Efficient Radioisotope Energy Transfer by Gold Nanoclusters for Molecular Imaging.

Beta-emitting isotopes Fluorine-18 and Yttrium-90 are tested for their potential to stimulate gold nanoclusters conjugated with blood serum proteins (AuNCs). AuNCs excited by either medical radioisotope are found to be highly effective ionizing radiation energy transfer mediators, suitable for in vivo optical imaging. AuNCs synthesized with protein templates convert beta-decaying radioisotope energy into tissue-penetrating optical signals between 620 and 800 nm. Optical signals are not detected from AuNCs incubated with Technetium-99m, a pure gamma emitter that is used as a control. Optical emission from AuNCs is not proportional to Cerenkov radiation, indicating that the energy transfer between the radionuclide and AuNC is only partially mediated by Cerenkov photons. A direct Coulombic interaction is proposed as a novel and significant mechanism of energy transfer between decaying radionuclides and AuNCs.

发射β射线的同位素氟 - 18和钇 - 90被测试其激发与血清蛋白共轭的金纳米团簇（AuNCs）的潜力。发现被任一医用放射性同位素激发的AuNCs是高效的电离辐射能量传递介质，适用于体内光学成像。用蛋白质模板合成的AuNCs将β衰变放射性同位素的能量转化为620至800纳米之间的可穿透组织的光信号。在与锝 - 99m（一种用作对照的纯γ发射体）一起孵育的AuNCs中未检测到光信号。AuNCs的光发射与切伦科夫辐射不成比例，这表明放射性核素与AuNC之间的能量传递仅部分由切伦科夫光子介导。提出直接库仑相互作用是衰变放射性核素与AuNCs之间能量传递的一种新颖且重要的机制。