Figure 2

Characterization of fluorescence and surface enhanced Raman scattering nanoprobes (F-SERS dots), FRES, and colon cancer cell lines. (a) The size of the F-SERS and antibody-conjugated F-SERS dots. The size of the F-SERS-A and EGFR-F-SERS-A dots was 318.6  ± 20.1 nm and 352.5  ± 37.1 nm, respectively, and the size of the F-SERS-B and VEGF-F-SERS-B dots were 326.3  ± 25.9  nm and 363.8  ± 34.3  nm, respectively. (b) Evaluation of FRES using antibody-conjugated F-SERS dots. EGFR-F-SERS-A dots showed a small dotted fluorescence signal (AF 610) and a 1648 cm⁻¹ intensity Raman signal (RITC).VEGF-F-SERS-B dots revealed small dotted fluorescence signals (AF 610) and a 1324 cm⁻¹ intensity Raman signal (FITC) (a.u. = arbitrary unit). (c) Characterization of HT29-effluc colon cancer cells. HT29-effluc cells showed high luciferase activity according to seeded cell number and a significant positive correlation with protein concentration (R² = 0.987, P < 0.001). HT29-effluc cells demonstrated EGFR and VEGF expression by western blot analysis (the loading control used was β-actin; CPS = count per sec). (d) Confocal laser scanning microscopy (CLSM) after spraying 10 µg of antibody-conjugated F-SERS dots onto cultured HT29-effluc cells. Multiple (EGFR-F-SERS-A and VEGF-F-SERS-B) or single (EGFR-F-SERS-A or VEGF-F-SERS-B) spraying of antibody-conjugated F-SERS dots were revealed by fluorescence, while the IgG-F-SERS-A/B dots (control) showed no fluorescence. Cell nuclei were labeled with DAPI.