A laser-assisted electrochemical biosensor based on folic acid-functionalized tungsten disulfide nanosheets for label-free cancer cell detection

This study reports a label-free and high-efficiency electrochemical biosensor based on functionalized tungsten disulfide (WS2) nanosheets with cysteine (CYS) and folic acid (FA) to diagnose cancer cells. The large surface area of WS2-CYS-FA nanosheets, combined with its strong binding affinity toward cancer cells, makes it an ideal material for modifying the working electrode to enhance the performance of cytosensors. The WS2 nanosheets were prepared using a liquid exfoliation method and decorated with FA through CYS. The successful preparation of WS2-CYS-FA was confirmed through various characterization techniques. The gold electrode was then modified with WS2-CYS-FA for the electrochemical detection of two breast cancer cell lines, MDA-MB-231 and MCF-7, classified as FR-positive cells, and the HUVEC cell line as FR-negative control cells. During electro-chemical measurements, the WS2-CYS-FA@Au working electrode was irradiated with laser light. Electron-hole pairs generated by laser photons boosted interfacial electron transfer and improved electrochemical efficiency. The electrochemical results showed that the proposed cytosensor has great sensitivity and selectivity with a detection limit of 10 cells/mL of MDA-MB-231 cells in a linear concentration range from 20 to 2 x 105 cells/mL (S/N = 3). The fabricated biosensors were successfully tested with whole blood samples and had a high recovery rate.