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1.
Food Chem ; 366: 130539, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34284191

RESUMO

The exploration of novel functional packaging films is of great scientific and technological interest. Herein, a novel chitosan/hollow g-C3N4/curcumin (CS-HCNS-Cur) biocomposite films was successful fabricated with integrated functions of slow release, antimicrobial activity and food freshness preservation. CS-HCNS-Cur films take the advantages of the excellent thermal stability and slow-release ability of HCNS to curcumin. Among the characterizations including scanning electron microscopy, transmission electron microscope, atomic force microscopy, fourier transform infrared spectroscopy, mechanical properties and the rheological properties measurements confirmed the successful fabrication of CS-HCNS-Cur films. The averaged water contact angle and water vapor permeability of this film were 105.83° and 105.03 × 10-5 g·mm (m2·h·kPa)-1, respectively. This film showed pH-responsive and slow-release ability. Moreover, this film can effectively store bananas for 10 days. Therefore, CS-HCNS-Cur films have promising potential for applications in functional food packaging.


Assuntos
Quitosana , Curcumina , Musa , Nanopartículas , Grafite , Compostos de Nitrogênio , Espectroscopia de Infravermelho com Transformada de Fourier
2.
Food Chem ; 366: 130573, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34311232

RESUMO

Based on a murine monoclonal antibody (mAb) against tiamulin (TML), an electrochemical immunosensor was proposed using silver-graphene oxide (Ag-GO) nanocomposites and gold nanocomposites (AuNPs) to detect tiamulin (TML). Due to the synergetic properties of Ag-GO nanocomposites and AuNPs, the conductivity of the immunosensor was significantly enhanced. On account of the specific mAb and conductive nanocomposites, the proposed electrochemical immunosensor exhibited a low LOD of 0.003 ng mL-1 for the detection of TML in a wide linear range of 0.01 to 1000 ng mL-1. In addition, the immunosensor did not involve additional redox species. Furthermore, the efficient and simple electrochemical immunosensor was employed to detect TML in real samples with high accuracy, suggesting a potential detection platform for other veterinary antibiotics in animal derived foods.


Assuntos
Técnicas Biossensoriais , Grafite , Nanopartículas Metálicas , Nanocompostos , Animais , Anticorpos Monoclonais , Diterpenos , Técnicas Eletroquímicas , Ouro , Imunoensaio , Limite de Detecção , Camundongos
3.
Food Chem ; 367: 130676, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34365250

RESUMO

Antimony(III) is a rare electroactive specie present on Earth, whose concentration is not typically determined. The presence of high concentrations of antimony is responsible for a variety of diseases, which makes it desirable to find convenient and reliable methods for its determination. We have developed a convenient glassy carbon modified electrode with electroreduced graphene oxide GC/rGO for the first time determination of Sb(III) in commercial lettuce, celery, and beverages. The surface of the electrode was characterized by scanning electron microscopy (SEM) and cyclic voltammetry, indicating a heterogeneous and rough surface with a real area of 0.28 cm2, which is ~2.5 times the area of GC. The optimal chemical and electrochemical parameters used were: sodium acetate buffer (pH = 4.3), an accumulation potential of -1.0 V and an accumulation time of 150 s. The analytical validation was developed evaluating the linear range (10-60 µg L-1), limit of detection (2.5 µg L-1), accuracy, repetibility and reproducibility with satisfactory results (relative standard deviation (RSD) values lower than 10%). All the analyzes performed in real samples by stripping voltammetry were compared with GF-AAS, showing statistically similar values, demonstrating that GC/rGO could be effectively applied in the analysis of food samples.


Assuntos
Grafite , Antimônio/análise , Bebidas , Eletrodos , Plantas Comestíveis , Reprodutibilidade dos Testes
4.
Food Chem ; 367: 130727, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34371276

RESUMO

An electrochemical sensor was fabricated by modifying nanoporous gold (NPG)-coated glassy carbon electrode (NPG/GCE) with functionalized graphene oxide /chitosan/ionic liquid nanocomposites (fGO/CS/IL). The introduction of ionic liquid (IL) and chitosan (CS) induced higher dispersibility of functionalized graphene oxide (fGO), and was beneficial for the combination of fGO/CS/IL with NPG/GCE. As a result of the synergistic effect of NPG and fGO/CS/IL, the resulted functionalized graphene oxide/chitosan/ionic liquid nanocomposites/nanoporous gold /glassy carbon electrode (fGO/CS/IL/NPG/GCE) showed the highest redox peak current response signal of Amaranth (E123) due to ultrahigh surface area, electronic conductivity as well as the improvement of the surface structure. Under optimized conditions, the enhanced peak currents represented excellent analytical performance for detection of Amaranth in the concentration range from 8.0 to 1200.0 nM. Meanwhile, the fGO/CS/IL/NPG/GCE presented satisfactory sensitivity and selectivity, excellent reproducibility, and long-time stability. For practical applications, the fGO/CS/IL/NPG/GCE was validated for the determination of Amaranth in three types of drinks with satisfactory results.


Assuntos
Técnicas Biossensoriais , Quitosana , Grafite , Líquidos Iônicos , Nanocompostos , Nanoporos , Técnicas Eletroquímicas , Eletrodos , Ouro , Reprodutibilidade dos Testes
5.
Talanta ; 236: 122830, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34635220

RESUMO

A sensitive biosensor that can be used for the determination of matrix metalloproteinase 2 (MMP-2) was proposed. The biosensor was developed by using an excellent self-enhanced nanocomposites as an illuminant and a peptide as a recognition element. For the electrostatic attraction between Ru(bpy)32+ and nitrogen-doped graphene quantum dots (NGQDs), the self-enhanced electrochemiluminescence (ECL) nanocomposites of NGQDs-Ru(bpy)32+-doped silica nanoparticles (NGQDs-Ru@SiO2) were synthesized through a simple sol-gel process. Then, a specific peptide (labeled sulfhydryl) was combined with the self-enhanced ECL nanocomposites (carboxyl in NGQDs) via acylation reaction to obtain the peptide-NGQDs-Ru@SiO2 nanoprobe, which was fabricated onto the gold electrode surface via Au-S bond. The peptide of the ECL nanoprobe was exposed to cleavage in the presence of MMP-2, which caused the signal substance to move farther away from the electrode, leading to a decrease of the ECL signal. The proposed NGQDs-Ru@SiO2-labeled peptide ECL biosensor displayed a lower detection limit of 6.5 pg mL-1 than those of reported ECL methods. The proposed biosensor provided an outlook for future applications in other disease-associated biomarkers.


Assuntos
Técnicas Biossensoriais , Grafite , Neoplasias , Pontos Quânticos , Biomarcadores Tumorais , Técnicas Eletroquímicas , Humanos , Medições Luminescentes , Metaloproteinase 2 da Matriz , Nitrogênio , Dióxido de Silício
6.
Talanta ; 236: 122859, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34635243

RESUMO

The sensitivity and selectivity of electrochemical analysis are challenging due to the materials used for electrode modification as well as electrical conductivity, catalytic activity and recognition ability of the working electrode. In this work, a portable 3D-printed electrochemical electrode clamp was designed and applied in combination with the developed covalent organic framework (COF DQTP)-modified pencil graphite electrode (DQTP/PGE). The ß-ketoenamine-linked COF DQTP synthesized by 1,3,5-triformylphloroglucinol (TP) and 2,6-diaminoanthraquinone (DQ) through solvothermal method is a porous crystalline with excellent conductivity and large periodic π-arrays, coupled with commercial available pencil graphite electrode to fabricate a disposable sensor for simultaneous determination of environmental endocrine disruptors bisphenol A and bisphenol S. The DQTP/PGE sensor exhibited high electrical conductivity and catalytic activity, and a good linearity was obtained in a range of 0.5-30 µM for two bisphenols with a detection limit of 0.15 µM (S/N = 3). Moreover, the sensor showed a reproducible and stable response over one month with negligible interference, and an accepted recovery with real food packaging samples.


Assuntos
Grafite , Estruturas Metalorgânicas , Compostos Benzidrílicos , Eletrodos , Fenóis , Sulfonas
7.
Talanta ; 236: 122864, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34635246

RESUMO

Real time controllable assembling/aptasensing approach via plasmonic graphene oxide (GO) nanocomposites has been firstly proven to simultaneously give tuning of micro-nano structure of plasmonic GO and ultrasensitive detection of MC-LR toxin. In order to fabricate the assembly, a high-quality hollow triangular nanoplate AgClAu:p-GO (HTNP AgClAu:p-GO) can act as a template; furthermore, we combine DNA-hybridization with biotin-strepavidin binding protocol for tuning the HTNP AgClAu:p-GO assemblies from networks to laminar structure, and simultaneously loading Raman reporters into the assemblies. The dynamic assembling process can be utilized as a real time SERS aptasensor for detecting MC-LR due to ratiometric introduction of MC-LR toxin inhibiting formation of plasmonic p-GO assembly via toxin/aptamer bioconjugation and causing reverse alteration of SERS signal for giving ultrasensitive SERS detection of MC-LR. A detection limit of 6.3pM with a wide linear range from 10pM to 5 nM can be achieved. When the aptasensor has been applied in real samples, the real time assembling/aptasensing approach shows recoveries from 98% to 103% with relative standard deviation (RSD) lower than 3%, expecting that one-step nanofabrication and sensing strategy can be extended to in-field test of environmental contaminants.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Grafite , Limite de Detecção , Toxinas Marinhas , Microcistinas
8.
Talanta ; 236: 122874, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34635254

RESUMO

Herein, a one-pot alkali cutting-assisted synthesis approach has been developed to gain fluorescence (FL) tunable amino functionalized GQDs (NH2-GQDs), which exhibit concentration- and excitation-dependent FL behaviors, due to the self-assembled J-type aggregation effect and different electronic transitions governed by graphene basal plane and functional groups. While NH2-GQDs possess brighter FL emission than pristine GQDs, owning to the functionalization of amino groups with strong electron withdrawing ability. Particularly, the pH-dependent FL behavior of NH2-GQDs further reflects the FL emission mechanism originated from the intrinsic zigzag sites and introduced amino and carboxylic groups, which is available for pH sensing. Moreover, the NH2-GQDs also show a FL quenching upon reaction with tannic acid (TA), resulting in the construction of a FL turn-off TA sensing platform. A good linear relationship is obtained between logarithm of FL intensity (log F) and TA concentration in a linear dynamic range of 1-40 µM and a limit of detection of 43.3 nM (3σ/s, n = 9) is achieved, with a precision of 0.08% RSD at a concentration level of 5 µM (n = 9). This work features a simple and direct approach to acquire multifunctional nanosensor, providing great potential for further applications in chem/biosensing.


Assuntos
Grafite , Pontos Quânticos , Álcalis , Fluorescência , Concentração de Íons de Hidrogênio , Taninos
9.
Talanta ; 236: 122885, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34635265

RESUMO

Domoic acid, namely amnesic shellfish toxin, is a highly neurotoxic substance to marine animals and humankind. To reduce the incidence of poisoning accidents, the exploitation of specific and rapid detection method for domoic acid monitoring is highly required. Herein, an electrochemical molecularly imprinted polymer (MIP) sensor based on polydopamine-reduced graphene oxide/polyacrylamide composite (PDA-rGO/PAM) was constructed successfully to detect domoic acid. The domoic acid molecule could be recognized in imprinted cavities of PAM reversibly through hydrogen bonding. PDA-rGO promoted the loading capacity of PAM and improved the charge transfer rate, which amplified the electrical signal response of the MIP sensor. The screen-printed electrode (SPE) modified with PDA-rGO/PAM displayed satisfactory response toward toxin contaminated sample at a linear range from 1 to 600 nM and a low detection limit of 0.31 nM, demonstrating the prospective application of the transducer as a portable sensing platform for the on-site detection of hazardous marine biotoxin. Moreover, benefiting from the superior specificity and stability of MIP, the fabricated sensor could be utilized to detect the domoic acid content in mussel extracts directly without complex pretreatment operation.


Assuntos
Impressão Molecular , Resinas Acrílicas , Animais , Grafite , Indóis , Ácido Caínico/análogos & derivados , Limite de Detecção , Polímeros
10.
Food Chem ; 368: 130856, 2022 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-34425333

RESUMO

In this work, we present a novel dual-emissive fluoroimmunoassay for synchronous monitoring of okadaic acid (OA) and saxitoxin (STX) using multicolor fluorescent labels composed of sulfur, phosphorous co-doped graphene quantum dots (S, P-GQDs), and ovalbumin (OVA)-coated gold nanoparticles (OVA-AuNPs). The novel OVA-AuNPs were prepared by the reduction of chloroauric acid under alkaline conditions using OVA as a reducing agent. Both S, P-GQDs and OVA-AuNPs exhibit bright fluorescence, more importantly, a large emission wavelength difference (Δλ = 156 nm) under an excitation of 400 nm and relatively independent fluorescence behavior, which are essential to realizing the dual-signal marks in a directly mixing system. Using a competitive fluorescence-linked immunosorbent assay (cFLISA) format, the dual-emissive cFLISA was successfully utilized to measure OA and STX contents in Alectryonella plicatula (commonly named as fingerprint oyster) and the detection results were in good agreement with the commercial enzyme-linked immunosorbent assay (ELISA) kits.


Assuntos
Grafite , Nanopartículas Metálicas , Pontos Quânticos , Ouro , Imunoensaio , Ácido Okadáico , Saxitoxina , Frutos do Mar/análise
11.
Food Chem ; 368: 130684, 2022 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-34391099

RESUMO

In this study, we tested the in vitro efficacy of a graphene oxide-chitooligosaccharide (GO-COS) complex developed to protect blueberry anthocyanins (An) from degradation by various physicochemical factors and the digestive process. We prepared a GO-COS complex to adsorb An and protect them from the destructive effects of their ambient environment. The complex protected the An under various temperature, pH, light, oxidant, and reductant conditions. We evaluated An content and composition in a simulated digestive system using the pH differential method and the high performance liquid chromatography-mass spectrometry (HPLC-MS). The GO-COS carrier stabilized An in the intestine and protected their peroxyl radical-scavenging capacity. Additionally, we observed a dose-response relationship between An content and cellular antioxidant activity, and simultaneous improvement of An bioavailability when the An were encapsulated in the complex. The complex inhibited HepG2 cell proliferation at the tested dose range. This study provides valuable information for stability of An-rich products.


Assuntos
Mirtilos Azuis (Planta) , Antocianinas/análise , Antioxidantes , Quitosana , Cromatografia Líquida de Alta Pressão , Digestão , Grafite , Oligossacarídeos , Extratos Vegetais
12.
J Pharm Biomed Anal ; 206: 114389, 2021 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-34601206

RESUMO

HKUST-1, a kind of metal-organic framework (MOF) composed by Cu2+ and trimesic acid, loaded on reduced graphene oxide and multi-walled carbon nanotubes nanocomposite [HKUST-1 @ (RGO-MWCNT)] was successfully synthesized by a facile and simple route. Then, a highly sensitive non-enzymatic salvianic acid A (SAA) electrochemical sensor was fabricated by modifying HKUST-1 @ (RGO-MWCNT) on a glassy carbon electrode, taking full advantage of the synergistic effect between the redox catalytic capacity of Cu2+ and the electrical conductivity of carbon materials. The sensor showed a low limit of detection of 0.081 µM, limit of quantitation of 0.27 µM, high sensitivity of 509.6 µA/mM and a good relationship between reduction peak current and concentration of SAA from 2 to 4600 µM. Meanwhile, the sensor had the advantages of repeatability and stability. Finally, it was used to detect SAA in real samples with noteworthy electroanalytical performance. In short, the sensor has considerable potential for the electroanalysis of SAA. Moreover, the study provides a promising composite of MOF and carbon materials with potential application in the analysis of effective components of herbaceous medicinal plants.


Assuntos
Grafite , Estruturas Metalorgânicas , Nanotubos de Carbono , Preparações Farmacêuticas , Técnicas Eletroquímicas
13.
Anal Chim Acta ; 1183: 338966, 2021 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-34627513

RESUMO

CircRNA is a type of covalently closed circular RNA molecule that serves as a potential biomarker for the disease early diagnosis and clinical researches. To achieve living cell imaging of specific circRNA, we developed a novel graphene oxide (GO)-based catalytic hairpin assembly (CHA) and hybridization chain reaction (HCR) signal dual amplification system (GO-CHA-HCR, abbreviated GO-AR) for circ-Foxo3 imaging in living cells. The developed system consists of four types of designed hairpin DNA HP1, HP2, H1, and fluorophore-labeled H2, which are absorbed on the GO nanosheets surface leading to fluorescence quenching. In the presence of circ-Foxo3, the CHA cycle was initiated to form a hybrid chain with split fragments, which triggered the HCR cycle to generate dsDNA nanowires that were then released from GO. This process recovered the quenched fluorescence, realizing two-stage signal amplification. The GO-AR system effectively improved the signal-to-noise ratio compared to the traditional GO-CHA and GO-HCR detection system. The detection limit of circ-Foxo3 was as low as 15 pM with excellent sensitivity and selectivity. In addition, the enzyme-free sensing system was successfully applied in living cell circRNA imaging and serum circRNA detection, indicating its high potential in clinical diagnostics.


Assuntos
Grafite , RNA Circular , DNA/genética , Hibridização de Ácido Nucleico
14.
Anal Chim Acta ; 1183: 338951, 2021 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-34627527

RESUMO

The simultaneous detection of multiple heavy metal ions in solution is an important yet highly challenging problem. In this work, a metal-free g-C3N4/carbon black (CB) composite electrode was synthesized by a one-step thermal polycondensation method and characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and ultraviolet visible light spectroscopy. In addition, the photoelectrochemical response of the g-C3N4/CB nanocomposite to Cd2+, Pb2+ and Hg2+ both separately and as a mixture of the three analytes was investigated by differential pulse anodic stripping voltammetry. The g-C3N4/CB electrode demonstrated an excellent sensing performance to Cd2+, Pb2+ and Hg2+ in the range of 0-700 nM, 0-300 nM and 0-500 nM, respectively, with limits of detection (LOD) of Cd2+, Pb2+, and Hg2+ of 2.1, 0.26 and 0.22 nM, respectively. The LOD of the combined solution of the three analytes was slightly higher at 3.3 nM. Additionally, the metal-free g-C3N4/CB photoelectrochemical sensor exhibited excellent electrochemical stability and electrode reproducibility. Finally, g-C3N4/CB sensor also showed satisfactory results in the detection of trace analyte ions in real environmental systems. This work provides a novel and promising approach in the simultaneous detection of multiple heavy metal ions in solution for practical applications.


Assuntos
Metais Pesados , Fuligem , Grafite , Íons , Compostos de Nitrogênio , Reprodutibilidade dos Testes
15.
Zhongguo Yi Liao Qi Xie Za Zhi ; 45(5): 492-496, 2021 Sep 30.
Artigo em Chinês | MEDLINE | ID: mdl-34628759

RESUMO

Atherosclerosis is a chronic inflammatory disease commonly seen in clinical practice. It can lead to thickening of vascular intima, occlusion of lumen stenosis and thrombosis, leading to angina pectoris, hypertension, myocardial infarction and other diseases, posing a serious threat to human life and health. This study provides a method for removing shield needles from graphene oxide thrombus and its preparation. The graphene oxide shield needle mainly includes flexible rotating shaft, radial flexible rod, rotating needle, adsorption main pipe and dosing main pipe, laser measuring device, high definition camera and other structures, which has the following advantages:firstly, it achieves multi-angle rotation grinding thrombosis, precise rotation grinding, avoids vascular damage and infection; secondly, thrombolytic drugs can be applied in the process of rotary grinding and small thrombus can be adsorbed to effectively avoid secondary embolization of blood vessels; thirdly, it a coating of graphene oxide on a rotating needle, which protects against bacteria and infection. This study has practical reference value for the development of thrombotherapy and the application of graphene in the medical field.


Assuntos
Grafite , Trombose , Adsorção , Humanos , Agulhas , Trombose/prevenção & controle
16.
Sensors (Basel) ; 21(19)2021 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-34640950

RESUMO

A sample of nitrogen and boron co-doped graphene (NB-Gr) was obtained by the hydrothermal method using urea and boric acid as doping sources. According to XRD analysis, the NB-Gr sample was formed by five-layer graphene. In addition, the XPS analysis confirmed the nitrogen and boron co-doping of the graphene sample. After synthesis, the investigation of the electro-catalytic properties of the bare (GC) and graphene-modified electrode (NB-Gr/GC) towards cymoxanil detection (CYM) was performed. Significant differences between the two electrodes were noticed. In the first case (GC) the peak current modulus was small (1.12 × 10-5 A) and appeared in the region of negative potentials (-0.9 V). In contrast, when NB-Gr was present on top of the GC electrode it promoted the transfer of electrons, leading to a large peak current increase (1.65 × 10-5 A) and a positive shift of the peak potential (-0.75 V). The NB-Gr/GC electrode was also tested for its ability to detect cymoxanil from a commercial fungicide (CURZATE MANOX) by the standard addition method, giving a recovery of 99%.


Assuntos
Grafite , Acetamidas , Boro , Nitrogênio
17.
Nano Lett ; 21(19): 8236-8243, 2021 10 13.
Artigo em Inglês | MEDLINE | ID: mdl-34597051

RESUMO

Graphene oxide (GO) is receiving tremendous attention in membrane separation; however, its desalination performances remain suboptimal because of excessive swelling and tortuous transport pathways. Herein, we chemically joint GO nanosheets and phenolic nanomeshes together to form laminated membranes comprising through-plane nanopores and stabilized nanochannels. GO and phenolic/polyether nanosheets are mixed to form stacked structures and then treated in H2SO4 to remove polyether to produce nanomeshes and to chemically joint GO with phenolic nanomeshes. Thus-synthesized laminated membranes possess enhanced interlayer interactions and narrowed interlayer spacings down to 6.4 Å. They exhibit water permeance up to 165.6 L/(m2 h bar) and Na2SO4 rejection of 97%, outperforming most GO-based membranes reported so far. Moreover, the membranes are exceptionally stable in water because the chemically jointed laminates suppress the swelling of GO. This work reports hybrid laminated structures of GO and phenolic nanomeshes, which are highly desired in desalination and other applications.


Assuntos
Grafite , Nanoporos , Membranas Artificiais , Água
18.
Nanoscale ; 13(34): 14316-14329, 2021 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-34477715

RESUMO

Non-invasive liquid biopsies offer hope for a rapid, risk-free, real-time glimpse into cancer diagnostics. Recently, hydrogen peroxide (H2O2) was identified as a cancer biomarker due to its continued release from cancer cells compared to normal cells. The precise monitoring and quantification of H2O2 are hindered by its low concentration and the limit of detection (LOD) in traditional sensing methods. Plasmon-assisted electrochemical sensors with their high sensitivity and low LOD make a suitable candidate for effective detection of H2O2, yet their electrical properties need to be improved. Here, we propose a new nanostructured microfluidic device for ultrasensitive, quantitative detection of H2O2 released from cancer cells in a portable fashion. The fluidic device features a series of self-organized gold nanocavities, enhanced with graphene nanosheets having optoelectrical properties, which facilitate the plasmon-assisted electrochemical detection of H2O2 released from human cells. Remarkably, the device can successfully measure the released H2O2 from breast cancer (MCF-7) and prostate cancer (PC3) cells in human plasma. Briefly, direct amperometric detection of H2O2 under simulated visible light illumination showed a superb LOD of 1 pM in a linear range of 1 pM-10 µM. We thoroughly studied the formation of self-organized plasmonic nanocavities on gold electrodes via surface and photo-electrochemical characterization techniques. In addition, the finite-difference time domain (FDTD) simulation of the electric field demonstrates the intensity of charge distribution at the nanocavity structure edges under visible light illumination. The superb LOD of the proposed electrode combining gold plasmonic nanocavities and graphene sheets paves the way for the development of non-invasive plasmon-assisted electrochemical sensors that can effectively detect low concentrations of H2O2 released from cancer cells.


Assuntos
Grafite , Neoplasias , Técnicas Eletroquímicas , Ouro , Humanos , Peróxido de Hidrogênio , Dispositivos Lab-On-A-Chip , Neoplasias/diagnóstico
19.
Nanoscale ; 13(30): 13072-13084, 2021 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-34477791

RESUMO

Graphdiyne oxide (GDYO) is a carbon-based nanomaterial possessing sp2 and sp-hybridized carbon atoms with many promising applications. However, its biocompatibility and potential biodegradability remain poorly understood. Using human primary monocyte-derived macrophages as a model we show here that GDYO elicited little or no cytotoxicity toward classically activated (M1) and alternatively activated (M2) macrophages. Moreover, GDYO reprogrammed M2 macrophages towards M1 macrophages, as evidenced by the elevation of specific cell surface markers and cytokines and the induction of NOS2 expression. We could also show inducible nitric oxide synthase (iNOS)-dependent biodegradation of GDYO in M1 macrophages, and this was corroborated in an acellular system using the peroxynitrite donor, SIN-1. Furthermore, GDYO elicited the production of pro-inflammatory cytokines in a biodegradation-dependent manner. Our findings shed new light on the reciprocal interactions between GDYO and human macrophages. This is relevant for biomedical applications of GDYO such as the re-education of tumor-associated macrophages or TAMs.


Assuntos
Grafite , Óxidos , Citocinas , Humanos , Macrófagos , Óxido Nítrico Sintase Tipo II/genética
20.
Anal Chim Acta ; 1178: 338788, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34482861

RESUMO

Phenol is a common pollutant found in wastewater, and its allowable discharge limit is 0.5 parts-per-million (ppm). Therefore, it is critical to monitor phenol in the sub-ppm range with high sensitivity and a low limit of detection. Herein, we report a quantitative method for detecting phenol in industrial wastewater through square wave voltammetry (SWV), in which phenol is oxidized to phenoxyl radicals and then became catechol and hydroquinone for detection. By using this method, phenol in the sub-ppm range can be detected reliably over a wide pH range. The sensitivity can be further improved by using a pre-concentration step for phenol before scanning. The method has a limit of detection of 0.1 ppb for phenol. Finally, three graphite electrodes were applied as working, counter and reference electrodes, respectively, in a millifluidic device for continuous detection of phenol in industrial wastewater flowing at 300 µL/min. Because of its simplicity, the sensor can be mass-produced and deployed on a large scale to monitor phenol in industrial wastewater.


Assuntos
Grafite , Fenol , Eletrodos , Fenol/análise , Fenóis , Águas Residuárias
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