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A Dual‐Modal SERS/Fluorescence Gold Nanoparticle Probe for Mitochondrial Imaging
Author(s) -
Eling Charlotte J.,
Price Thomas W.,
Marshall Addison R. L.,
Narda Viscomi Francesco,
Robinson Peter,
Firth George,
Adawi Ali M.,
Bouillard JeanSebastien G.,
Stasiuk Graeme J.
Publication year - 2017
Publication title -
chempluschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.801
H-Index - 61
ISSN - 2192-6506
DOI - 10.1002/cplu.201600593
Subject(s) - fluorescence , colloidal gold , nanotechnology , nanoparticle , dual (grammatical number) , fluorescence lifetime imaging microscopy , dual mode , materials science , modal , chemistry , optics , physics , polymer chemistry , art , literature , engineering , aerospace engineering
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 a at pH 6.62, which makes it an ideal candidate for a pH‐sensitive imaging probe in the biological range (pH 6.5–7.4). The observed pH sensitivity of the ligand when attached to the AuNP is thought to be due to the formation of a spirolactam ring, going from positively charged (+18 mV) to negatively charged (−60 mV) as the pH is changed from acidic to basic. Additionally, conjugation of the ligand to the AuNP serves to enhance the Raman signal of the rhodamine ligand through surface‐enhanced Raman scattering (SERS). Confocal microscopy has shown that the probe enters HEK293 (kidney), A2780 (ovarian cancer) and Min6 (pancreatic beta) cells within an hour and a half incubation time. The probe was shown to localise in the mitochondria, thus providing a novel pH‐dependent SERS/fluorescent multimodal imaging probe for mitochondria.