Quinoline yellow acts as a novel amyloid fibrillation probe by using surface-enhanced Raman spectroscopy

Area of Science:

• Biochemistry
• Neuroscience
• Analytical Chemistry

Background:

• Protein amyloid fibrillation is implicated in neurodegenerative diseases.
• Protein oligomers are neurotoxic intermediates in fibrillation.
• Early detection and inhibition of fibrillation are crucial for disease intervention.

Purpose of the Study:

• To develop a novel inhibitor for protein fibrillation.
• To establish a sensitive method for detecting protein oligomers.
• To explore the therapeutic and diagnostic potential of quinoline yellow (QY) and surface-enhanced Raman spectroscopy (SERS).

Main Methods:

• Developed quinoline yellow (QY) as an amyloid inhibitor.
• Utilized fluorescence, morphology characterization, and circular dichroism to assess QY's inhibitory effects on insulin fibrillation.
• Applied surface-enhanced Raman spectroscopy (SERS) with QY as a probe for oligomer detection and interaction analysis.
• Validated the methodology in human serum samples.

Main Results:

• QY effectively inhibits insulin fibrillation by impeding nucleation.
• SERS coupled with QY achieved sensitive detection of insulin oligomers with a threshold of 0.2 μM.
• QY demonstrated a linear detection range of 1.0–58.0 μM for oligomers.
• SERS elucidated the binding sites and interaction mechanisms between QY and insulin.

Conclusions:

• Quinoline yellow is a potent inhibitor of insulin fibrillation.
• SERS provides a highly sensitive platform for detecting amyloid oligomers.
• The combined approach holds significant promise for pharmaceutical development and disease diagnostics, including in complex biological matrices like human serum.