A single-molecule electrical approach for amino acid detection and chirality recognition

Area of Science:

• Analytical Chemistry
• Nanotechnology
• Biophysics

Background:

• Efficient discrimination of amino acids is a key challenge in analytical chemistry.
• Current methods for amino acid analysis can be time-consuming or lack single-molecule resolution.

Purpose of the Study:

• To develop a single-molecule electrical method for rapid and precise amino acid identification.
• To demonstrate the capability of molecular nanocircuits for distinguishing amino acids and their enantiomers.

Main Methods:

• Fabrication of stable graphene-molecule-graphene single-molecule junctions using a molecular machine with permethylated-β-cyclodextrin.
• Utilizing pH variation to alter amino acid charge and host-guest interactions within the nanocircuit.
• Analyzing distinct current fluctuations and conductance data for real-time, in situ measurements.

Main Results:

• Observed unique multimodal current fluctuations corresponding to different amino acids.
• Characterized dwell times and shuttling rates for individual amino acids.
• Successfully distinguished between four amino acids and their enantiomers within microseconds.

Conclusions:

• The developed molecular nanocircuit methodology enables facile and precise amino acid identification at the single-molecule level.
• This approach holds potential for advancing single-molecule protein sequencing and other biochemical analyses.