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1.
Talanta ; 206: 120204, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31514833

RESUMO

As a rapid and facile means for foodborne bacteria detection in situ, lateral flow immunoassay (LFA) still has intrinsic limitations in the construction of the existing sandwich LFA format, e.g. screening difficulties of paired antibodies (Abs), poor stability of Ab probe, etc. Here, combined the strong affinity of antibiotic with the superior specificity of antibody molecules, a novel and robust LFA based on a dual recognition strategy and magnetic separation was designed to achieve specific and sensitive determination of Salmonella enteritidis (S. enteritidis). In this work, ampicillin (Amp), a broad-spectrum antibiotic against bacteria, was employed as an ideal Ab replacer to anchor cells of target bacteria. By coating Amp on magnetite nanoparticles (MNPs), the Amp-MNPs showed remarkable binding, separation and enrichment capacities toward bacteria even under complex sample matrices. To ensure the selectivity of this protocol, anti-S. enteritidis monoclonal antibody was then adopted as the second anchoring agent to form a sandwich complex with Amp-MNPs. Based on these facts, S. enteritidis, as low as 102-103 CFU/mL, could be detected by naked eyes in food samples. Therefore, this creative antibiotic-bacteria-antibody LFA sandwich pattern shows great application potential in the monitoring of food contamination and infectious diseases caused by pathogenic bacteria. Compared to the common paired Abs based sandwich method, the proposed approach was cost-effective, non-labor intensive, stable, sensitive and efficient.

2.
Inorg Chem ; 58(17): 11382-11388, 2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31402664

RESUMO

Enzyme-like metal-organic frameworks (MOFs) are currently one type of starring material in the fields of artificial enzymes and analytical sensing. However, there has been little progress in making use of the MOF structures based on the catalytically active metal center with multiple valences. Herein, we report a mixed-valence Ce-MOF (Ce-BPyDC) that can exhibit both oxidase-like and peroxidase-like activities. Ce-BPyDC was synthesized by a facile hydrothermal method, which preserves the rare coexistence of Ce(III) and Ce(IV) in the MOF structure. The enzymatic studies demonstrated the enzyme-like activities of Ce-BPyDC follow the Michaelis-Menten kinetics and are strongly dependent on temperature, pH, and reaction time. Ce-BPyDC was also revealed to exert high catalytic activity that could transcend horseradish peroxidase and other MOF nanozymes, due to the redox-active Ce(III)/Ce(IV) cycles inside. Furthermore, the simple synthesis, high nanozyme activity, and great stability of Ce-BPyDC motivated us to establish a colorimetric biosensing platform using 3,3',5,5'-tetramethylbenzidine as a color reagent. Adopting this strategy, we established a visual, sensitive, and selective colorimetric method for ascorbic acid (AA) detection, for which the linear interval and limit of detection were 1-20 and 0.28 µM, respectively. The successful AA detection in real juice samples implies the promising use of such mixed-valence MOF nanozymes in food and biomedical samples.


Assuntos
Técnicas Biossensoriais , Cério/química , Colorimetria , Estruturas Metalorgânicas/química , Ácido Ascórbico/análise , Catálise , Concentração de Íons de Hidrogênio , Estruturas Metalorgânicas/síntese química , Temperatura Ambiente
3.
ACS Appl Mater Interfaces ; 11(32): 29177-29186, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31317741

RESUMO

The high sensitivity and long-term storage stability of a plasmonic substrate are vital for practical applications of the surface-enhanced Raman scattering (SERS) technique in real-world analysis. In this study, a rationally designed, ternary film-packaged, silver-coated gold-nanoparticle (Au@Ag NP) plasmonic array was fabricated and applied as a stable and high-performance SERS chip for highly sensitive sensing of thiabendazole (TBZ) residues in fruit juices. The ternary films played different roles in the plasmonic chip: a newborn poly(methyl methacrylate) (PMMA) film serving as a template for fixing the self-assembled closely packed monolayer Au@Ag NP array that provided an intensive hot spot, a fluorescent quantitative polymerase chain reaction adhesive film (qPCR film) acting as a carrier to retrieve the Au@Ag/PMMA film that was used to improve the robustness of the plasmonic array, and a polyethylene terephthalate (PET) film covered over the Au@Ag/PMMA/qPCR film performing as a barrier to improve the stability of the chip. The Au@Ag/PMMA/qPCR-PET film chip showed high sensitivity with an enhancement factor of 3.14 × 106, long-term storage stability without changing SERS signals for more than 2 months at room temperatures, and a low limit of detection for sensing TBZ in pear juice (21 ppb), orange juice (43 ppb), and grape juice (69 ppb). In addition, the procedure for fabricating the Au@Ag/PMMA/qPCR-PET film SERS chip was easy to handle, offering a new strategy to develop flexible and wearable sensors for on-site monitoring of chemical contaminants with a portable Raman spectrometer in the future.

4.
Nanoscale ; 11(19): 9468-9477, 2019 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-31044197

RESUMO

Numerous infectious diseases that cause clinical failures and relapses after antibiotic therapy have been confirmed to be induced by pathogenic intracellular bacteria. The existing therapeutic strategies fail to eliminate intracellular bacteria mainly due to a guard reservoir provided by the cell membrane, which can deactivate antibiotics. Herein, we have reported the design of a pH-responsive metal organic framework (MOF)/antibiotic synergistic system for the targeted highly efficient elimination of intracellular bacteria. The obtained tetracycline (Tet)@ZIF-8@ hyaluronic acid (HA) system (abbreviated to TZH) can be taken up by cells owing to the presence of CD44 receptors on the cell surface via an HA-mediated pathway. Zinc ions and antibiotics, released from TZH under acidic conditions caused by bacteria, have a synergistic antibacterial effect both in vitro and in vivo. The clearance rate of TZH to the intracellular bacteria reached over 98% within the limits of biotoxicity, which indicated that this delivery system can pass the cell membrane "barriers" and restore the efficacy of endangered antibiotics. This synergistic strategy shows potential in optimizing the efficacy-dosage correlation of antibiotics for related infection treatments and constructing versatile controlled release delivery systems for a broad range of applications.

5.
J Agric Food Chem ; 67(23): 6642-6649, 2019 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-31117488

RESUMO

The rapid monitoring of foodborne pathogens by monoclonal antibody (McAb)-based immunochromatographic tests (ICTs) is desirable but highly challenging as a result of the screening obstacle for a superior performance probe, which will greatly determine the capture efficiency of targets and the sensitivity of the immunoassay. In this work, on the basis of two-dimensional (2D) nanosheets (including MoS2 and graphene) as the extraordinary capture probe and signal indicator, we fabricated a label-free ICT method for Salmonella enteritidis detection. Especially, without the customarily labeled antibody probe, these 2D versatile probes presented strong capture ability toward bacteria by directly assembling onto the surface of bacteria. An ideal analytical performance with high sensitivity and specificity was achieved by virtue of the novel nanosheet-bacteria-McAb sandwich format. On the basis of MoS2 2D nanosheets as a fabulous probe element, the developed ICT exhibited a lowest detectable concentration of 103 colony-forming units/mL for S. enteritidis and could be well-applied in drinking water and watermelon juice samples. By the smart design, this work removes a series of conditionality issues of traditional double antibody sandwich-based ICTs and can give a new application direction for 2D nanosheet materials in the rapid detection field.


Assuntos
Água Potável/microbiologia , Sucos de Frutas e Vegetais/microbiologia , Imunoensaio/métodos , Salmonella enteritidis/isolamento & purificação , Citrullus/química , Citrullus/microbiologia , Grafite/química , Imunoensaio/instrumentação , Nanoestruturas/química , Salmonella enteritidis/química , Sensibilidade e Especificidade
6.
Mikrochim Acta ; 186(4): 247, 2019 03 16.
Artigo em Inglês | MEDLINE | ID: mdl-30879138

RESUMO

The authors describe a fluorometric method for the quantification of tannic acid (TA). MoO3-x quantum dots (QDs) can selectively capture TA via the formation of an organic molybdate complex. This causes an electron transfer effect and an inner filter effect to result in synergistic quenching of the fluorescence of the QDs. TA can be detected via this effect with a linear response in the of 0.1-10 µM concentration range and a lower detection limit of 30 nM within 1 min. The use of such QDs as a quenchable fluorescent probe warrants good selectivity even in the presence of relatively high concentration of potentially interferents and makes the method suitable for real sample analysis. Graphical abstract Tannic acid can be rapidly and selectively detected in food using a MoO3-x quantum dots based fluorometric assay.

7.
Inorg Chem ; 58(2): 1638-1646, 2019 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-30604958

RESUMO

The nanozyme-based strategy is currently one of the frontiers in the detection of toxic heavy metal ions. However, the utilization of noble metal free nanozymes to construct an economically and environmentally sustainable methodology remains largely unknown. Here, chitosan-functionalized molybdenum(IV) selenide nanosheets (CS-MoSe2 NS), greenly synthesized by an ionic liquid-assisted grinding method, were exploited for the colorimetric sensing of mercury ions (Hg2+). The sensing principle was based on the activating effect of Hg2+ on CS-MoSe2 NS nanozyme activities, triggered by the in situ reduction of chitosan-captured Hg2+ ions on a MoSe2 NS surface. Using 3,3',5,5'-tetramethylbenzidine (TMB) as a colorimetric indicator, the concentrations of activator-like Hg2+ ions could be quantitatively and selectively monitored, reaching a limit of detection of 3.5 nM with the ultraviolet-visible spectrophotometer. In addition, the integration system of CS-MoSe2 NS with a smartphone achieved a portable detection limit as low as 8.4 nM Hg2+ within 15 min and showed high specificity and anti-interfering ability over other ions and great practicability in real water and serum samples. The eco-friendly properties of such sensing system were also confirmed. This work emphasizes the rational portable assembly of biocompatible nanozymes like CS-MoSe2 NS for the field detection of Hg2+ in food, biological, and environmental samples.


Assuntos
Quitosana/química , Colorimetria , Mercúrio/análise , Molibdênio/química , Nanopartículas/química , Compostos de Selênio/química , Poluentes Químicos da Água/análise , Animais , Bovinos , Humanos , Tamanho da Partícula , Propriedades de Superfície
8.
Food Chem ; 274: 816-821, 2019 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-30373015

RESUMO

Here, a facile, label-free and sensitive lateral flow strip (LFS) biosensor for foodborne pathogens was established relying on the innovative introduction of Gram staining and the direct immunoreaction. Target bacteria can be directly marked with crystal violet (CV) by one-step staining which is superior to traditional signal marking techniques in LFS assay, and the method's selectivity can be guaranteed by high-specificity monoclonal antibody. With Salmonella Enteritidis (S. Enteritidis) as a model target, this protocol can selectively detect 80 CFU mL-1S. Enteritidis within 11 min in the optimized conditions. Moreover, with Listeria monocytogenes as another model target, the biosensor shows a high universality for detections of both gram-negative and gram-positive bacteria. The unexpected applicability of biological dye tracer in strip biosensor reveals that the biological dye can be a potential tool serving as a universal signal tracer for pathogenic microorganisms in food safety monitoring and early clinical diagnosis.


Assuntos
Técnicas Biossensoriais/métodos , Microbiologia de Alimentos/métodos , Listeria monocytogenes/imunologia , Salmonella enteritidis/imunologia , Anticorpos Monoclonais/imunologia , Especificidade de Anticorpos , Água Potável/microbiologia , Inocuidade dos Alimentos/métodos , Violeta Genciana , Limite de Detecção , Lycopersicon esculentum/microbiologia , Fenazinas , Carne Vermelha/microbiologia
9.
Food Chem ; 261: 131-138, 2018 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-29739573

RESUMO

We presented a signal amplified lateral flow assay (LFA) based on magnetite nanoparticles (MNPs) labeled dual-probe and applied it in the high sensitive and rapid on-site detection of furazolidone metabolite of 3-amino-2-oxazolidinone (AOZ). The amplified signal benefited from high affinity between two probes of MNPs labeled murine monoclonal antibody (MNPs-MAb) and goat anti-mouse antibody (MNPs-GAMA) and was achieved by the generation of dual-probe network complex. This developed method could realize high sensitive detection of AOZ with a threshold value of 0.88 ng mL-1 and a detection limit of 0.044 ng mL-1, the sensitivity was at least 10-fold improved than that of the traditional gold nanoparticle based LFA. This facile developed assay was successfully applied for rapid detection of AOZ in milk samples. The proposed method paves a new way for on-site screening of other hazardous substances in food and can be referred in all lateral flow assays.


Assuntos
Análise de Alimentos/métodos , Furazolidona/análise , Nanopartículas de Magnetita/química , Leite/química , Animais , Furazolidona/química , Limite de Detecção , Oxazolidinonas/análise
10.
Food Chem ; 262: 48-55, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-29751920

RESUMO

Immunochromatographic assays (ICAs) are most frequently used for on-site rapid screening of clenbuterol. To improve sensitivity, a novel probe with bacteria as signal carriers was developed. Bacteria can load a great deal of gold nanoparticles (AuNPs) on their surface, meaning much fewer antibodies are needed to produce clearly visible results, although low concentrations of antibody could also trigger fierce competition between free analyte and the immobilized antigen. Thus, a limited number of antibodies was key to significantly improved sensitivity. Analytical conditions, including bacterial species, coupling method, and concentration, were optimized. The visual detection limit (VDL) for clenbuterol was 0.1 ng/mL, a 20-fold improvement in sensitivity compared with traditional strips. This work has opened up a new route for signal amplification and improved performance of ICAs. Furthermore, inactivated bacteria could also be environment-friendly and robust signal carriers for other biosensors.


Assuntos
Técnicas Biossensoriais/métodos , Cromatografia de Afinidade/métodos , Clembuterol/análise , Escherichia coli , Nanopartículas Metálicas/química , Animais , Anticorpos/imunologia , Antígenos , Cromatografia de Afinidade/instrumentação , Feminino , Ouro/química , Limite de Detecção , Camundongos Endogâmicos BALB C , Sensibilidade e Especificidade
11.
Inorg Chem ; 57(9): 5560-5566, 2018 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-29634244

RESUMO

We have demonstrated that natural sugars can efficiently exfoliate inorganic layered nanomaterials with direct stirring. The representative transition-metal dichalcogenides (MoS2 and WS2), transition-metal oxide (MoO3), and graphene were explored, and the formation of ultrathin nanosheets was verified. Glucose and MoS2 selected each other as the perfect partner with superior exfoliation and excellent properties. The obtained inorganic layered nanosheets possess favorable stability and dispersity, which renders it suitable for direct homogeneous liquid applications, such as catalytic activities and sensors. With a high-throughput and green process, the sugar-assisted method may offer new ideas for inorganic layered nanomaterials synthesis and applications in a more ecofriendly way.

12.
Anal Bioanal Chem ; 410(13): 3161-3170, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29594429

RESUMO

Small molecules are difficult to detect by conventional gold lateral flow assay (GLFA) sensitively because the test system must satisfy the conflict requirements between enough signal intensity and limited antibody (Ab) amount. In this work, a paired labels recognition (PLR)-based biosensor was designed by utilizing the specific binding of Ab and secondary antibody (anti-Ab) to enhance signal intensity and reduce antibody amount applied in small molecule detection. The PLR amplification system is fabricated by self-assembling the common detection probe, Au-labeled Ab (Au-Ab), and the signal booster, Au-labeled anti-Ab (Au-anti-Ab). Benefiting from this, a powerful network structure can be generated to accumulate numerous gold nanoparticles (GNPs) and thus significantly strengthen the signal intensity of detection. Therefore, a lower Ab amount will be applied to offer adequate signal strength, and further, the limit of detection will be obviously downregulated due to the more effective competition reaction. Using furazolidone (FZD) as a model analyte, we achieve a detection limit of as low as 1 ng mL-1, which was at least fivefold improved over that of the traditional GLFA. Furthermore, the practicality of this strategy was certificated in five different food samples. Graphical abstract A paired labels recognition (PLR) amplification system is fabricated by self-assembling the common detection probe, Au-labeled Ab (Au-Ab), and the signal booster, Au-labeled anti-Ab (Au-anti-Ab). In this novel strategy, owing to the recognition of both Ab and anti-Ab labeled on gold nanoparticles (GNPs), a powerful network structure can be generated to accumulate numerous GNPs and thus significantly strengthen the signal intensity of detection.


Assuntos
Anti-Infecciosos Locais/análise , Técnicas Biossensoriais/instrumentação , Análise de Alimentos/instrumentação , Furazolidona/análise , Ouro/química , Nanopartículas Metálicas/química , Fitas Reagentes/análise , Animais , Anticorpos Imobilizados/química , Galinhas , Desenho de Equipamento , Limite de Detecção , Carne/análise , Leite/química , Penaeidae , Carne Vermelha/análise , Frutos do Mar/análise , Suínos
13.
Mikrochim Acta ; 185(4): 234, 2018 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-29594717

RESUMO

A method is described for the rapid fluorometric determination of dopamine (DA) by using molybdenum disulfide quantum dots (MoS2 QDs) that were fabricated via an ammonium hydroxide etching method. The probe has a fluorescence (with excitation/emission peaks at 267/380 nm) that is quenched by DA with high selectivity over various interferences. This is attributed to a reaction that occurs between DA and the molybdate ions in pH 9 solutions of MoS2 QDs. The formation of organic molybdate complexes and of dopamine-quinone results in strong quenching of the fluorescence of the QDs which is due to both electron transfer and an inner filter effect. Under the optimum conditions, the assay works in the 0.1-100 µM DA concentration range, with two linear ranges and a 10 nM detection limit. The method was applied to the determination of DA in spiked artificial urine samples, where it gave recoveries ranging from 97.6 to 102.2%, demonstrating that the method a promising tool for rapid and selective detection of DA. Graphical abstract MoS2 QDs are facilely synthesized via the etching effect of ammonium hydroxide for highly selective fluorometric detection of dopamine.

14.
ACS Appl Mater Interfaces ; 9(38): 32720-32726, 2017 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-28872826

RESUMO

The selective adsorption by suitable substrate materials is considered one of the most economical methods. In this work, an all-inorganic bimetallic Mo-Fe-S cluster is facilely achieved through in situ chemical fixation of tetrathiomolybdate (TTM) on Fe3O4 nanoparticles (NPs) at room temperature (donated as FeMoS NPs). The bimetallic building blocks on the obtained FeMoS NPs possess a monovacancy species of sulfur, endowing FeMoS NPs with a selectivity order of Zn2+, Mn2+, Ni2+ < Cd2+ ≪ Cu2+ < Pb2+ for metal-ion adsorption, a novel application for the Mo-Fe-S clusters. Particularly, with the highest selectivity for Pb2+ (Kd ≈ 107), which is about 3 × 103-1 × 106 times higher than those for other ions and has exceeded that of a series of outstanding sorbents reported for Pb2+, FeMoS NPs can efficiently reduce the concentration of Pb2+ from ∼10 ppm to an extremely low level of ∼1 ppb. This facile and rational fabrication of the Mo-Fe-S cluster with Fe3O4 represents a feasible approach to cheaply develop novel and efficient materials for the selective removal of lead(II).

15.
Nanotechnology ; 28(22): 225101, 2017 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-28480869

RESUMO

The emergence of antibiotic resistance has resulted in increasing difficulty in treating clinical infections associated with biofilm formation, one of the key processes in turn contributing to enhanced antibiotic resistance. With the rapid development of nanotechnology, a new way to overcome antibiotic resistance has opened up. Based on the many and diverse properties of MoS2 nanosheets that have attracted wide attention, in particular their antibacterial potential, herein, a novel antimicrobial agent to combat resistant gram-positive Staphylococcus aureus and gram-negative Salmonella was prepared using chitosan functionalized MoS2 nanosheets loading tetracycline hydrochloride drugs (abbreviated to CM-TH). The antibacterial and anti-biofilm activities of the CM-TH nanocomposites showed the synergetic effect that the combination of nanomaterials and antibiotics was more efficient than either working alone. In particularly, the minimum inhibitory concentration values generally decreased by a factor of dozens, suggesting that CM-TH may become a possible alternative to traditional antibiotics in disrupting biofilms and overcoming antibiotic resistance in treating medical diseases.

16.
Nanotechnology ; 2017 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-28398220

RESUMO

The emergence of antibiotic resistance has resulted in an increasing difficulty treating clinical infections associated with biofilms formation, one of the key processes contributed to enhance antibiotic resistance in return. With the rapid development of nanotechnology, a new way to overcome antibiotic resistance was opened up. Based on multiple properties especially antibacterial potential of MoS2 nanosheets that have aroused wide attention, herein, a novel antimicrobial agent to combat resistant gram-positive Staphylococcus aureus (S. aureus) and gram-negative Salmonella was prepared using chitosan functionalized MoS2 nanosheets loading tetracycline hydrochloride drugs (abbreviated to CM-TH). The antibacterial and anti-biofilm activities of CM-TH nanocomposites expressed a synergy effect that the combination of nanomaterials and antibiotics were more efficient than both alone did. Particularly, the MIC values were generally decreased by a factor of dozens, suggesting CM-TH may become a possible alternative to traditional antibiotics in disrupting the biofilms and further to overcome antibiotic resistance in treating medical diseases.

17.
Mikrochim Acta ; 185(1): 7, 2017 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-29594417

RESUMO

The authors have discovered that vanadium disulfide (VS2) nanosheets, synthesized by a hydrothermal method, exert stable peroxidase-like activity. The catalytic activity, with H2O2 as a cosubstrate, follows Michaelis-Menten kinetics and varies with temperature, pH value and H2O2 concentration. Two-dimensional VS2 sheets acting as peroxidase (POx) mimics can replace horseradish peroxidase due to their availability, robustness, and reusability. The POx-like activity of VS2 sheets was exploited to design a colorimetric glucose assay by using 3,3',5,5'-tetramethylbenzidine as a substrate and by working at an analytical wavelength of 652 nm. The assay covers the 5 to 250 µM glucose concentration range with a 1.5 µM detection limit. It was applied to the analysis of glucose in fruit juice. In our perception, the peroxidase-like nanozyme out of the family of transition metal dichalcogenides presented here has a wide scope in that it may stimulate promising biocatalytic applications in biotechnology and analytical chemistry. Graphical abstract Layered VS2 nanosheets were prepared via hydrothermal synthesis and are shown to exert superior peroxidase-mimicking activity. Using these POx nano-mimics, a sensitive colorimetric assay for glucose was developed and applied to fruit juice analysis. This work unlocks the access of VS2 to biocatalysis and bioassays.

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