Folic acid-functionalized zirconium metal-organic frameworks based electrochemical impedance biosensor for the cancer cell detection

The effective capture and sensitive detection of cancer cells are of great significance to the basic research as well as to the clinical diagnosis and therapy. Here we proposed a simple, low-cost, and high-efficient impedance cytosensor based on folic acid-functionalized zirconium metal-organic frameworks (MOF). Folic acid (FA)-functionalized zirconium MOFs (UiO-66) was utilized as the sensitive element due to the high surface area and porosity, in which FA can be effectively modified onto UiO-66 by the coordinative interaction. The successful preparation of FA@UiO-66 nanocomposite was carefully validated by power X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, UV spectra, zeta potential, transmission electron microscope (TEM), and scanning electron microscope (SEM). The obtained electrochemical impedance results indicated that this impedance sensor functionalized with FA@UiO-66 nanocomposite exhibited good analytical performances in a linear range from 1 × 10 2 to 1 × 10 6  cells/mL. The detection limit was calculated to be as low as 90 cells/mL. It also showed good selectivity in distinguishing FAR-rich cancer cells (e.g. HeLa and H1299 cells) and FAR-negative cells (e.g. HEK-293 cells). HeLa cells spiked in blood samples can also be detected with good recovery rates. All the results demonstrated that this simple and universal approach has great potential to develop disposable and portable biosensors and be applied in the early-stage cancer diagnosis.