Imaging soft matters in water with torsional mode atomic force microscopy

Area of Science:

• Surface science
• Nanotechnology
• Biophysics

Background:

• Atomic force microscopy (AFM) is crucial for nanoscale imaging.
• Imaging soft materials in aqueous environments presents challenges due to tip-sample interactions and resolution limitations.
• Existing AFM modes may struggle to provide high-resolution data under diverse solution conditions.

Purpose of the Study:

• To develop a high-sensitivity AFM mode for aqueous environments.
• To evaluate the capability of a torsional resonance mode for imaging soft materials.
• To demonstrate the utility of this mode for probing surface properties under varying solution conditions.

Main Methods:

• Development of a novel high-sensitivity AFM mode utilizing cantilever torsional resonance.
• Operation of the AFM in an aqueous environment.
• Imaging of soft materials, including DNA molecules and purple membrane.

Main Results:

• The torsional resonance mode achieved good spatial resolution, even with a relatively large tip.
• High-resolution images of purple membrane were obtained in water at low ion concentrations.
• The imaging was facilitated by exploiting long-range electrostatic forces.

Conclusions:

• The developed torsional resonance AFM mode offers high sensitivity and resolution in aqueous solutions.
• This technique enables the investigation of surface structures and properties of soft materials under a wide range of solution conditions.
• It provides a valuable tool for researchers studying biological and soft matter systems in their native environments.