Impedimetric biosensor for detection of cancer cells employing carbohydrate targeting ability of Concanavalin A.

The successful development of selective detection of cancer cells from normal cells is a highly demanded but challenging task. Herein, we have developed a rapid and label-free impedimetric biosensor for quantitative determination of cancer cells with high glycoprotein expression. Homogenously distributed 2-9 nm graphene quantum dots (GQDs) was anchored on the surface Fe3O4 through covalent bonding. Concovalin A (ConA) was then adhered onto GQDs by physical mixing to fabricate ConA-GQD@Fe3O4 nanosensing probe. A good dynamic range in the cell concentration of 5 × 102-1 × 105 cells mL-1 with LOD values of 246 and 367 cells mL-1 for HeLa and MCF-7, respectively, is obtained. The impedimetric responses to the cancerous HeLa and MCF-7 cells are 16.7 and 13.1 times higher than those of their original sensor electrodes. However, the interaction between sensing probe and normal MCF-10 and bEnd.3 cells is negligible, confirming the specific selectivity toward cancer cells. Cellular uptake images as well as in-vitro cytotoxicity corroborates the electrochemical results. In addition, the successful detection of cancer cells in human serum and circulating tumor cells in blood sample envisions the feasibility of using ConA-GQD@Fe3O4 as the nanosensing probe for clinically early diagnosis of cancer cells with high glycoprotein expression.