Chemical pulsed-force microscopy of single polyethyleneimine molecules in aqueous solution
Chemical pulsed-force microscopy of single polyethyleneimine molecules in aqueous solution
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DOI：
10.1021/la0113116
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发表时间：
2002-02-05
期刊：
影响因子：
3.9
通讯作者：
Möhwald, H
中科院分区：
文献类型：
--
作者：
Schneider, M;Zhu, M;Möhwald, H
使用原位氨基和甲基封端基团修饰的扫描探针提供了增强化学灵敏度的扫描力显微镜（SFM）成像的可能性。样品是一种带正电荷的高分子量聚乙烯亚胺（支链），吸附在带负电荷的云母表面上，以实现单个聚乙烯亚胺（PEI）分子的排列。单个PEI分子的化学成像揭示了从SFM的脉冲力模式测量获得的粘附力和接触刚度的差异。我们得出结论，静电和疏水力是负责在系统中的粘附对比度。测量还显示了基于改性的尖端和基板之间的相互作用的类型的pH依赖性。我们表明，化学脉冲力显微镜是一个合适的工具，调查强带电聚合物上的相反电荷的表面。
Using scanning probes modified with amino- and methyl-terminated groups in situ offers the possibility of scanning force microscopy (SFM) imaging with enhanced chemical sensitivity. The sample, a positively charged high molecular weight polyethyleneimine (branched), is adsorbed on the negatively charged mica surface to achieve an arrangement of single polyethyleneimine (PEI) molecules. Chemical imaging of individual PEI molecules is revealed by differences in adhesion and contact stiffness obtained from the pulsed-force mode measurements by SFM. We conclude that electrostatic and hydrophobic forces are responsible for the adhesion contrast in the system. The measurements also show a pH dependence based on the type of interaction between the modified tip and the substrate. We demonstrate that the chemical pulsed force microscopy is a suitable tool for the investigation of strongly charged polymers on an oppositely charged surface.