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1.
Spectrochim Acta A Mol Biomol Spectrosc ; 284: 121771, 2023 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-36027790

RESUMO

A highly sensitive and selective sensor for the quantitative assay of inorganic pyrophosphatase (PPase) activity was developed based on a fluorescence "turn-off" strategy. Carbon quantum dots@Cu(II)-based metal-organic framework nanotubes (CQDs@Cu-MOF) with length less than 300 nm and width less than 20 nm were synthesized. CQDs in the nanotubes exhibited weak fluorescence owing to static quenching. The coordination reaction between pyrophosphate ion (PPi) and Cu(II) decomposed CQDs@Cu-MOF and led to the release of CQDs, of which the fluorescence recovered. In the presence of PPase, the hydrolysis of PPi generated phosphate ion (Pi). CQDs@Cu-MOF remained their structural stability and the fluorescence turned off. The fluorescence intensity difference of the mixture of CQDs@Cu-MOF and PPi in the absence and presence of PPase (-ΔF) was proportional to the PPase concentration from 0.1 to 5 mU mL-1 and that from 5 to 50 mU mL-1, and a limit of detection at 0.03 mU mL-1 was obtained. PPase activity in human serum was analyzed using the proposed fluorescence sensor and the recovery values were found to vary from 95.0% to 104 %.


Assuntos
Estruturas Metalorgânicas , Nanotubos de Carbono , Pontos Quânticos , Carbono , Difosfatos , Fluorescência , Humanos , Pirofosfatase Inorgânica/metabolismo , Pirofosfatases/química , Pirofosfatases/metabolismo
2.
Food Chem ; 402: 134150, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36303374

RESUMO

In this work, a novel electrochemical aptasensor was designed for the sensitive and specific detection of STR in milk samples. First, a gold nanoparticle@poly(diallyldimethylammonium chloride) nitrogen-doped carbon nanotube/polyethyleneimine-functionalized metal-organic framework (MOF) (Au@P-N-CNT/PEI-MIL-101(Cr)) composite was synthesized and characterized by various technique. The Au@P-N-CNT/PEI-MIL-101(Cr) composite was then modified on a bare glassy carbon electrode (GCE) surface, providing a favorable platform (Au@P-N-CNT/PEI-MIL-101(Cr)/GCE) for aptamer immobilization and current signal amplification. The STR aptamer was grafted to the Au@P-N-CNT/PEI-MIL-101(Cr)/GCE through the formation of Au-S bonds and π-π stacking interactions. The immobilized STR aptamer binds specifically STR, resulting in an obvious decrease in the current signal. Under the optimal experimental conditions, the linear range of the electrochemical aptasensor for STR detection was 0.01-250 nM which the detection limit (LOD) was calculate as 2.31 nM. This strategy is expected to be a novel platform for the rapid and sensitive detection of STR.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Grafite , Nanopartículas Metálicas , Estruturas Metalorgânicas , Nanotubos de Carbono , Animais , Ouro/química , Nanotubos de Carbono/química , Estruturas Metalorgânicas/química , Aptâmeros de Nucleotídeos/química , Estreptomicina , Técnicas Eletroquímicas/métodos , Técnicas Biossensoriais/métodos , Leite , Grafite/química , Limite de Detecção , Nanopartículas Metálicas/química , Polietilenoimina/química
3.
Chemosphere ; 310: 136740, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36209852

RESUMO

The shortage of freshwater supplies has restricted societal development. Capacitive deionization (CDI) is an emerging technology for desalination of seawater or brackish water, the performance of which is highly dependent on electrode materials. In this work, a molybdenum disulfide/carbon nanotube composite (CNTs-b-MoS2) with high capacitance was successfully synthesized using a hydrothermal method. The composite exhibited a specific capacitance of 112.79 F g-1. To reduce costs and determine the practicality of using CNTs-b-MoS2 for CDI, we combined activated carbon (AC) with CNTs-b-MoS2 as a CDI electrode. The research demonstrated that after doping with 5% (mass ratio) CNTs-b-MoS2, the specific capacitance and electrosorption capacity of AC were significantly improved and the maximum desalination capacity of CNTs-b-MoS2/AC reached 8.19 mg g-1. The low dosage of CNTs-b-MoS2 combined with the high specific surface area of AC avoided the shortcomings of CNTs-b-MoS2, namely low specific surface area and high cost. Moreover, the outstanding conductivity of CNTs-b-MoS2 improved the conductivity and enhanced the adsorption capacity of AC, giving CNTs-b-MoS2/AC potential as an advanced, low-cost CDI electrode material.


Assuntos
Nanotubos de Carbono , Purificação da Água , Carvão Vegetal , Molibdênio , Purificação da Água/métodos , Eletrodos
4.
Chemosphere ; 310: 136771, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36241109

RESUMO

Electrified carbon nanotube membranes (ECM) are used as electroactive porous materials for the degradation of micropollutants. It integrated design of both electrochemical processes and filtration functions. In this study, CeO2 modified carbon nanotube electrified membrane (CeO2@CNT membrane) was prepared and activate NaClO towards degradation of antibiotics. As CeO2 with face-centered cubic (Fcc) fluorite structure was loaded onto the CNT sidewalls, the CeO2@CNT membrane showed a higher over potential and a smaller equivalent polarization resistance compared to ECM. More reactive oxygen species (ROS) and reactive chlorine species (RCS) were generated by CeO2@CNT membrane due to faster electron transfer at the solid-liquid interface. Thus, the removal efficiencies of DCF, SMX, CIP, TC and CBZ were more than 91.2%, 91.3%, 94.4%, 99.3% and 89.4% by the CeO2@CNT membrane with NaClO, respetively. And the apparent reaction rate constant (k) of the CeO2@CNT membrane was 2.9 times of that of ECM. The selective capping experiments and density functional theory (DFT) calculation showed that the oxygen vacancies of CeO2 contributed to the generation of ‧OH, and the generation of ClO‧ and ‧O2- would mainly occur on Lewis acid sites of CeO2. In addition, the CeO2@CNT membrane showed a reasonable stability to treat actual water samples and reduced disinfection byproducts (DBPs) formation, suggesting that it can potentially be combined with the conventional chlorine disinfection to degrade antibiotics in water.


Assuntos
Nanotubos de Carbono , Nanotubos de Carbono/química , Cloro , Antibacterianos/química , Filtração , Oxigênio , Água
5.
Food Chem ; 403: 134375, 2023 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-36162268

RESUMO

Trace detection of ochratoxin A (OTA) in foods is essential to mitigate risks to human health. Herein, a label-free electrochemical (EC) aptasensor based on dual-signal amplification of Nafion dispersed multi-walled carbon nanotubes (Nafion-MWCNTs) and Au nanopopcorns was developed for ultrasensitive detection of OTA. Nafion solution prevented the leaching of MWCNTs, and the Nafion-MWCNTs modified screen-printed carbon electrode (SPCE) acted as the sensing substrate which facilitated the uniform distribution of the electrodeposited Au nanopopcorns. The in-situ generated Au nanopopcorns could not only load a large amount of aptamers for specific identification of OTA, but also promote the electron transfer of the sensing platform. The incorporation of Nafion-MWCNTs and Au nanopopcorns realized dual-amplification of the aptasensor due to the enhanced conductivity and the increased electroactive surface area of the electrode. The modified electrodes were characterized through scanning electron microscopy, X-ray photoelectron spectroscopy and EC evaluation. Under optimal conditions, the electrochemical impedance spectroscopy (EIS) was measured for the determination of OTA. The as-fabricated Au nanopopcorns/Nafion-MWCNTs impedimetric aptasensor displayed excellent sensitivity with a detection limit as low as 1 pg/mL and a wide linear range of 1 pg/mL-10 ng/mL for OTA. Practical application of the aptasensor in the spiked malt samples achieved satisfactory recoveries of 89.82-95.65 %, which was also successfully verified to detect OTA in eleven batches of actual malt samples collected from the local market. The creative aptasensor is simple, cost-effective, sensitive, and accurate, showing great promise for on-site monitoring of other trace contaminants in foods by simply replacing the aptamers.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Nanotubos de Carbono , Ocratoxinas , Humanos , Aptâmeros de Nucleotídeos/química , Técnicas Eletroquímicas/métodos , Técnicas Biossensoriais/métodos , Ocratoxinas/análise , Eletrodos , Limite de Detecção
6.
Chemosphere ; 311(Pt 1): 136804, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36228723

RESUMO

Keeping the high potential of some microorganisms in adsorption of radionuclides in view, the adsorption properties of Enterobacter cloacae towards uranium were attentively scrutinized, and then it was used for preconcentration of uranium in different samples, using Enterobacter cloacae/carbon nanotube composite. First, using ultrasonic agitation, the effects of operational factors on biosorption of uranium on the inactive Enterobacter cloacae were appraised and modeled by central composite design, and a comprehensive study was performed on the equilibrium, kinetics, thermodynamic, and selectivity aspects of biosorption. The optimization studies along with the evaluations of the adsorption properties revealed that Enterobacter cloacae have a high affinity for fast and selective biosorption of uranium ions, at pH 5.1. Second, the Enterobacter cloacae/carbon nanotube was synthesized, characterized, and utilized for preconcentration of uranium in different samples, using a mini-column packed with the composite. The optimization of operational factors on recovery of uranium, using the central composite design, showed that uranium can be quantitively adsorbed at a sample flow rate lower than 4.5 mL min-1 and the desorption could be accomplished with 3.0 mL HCl 0.6 M solution. Finally, the mini-column was exploited for preconcentration and determination of uranium in different samples. The results revealed the low detection limit (0.015 µg.L-1), high precision (RSDs ≤3.92%), and good accuracy of the proposed procedure.


Assuntos
Nanotubos de Carbono , Urânio , Urânio/análise , Adsorção , Enterobacter cloacae , Íons , Cinética , Água , Concentração de Íons de Hidrogênio
7.
Chemosphere ; 311(Pt 1): 136925, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36283432

RESUMO

Antibiotic abuse will seriously affect the ecology and environment. Photocatalytic oxidation technology based on carbon nitride (g-C3N4) has been widely adopted to treat wastewater containing antibiotics. Here, a novel composite photocatalyst MCNT was prepared by loading manganese oxide (Mn3O4) on the surface of g-C3N4 nanotubes (CNT). Three typical antibiotics, trimethoprim (TMP), norfloxacin (NOR), and tetracycline (TC) were used as model contaminants to evaluate the oxidative properties of prepared materials. Compared with bulk g-C3N4, the degradation rates of TMP, NOR, and TC catalyzed by MCNT-5 were increased by 2, 3, and 1.4 times, respectively, mainly due to 1) the larger specific surface area of the nanotube structure of CNT, which provides abundant active sites for antibiotic adsorption and catalytic oxidation, and 2) the loading of Mn3O4, which promotes the directional migration of photogenerated charges and improves the separation efficiency of photogenerated electrons and holes. The free radical capture and quenching experiments confirmed that MCNT degraded the target organic pollutants with hydroxyl radical (·OH) and singlet oxygen (1O2) as the main active oxidants. This catalyst maintained 80% photocatalytic oxidation performance after five cyclic experiments. This study provides new insights into developing efficient, stable, and environmentally-friendly photocatalysts and provides a new dimension to mitigate the antibiotic pollution problem.


Assuntos
Nanotubos de Carbono , Antibacterianos/química , Água , Nitrilas/química , Catálise , Tetraciclina
8.
Sci Total Environ ; 856(Pt 1): 158810, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36162572

RESUMO

The application of carbon-based materials (CBMs) for heavy metal polluted soil remediation has gained growing interest due to their versatile properties and excellent remediation performance. Although the progresses on applications of CBMs in removing heavy metal from aqueous solution and their corresponding mechanisms were well known, comprehensive review on applications of CBMs in heavy metal polluted soil remediation were less identified. Therefore, this review provided insights into advanced progresses on utilization of typical CBMs including biochar, activated carbon, graphene, graphene oxide, carbon nanotubes, and carbon black for heavy metal polluted soil remediation. The mechanisms of CBM remediation of heavy metals in soil were summarized, mainly including physical adsorption, precipitation, complexation, electrostatic interaction, and cationic-π coordination. The key factors affecting the remediation effect include soil pH, organic matter, minerals, microorganisms, coexisting ions, moisture, and material size. Disadvantages of CBMs were also included, such as: potential health risks, high cost, and difficulty in achieving co-passivation of anions and cations. This work will contribute to our understanding of current research advances, challenges, and opportunities for CBMs remediation of heavy metal-contaminated soils.


Assuntos
Recuperação e Remediação Ambiental , Metais Pesados , Nanotubos de Carbono , Poluentes do Solo , Solo/química , Poluentes do Solo/análise , Metais Pesados/análise , Cátions
9.
Anal Biochem ; 660: 114971, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-36328214

RESUMO

Exosome is an emerging tumor marker, whose concentration level can reflect the occurrence and development of tumors. The development of rapid and sensitive exosome detection platform is of great significance for early warning of cancer occurrence. Here, a strategy for electrochemical detection of A549-cell-derived exosomes was established based on DNA/ferrocene-modified single-walled carbon nanotube complex (DNA/SWCNT-Fc). DNA/SWCNT-Fc complexes function as a signal amplification platform to promote electron transfer between electrochemical signal molecules and electrodes, thereby improving sensitivity. At the same time, the exosomes can be attached to DNA/SWCNT-Fc nanocomposites via the established PO43--Ti4+-PO43- method. Moreover, the application of EGFR antibody, which can specifically capture A549 exosomes, could improve the accuracy of this sensing system. Under optimal experimental conditions, the biosensor showed good linear relationship between the peak current and the logarithm of exosomes concentration from 4.66 × 106 to 9.32 × 109 exosomes/mL with a detection limit of 9.38 × 104 exosomes/mL. Furthermore, this strategy provides high selectivity for exosomes of different cancer cells, which can be applied to the detection of exosomes in serum samples. Thus, owing to its advantages of high sensitivity and good selectivity, this method provides a diversified platform for exosomes identification and has great potential in early diagnosis and biomedical applications.


Assuntos
Exossomos , Nanotubos de Carbono , Metalocenos , DNA
10.
Sci Total Environ ; 855: 158865, 2023 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-36165910

RESUMO

Glyphosate (GLY) is the most widely used non-selective broad-spectrum herbicide worldwide under well-reported side effects on the environment and human health. That's why it's necessary to control its presence in the environment. This work describes the development of an affordable, simple, and accurate electrochemical biosensor using a pencil graphite electrode as support, a horseradish peroxidase enzyme immobilized on a polysulfone membrane doped with multi-walled carbon nanotubes. The developed electrochemical sensor was used in the determination of GLY in river and drinking water samples. Cyclic voltammetry and amperometry were used as electrochemical detection techniques for the characterization and analytical application of the developed biosensor. The working mechanism of the biosensor is based on the inhibition of the peroxidase enzyme by GLY. Under optimal experimental conditions, the biosensor showed a linear response in the concentration range of 0.1 to 10 mg L-1. The limits of detection and quantification are 0.025 ± 0.002 and 0.084 ± 0.007 mg L-1, respectively, which covers the maximum residual limit established by the EPA for drinking water (0.7 mg L-1). The proposed biosensor demonstrated high reproducibility, excellent analytical performance, repeatability, and accuracy. The sensor proved to be selective against other pesticides, organic acids, and inorganic salts. Application on real samples showed recovery rates ranging between 98.18 ± 0.11 % and 97.32 ± 0.23 %. The analytical features of the proposed biosensor make it an effective and useful tool for the detection of GLY for environmental analysis.


Assuntos
Técnicas Biossensoriais , Água Potável , Grafite , Nanotubos de Carbono , Humanos , Grafite/química , Nanotubos de Carbono/química , Reprodutibilidade dos Testes , Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas/métodos , Eletrodos
11.
Talanta ; 252: 123838, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36027615

RESUMO

Aggregation of α-synuclein has been recognized as a critical event in the pathogenesis of Parkinson's disease whose prevalence is increasing with great socio-economic challenges for future generations. Here, we developed a sensitive and specific electrochemical immunosensor for the detection and quantification of this biomarker, based on the voltammetric study of a redox indicator signal, which decreases upon the analyte recognition by the antibody due to the electronic resistance increase. The proposed immunosensor is based on a screen-printed carbon electrode modified in a layer-by-layer approach, which through extensive characterization led to the successful nanostructuration of the transducer, through the drop-cast of 3.0 µL of a 0.1 mg mL-1 single-walled carbon nanotubes suspension followed by electrodeposition of gold nanoparticles in a 3 mM HAuCl4 solution under a -0.2 V potential for 150 s. Monoclonal antibodies were immobilized on the gold nanoparticles surface through chemical modification at an optimal concentration of 200 µg mL-1. Using the proposed immunosensor, α-synuclein was detected in the range of 0.01-10 ng mL-1 with a 4.1 and 12.6 pg mL-1 limits of detection and quantification, respectively. Recovery values of 96.7, 106.2 and 102.9% were attained for the tested concentrations spiked in fetal bovine serum while also presenting excellent specificity and stability throughout one month. The nanostructured immunosensor provided a great interface for electronic transduction and biological recognition events, which enabled fast, sensitive and specific detection of α-synuclein while being based on a simple and inexpensive technology requiring small sample volumes, crucial characteristics for application in point-of-care testing.


Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , Nanotubos de Carbono , Doença de Parkinson , Humanos , Ouro/química , alfa-Sinucleína , Nanopartículas Metálicas/química , Imunoensaio , Nanotubos de Carbono/química , Doença de Parkinson/diagnóstico , Eletrodos , Biomarcadores , Técnicas Eletroquímicas , Limite de Detecção
12.
Talanta ; 252: 123869, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36058197

RESUMO

In this study, nanoporous C was prepared from the roots, stems and leaves of liquorice and modified via element doping. Then, the nitrogen and sulfur co-doped liquorice carbon (N, S-LC) and functional multiwall carbon nanotubes (f-MWCNTs) were dispersed using an ultrasonic dispersion technology, and a binary nanocomposite was prepared. N, S-LC plays a key role in the formation and electrochemical efficiency of binary nanocomposites, and electrochemical impedance spectroscopy indicates that the binary complexes formed by the hybridisation of N, S-LC and f-MWCNTs can improve the electron transfer ability of an electrode. The electrochemical behaviour of Licochalcone A (LicA) and Liquiritin (LQ) on GCE modified by N, S-LC/f-MWCNTs binary nanocomposite was investigated via differential pulse voltammetry (DPV) and cyclic voltammetry (CV). The interpeak potential difference between LicA and LQ were 0.48 V. The calibration curves for LicA and LQ were obtained in the range of 0.4-70.0 µM and 0.1-150.0 µM, respectively, and the detection limits are 33 and 25 nM (S/N=3), respectively. The modified electrode has been successfully applied to the simultaneous determination of LicA and LQ in licorice with satisfactory recoveries as confirmed by HPLC method.


Assuntos
Glycyrrhiza , Nanocompostos , Nanotubos de Carbono , Nanotubos de Carbono/química , Técnicas Eletroquímicas/métodos , Nanocompostos/química , Eletrodos , Limite de Detecção
13.
Food Chem ; 404(Pt B): 134708, 2023 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-36323040

RESUMO

Metribuzin (MTZ) is an important herbicide widely used in fields and represents a big threat to the environment and health. Herein, an electrochemical sensor was designed for its detection in commercial product (Egyscor® 70%), spiked tomatoes and potatoes samples with recovery values ranging from 97.12 to 103.41%. Bulk-polymerized MTZ molecularly imprinted polymer (MIP) was developed, using itaconic acid (functional monomer), ethylene glycol dimethacrylate (cross-linker) at an optimum molar ratio 1:5:30, respectively. Differential pulse voltammetry was used to examine the optimization variables of the MIP based sensor such as the variation of (template: monomer: cross-linker) ratio, accumulation time, multi walled carbon nanotubes amount, pH and scan rate, while cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the sensor. The sensor showed selective adsorption ability and a good linearity over the concentration range of 0.2 ng/mL to 21.429 µg/mL, with LOD and LOQ of 0.1 pg/mL and 0.3 pg/mL, respectively.


Assuntos
Herbicidas , Impressão Molecular , Nanotubos de Carbono , Impressão Molecular/métodos , Nanotubos de Carbono/química , Polímeros/química , Técnicas Eletroquímicas/métodos , Limite de Detecção , Eletrodos
14.
J Pharm Biomed Anal ; 223: 115091, 2023 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-36356403

RESUMO

Naproxen sodium (NAP) and Sumatriptan (SUM) are pharmacological migraine therapies that are more efficient when administered in combination. In the present work, an electrochemical sensor was developed for simultaneous and sensitive NAP and SUM detection using MWCNTs decorated with ZnO, NiO and Fe3O4 nanoparticles on glassy carbon electrode (GCE). This report is the first research on simultaneous electrochemical measuring the target drugs based on the literature. The data show that modification of the GCE surface with ZnO/NiO/Fe3O4/MWCNTs nanocomposite remarkably improves the electro-oxidation peaks currents but the peaks potential of NAP and SUM have shifted to the lower potential which demonstrates that electro-oxidation of target drugs have done more easier than GCE at the surface of modified electrode. The nanocomposite was recognized by using Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FE-SEM), and X-ray diffraction (XRD). The improved electrode was estimated by various methods, including cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS) techniques. Influencing parameters containing the supporting electrolytes, pH, scan rate, deposition potential, and accumulation time were optimized. The linear detection ranges were from 4.00 nMto 350.00 µM for NAP and from 6.00 nM to 380.00 µM for SUM, with the detection limits of 3.00 nMfor NAP and 2.00 nM for SUM, respectively. The repeatability, linearity, and selectivity of ZnO/NiO/Fe3O4/MWCNTs/GCE were investigated, and the received outcomes divulged the efficiency of the electrode. The consequence of high-performance liquid chromatography (HPLC) and recovery show the method's suitability for the simultaneous determination of NAP and SUM in the biological fluids and pharmaceutical compounds.


Assuntos
Nanocompostos , Nanotubos de Carbono , Óxido de Zinco , Naproxeno , Sumatriptana , Técnicas Eletroquímicas/métodos , Nanotubos de Carbono/química , Nanocompostos/química
15.
Food Chem ; 404(Pt A): 134609, 2023 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-36272300

RESUMO

Due to a small amount of Cu (Ⅱ) ions being beneficial and too much being harmful, it is necessary to establish a rapid and direct detection method. Herein, we reported a platform based on multiwalled carbon nanotubes (MWCNTs), 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6), and Nafion solution-modified glassy carbon electrode (GCE) for the direct electrochemical detection of Cu (II) ions. We used differential pulse anodic stripping voltammetry, including the electrodeposition of Cu (Ⅱ) ions on the modified GCE and subsequent anodic stripping. Under the optimum conditions, the linear range was 20 µg·L-1 âˆ¼ 950 µg·L-1, the limit of detection (LOD) was 16 µg·L-1, and the limit of quantification (LOQ) was 54 µg·L-1 for Cu (II). We realized the quantitative detection of Cu (Ⅱ) ions in juice and tea beverage without tedious pretreatment. The result showed that the sensor had good anti-interference and practicability for actual food samples.


Assuntos
Nanotubos de Carbono , Eletrodos , Íons , Bebidas , Chá , Técnicas Eletroquímicas/métodos
16.
Food Chem ; 401: 134058, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36095998

RESUMO

Sodium dehydroacetate (SDA) is one of the most common additives and preservatives in food, especially for strawberries, due to its fungicidal and antibacterial effects. Therefore, an innovative electrochemical sensor, depending on carbon paste electrode (CPE) modulated with multi-walled carbon nanotubes and molecularly imprinted polymers, was constructed for in situ detection of SDA. Based on density functional theory calculations, the polymer film was imprinted on the modified CPE surface via electrochemical polymerization of pyrrole in the presence of SDA. The morphology and electrochemical behavior of the synthesized sensors were characterized using different techniques. Under optimal conditions,a wide linear range (4.1 × 10-6 -1.2 mM)with a detection limit of 0.13 nM was obtained using differential pulse voltammetry and electrochemical impedance spectroscopy. The proposed sensor displayed superb selectivity for SDA, good precision (RSD = 2.7%), and high stability (˃4 weeks). Thus, it was successfully applied to determine SDA in strawberry samples with excellent recoveries (96.7%-100%).


Assuntos
Fragaria , Impressão Molecular , Nanotubos de Carbono , Impressão Molecular/métodos , Nanotubos de Carbono/química , Técnicas Eletroquímicas/métodos , Pirróis , Polímeros Molecularmente Impressos , Eletrodos , Polímeros/química , Antibacterianos , Limite de Detecção
17.
Anal Chim Acta ; 1237: 340631, 2023 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-36442944

RESUMO

Composited carbon nanomaterials have attracted wide attention and are used for high-sensitivity biological assays due to their low toxicity, good biocompatibility, and excellent electrical conductivity. To further promote electron transfer and enhance electrocatalytic activity to detect dopamine (DA), this study proposed carbon dots (CDs) based on glycerol synthesized by liquid dielectric barrier discharge (DBD) microplasma. Combined with the multi-walled carbon nanotubes (MWCNTs) with excellent electrical conductivity, a composited carbon nanomaterial electrode of CDs/MWCNTs was constructed. As a DA biosensor, the interaction and electron exchange between MWCNTs, CDs, and DA can be enhanced thanks to the π-π stacking force, thereby facilitating the sensitive electrochemical detection of DA. The sensor exhibits good sensing performance toward DA detection with a linear range of 2.0-100 µM, a limit of detection (LOD) of 11.08 nM (S/N = 3), and a sensitivity of 29020 µA cm-2 mM-1. The proposed electrode successfully detected DA levels in human serum samples with satisfactory selectivity and recovery rate. The microplasma-enabled synthesized method provides a promising path for preparing and applying carbon-based nanomaterials.


Assuntos
Dopamina , Nanotubos de Carbono , Humanos , Eletrodos , Condutividade Elétrica , Limite de Detecção
18.
Environ Res ; 216(Pt 2): 114629, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-36279909

RESUMO

Selenium is targeted as a priority pollutant to be removed due to its high toxicity level and lethal effects. In this research, a novel nano sorbent was fabricated using ionic liquid on multiwalled carbon nanotubes (IL-MCNT) and employed for Selenium remediation from aqueous media. Besides solution pH, nanocomposite dosage, the initial selenium concentration, temperature and sorption time were also examined as operating variables. At optimal pH 2.0, 96% of the selenium was removed with maximum efficiency with 100 mg/L of IL-MCNT at 308 K, 45 min of contact time, and 110 g of IL-MCNT dosage. From kinetic studies, it appears that the Langmuir isotherm fits the observed data (R2 > 0.9813), supporting the hypothesis that monolayer attachment occurs. The Langmuir isotherm parameters are evaluated as qm = 125 mg/g and KL = 0.172 L/mg. As a result of testing several kinetic models, the pseudo-second-order model was the most suitable for experimental data (R2 > 0.9746). Scanning Electron Microscopy images, FTIR spectra, and thermogravimetric study were used to examine the synthesized nanomaterial.


Assuntos
Recuperação e Remediação Ambiental , Nanotubos de Carbono , Selênio , Poluentes Químicos da Água , Cinética , Adsorção , Termodinâmica , Concentração de Íons de Hidrogênio
19.
J Colloid Interface Sci ; 631(Pt B): 239-248, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36401931

RESUMO

Recently, conductive composites have been used in flexible electronic devices and have attracted attention. The integration of self-healing, high sensitivity, large tensile strength, environmental stability, and easy recyclability into conductive composites is very desirable yet challenging. Hence, a conductive composite as a flexible strain sensor with a self-healing and recyclability is facilely developed, with a polyurethane (PU) elastomer bearing dynamic boronic ester as the polymer matrix and carbon nanotubes (CNTs) as a conductive filler. Due to the dynamic boronic ester bond and hydrogen bond, the prepared polyurethane conductive composite has good self-healing and mechanical properties. It not only has a high healing efficiency of 78 % but also has a tensile strength of 15.4 MPa and an elongation at break of 420 %. In addition, the prepared conductive composite has high conductivity (0.57 mS/cm) and sensitivity. As a wearable sensor, it can identify human activities in all directions, such as elbow and finger bending, speaking, and facial changes. Consequently, the polyurethane conductive composite prepared in this study exhibited wonderful application potential in wearable electronic devices such as self-healing strain sensors.


Assuntos
Nanotubos de Carbono , Dispositivos Eletrônicos Vestíveis , Humanos , Poliuretanos , Condutividade Elétrica , Ésteres
20.
Talanta ; 251: 123788, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-35933847

RESUMO

As various aptasensors are adopted in clinical diagnosis, the development of convenient multiple-target determination is a field of ever-increasing interests. Herein, a label-free and amplified electrochemiluminescence (ECL) sensing platform was constructed to detect multiple targets of hemin, glucose and thrombin (TB) using peroxydisulfate (S2O82-) solution, which was one of the most convenient and economical ECL systems. It was worth mentioning that the target-induced bi-enzyme cascade catalysis reaction was developed to increase the ECL response strongly of S2O82- solution due to the production of (1O2)2* from the inter-reaction between reactive oxygen species (ROS) and sulfate radical (SO4•-). Specifically, with the layer-by-layer assembly of multi-walled carbon nanotubes (MWCNTs), glucose oxidase (GOx) and gold nanoparticles (AuNPs) as the interface, the guanine-rich (G-rich) thrombin aptamer (TBA) was anchored for hemin (target 1) detection, due to the electrocatalysis of hemin/G-quadruplex as a horseradish peroxidase mimicking DNAzyme (HRP-DNAzyme) towards dissolved oxygen for ROS generation. Second, in the presence of glucose (target 2), the ECL intensity was improved because glucose was the substrate of the bi-enzyme cascade catalysis reaction. Third, when TB (target 3) was sequentially incubated based on the above-mentioned aptasensor, the bi-enzyme catalysis was inhibited to decrease the ECL signal, due to the steric hindrance effect of the TB protein. As a result, the aptasensor achieved the nanomolar detection for hemin (3.33 nM), the micromolar detection for glucose (0.33 µM) and the femtomolar detection for TB (3.33 fM), respectively.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , DNA Catalítico , Nanopartículas Metálicas , Nanotubos de Carbono , DNA Catalítico/metabolismo , Técnicas Eletroquímicas , Glucose , Glucose Oxidase/metabolismo , Ouro , Guanina , Hemina , Peroxidase do Rábano Silvestre/metabolismo , Oxigênio , Espécies Reativas de Oxigênio , Trombina
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