A highly efficient chiral sensing platform for tryptophan isomers based on a coordination self-assembly.

Area of Science:

• Biochemistry and Medical Science
• Analytical Chemistry
• Nanomaterials Science

Background:

• Accurate enantiomer identification is crucial for biochemistry and medicine.
• Tryptophan (Trp) enantiomers have distinct biological roles.
• Existing chiral recognition methods require improvement in convenience and effectiveness.

Purpose of the Study:

• To design and investigate an effective sensor for the chiral recognition of tryptophan enantiomers.
• To explore the self-assembly of copper(II) ion-modified beta-cyclodextrin on poly-L-arginine/multi-walled carbon nanotubes.
• To enable sensitive and selective determination of tryptophan enantiomers.

Main Methods:

• Fabrication of a sensor using self-assembled Cu(II)-modified β-cyclodextrin (Cu-β-CD) on poly-L-arginine/multi-walled carbon nanotubes (PLA/MWCNTs).
• Utilizing Cu(II) as a 'cap' to confine high-energy water and guide Trp enantiomers into the β-CD cavity.
• Employing hydrogen bond formation between L-Trp and confined water for specific recognition.

Main Results:

• The sensor demonstrated favorable chiral recognition of L-Trp over D-Trp with a separation coefficient of 3.37.
• Excellent sensitivity was achieved for enantiomer determination, with a linear correlation from 1 × 10⁻⁶ M to 5.5 × 10⁻⁵ M.
• A low detection limit of 3.3 × 10⁻⁷ M (S/N = 3) was obtained, and the sensor could predict D-Trp percentage in racemic mixtures.

Conclusions:

• The developed Cu-β-CD/PLA/MWCNTs sensor provides a convenient and effective method for tryptophan enantiomer identification.
• The sensor exhibits high sensitivity and selectivity, suitable for quantitative enantiomer analysis.
• This platform shows significant potential for applications in enantiomer recognition and analysis in complex mixtures.