RESUMEN
Objective To evaluate the hypoxia selectivity of 99 Tcm O?labeld MAG3?nitroimidazole complexes with different spacers. Methods Four kinds of 99 Tcm O?labeled MAG3?2?nitroimidazole hypoxia imaging agents with different spacers were synthesized and radiolabeled. The stability and lipid solubility of BzMAG3?2NIEA(1), BzMAG3?2NIPA(2), BzMAG3?2NIHA(3) and BzMAG3?2NIUA(4) were measured. The uptake was investigated by biodistribution experiment using S180?bearing mice. Two?sample t test was used for statistical analysis. Results All 4 99 Tcm O?MAG3 complexes were stable and negatively charged, showing an increasing trend in fat solubility with the increase of spacer length. In biodistribution study, tumor uptake of 99TcmO?1 and 99TcmO?2 with medium? and short?carbon chain were (0.67±0.18) and (0?65±0.18) %ID/g 2 h post injection, which were (0.19±0.03) and (0.39±0.05) %ID/g for 99TcmO?3 and 99TcmO?4 with long?carbon chain (t=2.78-5.88, all P<0.05). Conclusion Molecular structure of spacers has a significant effect on the physicochemical properties and tumor targeting of 99 Tcm O?labeled MAG3?2?nitroimidazole hypoxia imaging agents, such that the medium?and short?carbon chain spacers show the best hypoxia?selective property.