Simmons S R, Albrecht R M
University of Wisconsin, Madison 53706.
Scanning Microsc Suppl. 1989;3:27-33; discussion 33-4.
Colloidal gold can be produced in sizes ranging from 1.0nm to 150nm. All sizes of gold can be conjugated, principally by hydrophobic bonding, to a variety of molecules including ligands, enzymes and antibodies, as well as lectins and polysaccharides. The activity of most of these biological molecules is retained on conjugation with gold particles irregardless of size range, although the ratio of protein surface area to gold particle surface area varies widely depending on particle and protein size. We have employed low voltage high resolution scanning electron microscopy to compare, microscopically, the shapes of biological molecules unbound, bound to very small (3nm) gold particles, and bound to larger (18nm-30nm) gold particles. When very small gold particles are conjugated to large protein molecules, several particles bind along the length of each molecule, while smaller protein molecules often wrap around a single small gold particle. With larger gold particles, several biological molecules bind to a single gold particle. In addition, the shape of protein molecules bound to larger gold particles differs from that of molecules bound to small gold particles.
胶体金的粒径范围为1.0纳米至150纳米。所有粒径的金都可以通过疏水键主要与多种分子结合，这些分子包括配体、酶、抗体以及凝集素和多糖。尽管蛋白质表面积与金颗粒表面积的比例会因颗粒和蛋白质大小的不同而有很大差异，但大多数这些生物分子在与金颗粒结合后仍能保持其活性，而不论粒径范围如何。我们采用了低电压高分辨率扫描电子显微镜，从微观角度比较了未结合的生物分子、与非常小的（3纳米）金颗粒结合的生物分子以及与较大的（18纳米至30纳米）金颗粒结合的生物分子的形状。当非常小的金颗粒与大的蛋白质分子结合时，几个颗粒会沿着每个分子的长度方向结合，而较小的蛋白质分子通常会缠绕在单个小金颗粒周围。对于较大的金颗粒，几个生物分子会结合到单个金颗粒上。此外，与较大金颗粒结合的蛋白质分子的形状与与小金颗粒结合的分子的形状不同。
