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1.
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
2.
J Environ Sci (China) ; 125: 26-36, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36375912

RESUMO

Herein, a one-step co-pyrolysis protocol was adopted for the first time to prepare a novel pyrogenic carbon-Cu0/Fe3O4 heteroatoms (FCBC) in CO2 ambiance to discern the roles of each component in PDS activation. During co-pyrolysis, CO2 catalyzed formation of reducing gases by biomass which facilitated reductive transformation of Fe3+ and Cu2+ to Cu0 and Fe3O4, respectively. According to the analysis, the resulting metal (oxide) catalyzed graphitization of biocharand decomposition of volatile substances resulting in an unprecedented surface area (1240 m2/g). The resulting FCBC showed greater structural defects and less electrical impedance. Batch experiments indicated that Rhodamine B (RhB) degradation by FCBC (100%) was superior to Fe3O4 (50%) and Cu0/Fe3O4 (76.4%) in persulfate (PDS) system, which maintained reasonable efficiency (75.6%-63.6%) within three cycles. The reactive oxygen species (ROS) associated with RhB degradation was identified by an electron paramagnetic resonance and confirmed by scavenging experiments. RhB degradation invoked both (sulfate and dominantly hydroxyl) radical and non-radical (singlet oxygen, 1O2) pathways. Regarding FCBC, Cu0 can continuously react with Fe3+ in Fe3O4 to generate larger quantities of Fe2+, and both Cu0 and Fe2+ activated PDS to yield sulfate radicals which was quickly converted to hydroxyl radical. Besides, Cu0/Cu2+ could complex with PDS to form a metastable complex, which particularly contributed to 1O2 generation. These cascade reactions by FCBC were reinforced by carbonyl group of biochar and favorable electron transfer ability. This work highlighted a new approach to prepare a magnetic and environment-benign heterogonous catalyst to remove organic pollutants in water.


Assuntos
Grafite , Pirólise , Dióxido de Carbono , Carvão Vegetal/química , Sulfatos/química , Radical Hidroxila
3.
Talanta ; 251: 123755, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-35932635

RESUMO

We report a new sensitive label-free electrochemical immunosensor to detect Vitamin D3 (25-OHD3) in untreated serum samples. To this aim, a graphite screen printed electrode (SPE) was modified using cysteamine (CYM) functionalized core-shell magnetic nanoparticles (Au@MNPs) then, the 25-OHD3 antibody (AbD) was immobilized via glutaraldehyde crosslinking. The several steps involved in the immunosensor development and 25-OHD3 analysis were monitored by using differential pulse voltammetry (DPV). The developed immunosensor showed a LOD of 2.4 ng mL-1 and a linear range between 7.4 and 70 ng mL-1. The effectiveness of the immunosensor in human serum analysis was assessed by comparing the results obtained with the chemiluminescence-immunoassay (CLIA) reference method. The high sensitivity and excellent agreement with the reference method suggest its potential use as a POCT to monitor hypovitaminosis 25-OHD levels.


Assuntos
Técnicas Biossensoriais , Grafite , Nanopartículas Metálicas , Técnicas Biossensoriais/métodos , Colecalciferol , Cisteamina , Técnicas Eletroquímicas/métodos , Eletrodos , Glutaral , Ouro , Humanos , Imunoensaio/métodos , Limite de Detecção
4.
Talanta ; 251: 123758, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-35940113

RESUMO

Metronidazole is a well-known antimicrobial drug that belongs to the nitroimidazole family of antibiotics. It has been widely used in the treatment of infections, but its accumulation in aquatic environments is an emerging concern. In this study a glassy carbon electrode was modified with graphene (Gr) nanoplatelets and bismuth. Both the Gr and Bi were electrochemically deposited onto the glassy carbon and the modified electrode was employed in the electrochemical detection of metronidazole. At the modified electrode, the reduction of metronidazole was found to be an adsorption-controlled reaction. The optimised sensor, which was fabricated within 6 min, exhibited good selectivity in the presence of various inorganic and organic compounds, good recovery in tap water, and exhibited a linear calibration curve extending from 0.005 to 260 µM, with a limit of detection of 0.9 nM. The sensor was easily regenerated through the simple oxidation of the Bi deposit followed by a 100 s reduction period in the Bi(III) solution to give a newly generated surface. Good reproducibility was achieved using this simple regeneration approach.


Assuntos
Anti-Infecciosos , Grafite , Antibacterianos , Bismuto , Carbono/química , Técnicas Eletroquímicas , Eletrodos , Galvanoplastia , Grafite/química , Metronidazol , Regeneração , Reprodutibilidade dos Testes , Água
5.
Talanta ; 251: 123812, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-35961083

RESUMO

This study describes the development of electrochemical paper-based analytical devices (ePADs) using carbon-based paste combining silicone glue and graphite powder. The ePADs were manufactured using the screen-printing technique, which consisted of depositing the conductive ink on a screencast on the paper surface. In addition, an alternative electrical connector was designed and 3D-printed to make the detection method cheaper, portable and reproducible. The morphological, structural, and electrochemical properties of the conductive material developed were investigated through scanning electron microscopy (SEM), Raman spectroscopy, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) measurements. The ePADs combined with the alternative connector revealed high repeatability, reproducibility, and stable responses considering a well-known redox probe ([Fe(CN)6]4-/3-). In addition, the proposed ePAD provided a linear response for standard solutions of ascorbic acid (AA) in the concentration range between 0.1 and 2.0 mmol L-1. The achieved limit of detection was 4.0 µmol L-1. As proof of applicability, the ePADs were evaluated for AA analysis in synthetic biofluids (blood plasma and urine), vitamin C tablets, and food (gelatine and orange juice) samples. The analytical parameters of the proposed device were compared with other reports in the literature and exhibited similar or even superior performance, highlighting its feasibility for sensing applications.


Assuntos
Grafite , Ácido Ascórbico , Carbono/química , Técnicas Eletroquímicas/métodos , Eletrodos , Grafite/química , Tinta , Pós , Reprodutibilidade dos Testes , Silicones , Comprimidos
6.
Talanta ; 251: 123783, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-35977451

RESUMO

The current approaches of diagnostic platforms for detecting SARS-CoV-2 infections mostly relied on adapting the existing technology. In this work, a simple and low-cost electrochemical sensing platform for detecting SAR-CoV-2 antigen was established. The proposed sensor combined the innovative disposable paper-based immunosensor and cost-effective plant-based anti-SARS-CoV-2 monoclonal antibody CR3022, expressed in Nicotiana benthamiana. The cellulose nanocrystal was modified on screen-printed graphene electrode to provide the abundant COOH functional groups on electrode surface, leading to the high ability for antibody immobilization. The quantification of the presence receptor binding domain (RBD) spike protein of SARS-CoV-2 was performed using differential pulse voltammetry by monitoring the changing current of [Fe(CN)6]3-/4- redox solution. The current change of [Fe(CN)6]3-/4- before and after the presence of target RBD could be clearly distinguished, providing a linear relationship with RBD concentration in the range from 0.1 pg/mL to 500 ng/mL with the minimum limit of detection of 2.0 fg/mL. The proposed platform was successfully applied to detect RBD in nasopharyngeal swab samples with satisfactory results. Furthermore, the paper-based immunosensor was extended to quantify the RBD level in spiked saliva samples, demonstrating the broadly applicability of this system. This electrochemical paper-based immunosensor has the potential to be employed as a point-of-care testing for COVID-19 diagnosis.


Assuntos
Técnicas Biossensoriais , COVID-19 , Grafite , Anticorpos Monoclonais/química , Anticorpos Neutralizantes , Anticorpos Antivirais , Técnicas Biossensoriais/métodos , COVID-19/diagnóstico , Teste para COVID-19 , Celulose , Técnicas Eletroquímicas/métodos , Grafite/química , Humanos , Imunoensaio/métodos , SARS-CoV-2 , Glicoproteína da Espícula de Coronavírus
7.
Talanta ; 251: 123791, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-35987023

RESUMO

Due to their fascinating chemical, optical, electrical, and biological properties carbon dots (CDs or CDots), carbon quantum dots (CQDs), and graphene quantum dots (GQDs) have attracted attention in biosensing as they can greatly improve the detection limit, sensitivity, and selectivity of biosensors. In general, CDs, CQDs, and GQDs are a class of carbon-based nanomaterials that are characterized by extraordinary fluorescence, a size less than 10 nm, high stability, low toxicity, and being easy to synthesize and presenting functional groups in their surface area that vary according to their synthesis source. In this review, a general description of the main methods and precursors reported in the scientific literature for the synthesis of CDs, CQDs, and GQDs are presented, as well as the chemical, optical, electrical, and biological properties that stand out the most from them; moreover, the main objective of this review is to summarize the application of these carbonaceous nanomaterials in biosensors for the detection of communicable and non-communicable diseases. The article summarizes the applications of CDs, CQDs, and GQDs according to the group of diseases they detected using the international classification of diseases in its 10th edition (ICD-10). To facilitate the reader's access to significant information from these biosensors, several tables summarize the information associated with the type of biomarker, the working ranges, and the biosensor assembly.


Assuntos
Técnicas Biossensoriais , Grafite , Doenças não Transmissíveis , Pontos Quânticos , Biomarcadores , Técnicas Biossensoriais/métodos , Carbono/química , Grafite/química , Humanos , Pontos Quânticos/química
8.
J Colloid Interface Sci ; 629(Pt A): 582-592, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36088703

RESUMO

Photothermal responsive slippery surfaces with switchable superwettability are promising in the fields of biomedicine, self-cleaning, anti-corrosion, and lab-on-a-chip systems. However, the development of a light switchable slippery surface that combines high-performance photothermal materials with hierarchical microstructures of special orientation remains challenging, which limits the applications in anisotropic droplet manipulation. Herein, we demonstrate a photothermal responsive slippery surface based on laser-structured graphene and polyvinylidene difluoride composites (L-G@PVDF) for controllable droplet manipulation. The L-G@PVDF film exhibits high light absorption (∼95.4%) in the visible and NIR region. After lubricating with paraffin, the resultant surface shows excellent self-healing ability and light-responsive wettability change due to the photothermal effect of L-G@PVDF and the hot melting effect of paraffin. Additionally, by introducing anisotropic grooved structures, the paraffin-infused L-G@PVDF surface displays anisotropic wettability that further affects droplet manipulation under light irradiation. Also, the photothermal responsive slippery property endows the paraffin-infused L-G@PVDF surface with excellent anti-frosting and de-icing capability. Moreover, the smart paraffin-infused L-G@PVDF surface can be combined with a microfluidics chip for light-driven automatic sampling. This study offers insight into the rational design of photothermal responsive slippery surfaces for controllable droplet manipulation.


Assuntos
Grafite , Grafite/química , Parafina , Molhabilidade , Lasers
9.
J Colloid Interface Sci ; 629(Pt A): 908-915, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36150268

RESUMO

In recent years, flexible electronic devices have great application potential in the fields of healthcare, VR virtual reality, electronic skin and intelligent robots. However, electronic devices fail during operation due to fatigue, corrosion or damage, making it difficult and expensive to maintain highly integrated portable/wearable electronic devices. In this study, highly healable, flame retardant, shape memorized supramolecular PTAZ/GO was fabricated by restricting the crosslinking of zinc ions, carboxyl graphene and poly-(thioctic acid) via self-polymerization in ethanol inducing self-assembly. The rich carboxyl groups associated with hydroxyl and disulfide groups in the system provide excellent self-healing efficiency and shape memory properties for supramolecular ionomers. The results of a microscale combustion calorimeter (MCC) test in this study showed a 65.3 % reduction in the peak heat release rate (pHRR) for ionomers compared to pure polymer, thus implying that ionic coordination cross-linking and GO nanosheets are beneficial for improving the fire safety of the materials. For the shape-memory device, the supramolecular elastomers can switch LED lights on and off by changing the shape, and the conductivity can be restored after reconnection of two damaged parts. Thus, the proposed materials have wide applications in electronic engineering.


Assuntos
Retardadores de Chama , Grafite , Ácido Tióctico , Etanol , Elastômeros , Polímeros , Eletrônica , Íons , Dissulfetos , Zinco
10.
J Colloid Interface Sci ; 630(Pt A): 127-139, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36228343

RESUMO

Herein, PDI-g-C3N4/g-C3N4 homojunction has been fabricated via the multiscale modification strategy to enhance photocatalytic atrazine degradation. The morphological scale modification was realized by multistep thermal condensation, where the released gas could act as templates to form the porous structure. The molecular scale modification was achieved by the pyromellitic diimide (PDI) decoration, which could distort the planar nanosheet to induce a porous structure and provide more chromophores for better light absorption. The electronic scale modification was realized by the built-in electric field between the PDI-g-C3N4/g-C3N4 homojunction interfaces, which suppressed the recombination of photocarriers. The PDI-g-C3N4/g-C3N4 strengthened photocatalytic atrazine degradation was well-adapted to different environmental influence interference. The optimum atrazine degradation rate within one hour reached 90% in a strong acidic condition (pH = 3.09). It was found that the highly pH-dependent ATZ removal is related to the H2O2 generation during photocatalysis. Within one hour, the PDI-g-C3N4/g-C3N4 could generate 147.38 µM H2O2. In addition, 1O2, ·O2-, h+, and ·OH were found to have contributed to the ATZ decomposition. During photocatalysis, 14 intermediates and three pathways for atrazine degradation have been found. Hopefully, this study could pave a way for the development of the multiscale modification for the photocatalyst.


Assuntos
Atrazina , Grafite , Catálise , Grafite/química , Peróxido de Hidrogênio
11.
J Hazard Mater ; 443(Pt A): 130178, 2023 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-36252404

RESUMO

The development of efficient and eco-friendly Mn-based hybrids for the degradation of biorefractory organic pollutants via peroxymonosulfate (PMS) activation is highly desired. In this study, a novel graphite nanosheet (GNs)-based Fe-Mn bimetallic oxide (Fe doped birnessite MnO2, FeMn/GNs) was synthesized under mild conditions. Compared with monometallic Fe or Mn oxide on GNs, FeMn/GNs exhibited a higher surface area, decreased Mn oxidation states, stronger interaction with GNs, and more active sites for PMS adsorption. Among different Fe/Mn ratios, Fe2Mn1/GNs showed the optimum performance for bisphenol A (BPA) degradation with the first-order rate constant of 0.22 min-1, which was about 8.5 and 12.9 times higher than that of Mn/GNs and Fe/GNs, respectively. Different from the pollutant-catalyst-PMS electron transfer mechanism for Mn/GNs, the direct two-electron transfer in FeMn/GNs+PMS system, was mainly processed between the simultaneously activated BPA and PMS. This was probably based on the double adsorption sites of Fe and Mn species on the same catalyst: PMS was adsorbed by Fe species through hydroxyl groups, while BPA was mainly coordinated with Mn species due to the layered structure and hydrophobicity of the Mn oxide. This study is expected to provide the rational design of efficient Mn-based hybrids for PMS activation.


Assuntos
Poluentes Ambientais , Grafite , Óxidos , Poluentes Ambientais/química , Compostos de Manganês , Elétrons , Peróxidos/química , Grafite/química , Compostos Orgânicos
12.
J Hazard Mater ; 443(Pt A): 130204, 2023 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-36308934

RESUMO

In this study, a novel iron-encapsulated biochar (Fe@BC) was prepared using the biomass cultivated with an iron-containing solution. The iron in Fe@BC showed the phase change from Fe3O4 to α-Fe, and to CFe15.1, with the increase of pyrolysis temperature (500-900 °C), and a graphene shell formed on the surface of Fe@BC. In addition, the signals assigned to the π-π* shake up, pyridinic N, graphitic N, and defects of Fe@BC were found to be stronger as the pyrolysis temperature increased. The F4@B9 sample, which was prepared at 900 °C, exhibited an excellent performance (98.01 %) to activate peroxydisulfate (PDS) for the degradation of 2,4-dichlorophenol. Electron paramagnetic resonanceand chemical quenching experiments revealed that reactive oxygen radicals (ROS) including sulfate radical (•SO4-), hydroxyl radical (•OH), superoxide radical (•O2-), and singlet oxygen (1O2) existed in the F4@B9/PDS system. Furthermore, the micro-electrolysis process facilitated the generation of •O2- (12.35 %) and 1O2 (6.49 %) compared with the pure PDS system. Density functional theory revealed that, for the F4@B9-activated PDS process, the graphene shell of F4@B9 served as catalytic active sites as well. According to the correlation analysis, the iron specie of CFe15.1 was more favorable for the generation of ROS than α-Fe. Also, π-π* shake up, pyridinic N, graphitic N, and defects participated in the PDS activation. This study provides a new method for the preparation of high-performance catalysts from naturally grown biomass with high iron contents.


Assuntos
Grafite , Ferro , Ferro/química , Espécies Reativas de Oxigênio , Elétrons , Biônica , Carvão Vegetal/química
13.
J Pharm Biomed Anal ; 222: 115084, 2023 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-36183576

RESUMO

Alzheimer's disease (AD) is one of the most common types of neurodegenerative disorders. It is possible to identify AD early thanks to the measurement of specific biomarker levels. Owing to crucial roles of biomarkers in the AD, the detection of AD-related biomarkers may be suitable for predictive identification of AD. Biosensors is a novel tool that could be beneficial to appreciate recognition of several AD biomarkers as early as possible. Graphene and its derivatives containing graphene oxide (GO) and reduced-GO (rGO) can be good choice for biosensing approaches due to their unique properties. GO/rGO-based biosensors or nanosensors have been widely used for the determination of AD biomarkers. In this article, the general aspects of AD, its biomarkers, biosensors, and GO are overviewed. In addition, this review provides the current developments in the applications of graphene-based biosensors for recognition of AD biomarkers. Future perspectives and challenges of graphene-based biosensing as a new approach for detection of AD are discussed in brief as well.


Assuntos
Doença de Alzheimer , Técnicas Biossensoriais , Grafite , Humanos , Doença de Alzheimer/diagnóstico , Biomarcadores
14.
Food Chem ; 403: 134302, 2023 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-36162261

RESUMO

Toxicosis through food and feed has remained a point of concern to food sectors across the globe. Although strict regulations have been implemented in developed and developing countries, their detection in food matrices is an evolving science. This study focuses on the development and fabrication of an electrochemical microfluidic biosensor that deploys aptamers to detect trace concentrations of Aflatoxin-M1 (AF-M1) in milk samples. The use of graphene quantum dot composite with Au nanoparticles anchors the aptamer to the sensor surface and improves its signal conductivity. The screen-printed carbon electrode modified with graphene quantum dot-gold nanoparticles is placed between two polydimethylsiloxane layers to promote portability and improve mixing effects. Differential pulse voltammograms indicated that the linear range of the sensor was between 100 pM and 2 nM making the limit of detection 0.3 nM. Interfering molecules of similar size were analyzed, to evaluate sensor selectivity.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Grafite , Nanopartículas Metálicas , Pontos Quânticos , Ouro/química , Grafite/química , Aflatoxina M1/química , Pontos Quânticos/química , Aptâmeros de Nucleotídeos/química , Nanopartículas Metálicas/química , Técnicas Eletroquímicas , Limite de Detecção
15.
Food Chem ; 403: 134394, 2023 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-36179633

RESUMO

A rapid and efficient method based on a novel nitrogen-doped porous graphene nanostructure (NDPG) was used for the speciation of mercury in water and human blood samples by the CV-AAS. The mixture of the NDPG, ionic liquid, and acetone was rapidly injected into the human blood, water, and food samples for mercury separation by the cloud point assisted dispersive ionic liquid-micro solid-phase extraction (CPA-DIL-µ-SPE) at pH 7.5. The UV-microwave accessory converted the organic mercury (R-Hg) to inorganic mercury, and total mercury (TM) was determined. Finally, the organic mercury was calculated by subtracting the inorganic and entire mercury contents. By optimizing, the linear range, LOD, and enrichment factor were obtained (0.01-6.80 µg/L; 0.005-3.60 µg/L), (2.6 ng/L; 1.2 ng/L) and (9.8; 20.2) for the mercury species in human blood and water/food samples, respectively (Mean of RSD < 1.9 %). The CRM samples obtained the validation of the procedure.


Assuntos
Grafite , Líquidos Iônicos , Mercúrio , Nanoestruturas , Humanos , Mercúrio/química , Água/química , Líquidos Iônicos/química , Nitrogênio , Porosidade , Pirróis
16.
Chemosphere ; 310: 136759, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36228729

RESUMO

In this work, graphene oxide (GO) sheets were prepared via a facile electrochemical exfoliation of graphite in acidic medium and subsequent oxidation with potassium permanganate. The GO sheets were employed for preparation of reduced GO adorned with nanosized silver (rGO/Ag NPs) using green reduction of GO and Ag(I) via olive fruit extract as a reducing and immobilizing agent. The crystal phase, morphology, and nanostructure of the prepared catalyst were characterized by XRD, SEM, EDX, UV-Vis and Raman spectroscopy techniques. The as-prepared rGO/Ag NPs showed superior catalytic performance towards the complete reduction (up to 99%) of 4-nitrophenol (4-NPH) to 4-aminophenol (4-APH) and rhodamine B (RhB) to Leuco RhB within 180 s using NaBH4 at ambient condition. The rate constant (k) values were found to be 0.021 and 0.022 s-1 for 4-NPH and RhB reduction, respectively. In addition, the regenerated catalyst could be reused after seven cycles without losing any apparent catalytic efficiency. Accounting for the excellent catalytic capability, chemical stability and environment-friendly synthesis protocol, the rGO/Ag NPs has great potential working as a heterogeneous catalyst in the transforming harmful organic contaminants into less harmful or harmless compounds.


Assuntos
Poluentes Ambientais , Grafite , Nanopartículas Metálicas , Olea , Grafite/química , Prata/química , Nanopartículas Metálicas/química
17.
Chemosphere ; 310: 136900, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36265713

RESUMO

Carboxylated graphene oxide (C-GO) embedded in polysulfone (PSF) membrane composites were prepared with different wt. % (i.e., 0.2% M - 1, 0.3% M - 2, 0.4% M - 3, and 0.5% M - 4) using non-solvent induced phase separation (NIPS) method and ultrafiltration assembly was applied for the removal of dye effluents. The optimization of C-GO content into polymer matrix was found influencing factor in determining the composite membranes efficiency and application in various research fields. The membranes were characterized in terms of surface morphology (SEM), crystallinity (XRD), and functional groups identification (FTIR). The water permeability of the developed membranes was analyzed, and it is observed that increasing the content of C-GO in PSF membranes imposed a positive impact on permeation performance. M - 3 was found to be a potential candidate among all the membranes with a maximum water flux of about 183 LMH which is considerably higher as compared to the pristine PSF membrane's water flux (i.e., 27 LMH). Moreover, contact angle measurements of membranes were also checked to assess the hydrophilicity of PSF membranes. The results of contact angle also support the water permeability and efficient correlation was observed as contact angle decreases with increasing the content of C-GO. The minimum contact angle with excellent hydrophilicity was shown by the M - 3 membrane and it was found of about ±58.19° and this value is close to the M - 4 membrane having maximum C-GO content. The photocatalytic performance of the M - 3 membrane was checked under UV-254 nm using methylene blue dye and 97% dye removal was achieved within 220 min of reaction time under neutral pH conditions. The M - 3 membrane having C-GO content of 0.4% was found to be the best membrane with high pure water flux (183 LMH) and efficient dye rejection (82%) capability.


Assuntos
Grafite , Membranas Artificiais , Polímeros , Água
18.
Talanta ; 252: 123764, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-35969927

RESUMO

The external acid environment of cancer cells is different from that of normal cells, making a profound impact on cancer progression. Here we report a simple poly-l-lysine-modified graphene field-effect transistor (PLL@G-FET) for in situ monitoring of extracellular acidosis around cancer cells. PLL is a well-known material with good biocompatibility and is rich in amino groups that are sensitive to hydrogen ions. After a simple drop-casting of PLL on the reduced graphene oxide (RGO) FET surface, the PLL@G-FET was able to realize the real-time monitoring of the localized pH change of cancer cells after the cancer cells were grown on the device. The PLL@G-FET sensor achieved a Nernstian value of 52.9 mV/pH in phosphate buffer saline from pH 4.0 to 8.0. In addition, the sensor exhibited excellent biocompatibility as well as good anti-interference ability in the cell culture medium. Furthermore, the device was used to real-time monitor the extracellular pH changes of MCF-7 cells under the intervention of different concentrations of drugs. This developed pH-sensitive FET provides a new method to study the extracellular acid environment in situ and helps us to enhance our understanding of cancer cell metabolism.


Assuntos
Técnicas Biossensoriais , Grafite , Neoplasias , Humanos , Transistores Eletrônicos , Técnicas Biossensoriais/métodos , Grafite/toxicidade , Células MCF-7 , Concentração de Íons de Hidrogênio
19.
Talanta ; 252: 123836, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-35985191

RESUMO

A glassy carbon electrode was modified with nitrogen and sulfur co-doped graphene quantum dots immobilized in chitosan for the monitoring of multivitamins. The graphene quantum dots were synthesized using a simple citric acid/l-cysteine pyrolysis procedure. The co-doping with nitrogen and sulfur in the graphene matrix was confirmed by spectroscopic techniques. Electron microscopy results showed that the synthesized quantum dots had a diameter of 3.4 ± 1.4 nm. Electrochemical techniques showed excellent current responses to vitamin oxidation provided by the modified electrode compared to the bare electrode. The parameters of square wave voltammetry were optimized in order to obtain the best current responses and to study the electrochemical oxidation of vitamins. The calibration plots for vitamins B2, B6 and B12 were constructed in 0.1 mol L-1 sodium acetate buffer (pH 5.0) with limits of detection of 0.30, 30.1 and 0.32 nmol L-1, respectively. Lastly, the modified electrode was effectively implemented in the quantification of vitamins in classic and fruit-based energy drink samples.


Assuntos
Bebidas Energéticas , Grafite , Pontos Quânticos , Grafite/química , Pontos Quânticos/química , Nitrogênio/química , Eletrodos , Técnicas Eletroquímicas/métodos , Vitaminas , Enxofre , Limite de Detecção
20.
Anal Biochem ; 660: 114953, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-36243135

RESUMO

Human papillomaviruse type 16 (HPV16) is a high-risk serotype. As the main protective antigen protein, L1 protein is also the target protein for diagnosis. A simple label free electrochemical immunosensor (ECIS) was fabricated for ultrasensitive detection of HPV16 L1 protein in this work. Quasi-spherical Ag@Au core-shell nanoparticles on graphene oxide (Ag@AuNPs-GO) was developed as current response amplifier and characterized by UV-Vis Spectroscopy, Transmission Electron Microscopy and energy dispersive X-ray spectroscopy. Staphylococcal protein A was decorated on the modified electrode and utilized to immobilized the Fc portion of the monoclonal antibody specific for HPV16 L1 protein. Cyclic Voltammetry, Differential Pulse Voltammetry and Electrochemical Impedance Spectroscopy were used to verify the electrochemical performance and interfacial kinetic property. The increased concentration of HPV16 L1 protein led to slow electron transport and linearly decreased differential pulse voltammetry peak current with a detection limit of 0.002 ng mL-1 and a wide linear relationship in the range of 0.005-400 ng mL-1at a regression coefficient (R2) of 0.9948. Furthermore, this ECIS demonstrated acceptable accuracy with good reproducibility, stability and selectivity, suggesting a promising immunological strategy for HPV typing and early screening.


Assuntos
Alphapapillomavirus , Técnicas Biossensoriais , Grafite , Nanopartículas Metálicas , Humanos , Ouro/química , Técnicas Biossensoriais/métodos , Nanopartículas Metálicas/química , Imunoensaio/métodos , Reprodutibilidade dos Testes , Grafite/química , Técnicas Eletroquímicas/métodos , Limite de Detecção
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