Viscosity-sensitive NIR probe for detecting cellular state transitions in Normal, Cancer and apoptotic cells

Area of Science:

• Biochemistry
• Chemical Biology
• Molecular Imaging

Background:

• Intracellular viscosity is a crucial biomarker linked to various diseases and biological processes.
• Precise measurement of intracellular viscosity is vital for disease diagnosis and treatment evaluation.

Purpose of the Study:

• To synthesize and characterize a novel fluorescent probe for sensitive detection of intracellular viscosity.
• To explore the probe's mechanism, bio-imaging potential, and interaction with proteins.

Main Methods:

• Synthesis of a thiazolidinone-based deep-red fluorescent probe (T5).
• Spectroscopic analysis (UV-vis, fluorescence) to determine probe response to viscosity.
• Computational studies (DFT, TD-DFT, molecular docking, dynamics) to elucidate mechanism and interactions.
• Cell-based assays to monitor viscosity in normal, cancerous, and apoptotic cells.

Main Results:

• The T5 probe exhibited a "turn on" fluorescence response with high selectivity in viscous media, with emission intensity increasing with viscosity.
• The probe's mechanism is attributed to restriction of intramolecular rotation (RIR), supported by DFT analysis.
• Long-wavelength emission facilitated deeper tissue penetration and higher sensitivity in bio-imaging.
• The probe successfully monitored viscosity variations in different MDA-MB-231 cell states (normal, cancerous, apoptotic).
• Spectroscopic and computational studies confirmed T5 binds within the hydrophobic cavity of Bovine Serum Albumin (BSA).

Conclusions:

• The developed T5 probe is a sensitive and selective tool for detecting microenvironmental viscosity in biological systems.
• The probe can be utilized for disease diagnosis and monitoring treatment efficacy.
• T5 serves as a valuable tool for investigating protein conformational changes and interactions.