Nanoprobes that fluoresce when taken up by tumours and that can be used as a universal imaging agent during cancer surgery, as demonstrated in mice and described in a paper published online this week in Nature Biomedical Engineering.
For many cancers, surgery is the primary curative option. When cutting out a tumour, surgeons need to ensure that no cancer cells are left behind, particularly near the tumour margins. Image-guided surgery can help surgeons to detect any remaining tumour tissue and to find any tumour nodules small enough to be seen or felt. However, current imaging techniques for cancer surgery lack sufficient sensitivity and specificity, and can thus light up non-cancerous tissue ― for example, tissue that has an increased rate of metabolic activity such as brown fat.
Baran Sumer, Jinming Gao and colleagues synthesized nanoparticle probes carrying a clinically approved fluorescent dye compatible with standard cameras available in the operating room. The nanoprobes, which are injected intravenously, were optimized to fluoresce with dramatically amplified intensity only when taken up by tumours. Akin to a transistor, which switches on when the voltage is above a certain threshold, the nanoprobes ‘turned on’ only in acidic pH, a common hallmark of nearly all solid tumours. When used in image-guided surgery to remove head-and-neck tumours in mice, the authors found that the nanoprobes provided unprecedented specificity and sensitivity, lighting up tumour nodules smaller than 1 mm in diameter and avoiding false positives.