Nuclear Science and Techniques

《核技术》(英文版) ISSN 1001-8042 CN 31-1559/TL     2019 Impact factor 1.556

Nuclear Science and Techniques ›› 2012, Vol. 23 ›› Issue (1): 52-56 doi: 10.13538/j.1001-8042/nst.23.52-56


Study of chemical kinetics on labeling of 99mTc-N-ethyl-N_2S_2-Memantine

CAO Guoxian1,2,3,ZHOU Xingqin1,2,3 LIU Yingtao1,2,3 KONG Yanyan1,2,3 ZHANG Jiankang1,2,3   

  1. 1Key Laboratory of Nuclear Medicine,Ministry of Health,Wuxi 214063,China 2Key Laboratory of Molecular Nuclear Medicine of Jiangsu,Wuxi 214063,China 3Jiangsu Institute of Nuclear Medicine,Wuxi 214063,China
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CAO Guoxian, ZHOU Xingqin, LIU Yingtao, KONG Yanyan, ZHANG Jiankang. Study of chemical kinetics on labeling of 99mTc-N-ethyl-N_2S_2-Memantine.Nuclear Science and Techniques, 2012, 23(1): 52-56     doi: 10.13538/j.1001-8042/nst.23.52-56


In this work,a calculation method of chemical kinetics was established for labeling reaction of 99mTc-N-ethyl-N2S2-memantine,a potential NMDA receptor imaging agent prepared in our laboratory.Four groups of vials (3 vials per group) were added with 0.02 mL (1 mg/mL) N-ethyl-N2S2Memantine,0.08 mL (40 mg/mL) GH,0.05 mL (10 mg/mL) EDTA-2Na,0.035 mL (2 mg/mL) SnF2,0.8 mL phosphate buffer(1mol/L,pH 6.5) and 37 MBq Na99mTcO4.The vials were incubated at 70℃,80℃,90℃ or 100℃.Samples were taken with capillary from the vials at 2,5,10,20,30,40 and 60min.Labeling yields were determined by TLC.Order of reaction n,rate constant k,activation energy Ea and half life t1/2 of labeling reaction were calculated with the kinetics software we compiled.Mean labeling yields of 99m Tc-N-ethyl-N2S2-memantine at 2,5,10,20,30,40 and 60min were (1) 13.5,15.7,34.0,64.8,81.9,91.4 and 95.4 at 70℃; (2) 13.2,20.5,40.1,70.0,88.2,94.5 and 95.6 at 80℃; (3) 15.6,22.9,43.7,74.3,87.2,93.4 and 96.1 at 90℃; and (4) 20.5,25.8,45.3,81.1,92.2,95.6 and 96.0 at 100℃.The other parameters were; n =1; k=0.053,0.061,0.063 and 0.076 L/min at 70℃,80℃,90℃ and 100℃,respectively; Ea=12.38 kJ/L; t1/2=13.11,11.45,11.05 and 9.07min at 70℃,80℃,90℃ and 100℃,respectively.The mean labeling yield increased with temperature and time,optimized at 100℃ and 40-60min.The concentration of 99mTc-N-ethyl-N2S2-Memantine was larger than that of Na99mTcO4,so n=1.The k increased with reaction,hence the accelerated reaction rate at higher temperatures.The labeling reaction was not so difficult because of the low Ea.The t1/2 decreased with increasing reaction temperature,hence the acceleration of labeling reaction.

Key words: 99mTc-N-ethyl-N2S2-Memantine, NMDA receptor, Labelling, Chemical kinetics