A lysosome-located and rhodamine-based fluorescence probe for recognizing hydrogen polysulfide

Area of Science:

• Biochemistry
• Chemical Biology
• Analytical Chemistry

Background:

• Hydrogen polysulfide (H₂Sₙ, n≥2) is a reactive sulfur species (RSS) involved in protein regulation via S-sulfhydration.
• Understanding H₂Sₙ production, degradation, and regulatory mechanisms is crucial but requires further research.
• Existing methods for H₂Sₙ detection may lack specificity or sensitivity for biological applications.

Purpose of the Study:

• To develop an original lysosome-localized fluorescent probe for sensitive and selective detection of H₂Sₙ.
• To investigate the probe's performance, including response time, selectivity, sensitivity, and pH working range.
• To demonstrate the probe's utility in sensing endogenous and exogenous H₂Sₙ within cellular lysosomes.

Main Methods:

• Design and synthesis of a rhodamine-based fluorescent probe incorporating a morpholine lysosome-targeting unit and a 2-fluoro-5-nitrobenzoate recognition group.
• Characterization of the probe's structural and fluorescence changes upon reaction with H₂Sₙ.
• Quantitative analysis of H₂Sₙ concentration using fluorescence intensity, establishing a linear range and detection limit.
• Evaluation of probe performance in terms of response speed, selectivity, sensitivity, and pH stability.
• Application of the probe for sensing H₂Sₙ in lysosomes of living cells.

Main Results:

• A novel lysosome-localized fluorescent probe was successfully developed using rhodamine as the fluorogen.
• The probe exhibits a spironolactone structure with weak fluorescence, transitioning to a conjugated xanthene with green fluorescence upon reaction with H₂Sₙ.
• A linear relationship between fluorescence intensity and H₂Sₙ concentration was observed from 6.0×10⁻⁷ to 10.0×10⁻⁵ mol·L⁻¹, with a detection limit of 1.5×10⁻⁷ mol·L⁻¹.
• The probe demonstrated fast response, good selectivity, excellent sensitivity, and a broad pH working range.
• The probe was effectively utilized to detect both endogenous and exogenous H₂Sₙ in cellular lysosomes.

Conclusions:

• The developed fluorescent probe provides a powerful tool for sensitive and selective detection of H₂Sₙ in lysosomes.
• This probe facilitates the study of H₂Sₙ's biological roles and regulatory mechanisms within cellular compartments.
• The findings contribute to advancing the understanding of reactive sulfur species in biological systems.