High-performance assay of HepG2 cells through inertial separation in a microfluidic chip coupled with fluorescence and photoelectrochemical detection

As a non-invasive, highly specific and sensitive assay strategy, liquid biopsy plays an important role in the diagnosis, the prognosis and the adjuvant therapy of cancer. Circulating tumor cell (CTC) have been considered as a crucial biomarker for liquid biopsy. However, CTCs are difficult to be detected accurately due to their very low content in blood. Herein, HepG2 cells stained with Hcy-716 fluorescence probe were separated and enriched from blood through inertial separation in a microfluidic chip, and then were detected by fluorescent and photoelectrochemical strategies simultaneously. Sulfhydryl functionalized TLS11a aptamers were fixed on a gold nanorods modified screen printing electrode surface to supply a photoelectrochemical cytosensing platform for HepG2 cells. Under optimized conditions, the separation efficiency and the purity of HepG2 cells can reach 82.6% and 73.4%, respectively. A linear response was obtained in the range of 1 × 102 ∼ 5 × 105 cells mL−1, and the detection limit was calculated to be 15 cells mL−1. The separation with microfluid chip and detection with fluorescent imaging and photoelectrochemical aptasensing dual-model strategy provide a practical tool for CTCs assay, thus benefiting for liquid biopsy in cancer diagnosis.