Walker Shaun C, Allen Stephanie, Bell Gordon, Roberts Clive J
Laboratory of Biophysics and Surface Analysis, School of Pharmacy, The University of Nottingham, University Park, Nottingham, UK.
J Microsc. 2015 May;258(2):119-26. doi: 10.1111/jmi.12225. Epub 2015 Jan 22.
Leaf surfaces are highly complex functional systems with well defined chemistry and structure dictating the barrier and transport properties of the leaf cuticle. It is a significant imaging challenge to analyse the very thin and often complex wax-like leaf cuticle morphology in their natural state. Scanning electron microscopy (SEM) and to a lesser extent Atomic force microscopy are techniques that have been used to study the leaf surface but their remains information that is difficult to obtain via these approaches. SEM is able to produce highly detailed and high-resolution images needed to study leaf structures at the submicron level. It typically operates in a vacuum or low pressure environment and as a consequence is generally unable to deal with the in situ analysis of dynamic surface events at submicron scales. Atomic force microscopy also possess the high-resolution imaging required and can follow dynamic events in ambient and liquid environments, but can over exaggerate small features and cannot image most leaf surfaces due to their inherent roughness at the micron scale. Scanning ion conductance microscopy (SICM), which operates in a liquid environment, provides a potential complementary analytical approach able to address these issues and which is yet to be explored for studying leaf surfaces. Here we illustrate the potential of SICM on various leaf surfaces and compare the data to SEM and atomic force microscopy images on the same samples. In achieving successful imaging we also show that SICM can be used to study the wetting of hydrophobic surfaces in situ. This has potentially wider implications than the study of leaves alone as surface wetting phenomena are important in a range of fundamental and applied studies.
叶片表面是高度复杂的功能系统，其明确的化学性质和结构决定了叶片角质层的屏障和传输特性。在自然状态下分析非常薄且通常复杂的蜡状叶片角质层形态是一项重大的成像挑战。扫描电子显微镜（SEM）以及在较小程度上原子力显微镜是用于研究叶片表面的技术，但通过这些方法仍难以获得一些信息。SEM能够生成研究亚微米级叶片结构所需的高度详细和高分辨率图像。它通常在真空或低压环境中运行，因此一般无法处理亚微米尺度下动态表面事件的原位分析。原子力显微镜也具备所需的高分辨率成像能力，并且可以跟踪环境和液体环境中的动态事件，但可能会过度放大小特征，并且由于大多数叶片表面在微米尺度上固有的粗糙度而无法对其进行成像。扫描离子电导显微镜（SICM）在液体环境中运行，提供了一种潜在的互补分析方法，能够解决这些问题，并且尚未用于研究叶片表面。在这里，我们展示了SICM在各种叶片表面上的潜力，并将数据与同一样品上的SEM和原子力显微镜图像进行比较。在实现成功成像的过程中，我们还表明SICM可用于原位研究疏水表面的润湿性。这可能比单独研究叶片具有更广泛的意义，因为表面润湿现象在一系列基础研究和应用研究中都很重要。
