Tripeptide-Assisted Gold Nanocluster Formation for Fe³⁺ and Cu²⁺ Sensing

Area of Science:

• Nanomaterials Science
• Analytical Chemistry
• Bioconjugate Chemistry

Background:

• Fluorescent gold nanoclusters (AuNCs) are promising for metal ion sensing.
• Developing selective and sensitive sensors requires optimized surface ligands.
• Peptide-based ligands offer tunable properties for AuNC functionalization.

Purpose of the Study:

• To design and synthesize fluorescent AuNCs using simple tripeptides.
• To investigate the role of tyrosine in AuNC formation and metal ion sensing.
• To evaluate the selectivity and sensitivity of peptide-AuNCs for specific metal ions.

Main Methods:

• Synthesis of AuNCs using tyrosine-cysteine-tyrosine (YCY) and serine-cysteine-tyrosine (SCY) tripeptides.
• Characterization of AuNC fluorescence properties (blue and red emission).
• Metal ion sensing assays using various metal ions (Fe3+, Cu2+, etc.) and Dynamic Light Scattering (DLS) for aggregation studies.

Main Results:

• YCY peptides formed blue- and red-emitting AuNCs; SCY peptides formed blue-emitting AuNCs.
• Blue fluorescence of YCY- and SCY-AuNCs was selectively quenched by Fe3+ and Cu2+.
• Red fluorescence of YCY-AuNCs showed stability against 13 different metal ions, indicating high selectivity.
• Peptide-metal ion chelation induced aggregation and fluorescence quenching, dependent on tyrosine content.

Conclusions:

• Rational design of peptides enables the formation of fluorescent AuNCs for metal ion sensing.
• Peptide-AuNCs serve as highly selective and sensitive surface ligands, particularly for Fe3+ and Cu2+ detection.
• This approach offers a dual function for synthesizing AuNCs and detecting specific analytes, advancing sensing methodologies.