Photoinduced chromophore dissociation resulting in aggregation-induced red fluorescence

Area of Science:

• Biophysics
• Biochemistry
• Materials Science

Background:

• Fluorescent molecules are vital for bioimaging and cellular studies.
• Photoconvertible fluorescent proteins like PhoCl1 offer unique optical properties.
• PhoCl1 releases a peptide fragment upon photoexposure, losing its fluorescence.

Purpose of the Study:

• To investigate the fate of the photoreleased chromophore-peptide fragment from PhoCl1.
• To characterize the unexpected red fluorescence observed from the released fragment.
• To explore the potential applications of this phenomenon in developing new biosensors and biomaterials.

Main Methods:

• Dynamic light scattering (DLS) for aggregation analysis.
• Optical techniques (spectroscopy, anisotropy) for characterizing fluorescence properties.
• Molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) simulations.

Main Results:

• The photoreleased C-terminal peptide fragment (CTPF) exhibits dim red fluorescence.
• This fluorescence is attributed to the aggregation of CTPF molecules.
• Aggregation behavior is influenced by environmental factors (pH, NaCl, temperature).
• Simulations confirm CTPF aggregation and the chromophore's role in red fluorescence.

Conclusions:

• The aggregation of the chromophore-peptide conjugate is responsible for the observed red fluorescence.
• Findings provide insights into fluorescent chromophore-peptide interactions.
• This work supports the development of light-activated fluorescence systems, AIE-based biosensors, and tunable biomaterials.