Fig. 8.

Tumor-specific imaging with etchable QDs. (Intravenous delivery) Schematic of tumor-specific imaging with tumor-penetrating etchable QDs delivered through the circulation. The schematic depicts an early post-etching time point. Top panel: QDs (green particles), when injected alone, eventually accumulate mainly in the MPS by passing through the rich sinusoids. Some QDs may enter the extravascular tumor tissue because of the EPR effect. Middle panel: Pre-injection of iRGD facilitates extravasation and cell internalization of QDs in a tumor-specific manner. The QDs also eventually accumulate in the MPS. Bottom panel: Etching performed soon after the iRGD-mediated QD delivery into extravascular tumor cells causes quenching of intravascular and extracellular QDs leading to highly tumor-specific signals. (Intraperitoneal delivery) Schematic of peritoneal tumor imaging with intraperitoneally delivered etchable QDs. Top panel: intraperitoneal QDs attach to the tumor and peritoneal surfaces. Middle panel: iRGD facilitates local penetration of QDs specifically into peritoneal tumors. Bottom panel: Intraperitoneal etching differentially quenches the QDs that did not enter the tumors without affecting the intratumoral QDs, leading to highly tumor-specific signals