Fig. 9

a Schematic depiction of the nanoparticle structure. The gold nanostar core is encapsulated in a silica shell containing either IR780 (red) or IR140 (blue) Raman reporter dye. NPs are then functionalized with either a folate receptor targeting antibody (αFR-Ab) for targeted NPs (αFR-NPs, red) or with PEG (polyethylene glycol) for non-targeted NPs (nt-NPs, blue). b Whole abdomen imaging of representative control (left) and tumor-bearing (right) mice. Bioluminescence (BLI) signal is shown in the top row. The direct classical least-squares (DCLS) maps of both targeted (2nd row) and non-targeted (3rd row) show a nonspecific distribution of both probes throughout the peritoneal cavity. A mixture of the two SEPs was injected i.p. Twenty minutes later, luciferin was injected retroorbitally. For the sake of clear visualization, the abdominal cavity was incised and washed with 60 ml of PBS, the entire abdomen was exposed, and the bowel resected for a better overview of the pelvic organs and the peritoneum. Topically applied surface-enhanced resonance Raman ratiometric spectroscopy (TAS3RS, 4th row) shows no positive regions in the control (left) and a strong correlation to BLI in tumor-bearing mice (right). Alternatively, the TAS3RS map can be visualized in a simplified manner for surgical guidance (bottom row), showing only regions with positive ratios in red. Reference standard solutions in Eppendorf vials were placed in the imaged field of view, with (1) indicating the vial containing αFR-NPs and (2) the vial containing nt-NPs.