Conjugated structures based on quinazolinones and their application in fluorescent labeling

Area of Science:

• Organic Chemistry
• Biochemistry
• Analytical Chemistry

Background:

• Quinazolinone alkaloids possess valuable biological properties.
• Their conjugated structures are suitable for developing fluorescent probes.
• Designing multi-responsive probes is crucial for advanced diagnostics.

Purpose of the Study:

• To synthesize and characterize novel quinazolinone-based fluorescent probes.
• To investigate the probes' responses to viscosity and pH.
• To evaluate the probes' potential for cellular imaging and cancer diagnosis.

Main Methods:

• Synthesis of quinazolinone derivatives (probes 5a-c and 6b).
• Spectroscopic analysis (absorption and emission) in various solvents.
• Viscosity and pH sensitivity testing.
• Cellular imaging experiments in HeLa cells (mitochondrial and lysosomal targeting).
• Theoretical calculations to elucidate pH response mechanisms.

Main Results:

• Probes exhibited absorption/emission in the 420-600 nm range.
• Probe 5c demonstrated significant viscosity sensitivity (37.8x fluorescence increase in glycerol).
• Probes 5a-c and 6b showed sensitive pH responses (alkaline enhancement).
• Probes 5a/5b targeted mitochondria; probes 5c/6b targeted lysosomes in HeLa cells.
• Probe 5c successfully monitored lysosomal viscosity changes.

Conclusions:

• Novel quinazolinone probes exhibit distinct viscosity and pH sensitivity.
• Specific cellular organelle targeting (mitochondria and lysosomes) was achieved.
• Viscosity-sensitive probe 5c enables lysosomal viscosity monitoring.
• These findings guide the design of multi-responsive probes for cancer diagnosis.