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1.
Mikrochim Acta ; 187(9): 515, 2020 08 24.
Artigo em Inglês | MEDLINE | ID: mdl-32839875

RESUMO

To early effectively detect amyloid-beta (Aß) oligomers, a label-free reusable aptasensor was designed. This aptasensor based on a luminescent nanoscale lanthanum-based metal-organic framework (L-MOF)-armored single-stranded DNA antibody (MOF-armored-anti-DNA antibody) as signal tags and aptamer bound to magnetic beads (Apt-MB) as capture probe. The reusable aptasensor combines signal tag and capture probe with antigen-antibody interaction. When the reusable aptasensor is formed, the strong fluorescence intensity of L-MOF will "turn off" by photo-induced electron transfer from excited states to an unfilled d shell of iron cations on the nanoparticle surface. Upon the presence of Aß oligomers in serum samples, they can be especially distinguished with the Aß oligomers aptamer in capture probes and then signal tags are released into the solution for developing the fluorescence aptasensor under excitation/emission 365 nm/430 nm. Meanwhile, the aptamer was recovered from the complex of Aß oligomers/Apt-MB by heat treatment. When the temperature returns to room temperature, the recovered aptamer in the capture probe can once again bound to the MOF-armored-anti-DNA antibody for reuse. The label-free reusable aptasensor system detection has high sensitivity and selectivity toward Aß oligomers (LOD = 0.4 pg/mL) and an excellent linear range (0.001-100 ng/mL). This strategy is a fruitful step for the development of reusable aptasensor and may turn on new avenues for the applications of Aß oligomer detection in clinical diagnosis.Graphical abstract.


Assuntos
Doença de Alzheimer/diagnóstico , Peptídeos beta-Amiloides/sangue , Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Peptídeos beta-Amiloides/química , Anticorpos Imobilizados/imunologia , Aptâmeros de Nucleotídeos/imunologia , DNA de Cadeia Simples/química , DNA de Cadeia Simples/imunologia , Corantes Fluorescentes/química , Humanos , Separação Imunomagnética , Lantânio/química , Limite de Detecção , Nanopartículas de Magnetita/química , Estruturas Metalorgânicas/química , Estrutura Quaternária de Proteína , Espectrometria de Fluorescência
2.
J Org Chem ; 85(14): 9290-9300, 2020 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-32583669

RESUMO

A new enantioselective Michael addition between 3-(3-hydroxy-1H-pyrazol-1-yl)oxindole, a new synthon generated from isatin N,N'-cyclic azomethine imine 1,3-dipole, and ß-nitrostyrene has been disclosed. A series of chiral 3-(3-oxo-2,3-dihydro-1H-pyrazol-1-yl) disubstituted oxindoles were obtained in excellent results (up to 97% yield, up to 94% ee) with moderate to good diastereoselectivities (up to 4.3:1 dr).

3.
Mikrochim Acta ; 187(2): 114, 2020 01 09.
Artigo em Inglês | MEDLINE | ID: mdl-31919722

RESUMO

Amyloid-beta (Aß) oligomers causing neuron damage are regarded as potential therapeutic targets and diagnostic markers for Alzheimer's disease (AD). A homogeneous turn-on fluorometric aptasensor is described for Aß oligomers. It is highly selective and non-invasive and based on (a) the use of a luminescent metal-organic framework carrying aptamer-modified AuNPs (L-MOF/Apt-Au) as tracking agent, and (b) enzyme-assisted target recycling signal amplification. The tracking agent does not emit fluoresce by fluorescence resonance energy transfer (FRET) between the luminescent MOF as donor and Apt-Au as the acceptor under the excitation wavelength of 466 nm. When Aß oligomers are added to the tracking agent solution, the Apt-Au on tracking agent can preferentially bind with Aß oligomers and then be released. This turns the "off" signal of the luminescent MOF tracer to the "on" state. The enzyme (Rec Jf exonuclease) added into the supernatant further improves sensitivity due to enzyme-assisted target-recycling signal amplification. The assay has an excellent linear response to Aß oligomers from 1.0 pM to 10 nM, with a detection limit of 0.3 pM. This homogeneous turn-on fluorometric method is expected to have potential and applications in clinical diagnosis. Graphical abstractSchematic representation of fluorometric assay for amyloid-ß oligomers based on luminescence metal-organic framework nanocomposites as tracking agent with exonuclease-assisted target recycling.


Assuntos
Peptídeos beta-Amiloides/análise , Aptâmeros de Nucleotídeos , Fluorometria/métodos , Estruturas Metalorgânicas/química , Reciclagem/métodos , Doença de Alzheimer/diagnóstico , Técnicas Biossensoriais/métodos , Exonucleases , Ouro , Humanos , Limite de Detecção , Nanopartículas Metálicas/química
4.
J Org Chem ; 85(5): 3921-3928, 2020 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-31944112

RESUMO

An abnormal [3 + 2]-cycloaddition and highly effective and convenient one-step preparation of tetracyclic bispirooxindoles containing two all-carbon quaternary spirocenters from isatin N,N'-cyclic azomethine imine 1,3-dipole and 3-methyleneoxindole in the presence of catalytic organic base has been disclosed. A variety of bispirooxindoles bearing a dinitrogen heterocycle with four adjacent cycles have been obtained in excellent yields (up to 95%) and diastereoselectivities (>99:1) under mild conditions.

5.
Mikrochim Acta ; 186(8): 515, 2019 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-31280384

RESUMO

A visualization strategy is described for the detection of clenbuterol (CLB). It is using of antibody against dsDNA and G-quadruplex/hemin labeled on a metal organic framework of type MIL-101(Fe) (G-quadruplex/hemin-anti-DNA/MIL-101) acting as a peroxidase mimetic, and magnetic beads modified with aptamer and complementary DNA (MB/Apt-cDNA) as capture probes. The detection reagent was prepared via the reactions between the double stranded DNA (Apt-cDNA) in capture probes and anti-DNA in peroxidase mimetic. In the presence of CLB, the aptamer on the magnetic beads preferentially binds CLB, and the peroxidase mimetic is released to the supernatant after magnetic separation. The released peroxidase mimetic can catalyze the TMB/H2O2 chromogenic system under mild conditions. This leads to the development of a blue-green coloration whose absorbance is measured at 650 nm. The detection limit is as low as 34 fM of CLB. The method was applied to the determination of CLB in pork samples and gave results that were consistent with data obtained with an ELISA kit. Graphical abstract A visualization strategy is described for the detection of clenbuterol. The selectivity of detection system for clenbuterol is excellent compared with other interferents. The method was applied to the determination of CLB in pork samples.


Assuntos
Agonistas Adrenérgicos beta/análise , Clembuterol/análise , Contaminação de Alimentos/análise , Carne Vermelha/análise , Suínos , Agonistas Adrenérgicos beta/química , Animais , Anticorpos/química , Aptâmeros de Nucleotídeos/química , Biomimética , Clembuterol/química , Colorimetria , DNA/química , DNA/imunologia , Quadruplex G , Hemina/química , Ferro/química , Fenômenos Magnéticos , Estruturas Metalorgânicas/química , Peroxidase/química
6.
Dalton Trans ; 47(20): 6986-6994, 2018 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-29736509

RESUMO

Three new manganese 4'-(3,5-dicarboxyphenyl)-2,2':6',2'''-terpyridine (H2DATP) metal-organic framework materials have been generated through regulating the ratios of a binary solvent mixture (DMA/H2O) under solvothermal conditions. Compound 1 {[Mn2(DATP)(HDATP)(H2O)4](OH)·10H2O}n displaying a one-dimensional (1D) chainlike structure was crystallized from the DMA/H2O mixture with a molar ratio of 1 : 1, while the two-dimensional (2D) layer species, {[Mn(DATP)(H2O)]·2H2O}n (2) was produced by increasing the ratio of DMA/H2O to 5 : 1. Interestingly, the crystallization in pure DMA yields a three-dimensional (3D) interpenetrating network {[Mn(DATP)]·4H2O}n (3), featuring higher solvent stability and pH stability than compounds 1 and 2. It is proved that solvent not only influences the structural transformation process of crystals but also has a significant effect on their properties. These three compounds present different catalytic performances in the CO2 cycloaddition to epoxides with various substituent groups into corresponding cyclic carbonates, and only 3 can serve as an efficient and recyclable catalyst at mild temperature.

7.
Org Biomol Chem ; 16(8): 1297-1304, 2018 02 21.
Artigo em Inglês | MEDLINE | ID: mdl-29388660

RESUMO

A novel and diastereoselective [3 + 2] annulation of isoindigos and Morita-Baylis-Hillman carbonates has been developed for the highly efficient and one-step preparation of highly steric dispiro[cyclopent-3'-ene]bisoxindoles with two all-carbon quaternary spirocenters and three adjacent cycles in excellent yields (up to >99%) and diastereoselectivities (up to >20 : 1) under mild conditions within a few minutes. A series of dispiro[cyclopent-3'-ene]bisoxindoles were obtained and scale-up experiment was conducted with excellent results demonstrating the potential applications of this protocol.

8.
Org Lett ; 19(12): 3051-3054, 2017 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-28571319

RESUMO

A new isatin N,N'-cyclic azomethine imine 1,3-dipole was devised, and an unusual Michael addition with ß-nitrostyrene catalyzed by tributylamine under mild conditions has been developed. The new reaction featured the C3 umpolung of oxindole and an unusual formation of double bond. Notably, this new synthon performed as a donor rather than an acceptor. This protocol provided a promising method for the preparation of various 3-aminooxindoles with good yields in moderate diastereoselectivities.

9.
Org Lett ; 19(11): 2805-2808, 2017 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-28497972

RESUMO

An unusual and highly effective asymmetric annulation of nitrosoarenes with hydroxymaleimides catalyzed by a chiral bifunctional amine squaramide catalyst has been disclosed. A wide range of highly fused chiral N-hydroxyindolines with two consecutive quaternary stereocenters and multifunctional groups were directly and effectively prepared in excellent yields (up to >99%) with complete regioselective cyclization and excellent stereoselectivities (up to >99:1 dr and >99% ee). The efficiency and potentials of the new reaction and the target chiral entities were well demonstrated by delicate transformations into a series of new chiral indolines.

10.
BMC Surg ; 17(1): 37, 2017 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-28403863

RESUMO

BACKGROUND: Gastric duplication cysts are rare congenital alimentary tract anomalies and most cases are recognized during childhood. There were few reports about gastric duplication cysts in newborns and even fewer reports about laparoscopic resection of gastric duplication cysts in newborns. CASE PRESENTATION: We report a series of five newborns with gastric duplication cysts which were successfully resected by laparoscopy between January 2010 and April 2015. Case 1, a male newborn was admitted because of severe salivation, choking cough and dyspnea for 30 min after birth. Case 2, a male, was suspected of duodenal ileus by antenatal examination. Case 3, a female was admitted because of vomiting for 5 days. Case 4,a female without significant symptoms simply visited us for the abdominal cyst detected by antenatal examination. Case 5, a male was admitted because of vomiting for 4 days. All patients were performed with a surgery after assistant examinations. Case 1 was died of respiratory failure and the other patients recovered uneventfully. CONCLUSION: Gastric duplication cysts in newborns are very rare. Laparoscopic surgery play an important role on the diagnosis and treatment. Our experience and practice indicate that laparoscopic resection of gastric duplication cysts in newborns is viable and there is also a need to increase sample size to prove its safety and effectiveness.


Assuntos
Cistos/cirurgia , Laparoscopia/métodos , Vômito/etiologia , Feminino , Humanos , Íleus/cirurgia , Recém-Nascido , Masculino
11.
Chirality ; 29(7): 369-375, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28418612

RESUMO

Chiral diamine catalysts 11a-e derived from α,α-diphenyl prolinol were prepared and successfully applied to the Michael addition of aromatic oximes to α,ß-unsaturated aldehydes in mediocre to good yields (up to 78%) and good to high enantioselectivities (up to 93% ee).

12.
Biosens Bioelectron ; 86: 477-483, 2016 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-27434234

RESUMO

The present study aimed to explore a novel triple-amplification electrochemiluminescence (ECL) assay for detecting of chloramphenicol (CAP). This strategy was based on single-stranded DNA-binding protein (SSB) and horseradish peroxidase (HRP) enzyme-linked polymer (EnVision reagent, EV) labeled on Au nanoparticles (EV-Au-SSB) as nanotracer and exonuclease-assisted target recycling. The composite probes were prepared via immunoreactions between the CdS nanocrystal (CdS NC)-functionalized partial complementary DNA and aptamer (CdSNCs/Apt-ssDNA1) as capture probes, and EV-Au-SSB as nanotracer. When the composite probe solution co-existed with CAP and Exo I, the aptamer on the capture probes preferentially combined with CAP, and then CAP-Apt and nanotracer complex were released into the solution. Subsequently, Exo I in the solution could further digest the CAP-Apt from the 3'-end of the aptamer and release CAP, which could participate in further reaction with the probes. It was worth mentioning that EV contained a large number of HRPs on its dendritic chain. In the EV-Au-SSB, Au could enhance ECL intensity of CdS NCs by surface plasmon resonance. What's more, HRPs on EV could catalyze the reaction of H2O2, which could obviously enhance ECL intensity of CdS NCs. This study demonstrated excellent performance of the triple-amplification ECL assay, which makes this aptasensor system suitable and promising for the practical application of CAP residues in fish samples. Moreover, the assay might provide a promising avenue to develop efficient aptasensors to determine small-molecule harmful substances in environmental monitoring and food safety.


Assuntos
Antibacterianos/análise , Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Cloranfenicol/análise , Técnicas Eletroquímicas/métodos , Compostos de Cádmio/química , Proteínas de Ligação a DNA/química , Poluentes Ambientais/análise , Ouro/química , Peroxidase do Rábano Silvestre/química , Peróxido de Hidrogênio/química , Limite de Detecção , Medições Luminescentes/métodos , Nanopartículas/química , Nanopartículas/ultraestrutura , Sulfetos/química
13.
Anal Chim Acta ; 929: 49-55, 2016 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-27251948

RESUMO

In this work, a novel homogeneous and signal "off-on" aptamer based fluorescence assay was successfully developed to detect chloramphenicol (CAP) residues in food based on the fluorescence resonance energy transfer (FRET). The vesicle nanotracer was prepared through labeling single stranded DNA binding protein (SSB) on limposome-CdSe/ZnS quantum dot (SSB/L-QD) complexes. It was worth mentioning that the signal tracer (SSB/L-QD) with vesicle shape, which was fabricated being encapsulated with a number of quantum dots and SSB. The nanotracer has excellent signal amplification effects. The vesicle composite probe was formed by combining aptamer labeled nano-gold (Au-Apt) and SSB/L-QD. Which based on SSB's specific affinity towards aptamer. This probe can't emit fluoresce which is in "off" state because the signal from SSB/L-QD as donor can be quenched by the Au-aptas acceptor. When CAP was added in the composite probe solution, the aptamer on the Au-Apt can be preferentially bounded with CAP then release from the composite probe, which can turn the "off" signal of SSB/L-QD tracer into "on" state. The assay indicates excellent linear response to CAP from 0.001 nM to 10 nM and detection limit down to 0.3 pM. The vesicle probes with size of 88 nm have strong signal amplification. Because a larger number of QDs can be labeled inside the double phosphorus lipid membrane. Besides, it was employed to detect CAP residues in the milk samples with results being agreed well with those from ELISA, verifying its accuracy and reliability.


Assuntos
Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Cloranfenicol/análise , Transferência Ressonante de Energia de Fluorescência/métodos , Coloide de Ouro/química , Pontos Quânticos/química , Aptâmeros de Nucleotídeos/metabolismo , Compostos de Cádmio/química , Cloranfenicol/química , Cloranfenicol/metabolismo , Limite de Detecção , Lipossomos/química , Compostos de Selênio/química , Sulfetos/química , Compostos de Zinco/química
14.
Biosens Bioelectron ; 81: 454-459, 2016 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-27015148

RESUMO

A novel fluorescence aptasensor was successfully developed to respond to chloramphenicol (CAP) in food based on magnetic aptamer-liposome vesicle probe. In order to fabricate it, aptamer labeled on functionalized magnetic beads (MB) was firstly employed as capture adsorbent (MB-Apt), then SSB (single-stranded DNA binding protein) and DIL (1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanineperchlorate) coimmobilized liposomes (SSB/DIL-Lip) was employed as vesicle signal tracer. The composite vesicle probe is formed between SSB/DIL-Lip and MB-Apt based on SSB's specific recognition towards aptamer on vesicle signal tracer. Upon the vesicle probe solution reacted with CAP, the aptamer on the magnetic beads preferentially bounded with CAP, and then released SSB/DIL-Lip vesicle signal tracer in the supernatant after magnetic separation. The released tracer can emit fluorescence which was correspondence with the concentration of the analyte. At the optimum conditions, the aptasensor exhibited a good linear response for CAP detection in the range of 0.003-10nM with a detection limit of 1pM. Importantly, the methodology was further validated for analyzing CAP in fish samples with consistent results obtained by ELISA kit, thus providing a promising approach for quantitative monitoring of CAP and significant anti-interference ability in food safety.


Assuntos
Antibacterianos/análise , Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Cloranfenicol/análise , Análise de Alimentos/métodos , Alimentos Marinhos/análise , Animais , Peixes , Corantes Fluorescentes/química , Proteínas Imobilizadas/química , Limite de Detecção , Lipossomos/química , Imãs/química , Percloratos/química , Espectrometria de Fluorescência/métodos
15.
Talanta ; 147: 296-301, 2016 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-26592610

RESUMO

A selective and facile fluorescence "switch-on" scheme is developed to detect antibiotics residues in food, using chloramphenicol (CAP) as model, based on a novel magnetic aptamer probe (aptamer-Pt-luminol nanocomposite labeled with hemin/G-quadruplex). Firstly, the composite probe is prepared through the immuno-reactions between the capture beads (anti-dsDNA antibody labeled on magnetic Dynabeads) and the nanotracer (nano-Pt-luminol labeled with double-strand aptamer, as ds-Apt, and hemin/G-quadruplex). When the composite probe is mixed with CAP, the aptamer preferentially reacted with CAP to decompose the double-strand aptamer to ssDNA, which cannot be recognized by the anti-dsDNA antibody on the capture probes. Thus, after magnetic separation, the nanotracer can be released into the supernatant. Because the hemin/G-quadruplex and PtNPs in nanotracer can catalyze luminol-H2O2 system to emit fluorescence. Thus a dual-amplified "switch-on" signal appeared, of which intensity is proportional to the concentration of CAP between 0.001 and 100ng mL(-1) with detection limit of 0.0005ng mL(-1) (S/N=3). Besides, our method has good selectivity and was employed for CAP detection in real milk samples. The results agree well with those from conventional gas chromatograph-mass spectrometer (GC-MS). The switch-on signal is produced by one-step substitution reaction between aptamer in nanotracer and target. When the analyte is changed, the probe can be refabricated only by changing the corresponding aptamer. Thus, all features above prove our strategy to be a facile, feasible and selective method in antibiotics screening for food safety.


Assuntos
Antibacterianos/análise , Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Hemina/química , Luminol/química , Imãs/química , Platina/química , Antibacterianos/química , Aptâmeros de Nucleotídeos/genética , Sequência de Bases , Cloranfenicol/análise , Cloranfenicol/química , Corantes Fluorescentes/química , Quadruplex G , Peróxido de Hidrogênio/química , Limite de Detecção , Modelos Moleculares , Nanoestruturas/química , Espectrometria de Fluorescência
16.
Analyst ; 140(22): 7663-71, 2015 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-26442572

RESUMO

Herein, an ultrasensitive and selective colorimetric assay for antibiotics, using chloramphenicol (CAP) as the model analyte, was developed based on magnetic aptamer-HRP-platinum composite probes and exonuclease-assisted target recycling. The composite probes were prepared through immunoreactions between the double stranded DNA antibody (anti-DNA) labeled on core-shell Fe3O4@Au nanoparticles (AuMNP-anti-DNA) as the capture probe, and the double stranded aptamer (aptamer hybrid with its complementary oligonucleotides) labeled on Pt@HRP nanoparticles as the nanotracer (ds-Apt-HRP-PtNPs). When the CAP samples were incubated with the probes for 30 min at room temperature, they could be captured by the aptamer to form a nanotracer-CAP complex, which was then released into the supernatant after magnetic separation. This is because the anti-DNA on the capture probes cannot recognize the single strand aptamer-CAP complex. The exonuclease I (Exo I) added into the supernatant can further digest the aptamer-CAP from the 3'-end of the aptamer and the CAP in the aptamer-CAP complex can be released again, which can further participate in a new cycling process to react with the probes. Pt and HRP in the nanotracer could both catalyze and dual amplify the absorbance at 650 nm ascribed to the 3,3',5,5'-tetramethylbenzidine (TMB)-H2O2 system. Moreover, Exo I can assist the target recycling, which can further amplify the signal. Thus, the triple amplified signal can be quantified by ultraviolet-visible spectroscopy. The experimental results showed that the CAP detection possessed a linear range of 0.001-10 ng mL(-1) and a detection limit of 0.0003 ng mL(-1) (S/N = 3). The assay was successfully employed to detect CAP in milk, which is much more facile, time saving, and sensitive than the commercial ELISA kits.


Assuntos
Antibacterianos/análise , Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Cloranfenicol/análise , Nanopartículas de Magnetita/química , Leite/química , Platina/química , Animais , Antibacterianos/metabolismo , Aptâmeros de Nucleotídeos/metabolismo , Benzidinas/química , Cloranfenicol/metabolismo , Colorimetria/métodos , Exodesoxirribonucleases/metabolismo , Ouro/química , Peróxido de Hidrogênio/química , Limite de Detecção , Nanopartículas de Magnetita/ultraestrutura
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