‘Quantum dots’ could improve cancer imaging, treatment outcomes

The "quantum dot" method improves the specificity of tumor imaging by silencing fluorescence from noncancerous areas.

Scientists at Sanford Burnham Prebys Medical Discovery Institute (SBP) have developed a nanosystem that enhances the imaging of human tumors in mice. The method involves delivering fluorescence-emitting “quantum dots” to tumors and using an “etchant” to block signals from noncancerous tissue.

"Tumor imaging is an integral part of cancer detection, treatment and tracking the progress of patients after treatment," said Kazuki Sugahara, M.D., Ph.D., adjunct assistant professor at SBP, in a statement. "Although significant progress has been made in the last two decades, better and more sensitive detection, such as the method we are developing, will contribute to more personalized and potentially more effective interventions to improve the clinical outcomes of cancer patients."

The quantum dots are tiny particles that emit fluorescent signals when exposed to light. They are delivered intravenously with iRGD, a tumor-penetrating peptide, and travel through the bloodstream and into cancer cells. The etchant, which cannot cross membranes into tumor cells, is used to silence any quantum dots that remain in the bloodstream, boosting the specificity of the imaging.

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"The novelty of our nanosystem is how the etchant works," said Gary Braun, Ph.D., one of the scientists who developed the method, in the release. While the quantum dots that reach tumors stay fluorescent, the etchant reacts with zinc in the quantum dots, making them lose fluorescence and rendering them unable to enter tumor cells.

The SBP team developed the nanosystem using mice with human breast, prostate and gastric tumors. They used optical imaging to visualize the tumors, but that method isn’t always practical for human patients, Sugahara explained in the release. The study was published in Nature Communications.

"Moving forward we will focus on developing our novel nanosystem to work with routine imaging tests like PET scans and MRIs,” he said.