Label-Free in Situ pH Monitoring in a Single Living Cell Using an Optical Nanoprobe

Area of Science:

• Biomedical Engineering
• Cell Biology
• Nanotechnology

Background:

• Intracellular pH is crucial for cell functions and serves as a biomarker for cellular status.
• Disrupted intracellular pH can indicate cell dysfunction and deterioration.
• Existing pH detection methods face limitations like cell viability disruption and compromised long-term monitoring.

Purpose of the Study:

• To develop a novel fiber-optic fluorescent nanoprobe for label-free, subcellular pH sensing.
• To achieve high spatial resolution, fast response time, and minimal invasiveness in pH monitoring.
• To demonstrate the probe's applicability in monitoring cellular responses to external stimuli.

Main Methods:

• Development of a fiber-optic fluorescent nanoprobe.
• Characterization of probe response time, pH resolution, and invasiveness.
• Application of the probe for subcellular pH sensing in cultured A549 lung cancer cells.
• Testing the probe's efficacy in detecting pH variations under cytotoxic agent and nanoparticle administration.

Main Results:

• The nanoprobe offers label-free, subcellular pH sensing with high spatial resolution.
• It exhibits a fast response time (~20 seconds) and excellent pH resolution (0.02 pH units) within a biologically relevant range (6.17-8.11).
• The probe successfully detected pH variations in lung cancer cells exposed to toxins and nanoparticles, indicating early physiological changes.

Conclusions:

• The developed fiber-optic nanoprobe is a promising tool for minimally invasive, high-resolution intracellular pH monitoring.
• It enables direct observation of early physiological or pathological events with high spatiotemporal resolution.
• This platform holds potential for studying pH-related cellular mechanisms like inflammation, cytotoxicity, and carcinogenesis.