LHRH-targeting surface-enhanced Raman scattering tags for the rapid detection of circulating tumor cells

The rapid and simple detection of circulating tumor cells (CTCs) can enable early diagnosis and improve prognosis in cancer patients. Here, we fabricated luteinizing hormone releasing hormone (LHRH)-conjugated surface-enhanced Raman scattering (SERS) tags to detect CTCs expressing LHRH receptors (LHRHRs) in mouse blood. With optimization, 50 mu M 4-mercaptobenzoic acid (pMBA) as reporter molecule and 20 mu l of 20 mg/ml reduced bovine serum albumin(rBSA) as protecting layer resulted in the most stable SERS tag suspension. Cultures of HeLa cells, which overexpress LHRHRs, were then used to evaluate the selectivity, sensitivity, and cytotoxicity. Mouse blood was spiked with or without HeLa cells were used to test the practical application of our SERS tag-mediated CTC detection method. In consequence, CTCs can be rapidly detected in the mouse blood in a specific and sensitive manner down to the 5 cells/ml CTC concentration. Additionally, a good linear relationship was observed between CTC concentration and signal intensity. Therefore, this inexpensive method using LHRH-targeting SERS tags rapidly detects CTCs and could prove to be a novel platform for point-of-care testing in cancer patients.