Quantum Defect Sensitization via Phase-Changing Supercharged Antibody Fragments.

Area of Science:

• Quantum Information Science
• Biophysics
• Materials Science

Background:

• Quantum defects in single-walled carbon nanotubes (SWCNTs) are crucial for exciton localization, with potential in biodevices and quantum light sources.
• The influence of local electric fields on quantum defect emission and control mechanisms remain largely unexplored.

Purpose of the Study:

• To investigate quantum defect sensitization by engineering a protein to undergo a phase change at a quantum defect site.
• To develop a method for controlling quantum defect emission using protein conformational changes for biomarker detection.

Main Methods:

• Designed a supercharged single-chain antibody fragment (scFv) for ligand-induced folding.
• Conjugated the supercharged scFv to SWCNT quantum defects.
• Utilized interleukin-6 (IL-6) as a model proinflammatory biomarker.
• Performed quantum chemical simulations to understand the underlying mechanisms.

Main Results:

• Supercharged scFv-coupled quantum defects showed significant fluorescence wavelength shifts upon IL-6 binding and protein folding.
• The protein folding transition induced a substantial local electric field change at the quantum defect site.
• Quantum chemical simulations indicated amplified optical responses due to charge localization during protein folding.

Conclusions:

• Engineered proteins can effectively modulate quantum defect emission in SWCNTs.
• This approach enables sensitive biomarker detection and offers new strategies for protein biophysics studies.
• The findings pave the way for engineering proteins to control binding signal transduction in nanomaterials.