently required ultra-sensitive and rapid detection methods. CRISPR-based detection systems have great potential for rapid SARS-CoV-2 detection, but detecting ultra-low viral loads remains technically challenging. Here, we report an ultrasensitive CRISPR/Cas12a-based electrochemical detection system with an electrochemical biosensor, dubbed CRISPR-SPCE, in which the CRISPR ssDNA reporter was immobilized onto a screen-printed carbon electrode. Electrochemical signals are detected due to CRISPR cleavage, giving enhanced detection sensitivity. CRISPR-SPCE enables ultrasensitive SARS-CoV-2 detection, reaching as few as 0.27 copies µL-1. Moreover, CRISPR-SPCE is also highly specific and inexpensive, providing a fast and simple SARS-CoV-2 assay.


Assuntos
Técnicas Biossensoriais , COVID-19 , Técnicas Biossensoriais/métodos , COVID-19/diagnóstico , Teste para COVID-19 , Carbono , Eletrodos , Humanos , SARS-CoV-2/genética , Sensibilidade e Especificidade
10.
PLoS One ; 17(8): e0271075, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35944028

RESUMO

Tetracycline (TC) is widely-used antibiotic pollutant with high toxicity, refractory, persistence and bacteriostasis, and its removal from water needs to be enhanced. In this work, a novel Graphite-UiO-66(Zr)/Ti electrode was successfully prepared and evaluated for electrochemical oxidation degradation of TC. The electrochemical performance tests indicate the Graphite-UiO-66(Zr)/Ti electrode had higher electrochemical oxidation activity, which achieved higher TC removal efficiency (98.1% ± 1.5%) than Ti plate (65.2% ± 3.5%), Graphite-MIL-53(Al)/Ti electrode (79.5% ± 2.9%) and Graphite-MIL-100(Fe)/Ti electrode (89.0% ± 2.6%). The influence of operating condition was also systematically studied, and the optimized condition was pH 5.0, 20 mA/cm2 current density and 0.1 M electrolyte (Na2SO4). Through the liquid chromatography mass spectrometry (LC-MS), the TC degradation pathway by Graphite-UiO-66(Zr)/Ti electrode oxidation was proposed. Under the •OH free radical oxidative decomposition effect, the double bond, phenolic group and amine group of TC were attacked. TC was transformed into intermediate product ① (m/z = 447), then was further degraded to intermediates ② (m/z = 401) and ③ (m/z = 417). The latter was fragmented into small fractions ④ (m/z = 194), ⑤but-2-enedioic acid (m/z = 116) and ⑥oxalic acid (m/z = 90, the proposed intermediate). In addition, TC removal remained at 89.6% ± 2.7% in the sixth cycle of operation, which confirmed the efficient reusability and stability for antibiotics removal from water.


Assuntos
Grafite , Poluentes Químicos da Água , Antibacterianos/análise , Eletrodos , Grafite/química , Estruturas Metalorgânicas , Oxirredução , Ácidos Ftálicos , Tetraciclina/análise , Titânio/química , Água , Poluentes Químicos da Água/análise
11.
ACS Appl Mater Interfaces ; 14(31): 35809-35821, 2022 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-35912639

RESUMO

Microbial fuel cells (MFCs) are promising ecofriendly techniques for harvesting bioenergy from organic and inorganic matter. Currently, it is challenging to design MFC anodes with favorable microorganism attachment and fast extracellular electron transfer (EET) rate for high MFC performance. Here we prepared N-doped carbon nanotubes (NCNTs) on carbon felt (CF) and used it as a support for growing hierarchical Co8FeS8-FeCo2O4/NCNTs core-shell nanostructures (FeCo/NCNTs@CF). We observed improved wettability, specific areal capacitance, and diffusion coefficient, as well as small charge transfer resistance compared with bare CF. MFCs equipped with FeCo/NCNTs@CF displayed a power density of 3.04 W/m2 and COD removal amount of 221.0 mg/L/d, about 47.6 and 290.1% improvements compared with that of CF. Biofilm morphology and 16s rRNA gene sequence analysis proved that our anode facilitated the enrichment growth of exoelectrogens. Flavin secretion was also promoted on our hierarchical elelctrode, effectively driving the EET process. This work disclosed that hierarchical nanomaterials modified electrode with tailored physicochemical properties is a promising platform to simultaneously enhance exoelectrogen attachment and EET efficiency for MFCs.


Assuntos
Fontes de Energia Bioelétrica , Nanotubos de Carbono , Eletricidade , Eletrodos , Transporte de Elétrons , Nanotubos de Carbono/química , RNA Ribossômico 16S
12.
Mikrochim Acta ; 189(8): 307, 2022 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-35917034

RESUMO

The study aimed to develop an electrochemical sensor based on glassy carbon, mixed oxide (SiO2/TiO2/Sb2O5), and carbon black. The material was synthesized, characterized, and used to determine thiamethoxam in raw honey and water. The morphologic structure and electrochemical performance of the sensor was characterized by scanning electron microscopy and cyclic voltammetry. Differential pulse voltammetry with a concentration of 0.1 mol L-1 of Britton-Robinson buffer at pH 7.0 allowed the generation of a method to determine thiamethoxam in a linear range of 0.25 to 100.5 µmol L-1 and with a limit of detection of 0.012 µmol L-1. The system efficiently quantified traces of thiamethoxam in raw honey and tap water samples. The modified sensor did not present interferences of K+, Na+, Ca2+, Mg2+, glyphosate, imidacloprid, and carbendazim. In addition, the device showed good recovery values for thiamethoxam when applied directly to honey and water samples without any treatment, presenting an electrochemical sensor to monitor real-time hazardous substances in environmental and food matrices.


Assuntos
Mel , Óxidos , Técnicas Eletroquímicas/métodos , Eletrodos , Limite de Detecção , Óxidos/química , Dióxido de Silício , Fuligem , Tiametoxam , Titânio , Água
13.
Proc Natl Acad Sci U S A ; 119(33): e2203287119, 2022 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-35939711

RESUMO

Electrical neuron stimulation holds promise for treating chronic neurological disorders, including spinal cord injury, epilepsy, and Parkinson's disease. The implementation of ultrathin, flexible electrodes that can offer noninvasive attachment to soft neural tissues is a breakthrough for timely, continuous, programable, and spatial stimulations. With strict flexibility requirements in neural implanted stimulations, the use of conventional thick and bulky packages is no longer applicable, posing major technical issues such as short device lifetime and long-term stability. We introduce herein a concept of long-lived flexible neural electrodes using silicon carbide (SiC) nanomembranes as a faradic interface and thermal oxide thin films as an electrical barrier layer. The SiC nanomembranes were developed using a chemical vapor deposition (CVD) process at the wafer level, and thermal oxide was grown using a high-quality wet oxidation technique. The proposed material developments are highly scalable and compatible with MEMS technologies, facilitating the mass production of long-lived implanted bioelectrodes. Our experimental results showed excellent stability of the SiC/silicon dioxide (SiO2) bioelectronic system that can potentially last for several decades with well-maintained electronic properties in biofluid environments. We demonstrated the capability of the proposed material system for peripheral nerve stimulation in an animal model, showing muscle contraction responses comparable to those of a standard non-implanted nerve stimulation device. The design concept, scalable fabrication approach, and multimodal functionalities of SiC/SiO2 flexible electronics offer an exciting possibility for fundamental neuroscience studies, as well as for neural stimulation-based therapies.


Assuntos
Semicondutores , Dióxido de Silício , Animais , Eletrodos , Neurotransmissores , Óxidos , Dióxido de Silício/química
14.
Chempluschem ; 87(8): e202200165, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35943176

RESUMO

Homovanillate (HVA) and vanilmandelate (VMA) are recognized markers of diseases, including neuroblastoma. However, their detection in urine represents a challenging task due to the complexity of the matrix. Here, a design, synthesis and thorough investigation of polymerizable urea-based receptors interacting with HVA and VMA are reported. The selection of receptor with the best anion recognition properties for electrode coating is based on 1 H-NMR and UV-Vis complexation studies. The sensor is prepared by electropolymerization with progress monitoring by cyclic voltammetry. The deposited layer is characterized by IR and scanning electron microscopy. The obtained sensor shows an electrochemical impedance spectroscopy response to VMA with linear range 9.9×10-6 to 1.2×10-3  M and LOD of 3.4×10-6  M. The sensor selectivity was demonstrated by the determination of VMA level in the presence of 16 µM HVA and in artificial urine with and without phosphates, with standard deviations of 0.11, 0.17 and 0.09, respectively.


Assuntos
Neuroblastoma , Eletrodos , Humanos , Neuroblastoma/diagnóstico , Neuroblastoma/urina
15.
Mikrochim Acta ; 189(8): 303, 2022 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-35915284

RESUMO

A self-powered photoelectrochemical (PEC) aptasensor was constructed to sensitively detect 17ß-estradiol (E2). Firstly, a reasonable AgInS2@Co/Ni-UiO-66@Carbon Nanodots (CDs) photoelectrode with excellent photoelectrochemical performance was built by a simple two-step preparation method. The Co and Ni doping markedly improved the activity of UiO-66; the matched energy level of AgInS2 and Co/Ni-UiO-66 promoted the separation of electron-hole pairs, and the coupling of CDs further enhanced the conductivity and light utilization. Therefore, a steady anode-photocurrent signal output was obtained in 0.0 V bias voltage, providing a reliable photoelectric translating platform for assembling a self-powered PEC aptasensor. The E2-aptamer was adopted as a recognition unit to enhance the selectivity and sensitivity of the proposed aptasensor. The specific recognition reaction between E2 and aptamer administering to a raised photocurrent signal and the concentration of E2 was quantified by counting the fluctuation of the anode-photocurrent signal. The linear response range of the PEC aptasensor was 1.0 × 10-5-10 nmol/L, and the detection limit (S/N = 3) was lower than 3.0 fmol/L under optimal conditions. The fabricated aptasensor exhibited admirable selectivity, high sensitivity, rapid response, and wide linear range, demonstrating an extensive application prospect for environmental endocrine disruptor detection.


Assuntos
Aptâmeros de Nucleotídeos , Disruptores Endócrinos , Ácidos Ftálicos , Eletrodos , Disruptores Endócrinos/análise , Estruturas Metalorgânicas
16.
Zhongguo Yi Liao Qi Xie Za Zhi ; 46(4): 404-407, 2022 Jul 30.
Artigo em Chinês | MEDLINE | ID: mdl-35929155

RESUMO

This study introduces a portable multi-channel EEG signal acquisition system. The system is mainly composed of EEG electrode connector, signal conditioning circuit, EEG acquisition part, main control MCU and power supply part. The low-power EEG acquisition front-end ADS1299 and STM32 are used to form the signal acquisition and data communication part. The collected EEG signal can be transmitted to the PC for real-time display. After relevant tests, the system has small volume, low power consumption, high signal-to-noise ratio, and meets the requirements of portable wearable medical devices.


Assuntos
Fontes de Energia Elétrica , Eletroencefalografia , Eletrodos , Processamento de Sinais Assistido por Computador , Razão Sinal-Ruído
17.
Mikrochim Acta ; 189(9): 326, 2022 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-35948696

RESUMO

In a new approach, we considered the special affinity between Ni and poly-histidine tags of recombinant urate oxidase to utilize Ni-MOF for immobilizing the enzyme. In this study, a carbon paste electrode (CPE) was modified by histidine-tailed urate oxidase (H-UOX) and nickel-metal-organic framework (Ni-MOF) to construct H-UOX/Ni-MOF/CPE, which is a rapid, sensitive, and simple electrochemical biosensor for UA detection. The use of carboxy-terminal histidine-tailed urate oxidase in the construction of the electrode allows the urate oxidase enzyme to be positioned correctly in the electrode. This, in turn, enhances the efficiency of the biosensor. Characterization was carried out by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), and field emission scanning electron microscopy (FE-SEM). At optimum conditions, the biosensor provided a short response time, linear response within 0.3-10 µM and 10-140 µM for UA with a detection limit of 0.084 µM, repeatability of 3.06%, and reproducibility of 4.9%. Furthermore, the biosensor revealed acceptable stability and selectivity of UA detection in the presence of the commonly coexisted ascorbic acid, dopamine, L-cysteine, urea, and glucose. The detection potential was at 0.4 V vs. Ag/AgCl.


Assuntos
Técnicas Biossensoriais , Urato Oxidase , Técnicas Biossensoriais/métodos , Carbono/química , Eletrodos , Enzimas Imobilizadas/química , Histidina , Reprodutibilidade dos Testes , Urato Oxidase/química , Ácido Úrico
18.
J Vis Exp ; (185)2022 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-35913135

RESUMO

Ex vivo preparations enable the study of many neurophysiological processes in isolation from the rest of the body while preserving local tissue structure. This work describes the preparation of rat sciatic nerves for ex vivo neurophysiology, including buffer preparation, animal procedures, equipment setup and neurophysiological recording. This work provides an overview of the different types of experiments possible with this method. The outlined method aims to provide 6 h of stimulation and recording on extracted peripheral nerve tissue in tightly controlled conditions for optimal consistency in results. Results obtained using this method are A-fibre compound action potentials (CAP) with peak-to-peak amplitudes in the millivolt range over the entire duration of the experiment. CAP amplitudes and shapes are consistent and reliable, making them useful to test and compare new electrodes to existing models, or the effects of interventions on the tissue, such as the use of chemicals, surgical alterations, or neuromodulatory stimulation techniques. Both conventional commercially available cuff electrodes with platinum-iridium contacts and custom-made conductive elastomer electrodes were tested and gave similar results in terms of nerve stimulus strength-duration response.


Assuntos
Neurofisiologia , Nervo Isquiático , Potenciais de Ação/fisiologia , Animais , Condutividade Elétrica , Estimulação Elétrica/métodos , Eletrodos , Neurofisiologia/métodos , Ratos , Nervo Isquiático/fisiologia
19.
J Vis Exp ; (185)2022 07 22.
Artigo em Inglês | MEDLINE | ID: mdl-35938793

RESUMO

Wearable electronic devices are becoming key players in monitoring the body signals predominantly altered during physical activity tracking. Considering the growing interest in telemedicine and personalized care driven by the rise of the Internet of Things era, wearable sensors have expanded their field of application into healthcare. To ensure the collection of clinically relevant data, these devices need to establish conformable interfaces with the human body to provide high-signal-quality recordings and long-term operation. To this end, this paper presents a method to easily fabricate conformable thin tattoo- and soft textile-based sensors for their application as wearable organic electronic devices in a broad spectrum of surface electrophysiological recordings. The sensors are developed through a cost-effective and scalable process of cutaneous electrode patterning using poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), the most popular conductive polymer in bioelectronics, on off-the-shelf, wearable substrates. This paper presents key steps in electrode characterization through impedance spectroscopy to investigate their performance in signal transduction when coupled with the skin. Comparative studies are required to position the performance of novel sensors with respect to the clinical gold standard. To validate the fabricated sensors' performance, this protocol shows how to perform various biosignal recordings from different configurations through a user-friendly and portable electronic setup in a laboratory environment. This methods paper will allow multiple experimental initiatives to advance the current state of the art in wearable sensors for human body health monitoring.


Assuntos
Dispositivos Eletrônicos Vestíveis , Espectroscopia Dielétrica , Eletrodos , Humanos , Polímeros/química , Têxteis
20.
ACS Appl Mater Interfaces ; 14(27): 31455-31462, 2022 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-35776164

RESUMO

Flexible, fully printed immunosensors can meet the requirements of precision nutrition, but this demands optimized molecular architectures to reach the necessary sensitivity. Herein, we report on flexible and label-free immunosensor chips made with tree-like gold dendrites (AuDdrites) electrochemically formed by selective desorption of l-cysteine (L-cys) on (111) gold planes. Electrodeposition was used because it is scalable and cost-effective for a rapid, direct growth of Au hyperbranched dendritic structures. The 25-hydroxyvitamin D3 (25(OH)D3) metabolite was detected within 15 min with a limit of detection (LOD) of 0.03 ng mL-1. This high performance was possible due to the careful optimization of the electroactive layer and working conditions for square wave voltammetry (SWV). Electrocrystallization was manipulated by controlling the deposition potential and the molar ratio between HAuCl4 and L-cys. Metabolite detection was performed on human serum and saliva samples with adequate recovery between 97% and 100%. The immunosensors were stable and reproducible, unresponsive to interference from other molecules in human serum and saliva. They can be extended for use as wearable sensors with their mechanical flexibility and possible customization.


Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , Calcifediol , Dendritos , Técnicas Eletroquímicas , Eletrodos , Ouro/química , Humanos , Imunoensaio , Limite de Detecção , Nanopartículas Metálicas/química
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