Zhiping Liu1, Kai Wang1, Sha Wu1, Zhanhui Wang2, Guochun Ding1, Xiujing Hao3, Qing X Li4, Ji Li1, Shirley J Gee5, Bruce D Hammock5, Ting Xu1. 1. Department of ecological science and engineering, Beijing Key Laboratory of Biodiversity and Organic Farming, College of Resources and Environmental Sciences, China Agricultural University, Beijing, China. 2. Department of basic veterinary medicine, Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural University, Beijing Key Laboratory of Detection Technology for Animal-Derived Food Safety, Beijing Laboratory for Food Quality and Safety, Beijing, China. 3. Key lab of ministry of education for protection and utilization of special biological resources in western China, College of Life Science, Ningxia University, Ningxia, China. 4. Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, Honolulu, HI, USA. 5. Department of Entomology and UCD Comprehensive Cancer Center, University of California, Davis, CA, USA.
Abstract
BACKGROUND: The variable domain of camelid heavy-chain antibodies (VHH) is increasingly being adapted to detect small molecules in various matrices. The insecticide carbaryl is widely used in agriculture while its residues have posed a threat to food safety and human health. RESULTS: VHHs specific for carbaryl were generated from an alpaca immunized with the hapten CBR1 coupled to keyhole limpet hemocyanin. An enzyme-linked immunosorbent assay (ELISA) based on the VHH C1 and the coating antigen CBR2-BSA was developed for the detection of carbaryl in cereals. This assay, using an optimized assay buffer (pH 6.5) containing 10% methanol and 0.8% NaCl, has a half-maximum signal inhibition concentration of 5.4 ng mL-1 and a limit of detection (LOD) of 0.3 ng mL-1 for carbaryl, and shows low cross reactivity (≤0.8%) with other tested carbamates. The LOD of carbaryl using the VHH-based ELISA was 36 ng g-1 in rice and maize and 72 ng g-1 in wheat. Recoveries of carbaryl in spiked rice, maize and wheat samples were in the range of 81-106%, 96-106% and 83-113%, respectively. Relative standard deviations of repeatability and intra-laboratory reproducibility were in the range of 0.8-9.2% and 2.9-9.7%, respectively. CONCLUSION: The VHH-based ELISA was highly effective in detecting carbaryl in cereal samples after simple sample extraction and dilution.
BACKGROUND: The variable domain of camelid heavy-chain antibodies (VHH) is increasingly being adapted to detect small molecules in various matrices. The insecticide carbaryl is widely used in agriculture while its residues have posed a threat to food safety and human health. RESULTS:VHHs specific for carbaryl were generated from an alpaca immunized with the hapten CBR1 coupled to keyhole limpet hemocyanin. An enzyme-linked immunosorbent assay (ELISA) based on the VHH C1 and the coating antigen CBR2-BSA was developed for the detection of carbaryl in cereals. This assay, using an optimized assay buffer (pH 6.5) containing 10% methanol and 0.8% NaCl, has a half-maximum signal inhibition concentration of 5.4 ng mL-1 and a limit of detection (LOD) of 0.3 ng mL-1 for carbaryl, and shows low cross reactivity (≤0.8%) with other tested carbamates. The LOD of carbaryl using the VHH-based ELISA was 36 ng g-1 in rice and maize and 72 ng g-1 in wheat. Recoveries of carbaryl in spiked rice, maize and wheat samples were in the range of 81-106%, 96-106% and 83-113%, respectively. Relative standard deviations of repeatability and intra-laboratory reproducibility were in the range of 0.8-9.2% and 2.9-9.7%, respectively. CONCLUSION: The VHH-based ELISA was highly effective in detecting carbaryl in cereal samples after simple sample extraction and dilution.
Authors: Hee-Joo Kim; Mark R McCoy; Zuzana Majkova; Julie E Dechant; Shirley J Gee; Sofia Tabares-da Rosa; Gualberto G González-Sapienza; Bruce D Hammock Journal: Anal Chem Date: 2011-12-29 Impact factor: 6.986
Authors: Mireille Dumoulin; Alexander M Last; Aline Desmyter; Klaas Decanniere; Denis Canet; Göran Larsson; Andrew Spencer; David B Archer; Jurgen Sasse; Serge Muyldermans; Lode Wyns; Christina Redfield; André Matagne; Carol V Robinson; Christopher M Dobson Journal: Nature Date: 2003-08-14 Impact factor: 49.962
Authors: C Hamers-Casterman; T Atarhouch; S Muyldermans; G Robinson; C Hamers; E B Songa; N Bendahman; R Hamers Journal: Nature Date: 1993-06-03 Impact factor: 49.962