Conjugate agent: A GdIII enriched DNA-AuNP conjugate for intracellular magnetic resonance and fluorescence imaging is reported. The agent exhibits high relaxivity per particle and high cell uptake properties that provide a means to image and map small cell populations. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.