We have successfully integrated techniques for controlling cell adhesion and performing electrochemical differential pulse voltammetry (DPV) through the use of digitally controlled microfluidics and patterned transparent
indium tin oxide electrode arrays to enable rapid and sensitive enumeration of
cancer cells in a scalable microscale format. This integrated approach leverages a dual-working
electrode (WE) surface to improve the specificity of the detection system. Here, one of the WE surfaces is functionalized with anti-
Melanocortin 1 Receptor antibodies specific to
melanoma cancer cells, while the other WE acts as a control (i.e., without antibody), for detecting non-specific interactions between cells and the
electrode. The method is described and shown to provide effective detection of
melanoma cells at concentrations ranging between 25 to 300 cells per 20 μL sample volume after a 5 min incubation and 15 s of DPV measurements. The estimated limit of detection was ~17 cells. The sensitivity and specificity of the assay were quantified using addition of large fractions of non-target cells and resulted in a detection reproducibility of ~97%. The proposed approach demonstrates a unique integration of electrochemical sensing and microfluidic cell adhesion technologies with multiple advantages such as label-free detection, short detection times, and low sample volumes. Next steps for this platform include testing with patient samples and use of other cell-surface
biomarkers for detection and enumeration of
circulating tumor cells in prostate, breast, and
colon cancer.