Ferritin-based new magnetic force microscopic probe detecting 10 nm sized magnetic nanoparticles

Area of Science:

• Nanotechnology
• Biophysics
• Surface Chemistry

Background:

• Atomic Force Microscopy (AFM) is a powerful tool for nanoscale imaging and manipulation.
• Magnetic Force Microscopy (MFM) requires specialized probes for detecting magnetic interactions.
• Controlling single-molecule placement on AFM tips is challenging but offers unique sensing capabilities.

Purpose of the Study:

• To develop a method for precisely positioning a single ferritin protein molecule at the apex of an AFM tip.
• To create a "multifunctional" MFM probe capable of detecting both magnetic and biomolecular interaction forces.
• To demonstrate the utility of this single-molecule probe for advanced nanoscale imaging and analysis.

Main Methods:

• Utilized controlled dendron surface chemistry to facilitate the picking-up of a single ferritin protein molecule.
• Attached the functionalized ferritin protein to the end of an AFM tip.
• Employed the modified AFM tip for Magnetic Force Microscopy (MFM) imaging.
• Tested the probe's ability to detect magnetic nanoparticles and biomolecular interactions with DNA.

Main Results:

• Successfully realized a single-molecule ferritin picking-up process using AFM and dendron chemistry.
• The single ferritin tip effectively detected magnetic interactions from ~10 nm magnetic nanoparticles.
• The probe demonstrated multifunctional capabilities, sensing magnetic forces and biomolecular interactions (e.g., with DNA).
• The tip enabled simultaneous topographic, magnetic, and biomolecular interaction imaging.

Conclusions:

• The developed method allows for the creation of highly specific, single-molecule MFM probes.
• This versatile probe enables simultaneous investigation of magnetic and biomolecular interactions at the nanoscale.
• The established protein engineering and conjugation chemistry suggest straightforward adaptation for various single magnetic particle MFM probes.