RESUMO
Zeolitic imidazolate framework (ZIF-8) base-aptamer "gate-lock" biomaterial probes have been synthesized for monitoring intracellular deoxynivalenol (DON) and cytochrome c (cyt c) levels. The aptamer and organic fluorescent dye were regarded as a recognition element and a sensing element, respectively. In the presence of DON, the aptamers of DON and cyt c were specifically bound with the DON and induced cyt c, leading to the dissociation of aptamers from the porous surface of the probes. The gate was subsequently opened to release methylene blue (MB) and Rhodamine 6G (Rh6G), and their fluorescence (emission of MB at 700 nm and Rh6G at 550 nm) significantly recovered within 6 h. Cell imaging successfully monitored the exposure of DON and the biological process of cyt c discharge triggered by the activation of the DON-induced apoptosis pathway. In addition, the response between DON and cyt c was observed during the apoptosis process, which is of high significance for the comprehensive and systematic development of mycotoxins cytotoxicity.
Assuntos
Aptâmeros de Nucleotídeos , Tricotecenos , Zeolitas , Citocromos c/metabolismo , Tricotecenos/toxicidadeRESUMO
This paper describes the fabrication of an imprinted fluorescent nanoprobe based on SiO2-coated NaYF4: Yb, Er upconversion nanoparticles (UCNP) encapsulated with a molecularly imprinted polymer (MIP) for determination of acetamiprid. The fluorescent MIP nanoprobe was prepared using UCNP as the material for fluorescence signal readout, acetamiprid as template molecule, methylacrylic acid (MAA) as functional monomer, and ethyleneglycol dimethacrylate (EGDMA) as cross-linking agent. The molecular imprinting layers were immobilized on the surface of the UCNP@SiO2 by polymerization which occurred between the double bonds. UCNP@MIP shows a high selectivity towards acetamiprid with an imprinting factor (IF) of 7.84. When UCNP@MIP combines with acetamiprid, the fluorescence of the UCNP@MIP can be quenched due to the photo-induced electron transfer. Under optimum conditions, the fluorescence method shows a good linear relationship between the decreased fluorescence intensity (with excitation/emission peaks at 980/542 nm) and the variation of acetamiprid in the concentration range 20 to 800 ng mL-1. The limit of detection (LOD) is 8.3 ng mL-1. This fluorescence method was also successfully applied to detect acetamiprid in apple and strawberry samples. The recoveries range from 89.6 to 97.9%, with relative standard deviations between 1.6 and 2.9% (n = 5). Graphical abstractA simple fluorescence nanoprobe which integrates upconversion nanoparticles (UCNPs) and molecular imprinting polymer (MIP) was developed for the determination of acetamiprid. The limit of the detection was determined as 8.3 ng mL-1. The selectivity was enhanced by molecular imprinting, and the sensitivity was improved by the high sensitivity of the fluorescence emitted from the UCNPs.
Assuntos
Técnicas Biossensoriais , Fluorometria , Impressão Molecular , Nanopartículas/química , Neonicotinoides/análise , Adsorção , Fluorescência , Fluoretos/química , Estrutura Molecular , Tamanho da Partícula , Dióxido de Silício/química , Propriedades de Superfície , Itérbio/química , Ítrio/químicaRESUMO
Deoxynivalenol (DON) is considered a mycotoxin that is toxic to the agricultural environment and human body. It is necessary to study the pathophysiological mechanism of DON toxicity at the cellular level. Cytochrome c (Cyt c), as an important biomarker of DON-induced apoptosis that may lead to a bipartite 'point-of-no return' event, is of great significance to be detected using cell imaging. Herein, we synthesized a DON-deactivated emission ï¬uorescent probe, the molecularly imprinted polymer-coated quantum dots (CdTe@MIP), for monitoring the Cyt c level with a photoinduced electron transfer strategy. The CdTe@MIP probe can be easily loaded into cells and perform well due to its great sensitivity and selectivity and its fluorescence was gradually quenched with the increasing concentration (0-10 µM) and incubation time (0-7.5 h) of DON. Cell imaging results of apoptosis induced by DON was consistent with that of the cell counting kit-8 assay and flow cytometry technique. The developed method can be used to monitor DON-induced apoptosis and provide an early-warning system for the contaminant toxicity.
Assuntos
Compostos de Cádmio , Pontos Quânticos , Apoptose , Citocromos c , Elétrons , Corantes Fluorescentes , Humanos , Telúrio , TricotecenosRESUMO
Herein, a new double-enzymes-modulated fluorescent assay based on the quenching of upconversion nanoparticles (UCNPs) by Fe3+ was constructed for sensitive determination of OPs. OPs can inhibit the activity of acetylcholinesterase to reduce the production of choline and further lead to the lack of H2O2 in the presence of choline oxidase. Therefore, Fe2+ cannot be converted into Fe3+, resulting in "turn-on" fluorescence of UCNPs. Under optimal conditions, an excellent linear correlation between the inhibition efficiency and the logarithm of the chlorpyrifos concentration was achieved with a detection limit (LOD) of 6.7 ng/mL in the range of 20-2000 ng/mL. The recovery for chlorpyrifos in apples and cucumbers was 89.5-97.1%. The results were consistent with those obtained by GC-MS. Overall, the integration of UCNPs into the double-enzymes-mediated Fe3+/Fe2+ conversion endows this method with desirable rapidity, sensitivity, selectivity, stability, operational simplicity, and strong anti-interference capability, holding great potential in the application of food safety.
Assuntos
Acetilcolinesterase/metabolismo , Oxirredutases do Álcool/metabolismo , Técnicas Biossensoriais/métodos , Clorpirifos/análise , Ferro/química , Limite de Detecção , Nanopartículas/química , Praguicidas/análise , Espectrometria de FluorescênciaRESUMO
Techniques that are sensitive to detect mercury ion (Hg2+) are very important, due to its serious threat to public health and food security. In this work, a colorimetric aptasensor was fabricated for the detection of Hg2+ based on rolling circle amplification (RCA). The aptamer was immobilized onto the microplate and hybridized with its complementary strand (cDNA1) which linked with a primer for triggering the RCA reaction of circular template. The successfully RCA process led to the formation of long ssDNA chains on the microplate, which created many hybridized DNA fragments for bio-cDNA2. The tagged amount of horseradish peroxidase (HRP) was enhanced through the avidin/biotin binding between avi-HRP and bio-cDNA2. In the addition of TMB-H2O2, HRP was catalyzed and generated an optical signal. However, in the presence of target, Hg2+ specifically and preferentially bound with aptamer and formed a strong and stable T-Hg2+-T complex, which led to the release of cDNA1 and HRP cluster. Consequently, the optical signal decreased. Our results showed that the limit of detection (LOD) of this system was 1.6â¯nM with excellent specificity, and that the detection signals were enhanced by up to 18 times under RCA conditions when compared with detections without RCA. This method has been successfully used to detect Hg2+ in water samples with a recovery of 98%-105.74%.
Assuntos
Aptâmeros de Nucleotídeos/química , Colorimetria/métodos , Mercúrio/análise , Técnicas de Amplificação de Ácido Nucleico/métodos , Poluentes Químicos da Água/análise , Lagos , Limite de Detecção , Modelos Lineares , Mercúrio/química , Poluentes Químicos da Água/químicaRESUMO
Deoxynivalenol (DON) is one of the most globally prevalent mycotoxins mainly produced by Fusarium species. It can cause pollution to water environmental quality due to its water solubility. Therefore, it is necessary to develop a green and efficient detoxification technology for DON. More importantly, the toxicity of the degradation products should be assessed. Photocatalytic degradation technology has attracted increasing attention in the field of pollutants treatment, especially for wastewater treatment. Herein, the as-prepared NaYF4:Yb,Tm@TiO2 composite (UCNP@TiO2) was employed as a novel photocatalyst for the NIR-enhanced photocatalytic degradation of DON. Three intermediate products were identified by using the ESI/MS analysis and secondary mass spectrogram, with the m/z values of 329.399, 311.243 and 280.913, respectively. Furthermore, the in vitro safety of the product mixtures with various degradation time (30â¯min, 60â¯min, 90â¯min and 120â¯min) were evaluated through the influences on cell viability, cell morphology, cell cycle, intracellular reactive oxygen species (ROS) level, cell apoptosis and antioxidant capacity of HepG2 cells. There were no significant differences in these investigated indicators between the control (free of DON) and 120â¯min products treatment. Overall, the results indicated that the toxicity of degradation products after 120â¯min irradiation was much lower and even nontoxic than that of DON.
Assuntos
Micotoxinas/química , Titânio/química , Tricotecenos/química , Purificação da Água/métodos , Sobrevivência Celular/efeitos dos fármacos , Células Hep G2/citologia , Células Hep G2/efeitos dos fármacos , Células Hep G2/metabolismo , Humanos , Micotoxinas/análise , Nanopartículas/química , Espécies Reativas de Oxigênio/metabolismo , Tricotecenos/toxicidade , Águas Residuárias/análise , Águas Residuárias/química , Poluentes da Água/químicaRESUMO
Herein, we constructed an aptamer-based sensor for the sensitive and highly specific detection of Shigella sonnei via surface enhanced Raman spectroscopy (SERS) analysis. A composite material integrated of the Raman active 4-MBA ligand of the Eu-complex and citrate-stabilized Au nanoparticles (cit-Au NPs) was synthesized and served as both active substrate and Raman reporter. Aptamers targeted to S. Sonnei was then modified onto the surface of this dual-functional material. With the introduction of S. Sonnei, aptamer bound with target with high affinity and specificity, leaving the dual-functional material onto the bacteria. The SERS intensity response showed a strong positive linear correlation (Râ¯=â¯0.9956) with increasing concentrations of S. sonnei (ranging from 10 to 106 cfu/mL). High specificity was achieved at Shigella species (S. dysenteriae, S. flexneri, S. boydii) and other common bacteria (Salmonella typhimurium, Staphylococcus aureus and Escherichia coli). When applied in real samples, the approach showed recoveries from 92.6 to 103.8 %. The designed approach holds great potential for the construction of various aptasensors for the effective and convenient detection of different food hazards.
Assuntos
Antibacterianos/farmacologia , Aptâmeros de Nucleotídeos/farmacologia , Ouro/farmacologia , Nanopartículas Metálicas/química , Compostos Organometálicos/farmacologia , Shigella/efeitos dos fármacos , Antibacterianos/síntese química , Antibacterianos/química , Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais , Dimerização , Ouro/química , Testes de Sensibilidade Microbiana , Compostos Organometálicos/síntese química , Compostos Organometálicos/química , Tamanho da Partícula , Análise Espectral Raman , Propriedades de SuperfícieRESUMO
Deoxynivalenol (DON), a trichothecene mycotoxin, has attracted global attention due to its prevalence and substantial effects on animal and human health. DON induces the upregulation of intracellular reactive oxygen species (ROS) by disrupting the normal mitochondrial functionality, which causes oxidative stress, cell apoptosis, and even severe disorders. The aim of present work is to develop a simple, convenient, and in situ method for monitoring ROS and evaluating DON-mediated oxidative stress. Herein, polyethylene glycol-modified CdSe@ZnS quantum dots (QDs) were employed as simple and convenient nanoprobe for ROS imaging and oxidative stress evaluating induced by DON in living cells. The results demonstrated 5 ppm QDs nanoprobe can be easily loaded into cells via endocytosis without readily observable oxidative effects. Once in presence of DON, the augmented ROS directly oxidize the QDs nanoprobe, which leads to the destruction of the QDs structure and quenched fluorescence. According to the weakened fluorescence intensity (FI), the oxidative damage mediated by DON can be rapidly monitored and found that the oxidative stress was the most severe when the DON concentration exceeded 10 ppm. The developed QDs nanoprobe is also suitable for assessing other mycotoxins and chemicals. We hope it will be beneficial for the early screening of toxic and harmful substances in in vitro toxicology.
Assuntos
Compostos de Cádmio/química , Polietilenoglicóis/química , Pontos Quânticos , Espécies Reativas de Oxigênio/química , Compostos de Selênio/química , Sulfetos/química , Compostos de Zinco/química , Sobrevivência Celular/efeitos dos fármacos , Células Hep G2 , Humanos , Estresse Oxidativo , TricotecenosRESUMO
Deoxynivalenol (DON) is regarded as the most common contaminant of cereal grains. Therefore, finding an efficient and safe detoxification technology is of great significance in the field of food. In this study, upconversion nanoparticles@TiO2 composites were used for the photocatalytic degradation of DON in wheat. The effect of photocatalytic oxidation on wheat quality was also evaluated by studying the basic physical and chemical indexes of wheat. The results showed that the removal rate of DON in wheat could reach 72.8% within 90 min when the dosage of photocatalyst UCNP@TiO2 was 8 mg mL-1 and the ratio of wheat to liquid was 1 : 2. In addition, the composites can be easily removed by washing, thus ensuring the low exposure dose of the nanomaterials in wheat. Studies on the nutritional quality of wheat showed that photocatalytic technology had little effect on the starch, protein, amino acid content of wheat (p > 0.05). The whiteness of wheat flour decreased and the yellowness increased. The scanning electron microscopy (SEM) images of wheat starch showed that the surfaces of starch granules were damaged to varying degrees with the prolongation of illumination time. Meanwhile, the fatty acid value and wet gluten content and pasting properties of wheat decreased significantly during photocatalysis (p < 0.05). This study demonstrates that photocatalytic degradation will have a promising prospect in toxin removal.
RESUMO
Micro-nano composite material was prepared to adsorb Hg(II) ions via the co-precipitation method. Oyster shell (OS), Fe3O4 nanoparticles, and humic acid (HA) were used as the raw materials. The adhesion of nanoparticles to OS displayed by scanning electron microscopy (SEM), the appearance of the (311) plane of standard Fe3O4 derived from X-ray diffraction (XRD), and the transformation of pore sizes to 50 nm and 20 µm by mercury intrusion porosimetry (MIP) jointly revealed the successful grafting of HA-functionalized Fe3O4 onto the oyster shell surface. The vibrating sample magnetometer (VSM) results showed superparamagnetic properties of the novel adsorbent. The adsorption mechanism was investigated based on X-ray photoelectron spectroscopy (XPS) techniques, which showed the process of physicochemical adsorption while mercury was adsorbed as Hg(II). The effects of pH (3-7), initial solution concentration (2.5-30 mg·L-1), and contact time (0-5 h) on the adsorption of Hg(II) ions were studied in detail. The experimental data were well fitted to the Langmuir isotherm equation (R2 = 0.991) and were shown to follow a pseudo-second-order reaction model (R2 = 0.998). The maximum adsorption capacity of Hg(II) was shown to be 141.57 mg·g-1. In addition, this new adsorbent exhibited excellent selectivity.