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1.
Anal Chem ; 96(19): 7714-7722, 2024 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-38687680

RESUMO

Currently, fluorescent "turn-on" lateral flow assay (FONLFA) has shown enhanced "naked eye" detection sensitivity for small molecules, while it is urgent to adopt biocompatible fluorescent nanomaterials and needs new strategies to simplify the preparation process. In this study, a highly effective method was proposed to produce FONLFA strips for the detection of small molecules. The gold-silver nanoclusters (AuAgNCs) were immobilized onto the nitrocellulose membrane of the strips by the self-assembly of poly(sodium 4-styrenesulfonate), antigen, and AuAgNCs. The immobilization process entails a straightforward mixing of the three components, taking merely 1 min, thereby bypassing the necessity for chemical modification of fluorescent nanomaterials. The strategy offers a significantly simplified process, which substantially enhances the efficiency of the strip fabrication. Utilizing this method, a FONLFA was developed for carbendazim with a visual limit of detection (vLOD) reduced by 40-fold compared with the conventional colorimetric lateral flow assay (LFA). Furthermore, the approach demonstrates versatility by enabling the immobilization of AuAgNCs and streptavidin, which facilitates the development of aptamer-based FONLFAs. The designed aptamer-based FONLFA for kanamycin exhibited a 50-fold reduction in the vLOD compared with conventional colorimetric LFAs. Therefore, FONLFA holds promising potential for widespread applications in the analysis of small molecules.


Assuntos
Ouro , Nanopartículas Metálicas , Prata , Ouro/química , Prata/química , Nanopartículas Metálicas/química , Corantes Fluorescentes/química , Limite de Detecção , Aptâmeros de Nucleotídeos/química , Espectrometria de Fluorescência
2.
Small ; 20(35): e2401651, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38660702

RESUMO

A pH and redox dual responsive amphiphilic viologen is synthesized, which can be reversibly transformed among the zwitterionic (SVa), monovalent anionic (SV+), and divalent anionic (SVH2+) forms upon pH variation, exhibiting pH-controllable redox responsive properties. Switchable Pickering emulsions with different droplet size and viscosity are prepared by the mixture of hydrophilic silica nanoparticles and the viologens (SV+ or SVH2+) at acidic conditions, while such combination yielded an oil-in-dispersion emulsion at neutral pH value. Not only can rapid reversible demulsification/stabilization of the Pickering emulsions be achieved by redox reactions, but the rate of redox-demulsification can also be controlled by pH trigger. The dual-responsive amphiphilic viologens have potential applications in developing intelligent colloid materials and molecular logic systems.

3.
Molecules ; 29(19)2024 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-39407498

RESUMO

Aptamer-based lateral flow analysis (Apt-LFAs) has promising applications in many fields. Nanozymes have demonstrated high potential in improving the performance of Apt-LFAs and have been increasingly utilized in recent studies. In this study, we developed a nanozyme-based Apt-LFA for the rapid and sensitive detection of kanamycin by using a novel dual-functionalized AuNPs@polyA-DNA/GpG-Cu2+ nanozyme as a nanoprobe. In the nanoprobe design, the polyA-cDNA strand can discriminate a kanamycin aptamer from the kanamycin/aptamer complex, and the GpG-Cu2+ complex can amplify the detection signal by catalyzing the chromogenic reaction. The nanozyme Apt-LFA can quantify kanamycin in the range of 1-250 ng/mL with an LOD of 0.08 ng/mL, which demonstrated a 4-fold sensitivity improvement and had a wider linear range than the conventional AuNP-based LFA. The Apt-LFA was successfully applied to the detection of kanamycin in honey with good recoveries. Our dual-functionalized AuNP nanoprobe is easily prepared and can be highly compatible with the conventional AuNP-DNA-based LFA platform; thus, it can be extended to the application of Apt-LFAs for other small molecules.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Cobre , DNA , Ouro , Canamicina , Nanopartículas Metálicas , Canamicina/análise , Canamicina/química , Aptâmeros de Nucleotídeos/química , Ouro/química , Cobre/química , Cobre/análise , Nanopartículas Metálicas/química , Técnicas Biossensoriais/métodos , DNA/química , DNA/análise , Limite de Detecção , Mel/análise
4.
Langmuir ; 39(25): 8690-8697, 2023 06 27.
Artigo em Inglês | MEDLINE | ID: mdl-37314225

RESUMO

Aptamer-based lateral flow assay (Apt-LFA) has shown promising applications for small-molecule detection. However, the design of the AuNP (gold nanoparticle)-cDNA (complementary DNA) nanoprobe is still a big challenge due to the moderate affinity of the aptamer to small molecules. Herein, we report a versatile strategy to design a AuNPs@polyA-cDNA (poly A, a repeat sequence with 15 A bases) nanoprobe for small-molecule Apt-LFA. The AuNPs@polyA-cDNA nanoprobe contains a polyA anchor blocker, complementary DNA segment to DNA on the control line (cDNAc), partial complementary DNA segment with aptamer (cDNAa), and auxiliary hybridization DNA segment (auxDNA). Using adenosine 5'-triphosphate (ATP) as a model target, we optimized the length of auxDNA and cDNAa and achieved a sensitive detection of ATP. In addition, kanamycin was used as a model target to verify the universality of the concept. Therefore, this strategy can be easily extended to other small molecules; therefore, high application potential in Apt-LFAs can be envisaged.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Nanopartículas Metálicas , DNA Complementar , Ouro , DNA , Trifosfato de Adenosina , Poli A , Limite de Detecção
5.
Analyst ; 148(20): 5094-5104, 2023 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-37671915

RESUMO

A gold nanoparticle (AuNP) based immunochromatographic assay strip is a valuable tool for monitoring chemicals in foods. However, the sensitive ICA strip for SBT is rarely reported due to the fact that monoclonal antibodies (mAbs) against SBT with high affinity are commercially unavailable. Herein, a monoclonal antibody against SBT was prepared through a designed hapten with a carboxyl end-capped space arm. The obtained mAb showed high affinity for SBT and N-desmethylsibutramine, a metabolite of SBT. Furthermore, a series of core-shell NPs, polydopamine (PDA) coated AuNPs (PDA/AuNPs) with controlled shell thickness and packing density were synthesized. The obtained PDA/AuNP-mAb conjugate demonstrated high tolerance to salt and good stability in a wide pH range, which is beneficial for improving the matrix interference common in ICA. As a result, PDA/AuNP-based ICA could quantify SBT in the range of 3.39-69.60 ng mL-1 with a limit of detection (LOD) of 0.98 ng mL-1. This novel ICA improved the sensitivity of the traditional AuNP-based ICA by nearly 12 times. Method validation was conducted with spiked samples of slimming food and human serum and compared with HPLC-MS/MS. Consistent results indicated that high sensitivity, accuracy, and reliability of the PDA/AuNP-based ICA approach were achieved. To the best of our knowledge, this study reported the most sensitive immunoassay for SBT thus far.


Assuntos
Ouro , Nanopartículas Metálicas , Humanos , Ouro/química , Reprodutibilidade dos Testes , Colorimetria , Espectrometria de Massas em Tandem , Nanopartículas Metálicas/química , Imunoensaio/métodos , Limite de Detecção , Dieta
6.
Mikrochim Acta ; 189(7): 244, 2022 06 08.
Artigo em Inglês | MEDLINE | ID: mdl-35674802

RESUMO

A novel Apt-LFA has been established for kanamycin based on non-thiolated nucleic acid-modified colloidal gold nanoprobe (AuNPs@polyA-DNA). The improvement in nucleic acid hybridization speed and efficiency was verified by modifying AuNPs with polyA-DNA strands instead of thiolated oligonucleotides (SH-DNA) strands. Moreover, the AuNPs@polyA-DNA was explored to apply in an Apt-LFA. The experimental factors including the concentration of the aptamer, the concentration of SA-DNAT conjugate, the incubation time, and temperature were carefully investigated. In addition, the kanamycin aptamer was modified by extending several bases at its end to modulate the hybridization complementary strand, which was found to significantly improve the performance of Apt-LFA. Under optimal experimental conditions, the Apt-LFA can detect kanamycin in honey with a LOD of 250 ng mL-1 by the naked eyes. A linear range of 50-1250 ng mL-1 was obtained with a LOD of 15 ng mL-1 in honey by a portable reader. The Apt-LFA was successfully applied to the detection of kanamycin in honey with recoveries of 95.1-105.2%.


Assuntos
Aptâmeros de Nucleotídeos , Nanopartículas Metálicas , Ácidos Nucleicos , Aptâmeros de Nucleotídeos/genética , DNA , Ouro , Canamicina , Limite de Detecção , Poli A
7.
Mikrochim Acta ; 188(10): 346, 2021 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-34537909

RESUMO

Copper nanomaterials based on DNA scaffold (DNA-Cu NMs) are becoming a novel fluorescent material, but it is still challenging to obtain highly fluorescent DNA-Cu NMs with excellent stability. In this work, we report a kind of copper nano-assemblies (Cu NASs) with aggregation-induced emission enhancement (AIEE) property using DNA dendrimers with sticky end as template. The sticky end of the DNA dendrimers induced the formation of much bigger Cu NASs with average size ranging from 131 to 264 nm, depending on the length of the DNA dendrimer sticky end from 6 bases to 27 bases. Compared with complete complementary DNA dendrimer, nearly 6-fold fluorescence enhancement was achieved using DNA dendrimer with 27 bases sticky end. Moreover, the DNA dendrimer-Cu NASs demonstrated excellent stability in serum and could be rapidly quenched by Pb2+ ions. Based on the above property, highly sensitive and selective fluorescent detection of Pb2+ ions was possible with a linear range of 2.0-100 nM and a detection limit of 0.75 nM. Due to the sensitive and rapid response to Pb2+ as well as excellent stability in complex matrix, the proposed fluorescent Cu NASs demonstrated high potential as an excellent fluorescent probe for Pb2+ in complex matrix.


Assuntos
Cobre/química , DNA/química , Dendrímeros/química , Corantes Fluorescentes/química , Chumbo/análise , Nanopartículas/química , Fluorescência , Íons , Chumbo/química , Soroalbumina Bovina/química
8.
Mikrochim Acta ; 188(11): 363, 2021 10 04.
Artigo em Inglês | MEDLINE | ID: mdl-34606019

RESUMO

A core-shell QDs@mSiO2@y-AuNCs nanoprobe was prepared, and a new ratiometric fluorescent sensor for thiram detection was developed. The mechanism of thiram sensing was investigated using FTIR, surface-enhanced Raman, XPS spectra, etc. The sensing of thiram was mainly ascribed to the formation of Au-S bonds between thiram and Au atoms on y-AuNCs surface, resulting in the dissociation of 11-MUA ligand from the y-AuNCs surface and the charge transfer between thiram and y-AuNCs. In the ratiometric fluorescence detection of thiram based on QDs@mSiO2@y-AuNCs, a linear range of 0.5-60 ng/mL was obtained with a LOD of 0.19 ng/mL. Compared with the fluorescence detection based on y-AuNCs, the ratiometric fluorescence detection of thiram demonstrated 3-fold enhanced sensitivity. The improvement was ascribed to two aspects: the fluorescence emission of y-AuNCs was enhanced after they were loaded onto the QDs@mSiO2 nanoparticles; the ratiometric detection mode provided more precise sensing. The detection of thiram can be completed immediately after mixing the nanoprobe with thiram. Good recoveries of thiram in apple and pear samples were achieved. All the above results demonstrated the high potential of this method in practical applications.


Assuntos
Ouro
9.
Molecules ; 26(11)2021 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-34073353

RESUMO

New nanocomposites, Fe3O4@Au-FITC, were prepared and explored to develop a fluorescent detection of Pb2+. The Fe3O4@AuNPs-FITC nanocomposites could be etched by Pb2+ in the presence of Na2S2O3, leading to fluorescence recovery of FITC quenched by Fe3O4@Au nanocomposites. With the increase of Pb2+ concentration, the fluorescence recovery of Fe3O4@AuNPs-FITC increased gradually. Under optimized conditions, a detection limit of 5.2 nmol/L of Pb2+ with a linear range of 0.02-2.0 µmol/L were obtained. The assay demonstrated negligible response to common metal ions. Recoveries of 98.2-106.4% were obtained when this fluorescent method was applied in detecting Pb2+ spiked in a lake-water sample. The above results demonstrated the high potential of ion-induced nanomaterial etching in developing robust fluorescent assays.

10.
Mikrochim Acta ; 187(4): 255, 2020 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-32239351

RESUMO

We report the first use of metallic nanozyme as colorimetric probe for Pb2+ determination. The method is based on the surface leaching of Au@PtNP nanozyme by Pb2+-S2O32- ions, accompanied by a decreased catalytic activity of the metallic nanozyme. To construct this colorimetric determination, the Pt deposition onto the AuNPs was carefully investigated and other experimental factors including kind of substrate and buffer were optimized. With increasing Pb2+ concentration, the catalytic activity of the Au@PtNPs decreased gradually. As a result, the blue color at 650 nm from the oxidation of 3,3',5,5'-tetramethylbenzidine by H2O2 faded gradually. A determination limit of 3.0 nM Pb2+ with a linear range from 20 to 800 nM was obtained. The assay demonstrated negligible response to common metal ions even at elevated concentrations. This colorimetric method was applied to the determination of Pb2+ ions spiked in lake water samples, and good recoveries (96.8-105.2%) were obtained. The above results indicate the potential application of metallic nanozymes in developing robust colorimetric assays. Graphical abstract Schematic representation of the surface leaching of Au@PtNP nanozyme by Pb2+-S2O32- ions, accompanying the decreased catalytic activity of the metallic nanozyme.


Assuntos
Colorimetria/métodos , Chumbo/análise , Nanopartículas Metálicas/química , Benzidinas/química , Catálise , Compostos Cromogênicos/química , Ouro/química , Peróxido de Hidrogênio/química , Lagos/análise , Chumbo/química , Oxirredução , Platina/química , Tiossulfatos/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química
11.
Sensors (Basel) ; 18(8)2018 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-30111699

RESUMO

A new colorimetric detection of methylmercury (CH3Hg⁺) was developed, which was based on the surface deposition of Hg enhancing the catalytic activity of gold nanoparticles (AuNPs). The AuNPs were functionalized with a specific DNA strand (HT7) recognizing CH3Hg⁺, which was used to capture and separate CH3Hg⁺ by centrifugation. It was found that the CH3Hg⁺ reduction resulted in the deposition of Hg onto the surface of AuNPs. As a result, the catalytic activity of the AuNPs toward the chromogenic reaction of 3,3,5,5-tetramethylbenzidine (TMB)-H2O2 was remarkably enhanced. Under optimal conditions, a limit of detection of 5.0 nM was obtained for CH3Hg⁺ with a linear range of 10⁻200 nM. We demonstrated that the colorimetric method was fairly simple with a low cost and can be conveniently applied to CH3Hg⁺ detection in environmental samples.


Assuntos
Colorimetria/métodos , Ouro/química , Nanopartículas Metálicas/química , Compostos de Metilmercúrio/análise , Benzidinas/química , Colorimetria/normas , DNA/química , Peróxido de Hidrogênio/química , Limite de Detecção
13.
Food Chem ; 447: 138931, 2024 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-38484548

RESUMO

Gas sensors containing indicators have been widely used in meat freshness testing. However, concerns about the toxicity of indicators have prevented their commercialization. Here, we prepared three fluorescent sensors by complexing each flavonoid (fisetin, puerarin, daidzein) with a flexible film, forming a fluorescent sensor array. The fluorescent sensor array was used as a freshness indication label for packaged meat. Then, the images of the indication labels on the packaged meat under different freshness levels were collected by smartphones. A deep convolutional neural network (DCNN) model was built using the collected indicator label images and freshness labels as the dataset. Finally, the model was used to detect the freshness of meat samples, and the overall accuracy of the prediction model was as high as 97.1%. Unlike the TVB-N measurement, this method provides a nondestructive, real-time measurement of meat freshness.


Assuntos
Aprendizado Profundo , Flavonoides , Nitrogênio , Carne/análise , Redes Neurais de Computação , Corantes
14.
Biosens Bioelectron ; 250: 116044, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38271888

RESUMO

Ultra-sensitive LFA methods for pathogen detection commonly depended on tedious and time-consuming nucleic acid amplification. Here, a high affinity multivalent aptamer (multi-Apt) for S. aureus was obtained through exquisite engineering design. The scaffold and conformation of the multi-Apt were found to be key factors in the detection signal of aptsensors. After optimization, the binding affinity of the multi-Apt to S. aureus was improved by more than 8-fold from 135.9 nM to 16.77 nM. By the joint use of the multi-Apt and a multifunctional nanozyme Fe3O4@MOF@PtPd, a fast and ultra-sensitive LFA for S. aureus was developed (termed MA-MN LFA). In this method, a Fe3O4@MOF@PtPd nanozyme was modified with vancomycin and could efficiently capture and separate S. aureus. Moreover, the multi-Apt worked together with the nanozyme to bind with S. aureus to form a ternary complex at the same time, which simply the fabrication of LFA strip. The developed MA-MN LFA could detect S. aureus as low as 2 CFU/mL within 30 min and a wide linear range of 10-1 × 108 CFU/mL was obtained. The detection is easily operated, fast (can be completed within 30 min) and versatile for Gram-positive pathogens, thus has great potential as a powerful tool in pathogen detection.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Staphylococcus aureus/química , Técnicas Biossensoriais/métodos , Vancomicina , Oligonucleotídeos , Fenômenos Magnéticos , Aptâmeros de Nucleotídeos/química
15.
Food Chem ; 450: 139258, 2024 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-38626710

RESUMO

Pesticide detection based on nanozyme is largely limited in terms of the variety of pesticides. Herein, a spherical and well-dispersed Fe3O4/graphene oxide nanoribbons (Fe3O4/GONRs) composite nanozyme was applied to firstly develop an enzyme-free and sensitive colorimetric and fluorescence dual-mode detection of thiophanate-methyl (TM). The synthesized Fe3O4/GONRs possess excellent dual enzyme-like activities (peroxidase and catalase) and can catalyze H2O2 to oxidize 3,3',5,5'-tetramethylbenzidine (TMB) into oxidized TMB (oxTMB). We found that Fe3O4/GONRs can adsorb TM through the synergistic effect of multiple forces, thereby inhibiting the catalytic activities of nanozyme. This inhibition can modulate the transformation of TMB to oxTMB, producing dual responses of absorbance decrease (oxTMB) and fluorescence enhancement (TMB). The limits of detection (LODs) of TM were 28.1 ng/mL (colorimetric) and 8.81 ng/mL (fluorescence), respectively. Moreover, the developed method with the recoveries of 94.8-100.8% also exhibited a good potential application in the detection of pesticides residues in water and food samples.


Assuntos
Colorimetria , Grafite , Limite de Detecção , Tiofanato , Colorimetria/métodos , Grafite/química , Tiofanato/química , Tiofanato/análise , Contaminação de Alimentos/análise , Fluorescência , Resíduos de Praguicidas/análise , Resíduos de Praguicidas/química , Espectrometria de Fluorescência/métodos , Peróxido de Hidrogênio/química , Benzidinas
16.
Anal Chim Acta ; 1329: 343260, 2024 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-39396317

RESUMO

BACKGROUND: Sildenafil (SIL) is regarded as an illegal adulterant in functional foods. Some functional foods doped with SIL have posed significant concern about their safety risks. However, the facile colorimetric detection of SIL is rarely investigated. RESULTS: Herein, we prepared a monodispersed spherical composite nanozyme (Fe3O4-NH2/GONRs), possessing excellent peroxidase-like (POD-like) and catalase-like (CAT-like) activities and strong superparamagnetic property. The enzyme-like activities of Fe3O4-NH2/GONRs can be selectively inhibited by SIL due to the synergistic effect of hydrogen bonds and π-π stacking between Fe3O4-NH2/GONRs and SIL. Leveraging this mechanism, a highly sensitive and selective colorimetric detection for SIL with a detection limit (LOD) of 0.26 ng/mL was developed. In addition, we prepared a three-dimensional paper-based analytical device (3D-PAD) for SIL colorimetric detection with naked-eyes and the semi-quantitative analysis with a LOD of 88 ng/mL. SIGNIFICANCE: The proposed colorimetric and PAD detections demonstrated the advantages of low-cost, highly sensitive and selective, thus have promise application potential in the rapid detection of adulterated functional foods.


Assuntos
Colorimetria , Alimento Funcional , Grafite , Limite de Detecção , Papel , Citrato de Sildenafila , Citrato de Sildenafila/análise , Citrato de Sildenafila/química , Colorimetria/métodos , Grafite/química , Alimento Funcional/análise , Contaminação de Alimentos/análise
17.
ACS Omega ; 9(6): 7075-7084, 2024 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-38371773

RESUMO

Later flow immunochromatographic assay has been widely used in clinical, environmental, and other diagnostic applications owing to its high sensitivity and throughput. However, most immunoassays operate in the "turn-off" mode for detecting targets of low molecular weight. The signal intensity decreases as the analyte concentration increases, which poses a challenge for achieving ultrasensitive detection at low concentrations and is counterintuitive to new users. In this work, a fluorometric immunochromatographic assay (FICA) is developed to simultaneously read "turn-on" fluorescent and "turn-off" colorimetric signals, where ZnCdSe/ZnS quantum dots act as fluorescence donors and gold nanoparticles (AuNPs) act as quenchers. The fluorescent signal (excitation/emission wavelengths of 365/525 nm) is positively correlated with analytes' concentration. Taking sibutramine (SBT) as the analysis target, the visual limit of detection for SBT reached 3.9 ng/mL, and the limit of Quantitation was 5.0 ng/mg in spiked samples. The developed FICA achieves a high sensitivity in SBT detection, which is much lower than that of the colloidal gold-based immunochromatographic assay. This dual-function detection mode has great potential to be used as a rapid on-site semiquantitative method, providing an alternative mode for the determination of low levels of target analytes.

18.
Immunol Invest ; 42(6): 493-503, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23883286

RESUMO

In the present study, we obtained a specific monoclonal antibody (cross-reaction to analogues <5%) against cyhalothrin using two haptens. After 7 reaction steps, 3-cyano-[(cis)-3-(2-chloro-3, 3, 3-trifluoroethenyl-2, 2-dimethyl)-cyclopropane-carbonyloxy]-phenoxybenzyl propanoic acid was prepared with yield 35.9%. Four coating antigens and two immunogens were prepared. A heterologous enzyme-linked immunosorbent assay for cyhalothrin was established with the 50% inhibition concentration (IC50, 13.26 ± 1.23 ng mL(-1)) after optimizing various parameters including coating antigens, blocking agents, ionic strength, pH value and methanol concentration in the assay buffer. To evaluate the proposed immunoassay, spiked samples from river, tap water and drinking water at three levels (0.2, 1.0, 5.0 mg L(-1)) were tested after simple dilution. The mean recoveries ranged from 75.4% to 97.7% with coefficient of variation 5.1%-11.6%. The results from the above indicated the potencies of this ELISA in cyhalothrin analysis.


Assuntos
Anticorpos Monoclonais/imunologia , Haptenos/imunologia , Inseticidas/análise , Nitrilas/análise , Piretrinas/análise , Animais , Água Potável/análise , Ensaio de Imunoadsorção Enzimática/métodos , Inseticidas/imunologia , Camundongos , Nitrilas/imunologia , Piretrinas/imunologia , Rios/química , Poluentes Químicos da Água/análise
19.
Int J Mol Sci ; 14(10): 19474-83, 2013 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-24071944

RESUMO

It is challenging to detect 7-aminonitrazepam (7-ANZP) residue in animal tissues simply and sensitively by the enzyme-linked sorbent immunoassay (ELISA) method. This paper demonstrates that utilizing a bioconjugate of gold nanoparticles and enzyme-labeled antibody as a signal probe increases the sensitivity of a traditional ELISA for 7-ANZP by nearly 20 times. The sensitivity of this ELISA for 7-ANZP was 5.6 pg/mL in buffer, and the limit of detection (LOD) of 0.18 µg/kg for 7-ANZP in urine could be achieved after the urine samples were simply hydrolyzed and diluted by buffer. This simple and sensitive method has potential application for improving the sensitivity of ELISA methods against various small molecules.


Assuntos
Ensaio de Imunoadsorção Enzimática/métodos , Nanopartículas/química , Nitrazepam/análogos & derivados , Animais , Ouro/química , Imunoconjugados/química , Imunoglobulina G/química , Limite de Detecção , Nitrazepam/química , Proteínas/química , Sensibilidade e Especificidade
20.
Int J Mol Sci ; 14(4): 8603-10, 2013 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-23609493

RESUMO

Simple immuno-magnetic separation tandem fluorescent probes based on quantum dots-antibody (QDs-Ab) were developed to detect Salmonella with sensitivity of 500 cfu mL-1. With two monoclonal antibodies, which recognize different antigenic determinant on the surface of Salmonella, we prepared antibody-coated magnetic nanoparticles (MNPs) and conjugates of QDs-Ab. The immune-magnetic beads were verified with high enrichment efficiency for Salmonella (90%). A sandwich structure formed if the Salmonella solution was mixed together with immune-beads and QDs-Ab, and the fluorescent single from QDs was related to the amount of Salmonella. A linear response between fluorescence intensity and various concentrations of Salmonella (2.5 × 103 to 1.95 × 108 cfu mL-1) were observed with this proposed method. The total assay time for Salmonella was 30 min, and no cross-reaction to other microbial strains, such as Staphylococcus aureus, Escherichia coli (E. coli) and Escherichia coli O157:H7 (E. coli O157:H7), were found using this detection system. All our results showed that the simple homogeneous immunoassay could be applied in Salmonella screening without time-consuming extra-enrichment of bacteria.


Assuntos
Separação Imunomagnética/métodos , Nanopartículas de Magnetita , Pontos Quânticos , Salmonella/imunologia , Salmonella/isolamento & purificação , Animais , Anticorpos Antibacterianos , Técnicas Bacteriológicas/métodos , Reações Cruzadas , Escherichia coli/imunologia , Escherichia coli O157/imunologia , Corantes Fluorescentes , Microbiologia de Alimentos , Análise de Perigos e Pontos Críticos de Controle , Humanos , Imunoensaio/métodos , Staphylococcus aureus/imunologia
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