Photoelectrochemical aptasensing and fluorescence imaging co-joint detecting MCF-7 cells in whole blood via an inertial separation microfluidic chip.

The mortality rate of tumor is still very high till now. Circulating tumor cells (CTCs) are the major culprit of high cancer mortality. To improve survival rate of cancer patients, real-time monitoring and quantitative detection of CTCs are of indescribable value. However, due to the extremely small content and heterogeneous characteristics of CTCs, to accurately detect CTCs is still a tremendous challenge in clinical trials. Herein, the photoelectrochemical aptasensing and fluorescence imaging were co-joint to detect MCF-7 cells in whole blood via an inertial separation microfluidic chip. A portable inertial microfluidic chip with a height of 150 μm was designed to separate MCF-7 cells from whole blood samples. Niblue-C6-IMC was used to label and image MCF-7 cells through specifically reacting with COX-2 enzyme from the over-expression on the cellular surface. Subsequently, MCF-7 cells were detected with a BiOS nanoflower based photoelectrochemical sensing system. Parameters including the channel height and length, flow rate, focusing position, fluorescence probe concentration, and flow length of the microfluidic chip were optimized. The separation efficiency and purity of MCF-7 cells were 85 % and 80 %, respectively. For 1 mL of blood sample (100 cells mL), 85 cells and 90 cells could be calculated based on the signals from fluorescence imaging and photoelectrochemical response, respectively. Nevertheless, for assaying 1 mL of blood samples containing 50 MCF-7 cells, 40 cells and 39 cells were obtained from fluorescence imaging and photoelectrochemical responses, respectively.