摘要
Amantadine(AMD)residue can accumulate in organisms through the food chain and cause serious harm to human body.AMD can specifically bind to AMD specific aptamer and cause its conformation to change from a random single strand to a stem-loop structure.To avoid the influence of excess nucleotides on binding of aptamer to AMD,the truncation of the AMD original aptamer J was optimized by retaining an appropriate stem-loop structure,and a new type of truncation aptamers was developed in this work.By comparing the truncated aptamer with the original aptamer,it was found that the truncated aptamer J-7 had better affinity and specificity with AMD.The detection limit of AMD was 0.11 ng/mL by using J-7 as specific recognition element and molybdenum disulfide nanosheet(MoS2Ns)as signal amplification element.The developed method base on truncated aptamer J-7 was used for detection of AMD in milk,yogurt and SD rat serum samples for the first time with recoveries of 86.6%-108.2%.This study provided a reference for truncating other long sequence aptamers and provided a more sensitive detection method for monitoring AMD residues in food.
摘要
OBJECTIVE: To explore the effect of~(56)Fe~(17+)heavy ion on the expression of phosphorylated histone H2AX( γH2AX) of human lymphccytes. METHODS: The Epstein-Barr virus transformed human B lymphocyte cell lines( PengEBV) were selected and exposed to~(56)Fe~(17+)heavy ion at irradiation dose of 0. 0( control group),0. 1,0. 3,0. 5,0. 7,1. 0 and 2. 0 Gy,respectively,with the dosing rate of 0. 23-0. 55 Gy / min. Flow-cytometry was used to detect the changes of expression of γH2AX at time points of 0,2,4,8,48 and 72 hours after irradiation. RESULTS: The expression of γH2AX showed interaction existed between radiation dose and the treatment time after radiation( P < 0. 01). Compared with the control at the same time points,the expression of γH2AX increased at the dose of 0. 3-2. 0 Gy and the time points of 2-72hours( P < 0. 05). The expression of γH2AX at the dose of 0. 3-2. 0 Gy and time points of 8-72 hours was lower than those at the same dose and time points of 2 and 4 hours( P < 0. 05). When the dose was at 0. 5,1. 0 or 2. 0 Gy,the expression of γH2AX decreased with the increasing time of exposure in 72 hours( P < 0. 05). At the dose of 0. 0-1. 0 Gy and the time points of 2-4 hours,the expression of γH2AX increased with the increasing dose of irradiation( P < 0. 01). CONCLUSION: The expression of γH2AX in Peng-EBV cells shows a dose-response relationship within 2-4 hours after 0. 0-1. 0 Gy irradiation of~(56)Fe~(17+).