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1.
Sensors (Basel) ; 22(1)2022 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-35009895

RESUMO

The high conductivity of graphene material (or its derivatives) and its very large surface area enhance the direct electron transfer, improving non-enzymatic electrochemical sensors sensitivity and its other characteristics. The offered large pores facilitate analyte transport enabling glucose detection even at very low concentration values. In the current review paper we classified the enzymeless graphene-based glucose electrocatalysts' synthesis methods that have been followed into the last few years into four main categories: (i) direct growth of graphene (or oxides) on metallic substrates, (ii) in-situ growth of metallic nanoparticles into graphene (or oxides) matrix, (iii) laser-induced graphene electrodes and (iv) polymer functionalized graphene (or oxides) electrodes. The increment of the specific surface area and the high degree reduction of the electrode internal resistance were recognized as their common targets. Analyzing glucose electrooxidation mechanism over Cu- Co- and Ni-(oxide)/graphene (or derivative) electrocatalysts, we deduced that glucose electrochemical sensing properties, such as sensitivity, detection limit and linear detection limit, totally depend on the route of the mass and charge transport between metal(II)/metal(III); and so both (specific area and internal resistance) should have the optimum values.


Assuntos
Técnicas Biossensoriais , Grafite , Nanoestruturas , Análise Custo-Benefício , Técnicas Eletroquímicas , Eletrodos , Glucose , Óxidos
2.
Se Pu ; 40(1): 10-16, 2022 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-34985211

RESUMO

A graphene oxide aerogel was prepared and directly filled in a solid phase extraction (SPE) column without the aid of silica or other substrates. The aerogel was used to extract and detect residual organophosphorus pesticides (phoxim, temephos, fenthion, and fenitrothion) in food, and exhibited good elasticity and high mechanical strength. The graphene oxide aerogel was prepared by freeze-drying. Its morphology and physical properties were characterized by scanning electron microscopy, infrared spectroscopy, and BET surface adsorption. Results proved the successful synthesis of the graphene oxide aerogel. Scanning electron micrographs of the aerogel exhibited a layered and fold structure, with a surface area of 740.51 m2/g. The effect of experimental conditions on the extraction recovery of organophosphorus pesticides was systematically studied through a series of single-factor experiments. Due to limited adsorption sites, sample volumes of 5-60 mL were investigated, and 15 mL was determined was the optimum sample volume. The rate of sample loading was investigated in the range of 0.8-3.0 mL/min. When the rate of sample loading was higher than 3.0 mL/min, the insufficient contact between the analytes and sorbent appeared to cause a decrease in the extraction recovery. A lower rate of sample loading would prolong the operation time due to the re-elution of organophosphorus pesticides. The sample pH was optimized from a pH range of 2-11. An acidic solution was found to be good for inducing electrostatic interactions between the graphene oxide aerogel and organophosphorus pesticides. The maximum extraction recoveries were obtained at pH 4. Three eluents (acetonitrile, methanol, and acetone) were explored for optimization, and results showed that acetonitrile was the most appropriate eluent. The eluent volume (0.6-1.2 mL) was also investigated, and the optimal value was found to be 1.0 mL. Compared with commercial extraction materials including C18 silica, the anion exchange column (SAX), amino (-NH2), and Florisil, the extraction recovery of this new material showed distinct improvement. The lifetime of the extraction column directly filled with the graphene oxide aerogel was investigated. The column could be repeatedly used for 15 times, which overcame the issue of blocking of the sieve plates of fragmented graphene nanosheets dispersed without any matrix support. The linearities of the four organophosphorus pesticides were 1-200 µg/L for phoxim, temephos, and fenthion, and 2-200 µg/L for fenitrothion. The linear correlation coefficients were all ≥0.9949, and limits of detection were in the range of 0.2-0.5 µg/L. An extraction column was used to extract the analytes continuously for five times, and the RSDs of the extraction recoveries were ≤6.5%. Subsequently, five extraction columns were used to extract the analytes under the same conditions, and the RSDs of the extraction recoveries were ≤11.3%. Finally, the established method was applied for the extraction and detection of a real sample (apple peel); no organophosphorus pesticide was detected in the apple peel. The recoveries for spiked standard solutions were between 70.5% and 93.6%, and RSDs were ≤10.4%.


Assuntos
Grafite , Praguicidas , Compostos Organofosforados , Praguicidas/análise , Extração em Fase Sólida
3.
J Colloid Interface Sci ; 608(Pt 1): 131-141, 2022 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-34626962

RESUMO

The difficulty to achieve rapid detection is the limitation of many enzyme-free sensors today. Thus, designing tri-functionalsensors with ultra-fast and efficientdeterminationis a challenging taskin biological science. Herein, curly fish scales-like Ni2.5Mo6S6.7 active materials was anchored on poly (3,4-ethylenedioxythiophene)-reduced graphene oxide (PEDOT-rGO) hybrid membranes with uneven surface (Ni2.5Mo6S6.7/PEDOT-rGO) as a high-performance tri-functional catalyst for glucose, nitrite and hydrogen peroxide determination.The sensor constructed under optimal conditions exhibited ultrafast response performance towards glucose and nitrite within 2 s, and hydrogen peroxide within 1 s. Meanwhile, it provided the wide linear range with a low detection limit towards glucose (as low as 0.001 mM and up to 15.000 mM, and 0.33 µM), nitrite (as low as 0.001 mM and up to 10.000 mM, and 0.33 µM) and hydrogen peroxide (from 0.010 mM to 7.000 mM, and 0.79 µM), respectively. In addition, the sensor demonstrated satisfied selectivity, repeatability, reproducibility and stability. Furthermore, the sensor has potential application in real samples. This study may provide a new strategy for the construction of tri-functional electrode materials with the ultra-fast response.


Assuntos
Grafite , Peróxido de Hidrogênio , Animais , Compostos Bicíclicos Heterocíclicos com Pontes , Técnicas Eletroquímicas , Eletrodos , Glucose , Limite de Detecção , Nitritos , Polímeros , Reprodutibilidade dos Testes
4.
J Colloid Interface Sci ; 608(Pt 1): 294-305, 2022 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-34626976

RESUMO

Graphene-based nanomaterials that combine significant photocatalytic, antioxidant and antibacterial activity are very attractive candidates for biomedical and environmental applications. Conventional chemical synthesis routes may contaminate the resultant materials with toxic molecules, compromising their properties and limiting their use in biomedical applications. Ideally, to avoid any contamination, the nanomaterials should be synthesized from non-toxic precursors and reagents, e.g. foodstuff via a simple technology that does not rely on the use of hazardous chemicals yet produces materials of high quality. Here, we report an environmentally friendly, low cost reduced graphene oxide-silver-silver oxide nanocomposite with strong photocatalytic, antioxidant and antibacterial activity for environmental remediation. The reduced graphene oxide (FRGO) is synthesized from edible sunflower oil via a simple flame synthesis method. Next, silver nanoparticles (Ag/AgO/Ag2O) are produced by phytochemical reduction of AgNO3 using a reducing agent based on flavonoids from Coleus aromaticus (Mexican mint), also used in food industry. Thus-obtained FRGO-Ag/AgO/Ag2O composite is characterized using X-ray diffraction spectroscopy, scanning electron microscopy, fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The degradation of anionic textile dye Methylene blue (MB) is used as a measure of photocatalytic activity of FRGO and FRGO/Ag/AgO/Ag2O, with solution pH, initial dye concentration, and quantity of the catalyst considered as influencing factors. FRGO-Ag/AgO/Ag2O composites show strong antioxidant activity, with improved radical inhibition as well as dye degradation properties when compared to pristine FRGO.


Assuntos
Grafite , Nanopartículas Metálicas , Antibacterianos/farmacologia , Antioxidantes/farmacologia , Óxidos , Prata/farmacologia , Compostos de Prata
5.
Chemosphere ; 288(Pt 1): 132509, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34627811

RESUMO

Herein, polypyrrole/titanium oxide/reduced graphene oxide (PTi/r-GO) electrodes were prepared and successfully applied for the photoelectrocatalytic (PEC) degradation of methyl orange (MO) under visible light. Polypyrrole-TiO2 composites rich in p-n heterojunctions were first prepared, then modified with r-GO to improve the electrical conductivity and facilitate charge separation under visible light irradiation. The obtained PTi/r-GO composites were then deposited onto a titanium mesh, which served as the working electrode in PEC experiments. A MO removal efficiency of 93% was achieved in 50 min using PTi/r-GO electrode under PEC conditions (Xe lamp, λ > 420 nm, bias of 0.6 V, 0.1 M Na2SO4 electrolyte), which was far higher than MO removal efficiencies under electrocatalytic oxidation (22%) or photocatalytic oxidation (47%) conditions. This confirmed that excellent activity of the PTi/r-GO electrode under PEC conditions was due to a combination of electrochemical and photocatalytic oxidation processes (involving •OH and •O2- generation). Further, PTi/r-GO was very stable under the applied PEC conditions, with the MO removal efficiency remaining >90% after five cycles. PEC degradation pathways for MO on PTi/r-GO were explored, with a number of key intermediates in the MO mineralization process identified. Results demonstrate that PEC electrodes combining p-type polypyrrole, n-type TiO2 and rGO are very effective in the treatment of hazardous organic compounds in wastewater.


Assuntos
Polímeros , Titânio , Catálise , Corantes , Eletrodos , Grafite , Luz , Pirróis
6.
Biosens Bioelectron ; 196: 113686, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34628262

RESUMO

Artificial peroxisome is of critical importance to supersede natural peroxisome in fabricating protocell system and disease treatment. Nevertheless, developing feasible artificial peroxisome with various stable functions remains a monumental challenge. Nanozyme with multiple enzyme-like activities can mimic natural enzymes in peroxisome, which make it a prospective candidate for artificial peroxisome design. Herein, we prepared a nanozyme with multiple peroxisomal-like activities - Pd nanoparticles functionalized nitrogen-doped porous carbon-reduced graphene oxide (PdNPs/N-PC-rGO). Due to its sandwich-like structure, the incorporation of N heteroatoms and the synergistic effect between PdNPs and N-PC-rGO bi-support, the PdNPs/N-PC-rGO exhibited triple peroxisomal-like activities including oxidase (OXD), peroxidase (POD) and catalase (CAT), leading it a promising alternative for artificial peroxisome exploration. Furthermore, the PdNPs/N-PC-rGO showed high electrocatalytic activity, which could be employed for the detection of electrochemical active substances reduced glutathione (GSH). The PdNPs/N-PC-rGO modified electrode displayed a wide concentration range from 70 nM to 1500 µM, with a very low detection limit of 9.8 nM (S/N = 3). Therefore, PdNPs/N-PC-rGO was a promising nanozyme for various biotechnological applications such as artificial organelles, biosensing, cytoprotection, disease diagnosis and treatment.


Assuntos
Técnicas Biossensoriais , Grafite , Catálise , Eletrodos , Peroxissomos , Estudos Prospectivos
7.
J Colloid Interface Sci ; 608(Pt 1): 588-598, 2022 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-34628318

RESUMO

The low reactivity of zero-valent iron (ZVI) usually limits its application for pollutant remediation. Therefore, a microscopic galvanic cell (mGC) with short-circuited cathode and anode was synthesized to intensify its galvanic corrosion. The prepared mGC exhibited 7.14 times higher Fe(II) release performance than ordinary nanoscale-ZVI (nZVI), rendering efficient Cr(VI) removal performance. Density functional theory (DFT) revealed mutual-activation of the cathode and anode due to close proximity, dramatically enhancing the galvanic corrosion of Fe(0) in mGC. The corrosion potential of mGC was measured as -0.77 V, which was 100 mV more negative than nZVI. The released electrons and surface-bond Fe(II) from anode in mGC was proved to be the dominant reductive species. More importantly, Cr(VI) reduction was slightly inhibited by hydroxyl radicals generated by a series of inherent side-reactions in the system, which could be well eliminated by low concentrations of 4-acetamido phenol. This study provides a promising strategy for ZVI activation, and sheds light on its environmental applications.


Assuntos
Grafite , Poluentes Químicos da Água , Carbono , Cromo/análise , Ferro , Poluentes Químicos da Água/análise
8.
Sci Total Environ ; 806(Pt 4): 150942, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34655633

RESUMO

In this study, we comprehensively and critically discuss the aggregation mechanism of commercial graphene oxide (CGO) in surface aquatic environments. The aggregation kinetics and critical coagulation concentration of CGO were obtained through time-resolved dynamic light scattering and batch techniques over a wide range of water types. By employing transmission electron microscopy and elemental mapping, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy, we studied the effects of cations in natural waters on the microstructure transformation, element content and distribution, and oxygen-containing functional group vibrations of CGO. The aggregation of CGO in natural water is induced mainly by Ca2+ by complexing; Na+, with a higher concentration, plays a more important role than Mg2+ in inducing aggregation via electric double layer suppression. Ca2+ mainly interacts with C - COOH, while Mg2+ has a greater effect on C - OH. Na+ has less effect on the oxygen-containing functional group but decreases the C/O ratio in contrast with Mg2+/Ca2+/natural water, indicating the different inducing mechanisms. This study looks forward to providing pivotal knowledge to predict the environmental fate of CGO more accurately in natural surface water.


Assuntos
Grafite , Cátions , Cinética , Água
9.
Sci Total Environ ; 806(Pt 4): 150956, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34656568

RESUMO

The extensive use of nanofillers, such as graphene oxide (GO) and reduced graphene oxide (rGO), as plastic additives has led to the coexistence of microplastics (MPs) and nanomaterials in aquatic environments. However, there is a lack of studies on the adsorption behavior of MPs when coexisting with GO. Moreover, MPs and GO are prone to undergoing aging processes in real environments under conditions such as sunlight exposure, which changes their physicochemical properties and affects their adsorption behavior. In this study, the aging processes of MPs and GO in a real environment were simulated by ultraviolet (UV) irradiation and thermal treatments, respectively. The adsorption behavior of ciprofloxacin (CIP) on three types of MPs (polypropylene (PP), polyamide (PA), and polystyrene (PS)) before and after aging was explored. The MPs are ordered in terms of CIP adsorption capacity as aged-PA > aged-PS > aged-PP > PA > PP > PS, and the adsorption capacity of aged MPs was approximately twofold higher than that of pristine MPs. This paper also studied the adsorption performance of antibiotics in a coexisting system of aged MPs and GO/rGO, and the tetracycline (TC) adsorption capacity was increased by ~336% in aged PP-GO and ~100% in an aged PP-rGO coexisting system. GO/rGO with high degree of oxidation and concentration in an aged- PP-GO/rGO coexisting system are more conducive to the TC adsorption, due to the contribution of oxygen-containing functional groups. Surface and partition adsorption co-occurred during the TC adsorption process. The TC adsorption behavior in the MPs-GO/rGO coexisting system was strongly dependent on the solution pH, which was more favorable under acidic (pH = 3) or alkaline (pH = 11) conditions. This study improves the understanding of the environmental behavior of MPs, graphene, and antibiotics and guides research on strategies for preventing the migration of antibiotics in MPs-GO/rGO coexisting systems.


Assuntos
Grafite , Poluentes Químicos da Água , Adsorção , Antibacterianos , Microplásticos , Plásticos , Poluentes Químicos da Água/análise
10.
Sci Total Environ ; 806(Pt 3): 151258, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34710423

RESUMO

Modification of graphene oxide (GO) with polyethyleneimine (PEI) has been studied to develop a GO/PEI sponge material that not only performs well in the adsorption of Cu(II) but also is easily separated from water. The results showed that GO had excellent affinity for PEI, and GO/PEI prepared at pH 9.0 using PEI with a MW of 70,000 was shown to be a good adsorbent for Cu(II). This GO/PEI was characterized with SEM, XRD, XPS, FTIR and TG analyses and was investigated for Cu(II) adsorption further. The adsorption isotherm data of Cu(II) were fitted well with the Langmuir model, from which the maximum adsorption of GO/PEI was calculated to be 150.9 mg/g at pH 5.5. This was much higher than that of GO and two commercial resins. GO/PEI showed high selectivity towards Cu(II). In GO/PEI, the contributions of amino groups on PEI and negative charges on GO were 79.2% and 20.8%, respectively. Cu(II) adsorption on GO/PEI decreased with decreasing pH, and 1 M HCl caused nearly complete desorption of the adsorbed Cu(II). Experimental results of five cycles of adsorption-desorption indicated that this material could be reused. Column studies showed that GO/PEI performed well in terms of both Cu(II) adsorption and stability in water.


Assuntos
Polietilenoimina , Poluentes Químicos da Água , Adsorção , Cobre , Grafite , Cinética , Água , Poluentes Químicos da Água/análise
11.
Colloids Surf B Biointerfaces ; 209(Pt 1): 112172, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34715596

RESUMO

In this work, biocompatible, antimicrobial, and antiviral nanocomposites were prepared through two steps. In the first step, periodate oxidation of cellulose was performed to get dialdehyde cellulose (DAC). The second step included the reaction of DAC with sulfur-containing amino acids included Cysteine (Cys) and Methionine (Meth) in the presence of graphene oxide (GO). The prepared nanocomposites were characterized via FT-IR, SEM, TEM, and TGA. Antimicrobial and antiviral activities for all designed nanocomposites besides DAC were carried out. Both DAC/GO/Cys and DAC/GO/Meth exhibited a promising antimicrobial activity against Gram-negative (E. coli and P. aeruginosa), Gram-positive (B. subtilis and S. aureus), and unicellular fungi (C. Albicans and C. neoformans), while the DAC/GO/Cys/Meth nanocomposite was the lowest. Moreover, all designed nanocomposites have a strong antiviral activity against Herpes simplex virus 1(HSV-1) at minimum nontoxic concentration. Additionally, Computational procedures and Molecular docking showed the reactivity and stability of the molecules that have biological activity against Gram-positive, Gram-negative, and HSV-1. As well as DAC incorporation with amino acid enhanced their reactivity and their interaction.


Assuntos
Anti-Infecciosos , Grafite , Nanocompostos , Aminoácidos , Antibacterianos/farmacologia , Anti-Infecciosos/farmacologia , Antivirais/farmacologia , Celulose , Escherichia coli , Simulação de Acoplamento Molecular , Espectroscopia de Infravermelho com Transformada de Fourier , Staphylococcus aureus
12.
J Environ Manage ; 302(Pt A): 114044, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34735829

RESUMO

In order to solve the environmental problems caused by greenhouse gas emissions, cellulosenanofiber (CNF)/polyvinyl alcohol (PVA)/graphene oxide (GO) aerogel was obtained by step-by-step heating, tert-butanol replacement, freeze-drying, and high-temperature activation in this paper. The micromorphology, specific surface area, pore size distribution, and thermal stability of the prepared aerogels were analyzed by scanning electron microscopy, automatic surface area and porosity analysis, and thermo-gravimetric analysis. The interaction state and adsorption mechanism of CO2 and aerogel physical adsorption were described by Materials Studio simulation. The results showed that the adsorption process conformed to the Langmuir adsorption isotherm. After carbonization, the thermal stability of the aerogel was good (mass loss rate <1%). With the increase of GO content, its specific surface area increased (392.41 m2/g) and CO2 adsorption capacity increased (432.76 cm3/g at 273 K). The simulation results show that hydrogen bond energy and van der Waals adsorption are the main factors that help in adsorption of CO2 on the surface aerogel, and electrostatic adsorption is the secondary adsorption factor. The application of green material carbon-based aerogels is also in line with the concept of sustainable development.


Assuntos
Grafite , Álcool de Polivinil , Dióxido de Carbono , Simulação de Dinâmica Molecular
13.
J Environ Manage ; 302(Pt A): 114022, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34735832

RESUMO

In the present study, an attempt has been made to design a solar light driven N-rGO-ZnO- CoPc(COOH)8 nanocomposite for the degradation of cyanide. The morphological and structural characterization of the synthesized nanocomposite was performed by XRD, FT-IR, XPS, UV-vis DRS, FESEM, TEM, EDS, PL spectra and BET surface area. The results revealed that almost 91% degradation and 86% toxicity removal occurred at 25 mgL-1 of initial cyanide concentration by the N-rGO-ZnO-CoPc(COOH)8 nanocomposite under illumination of solar light within 120 min. Analysis of free radicals reveals that the generation of OH. radicals was the predominant species in the photocatalytic degradation process. The cyanide degradation follows pseudo-first order kinetics. The estimated apparent rate constant (Kapp) of the above nanocomposite was 3 times higher than that of the ZnO photocatalyst alone together with a very good recycle activities. This might be due to the application of metallpthalocyanine photosensitizer CoPc(COOH)8 which enhances the rate of visible light absorption efficiency and activates the higher band gap ZnO photocatalyst under visible light. In addition, the presence of residual oxygen in N-rGO also promotes nucleation and anchor sites for interfacial contact between ZnO and N-rGO for effective charge transfer. Further, the N-rGO-ZnO-CoPc(COOH)8 photocatalytic system showed significant antibacterial activities against mixed culture systems. Therefore, the N-rGO-ZnO-CoPc(COOH)8 nanocomposite may be an alternative solar light driven photocatalyst system for the removal of cyanide from the wastewater along with its strong disinfectant activities.


Assuntos
Nanocompostos , Óxido de Zinco , Catálise , Cianetos , Grafite , Espectroscopia de Infravermelho com Transformada de Fourier
14.
Spectrochim Acta A Mol Biomol Spectrosc ; 267(Pt 1): 120530, 2022 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-34740000

RESUMO

A sensitive fluorescent nanoprobe is reported for the determination of lamotrigine after its preconcentration by magnetic graphene oxide nanocomposite. The fluorescent nanoprobe is based on the quenching effect of lamotrigine on the nitrogen graphene quantum dots fluorescence at 440 nm, through strong hydrogen bonding. Under optimum conditions, the quenching fluorescent intensity of nitrogen graphene quantum dots shows linearity with the lamotrigine concentration in the range of 2.0-45.0 µg L-1, limits of detection (LOD), and quantification of 0.39 and 1.28 µg L-1 respectively. The parameters affecting the extraction and determination of lamotrigine were optimized via the central composite design (CCD) and one at the time method, respectively. The developed method was successfully employed for the extraction and quantification of lamotrigine in biological samples.


Assuntos
Grafite , Pontos Quânticos , Lamotrigina , Nitrogênio , Extração em Fase Sólida
15.
Food Chem ; 373(Pt A): 131321, 2022 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-34742040

RESUMO

Accurate and rapid detection of Aflatoxins as one of the most hazardous compounds in foodstuffs is very important. In this study, a label-free electrochemical aptasensor was developed to identify aflatoxin M1 using a reduced graphene oxide (rGO) and gold nanoparticles (AuNPs)-based pencil graphite electrode (PGE). The morphological characteristics of the electrode surface were investigated using SEM and rGO functional groups were confirmed by FTIR. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques were used to characterize various stages of electrode modification. In order to optimize the impedimetric response of the aptasensor, aptamer immobilization time, aptamer concentration, and binding aflatoxin M1 with aptamer time were optimized. Under optimal conditions, the linear concentration range of 0.5-800 ng/L and limit of detection (LOD) of 0.3 ng/L were obtained for aflatoxin M1 by measuring the resistance charge transfer data. Finally, the fabricated aptasensor was successfully used to measure AFM1 compared to HPLC method.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Grafite , Nanopartículas Metálicas , Aflatoxina M1/análise , Animais , Técnicas Eletroquímicas , Eletrodos , Ouro , Leite/química
16.
Food Chem ; 373(Pt A): 131421, 2022 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-34742047

RESUMO

In this study, an overhead rotating flat surface sorbent based solid-phase microextraction was developed as a rapid and efficient method for simultaneous separation and determination of sulfonamides in animal based-food products. 3D graphene oxide/ lanthanum nanoparticles @ Ni foam was introduced as a novel selective sorbent. SEM-EDX and FT-IR techniques were applied for characterization of the sorbent. At optimum conditions, the linear ranges of 0.4-700.0 (µg L-1), 0.3-900.0 (µg L-1), and 0.25-500 (µg L-1) and the enrichment factors of 606.8, 604.3, 608.9 were obtained for SDZ, SMX, and SMZ, respectively. The LOD (S/N = 3) of 0.14, 0.11, 0.08 (µg L-1) were achieved for SDZ, SMX, and SMZ, respectively. The intra-day and inter-day precision (%) (five days, n = 7) for the concentration of 100 µg L-1 were less than 4.3 and 3.8, respectively. The recoveries over 90.0 % revealed high capability of the method for utilization in complex matrixes.


Assuntos
Grafite , Nanopartículas , Animais , Lantânio , Limite de Detecção , Microextração em Fase Sólida , Espectroscopia de Infravermelho com Transformada de Fourier , Sulfonamidas
17.
Colloids Surf B Biointerfaces ; 209(Pt 1): 112169, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34752985

RESUMO

Two platforms based on reduced graphene oxide (rGO) functionalized with Pluronic® P123 (rGO-P123) and polyethyleneimine - PEI (rGO-PEI) polymers and loaded with amphotericin B (AmB) were fabricated and tested against Leishmania amazonensis, which can cause cutaneous and diffuse cutaneous leishmaniasis. The materials rGO-P123 and rGO-PEI were efficiently loaded with AmB - a polyene antibiotic - which resulted in rGO-P123-AmB (0.078 mg per mg of material) and rGO-PEI-AmB (0.086 mg per mg of material). Under near-infrared (NIR) light irradiation, the amount of AmB released from rGO-PEI-AmB at pH 5.0 and 7.4 doubled in comparison to AmB released in the absence of NIR light under identical conditions. It was accompanied by a photothermal effect. Otherwise, rGO-P123-AmB did not show a significant change in AmB released in the presence and absence of NIR light. Cytotoxicity studies in mammalian host macrophages revealed that rGO-PEI and rGO-PEI-AmB were nontoxic to the host cells, whereas rGO-123 and rGO-P123-AmB were very toxic, particularly the latter. Therefore, only rGO-PEI and rGO-PEI-AmB were tested against L. amazonensis promastigotes in the presence and absence of NIR light. In vitro antiproliferative effects revealed that rGO-PEI-AmB showed a more pronounced activity against the parasite than rGO-PEI, which was improved under NIR light irradiation. Scanning-transmission electron microscopy of L. amazonensis promastigotes after incubation with rGO-PEI or rGO-PEI-AmB suggested autophagic and necrotic cell death. Thus, the facile synthesis, high AmB loading capacity and good photothermal effect make the rGO-PEI-AmB platform a promising candidate for the topical treatment of cutaneous leishmaniasis.


Assuntos
Grafite , Leishmania , Anfotericina B/farmacologia , Animais , Óxidos , Terapia Fototérmica , Polímeros
18.
J Mol Graph Model ; 110: 108073, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34768229

RESUMO

Human serum albumin (HSA) is a blood protein serving as a carrier for a wide range of drugs and nutrients. A level of glycated HSA (GHSA) is used as a diabetes biomarker. A graphene-based aptasensor is one of potential techniques to detect GHSA. Not only the interactions of albumin and aptamer, but the albumin-graphene (GRA) binding mechanism are also crucial for developing a diabetes aptasensor. In this work, Molecular Dynamics simulations (MD) were employed to explore the binding of GRA to both GHSA and HSA. The GRA binding from the back and front sides of an albumin are fast and spontaneous. The multiple GRA binding sites are identified. GRA causes more denaturation of helical characteristics in GHSA (∼12% reduction of helical structure). Both back and front GRA adhesions generate comparable degrees of helical unfolding. Importantly, the presence of bound GRA induces the release of glucose from drug sites implying the loss of ligand-binding affinity. This loss of drug site activity is independent on the GRA binding positions because all bound positions lead to the exit of sugars. The GRA binding deconstructs not only secondary structure, but also albumin function. Apparently, GRA is a non-biocompatible material for albumin. To construct a potential graphene-based aptasensor to detect GHSA, it is necessary to be certain that no free GRA surface is available because a bare GRA can bind and denature both HSA and GHSA which can cause misleading data.


Assuntos
Grafite , Glucose , Humanos , Simulação de Dinâmica Molecular , Albumina Sérica , Albumina Sérica Humana
19.
Biosens Bioelectron ; 197: 113779, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34781176

RESUMO

Neuron-specific enolase (NSE) is a specific marker for small cell carcinoma (SCLC). Sandwich-type electrochemical immunosensors are powerful for biomarker analysis, and the electrocatalytic activity of the signal amplification platform and the performance of the substrate are critical to their sensitivity. In this work, N atom-doped graphene functionalized with hollow porous Pt-skin Ag-Pt alloy (HP-Ag/Pt/NGR) was designed as a dual signal amplifier. The hollow porous Pt skin structure improves the atomic utilization and the larger internal cavity spacing significantly increases the number of electroactive centers, thus exhibiting more extraordinary electrocatalytic activity and durability for H2O2 reduction. Using NGR with good catalytic activity as the support material of HP-Ag/Pt, the double amplification of the current signal is realized. For the substrate, polypyrrole-poly(3,4-ethylenedioxythiophene) (PPy-PEDOT) nanotubes were synthesized by a novel chemical polymerization route, which effectively increased the interfacial electron transfer rate. By coupling Au nanoparticles (Au NPs) with PPy-PEDOT, the immune activity of biomolecules is maintained and the conductivity is further enhanced. Under optimal conditions, the linear range was 50 fg mL-1 - 100 ng mL-1, and the limit of detection (LOD) was 18.5 fg mL-1. The results confirm that the developed immunosensor has great promise for the early clinical diagnosis of SCLC.


Assuntos
Técnicas Biossensoriais , Grafite , Nanopartículas Metálicas , Ligas , Técnicas Eletroquímicas , Ouro , Peróxido de Hidrogênio , Imunoensaio , Limite de Detecção , Fosfopiruvato Hidratase , Polímeros , Porosidade , Pirróis
20.
Biosens Bioelectron ; 197: 113777, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34781177

RESUMO

Wearable sensors in healthcare monitoring have recently found widespread applications in biomedical fields for their non- or minimal-invasive, user-friendly and easy-accessible features. Sensing materials is one of the major challenges to achieve these superiorities of wearable sensors for healthcare monitoring, while graphene-based materials with many favorable properties have shown great efficiency in sensing various biochemical and biophysical signals. In this paper, we review state-of-the-art advances in the development and modification of graphene-based materials (i.e., graphene, graphene oxide and reduced graphene oxide) for fabricating advanced wearable sensors with 1D (fibers), 2D (films) and 3D (foams/aerogels/hydrogels) macroscopic structures. We summarize the structural design guidelines, sensing mechanisms, applications and evolution of the graphene-based materials as wearable sensors for healthcare monitoring of biophysical signals (e.g., mechanical, thermal and electrophysiological signals) and biochemical signals from various body fluids and exhaled gases. Finally, existing challenges and future prospects are presented in this area.


Assuntos
Técnicas Biossensoriais , Grafite , Dispositivos Eletrônicos Vestíveis , Atenção à Saúde , Gases
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