Affordable and simple method for separating and detecting ovarian cancer circulating tumor cells using BSA coated magnetic nanoprobes modified with folic acid

The detection of circulating tumor cells (CTCs) offers a noninvasive method for early-stage cancer diagnosis. Although this is a challenging process, the detection and enumeration of CTCs are essential for assessing cancer progression. In this study, we demonstrated an inexpensive and simple method that used folic acid, FA, as targeting probe to replace antibodies for the enrichment and isolation of ovarian cancer CTCs. Bovine serum albumin (BSA) was decorated on magnetic nanoparticles (MNP) to form BSA-MNP, while FA was conjugated on the BSA-MNP surface through a PEG2K-linker. The FA-BSA-MNP complex showed efficient capture of ovarian cancer CTCs as low as 20 cells/mL. Moreover, this FA-BSA-MNP complex showed minimal nonspecific adsorption between the modified magnetic nanoprobes and ovarian cancer cells, resulting in high specific enrichment. More importantly, the MNP-BSA-FA complex was nontoxic to ovarian cancer cells. The isolated cancer cells remained highly viable, were readily grown in vitro without significant death rate with a viability of 92.7%, and without microscopically visible contamination. These results suggested that the FA-BSA-MNP complex could successfully be used for the capture of ovarian cancer CTCs from whole blood. Moreover, when combined with immunocytochemical staining method, the FA-BSA-MNP captured CTCs could be differentiated from the blood cells.