Designer variable repeat length polypeptides as scaffolds for surface immobilization of quantum dots

Area of Science:

• Biotechnology
• Materials Science
• Nanotechnology

Background:

• Semiconductor nanocrystals (quantum dots or QDs) offer unique optical properties.
• Controlling QD assembly and surface functionalization is crucial for advanced applications.
• Engineered de novo polypeptides provide a versatile platform for biomolecular engineering.

Purpose of the Study:

• To develop and characterize engineered polypeptides for quantum dot immobilization.
• To investigate the self-assembly and structural integrity of polypeptides on QD surfaces.
• To demonstrate the utility of polypeptide-QD conjugates in surface-based sensing.

Main Methods:

• Design and synthesis of variable-length de novo polypeptides with specific functional residues (dicysteine, hexahistidine).
• Characterization of polypeptide self-assembly onto quantum dots using fluorescence resonance energy transfer (FRET).
• Immobilization of biotinylated polypeptides onto functionalized substrates for subsequent quantum dot capture.

Main Results:

• Polypeptides self-assembled onto quantum dots while maintaining their beta-sheet conformation, irrespective of length.
• Surface-tethered polypeptides efficiently captured quantum dots via polyhistidine-nanocrystal interactions.
• A direct correlation was observed between surface peptide density and quantum dot capture capacity.
• Demonstrated the creation of diverse polypeptide-QD structures and a FRET-based nutrient sensor.

Conclusions:

• Engineered polypeptides serve as effective discrete immobilizers for quantum dots on functional surfaces.
• The length and density of surface-bound polypeptides can be tuned to control quantum dot capture.
• This strategy offers versatility for constructing complex nanostructures and functional biosensors.