(44) developed a dual-aptamer ratio SERS biosensor that demonstrated high affinity and specificity for surface proteins (Epithelial cell adhesion molecule (EpCAM) (45), Prostate specific antigen (PSA) (46), carcino-embryonic antigen (CEA) (47) etc) on exosomes derived from breast cancer cells, resulting in improved sensitivity (48). Here, CEACAM5 is linked to breast carcinoma.