# Label-Free Electrochemical Detection of K-562 Leukemia Cells Using TiO2-Modified Graphite Nanostructured Electrode

## TL;DR

A new electrochemical biosensor using a modified graphite electrode can detect leukemia cells quickly and accurately.

## Contribution

A novel TiO2-modified graphite electrode enables label-free detection of K-562 leukemia cells with high sensitivity and rapid response.

## Key findings

- The TiO2-m electrode achieved high reproducibility and strong linearity (R2 = 98%) in detecting leukemia cells.
- K-562 cells adhered to and formed pseudopods on the TiO2-m surface, which is unusual for these typically nonadherent cells.
- Electrochemical detection occurred within 25 seconds for cell concentrations ranging from 6250 to 1,000,000 cells/mL.

## Abstract

This manuscript presents the development of an electrochemical biosensor designed to detect K-562 chronic myeloid leukemia (CML) cells. The biosensor was made of highly oriented pyrolytic graphite (HOPG), functionalized with -OH and -COOH groups by surface etching with strong acids, and subsequently coated with modified titanium dioxide (TiO2-m). TiO2-m is TiO2 modified during its synthesis process using carbon nanotubes functionalized with -OH and -COOH groups. These changes improve the electron transfer kinetics and physicochemical properties of the electrode surface. TiO2-m improves the sensitivity and selectivity towards leukemic cells. The detection process involved three stages: cell culture, cell adhesion onto the TiO2–m electrode, and measurement of the electrochemical signal. Fluorescence microscopy and SEM-EDS confirmed cell adhesion and pseudopod formation on the TiO2-m surface, which is an important finding because K-562 cells are typically nonadherent. Cyclic voltammetry (VC) and differential pulse voltammetry (VDP) demonstrated rapid and sensitive detection of leukemic cells within the concentration range of 6250 to 1,000,000 cells/mL, achieving high reproducibility and strong linearity (R2 = 98%) with a detection time of 25 s. The VC and VDP demonstrated rapid and sensitive detection of leukemic cells over a concentration range of 6250 to 1,000,000 cells/mL, achieving adequate reproducibility and stable linearity (R2 = 98%), with a detection time of 25 s. These results indicate that the TiO2-m biosensor is a promising platform for the rapid and efficient electrochemical detection of leukemia cells.