Moreno-Herrero F, Colchero J, Gómez-Herrero J, Baró A M
Departamento de Física de la Materia Condensada, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
Phys Rev E Stat Nonlin Soft Matter Phys. 2004 Mar;69(3 Pt 1):031915. doi: 10.1103/PhysRevE.69.031915. Epub 2004 Mar 31.
The capabilities of the atomic force microscope for imaging biomolecules under physiological conditions has been systematically investigated. Contact, dynamic, and jumping modes have been applied to four different biological systems: DNA, purple membrane, Alzheimer paired helical filaments, and the bacteriophage phi29. These samples have been selected to cover a wide variety of biological systems in terms of sizes and substrate contact area, which make them very appropriate for the type of comparative studies carried out in the present work. Although dynamic mode atomic force microscopy is clearly the best choice for imaging soft samples in air, in liquids there is not a leading technique. In liquids, the most appropriate imaging mode depends on the sample characteristics and preparation methods. Contact or dynamic modes are the best choices for imaging molecular assemblies arranged as crystals such as the purple membrane. In this case, the advantage of image acquisition speed predominates over the disadvantage of high lateral or normal force. For imaging individual macromolecules, which are weakly bonded to the substrate, lateral and normal forces are the relevant factors, and hence the jumping mode, an imaging mode which minimizes lateral and normal forces, is preferable to other imaging modes.
原子力显微镜在生理条件下对生物分子成像的能力已得到系统研究。接触模式、动态模式和跳跃模式已应用于四种不同的生物系统：DNA、紫膜、阿尔茨海默病配对螺旋丝和噬菌体phi29。选择这些样本是为了在尺寸和底物接触面积方面涵盖广泛的生物系统，这使得它们非常适合于本研究中进行的比较研究类型。尽管动态模式原子力显微镜显然是在空气中对软样本成像的最佳选择，但在液体中并没有一种主导技术。在液体中，最合适的成像模式取决于样本特性和制备方法。接触模式或动态模式是对诸如紫膜等以晶体形式排列的分子组装体成像的最佳选择。在这种情况下，图像采集速度的优势超过了高横向力或法向力的劣势。对于成像与底物弱结合的单个大分子，横向力和法向力是相关因素，因此，使横向力和法向力最小化的跳跃模式比其他成像模式更可取。
