Visual Electrofluorochromic Detection of Cancer Cells via a Bipolar Electrode Array Chip with a COF@Au@Fc/FA Signal Probe.

Abstract

Highly sensitive tumor cell targeting detection played a pivotal role in the early diagnosis of cancer and identification of solid tumors. Herein, an imaging array chip based on bipolar electrode (BPE)-electrofluorochromism (EFC) was designed for ultrasensitive in situ detection of cancer cells. Taking advantage of the strong affinity between folic acid (FA) and the overexpressed folate receptors (FR) on the surface of cancer cells, covalent-organic framework@gold nanoparticles (COF@Au) comodified with FA and the electroactive molecule ferrocene (Fc) were prepared. Using HeLa cells as a model, Fc deposited on the cell surface at the anode of the BPE underwent electrochemical oxidation upon the application of the appropriate driving voltage. By the principle of electrical neutrality in the BPE system, 4-carboxy resazurin (CRz) at the cathode was concurrently reduced, resulting in the formation of highly fluorescent 4-carboxy resorufin (CRr), which was recorded by using a fluorescence microscope. The strong affinity of the FA loaded on the surface of the nanoprobes with the abundant presence of FR on the cell surface enabled selective tumor cells with high sensitivity by adopting BPE-EFC technology, allowing the detection of a limit down to 2 cells based on a sample volume of 5 μL. The proposed BPE-EFC imaging system offered an innovative methodology for specific cancer cell identification.