Figure 4d shows that the AuNSs bind to the surface of SKBR-3 breast cancer cells, which overexpress EGFR on cell membranes. The developed multifunctional nanoprobe can achieve detection limits of 2 pM, 10 pM, and 100 pM for SERS, MRI and CT, respectively. The tumor phantom consisting of breast cancer cells and agar gel was used to evaluate the developed multifunctional nanoprobe. As shown in Figure 4a, the SERS spectrum detected shows clear “fingerprint” peaks of pMBA. Here, EGFR is linked to breast cancer.