Hemozoin anchored MWCNTs for mediated reduction of hydrogen peroxide and real-time intracellular oxidative stress monitoring in colon cancer cells

Abstract

Hemozoin (HZ, a malarial pigment) is an insoluble crystalline byproduct formed during the intraerythrocytic breakdown of hemoglobin by some blood-feeding parasites, such as Plasmodium falciparum. It consists of polymerized iron–porphyrin molecular units linked by carboxylic bonds. Due to the rigid molecular structure, studying the electron transfer activity of HZ is challenging. In this work, we report the development of a redox-active HZ-functionalized multi-walled carbon nanotube (MWCNT) modified glassy carbon electrode (GCE/MWCNT@HZ-redox). Here, HZ-redox refers to the redox-active form of hemozoin. This electrode is designed to study the electron transfer activity and mimic the peroxidase enzyme's ability to mediate hydrogen peroxide reduction in a neutral pH solution. The modified electrode exhibited a stable and well-defined redox peak at −0.385 V vs. Ag/AgCl in N₂-purged PBS (pH 7.0) with a surface excess value of 1.64 × 10⁻⁹ mol cm⁻². The MWCNT@HZ-redox was characterized using Raman spectroscopy, FT-IR, and FESEM techniques. This biomimicking electrode showed excellent electrocatalytic reduction of H₂O₂ using cyclic voltammetry. Batch-injection analysis coupled with a screen-printed electrode demonstrated the electroanalytical performance for H₂O₂ sensing. The electrode exhibited a linear concentration range of 50–300 μM, with a sensitivity of 21 μA μM⁻¹ and a detection limit of 220 nM. As a bioanalytical application, we successfully demonstrated the in situ monitoring of H₂O₂ within the reactive oxygen species of HCT-116 colon cancer cells under stimulated conditions.