Using NTEGRA Prima Atomic Force Microscope (AFM) to Study Dynamic Molecular Structures in Aqueous Environment by NT-MDT

Table of Contents

Background
Performing AFM in Liquids
Materials and Equipment Used
     Sample
     AFM Equipment and Probe

Background

NT-MDT Co. was founded in 1991 with the intention to apply all gathered knowledge and experience in the field of nanotechnology to provide researchers with the instruments suitable to solve any possible task laying in nanometer scale dimensions. The company NT-MDT was established in Zelenograd — the hub of Russian Microelectronics. The development of products is based on the combination of the use of high-end microelectronic components and precision mechanical parts, power of modern software, and MEMS technology. NT-MDT Co. has existed as a commercial enterprise since 1993.

Performing AFM in Liquids

It is a widespread notion that performing AFM in liquids is a fairly complicated research approach. In fact, several tasks connected to the study of molecular structures and complexes in a liquid environment have high demands on the SPM equipment. The following image depicts an AFM scan of surfactant molecules that are dynamically self-assembled into parallel, hemicylindrical micelles on a hydrophobic graphite surface.

In this case, it was difficult to observe dynamically self-assembled molecular structure. The "soft contact mode" is the imaging mode used — that is scanning with constant force using a very low set point. The probe’s vertical force must be kept as close as possible to the set point — in this case — ~100 pN. The force exceeding this value will disturb the native molecular assembly (the periodicity of the micelles is ~5 nm.). The contrast disappears for lower forces. It must be noted that the vertical topography modulation is only 0.1-0.2 nm, but it is still considerably above the noise level. This example also demonstrates that NTEGRA nanolaboratory offers enough stability and sensitivity to investigate dynamic molecular structures in an aqueous environment.

Materials and Equipment Used

Sample

10 mM aqueous solution of cetyltrimethylammonium bromide surfactant in contact with HOPG.

AFM Equipment and Probe

AFM Probe — CSG01, 0.03 N/m
AFM Equipment — NTEGRA Prima, Constant force imaging mode in liquid cell using a very low set point ("so contact mode"- force ~100 pN).

Source: "Surfactant micelles in aqueous solution: critical resolution in AFM" by Hannes Schniepp, The College of William and Mary, Williamsburg, VA, USA

This information has been sourced, reviewed and adapted from materials provided by NT-MDT Spectrum Instruments.

For more information on this source, please visit NT-MDT Spectrum Instruments.

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