Khanal Dipesh, Dillon Eoghan, Hau Herman, Fu Dong, Ramzan Iqbal, Chrzanowski Wojciech
Faculty of Pharmacy, The University of Sydney, Sydney, NSW, 2006, Australia.
Anasys Instruments, 325 Chapala Street, Santa Barbara, CA, 93101, USA.
J Mater Sci Mater Med. 2015 Dec;26(12):272. doi: 10.1007/s10856-015-5605-1. Epub 2015 Oct 30.
Scanning probe microscopy has been widely used to obtain topographical information and to quantify nanostructural properties of different materials. Qualitative and quantitative imaging is of particular interest to study material-material interactions and map surface properties on a nanoscale (i.e. stiffness and viscoelastic properties). These data are essential for the development of new biomedical materials. Currently, there are limited options to map viscoelastic properties of materials at nanoscale and at high resolutions. Lorentz contact resonance (LCR) is an emerging technique, which allows mapping viscoelasticity of samples with stiffness ranging from a few hundred Pa up to several GPa. Here we demonstrate the applicability of LCR to probe and map the viscoelasticity and stiffness of 'soft' (biological sample: cell treated with nanodiamond), 'medium hard' (pharmaceutical sample: pMDI canister) and 'hard' (human teeth enamel) specimens. The results allowed the identification of nanodiamond on the cells and the qualitative assessment of its distribution based on its nanomechanical properties. It also enabled mapping of the mechanical properties of the cell to demonstrate variability of these characteristics in a single cell. Qualitative imaging of an enamel sample demonstrated variations of stiffness across the specimen and precise identification of enamel prisms (higher stiffness) and enamel interrods (lower stiffness). Similarly, mapping of the pMDI canister wall showed that drug particles were adsorbed to the wall. These particles showed differences in stiffness at nanoscale, which suggested variations in surface composition-multiphasic material. LCR technique emerges as a valuable tool for probing viscoelasticity of samples of varying stiffness's.
扫描探针显微镜已被广泛用于获取不同材料的形貌信息并量化其纳米结构特性。定性和定量成像对于研究材料间相互作用以及在纳米尺度（即刚度和粘弹性特性）绘制表面特性尤为重要。这些数据对于新型生物医学材料的开发至关重要。目前，在纳米尺度和高分辨率下绘制材料粘弹性特性的选择有限。洛伦兹接触共振（LCR）是一种新兴技术，它能够绘制刚度范围从几百帕到几吉帕的样品的粘弹性。在此，我们展示了LCR在探测和绘制“软”（生物样品：用纳米金刚石处理的细胞）、“中硬”（药物样品：pMDI药罐）和“硬”（人类牙釉质）样品的粘弹性和刚度方面的适用性。结果使得能够识别细胞上的纳米金刚石，并基于其纳米力学特性对其分布进行定性评估。它还能够绘制细胞的力学特性，以展示单个细胞中这些特性的变异性。牙釉质样品的定性成像显示了整个样品的刚度变化，并精确识别了釉柱（较高刚度）和釉柱间质（较低刚度）。同样，pMDI药罐壁的绘制表明药物颗粒吸附在壁上。这些颗粒在纳米尺度上显示出刚度差异，这表明表面组成——多相材料存在变化。LCR技术成为探测不同刚度样品粘弹性的有价值工具。
