Samorì B, Muzzalupo I, Zuccheri G
Dipartimento di Chimica, Università della Calabria, Cosenza, Italy.
Scanning Microsc. 1996;10(4):953-60; discussion 960-2.
The deposition of DNA molecules on mica is driven and controlled by the ionic densities around DNA and close to the surface of the substrate. Dramatic improvements in the efficiency and reproducibility of DNA depositions were due to the introduction of divalent cations in the deposition solutions. The ionic distributions on DNA and on mica determine the mobility of adsorbed DNA molecules, thus letting them assume thermodynamically equilibrated conformations, or alternatively trapping them in non-equilibrated conformations upon adsorption. With these prerequisites, mica does not seem like an inert substrate for DNA deposition for microscopy, and its properties greatly affect the efficiency of DNA deposition and the appearance of the molecules on the substrate. In our laboratory, we have some preliminary evidence that mica could also participate in DNA damage, most likely through its heavy metal impurities.
DNA分子在云母上的沉积受DNA周围以及靠近基底表面的离子密度驱动和控制。沉积溶液中引入二价阳离子使得DNA沉积的效率和可重复性有了显著提高。DNA和云母上的离子分布决定了吸附的DNA分子的迁移率，从而使其呈现热力学平衡构象，或者在吸附时将它们捕获在非平衡构象中。基于这些前提，云母对于用于显微镜观察的DNA沉积而言似乎并非惰性基底，其性质极大地影响了DNA沉积的效率以及分子在基底上的外观。在我们实验室，我们有一些初步证据表明云母也可能参与DNA损伤，最有可能是通过其重金属杂质。
