A Dual-Modal SERS/Fluorescence Gold Nanoparticle Probe for Mitochondrial Imaging

Area of Science:

• Nanotechnology
• Biomedical Imaging
• Chemical Biology

Background:

• Mitochondria are crucial organelles, and their dysfunction is linked to various diseases.
• Accurate imaging of mitochondrial pH is vital for understanding cellular processes and disease states.
• Existing imaging probes often lack sensitivity or specificity for mitochondrial environments.

Purpose of the Study:

• To synthesize and characterize a novel multimodal imaging probe for mitochondria.
• To investigate the pH-dependent properties of the synthesized probe.
• To evaluate the probe's efficacy in cellular imaging and mitochondrial localization.

Main Methods:

• Synthesis of gold nanoparticles (AuNP) functionalized with a rhodamine thiol derivative ligand.
• Characterization of the probe's pH-dependent fluorescence and surface charge.
• Surface-enhanced Raman scattering (SERS) measurements to assess Raman signal enhancement.
• Confocal microscopy to determine cellular uptake and mitochondrial localization in various cell lines (HEK293, A2780, Min6).

Main Results:

• A novel SERS/fluorescent multimodal imaging probe for mitochondria was successfully synthesized.
• The probe exhibits pH-dependent fluorescence with an inverted response compared to the free ligand, correlating to a pKa of 6.62.
• The probe demonstrates enhanced Raman scattering due to SERS.
• Confocal microscopy confirmed probe uptake and specific localization within mitochondria of kidney, ovarian cancer, and pancreatic beta cells within 1.5 hours.

Conclusions:

• The developed probe is a novel, pH-sensitive, multimodal imaging tool for mitochondria.
• Its pH sensitivity in the biological range makes it suitable for studying mitochondrial microenvironments.
• The probe's ability to enter and localize in mitochondria offers a new avenue for advanced cellular imaging and diagnostics.