Plasmon Coupling Effect-Enhanced Imaging of Metal Ions in Living Cells Using DNAzyme Assembled Core–Satellite Structures

We demonstrate a core–satellite plasmonic nanoprobe assembled via metal-ion-dependent DNA-cleaving DNAzyme linker for imaging intercellular metal ion based on plasmon coupling effect at a single-particle level. As metal ions are present in the system, the DNAzyme linker will be cleaved, and thus, disassembly of the core–satellite nanoprobes occurs, which results in distinct blue shift of the scattering spectra of Au core–satellite probes and naked color change of the scattering light. This change in scattering spectra has been supported by theoretical simulations. As a proof of concept, sensitive detection of Cu2+ with a limit of detection down to 67.2 pM has been demonstrated. The nanoprobes have been further utilized for intracellular Cu2+ imaging in living cells. The results demonstrate that the present strategy provides a promising platform for detection and imaging of metal ions in living cells and could be potentially applied to imaging other interesting target molecules simply by substituting the oligonucleotide sequence.