Exploring Fluorescence Spectral Shifts in Aptamer-Intercalating Cyanine Dye Complexes upon Binding to Specific Small...

Area of Science:

• Biochemistry
• Molecular Biology
• Analytical Chemistry

Background:

• DNA intercalating cyanine dyes (e.g., SYBR Green I, OliGreen) are vital for label-free fluorescent aptamer-based biosensors.
• The influence of dye concentration and specific interactions on aptasensor fluorescence response remains underexplored.

Purpose of the Study:

• To investigate how dye-to-base ratios (dbrs) affect the fluorescent response of DNA intercalating dyes in aptamer systems.
• To analyze the spectral shifts and signal changes in aptamer-based biosensors for adenosine triphosphate (ATP) and L-argininamide (LAA) detection.

Main Methods:

• Utilized SYBR Green I (SG) and OliGreen (OG) dyes with aptamers targeting ATP and LAA.
• Examined fluorescence spectral shifts across varying dbrs.
• Employed absorption spectroscopy, circular dichroism (CD), and control studies to understand interactions.

Main Results:

• Increased dbrs with SG and an ATP aptamer caused emission shifts to longer wavelengths.
• A 'signal-off' phenomenon was observed at low dbr (0.1), transitioning to blue shifts at higher dbrs (0.7, 2.0).
• OliGreen showed similar spectral shifts for L-argininamide detection, indicating target binding.

Conclusions:

• Dye selection and concentration critically influence fluorescence aptasensor performance.
• Spectral shifts confirm target binding, especially at higher dye loading, but excessive dye can impair aptamer binding affinity.
• Findings offer insights for designing sensitive and specific small molecule detection assays.