A pH responsive fluorescent probe based on dye modified i-motif nucleic acids.

Area of Science:

• Biochemistry
• Molecular Biology
• Materials Science

Background:

• DNA nanotechnology offers versatile platforms for molecular sensing.
• Aggregation-induced emission (AIE) materials provide sensitive fluorescent detection.
• pH monitoring is crucial for understanding cellular processes.

Purpose of the Study:

• To synthesize and characterize a novel DNA-based fluorescent probe.
• To investigate the pH-responsive aggregation-induced emission (AIE) properties of the probe.
• To evaluate the probe's utility for intracellular pH monitoring.

Main Methods:

• Synthesis of a hybrid molecule combining an i-motif forming sequence (IFS) and tetraphenylethene (TPE).
• Investigation of the probe's fluorescence behavior under varying pH conditions.
• Assessment of aggregation and AIE effects in response to pH changes.
• Application of the probe for real-time intracellular pH sensing.

Main Results:

• A distinct pH-responsive AIE effect was observed in the hybrid molecule.
• Fluorescence of the TPE unit was activated upon IFS folding under acidic conditions.
• Reduced solubility due to IFS folding led to nano-aggregate formation and AIE.
• The probe demonstrated excellent pH responsiveness and was successfully applied for intracellular pH monitoring.

Conclusions:

• The developed DNA-based probe exhibits significant pH-responsive AIE.
• The probe's mechanism involves pH-induced DNA folding, aggregation, and fluorescence enhancement.
• This probe represents a promising tool for sensitive and specific intracellular pH sensing.