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

A novel SERS/fluorescent multimodal imaging probe for mitochondria has been synthesised using 12 nm diameter gold nanoparticles (AuNP) surface functionalised with a rhodamine thiol derivative ligand. The normal pH-dependent fluorescence of the rhodamine-based ligand is inversed when it is conjugated with the AuNP and higher emission intensity is observed at basic pH. This switch correlates to a pK at pH 6.