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Li H.,Chinese Academy of Agricultural Sciences | Li H.,Key Laboratory of Biology and Genetic Improvement of Oil Crops | Li H.,Laboratory of Quality and Safety Risk Assessment for Oilseed Products Wuhan | Li H.,Key Laboratory of Detection for Mycotoxins | And 9 more authors.
Biosensors and Bioelectronics | Year: 2016

An ultrasensitive biosensor for carcinoembryonic antigen (CEA) was constructed based on fluorescence resonance energy transfer (FRET) between upconverting nanoparticles (UCPs) and palladium nanoparticles (PdNPs). PdNPs was synthesized by the addition of a solution of Na2PdCl4 into a mixture of N2H4·H2O as the reducing agent and 11-mercaptoundecanoic acid (MUDA) as the stabilizer. The CEA aptamer (5′-NH2-ATACCAGCTTATTCAATT-3′) was conjugated to hexanedioic acid (HDA) modified UCPs (HDA-UCPs) through an EDC-NHS coupling protocol. The coordination interaction between nitrogen functional groups of the CEA aptamer and PdNPs brought UCPs and PdNPs in close proximity, which resulted in the fluorescence quenching of UCPs to an extent of 85%. And the non-specific fluorescence quenching caused by PdNPs towards HDA-UCPs was negligible. After the introduction of CEA into the UCPs-CEA aptamer-PdNPs fluorescence quenching system, the CEA aptamer preferentially combined with CEA accompanied by the conformational change which weakened the coordination interaction between the CEA aptamer and PdNPs. So fluorescence recovery of UCPs was observed and a linear relationship between the fluorescence recovery of UCPs and the concentration of CEA was obtained in the range from 2 pg/mL to 100 pg/mL in the aqueous buffer with the detection limit of 0.8 pg/mL. The ultrasensitive detection of CEA was also realized in diluted human serum with a linear range from 4 pg/mL to 100 pg/mL and a detection limit of 1.7 pg/mL. This biosensor makes the most of the high quenching ability of PdNPs towards UCPs with negligible non-specific fluorescence quenching and has broad application prospects in biochemistry. © 2016 Elsevier B.V.

Dai X.,Chinese Academy of Agricultural Sciences | Dai X.,Laboratory of Quality and Safety Risk Assessment for Oilseed Products Wuhan | Bai Y.,Chinese Academy of Agricultural Sciences | Bai Y.,Laboratory of Quality and Safety Risk Assessment for Oilseed Products Wuhan | And 24 more authors.
Journal of Agricultural and Food Chemistry | Year: 2016

Cadmium (Cd) in 8698 peanut samples collected from China in 2009-2014 was studied to evaluate its contamination level, distribution, and health risk. The average Cd concentration was 0.1684 mg kg-1 the range of 2.5-97.5% was 0.0191-0.4762 mg kg-1, indicating the cadmium-contaminated peanut level was even lower. Some peanut strains for which protein contents had a significant correlation (Pearson correlation coefficient r = 0.86∗ ∗) with the Cd concentration level should be of concern. Under the same soil Cd background, the difference in Cd contents in different peanut varieties is extremely significant. For example, the Cd concentration of Silihong is about 0.4522 mg kg-1, being 7 times higher than that of Zhonghua 6. According to the exposure assessment using the probabilistic simulation method, the target hazard quotients (THQs) of all groups should be below 1. The THQ range in this study was from 0.0035 to 0.0202, suggesting that there were no potential noncinogenic effects in any group. © 2016 American Chemical Society.

Wang D.,Chinese Academy of Agricultural Sciences | Wang D.,Laboratory of Quality and Safety Risk Assessment for Oilseed Products Wuhan | Wang D.,Key Laboratory of Detection for Mycotoxins | Zhang Z.,Chinese Academy of Agricultural Sciences | And 11 more authors.
Journal of Agricultural and Food Chemistry | Year: 2015

Immunochromatographic (IC) assays are considered suitable diagnostic tools for the determination of mycotoxins. A europium nanospheres-based time-resolved fluorescence immunoassay (Eu-Nano-TRFIA), based on a monoclonal antibody and a portable TRFIA reader, was developed to determine total aflatoxin (including aflatoxins B1, B2, G1, and G2) levels in feed samples. Under optimized conditions, the Eu-Nano-TRFIA method detected total aflatoxin within 12 min. It showed good linearity (R2 > 0.985), LOD of 0.16 μg/kg, a wide dynamic range of 0.48-30.0 μg/kg, recovery rates of 83.9-113.9%, and coefficients of variation (CVs) of 3.5-8.8%. In the 397 samples from company and livestock farms throughout China, the detection rate was 78.3%, concentrations were 0.50-145.30 μg/kg, the highest total aflatoxin content was found in cottonseed meal, and corn was found to be the most commonly contaminated feed. This method could be a powerful alternative for the rapid and ultrasensitive determination of total aflatoxin in quality control and meet the required Chinese maximum residue limits. © 2015 American Chemical Society.

Ding X.,Chinese Academy of Sciences | Ding X.,Laboratory of Quality and Safety Risk Assessment for Oilseed Products Wuhan | Ding X.,Key laboratory of Detection for Mycotoxins | Ding X.,Key Laboratory of Biology and Genetic Improvement of Oil Crop | And 25 more authors.
Toxins | Year: 2015

Based on the 2983 peanut samples from 122 counties in six provinces of China’s Yangtze River ecological region collected between 2009-2014, along with the dietary consumption data in Chinese resident nutrition and health survey reports from 2002 and 2004, dietary aflatoxin exposure and percentiles in the corresponding statistics were calculated by non-parametric probability assessment, Monte Carlo simulation and bootstrap sampling methods. Average climatic conditions in the Yangtze River ecological region were calculated based on the data from 118 weather stations via the Thiessen polygon method. The survey results found that the aflatoxin contamination of peanuts was significantly high in 2013. The determination coefficient (R2) of multiple regression reflected by the aflatoxin B1. content with average precipitation and mean temperature in different periods showed that climatic conditions one month before harvest had the strongest impact on aflatoxin B1 contamination, and that Hunan and Jiangxi provinces were greatly influenced. The simulated mean aflatoxin B1 intake from peanuts at the mean peanut consumption level was 0.777-0.790 and 0.343-0.349 ng/(kg·d) for children aged 2-6 and standard adults respectively. Moreover, the evaluated cancer risks were 0.024 and 0.011/(100,000 persons·year) respectively, generally less than China’s current liver cancer incidence of 24.6 cases/(100,000 persons·year). In general, the dietary risk caused by peanut production and harvest was low. Further studies would focus on the impacts of peanut circulation and storage on aflatoxin B1 contamination risk assessment in order to protect peanut consumers’ safety and boost international trade. © 2015 by the authors; licensee MDPI, Basel, Switzerland.

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