Electrochemical detection of extracellular hydrogen peroxide released from RAW 264.7 murine macrophage cells based on horseradish peroxidase-hydroxyapatite nanohybrids

A new method developed for the reliable determination of extracellular and intracellular H2O2 is very useful for gaining a full understanding of the role that H2O2 plays in pathology and physiology, and the relationship between H2O2 and environmental stresses and lipid peroxidation. This work developed and validated an electrochemical approach for the determination of extracellular H2O2 released from RAW 264.7 murine macrophage cells. This approach is based on the electrocatalytic reduction of the released H2O2 at the biosensor of HRP-HAP/GC, which was fabricated by depositing the horseradish peroxidase-hydroxyapatite (HRP-HAP) nanohybrids on a glassy carbon (GC, 3 mm in diameter) electrode. The biosensor exhibited a rapid response (less than 2 s), a low detection limit (0.1 +/- 0.02 mu M), a wide linear range (5 mu M to 0.82 mM), as well as good stability and repeatability. In addition, the common interfering species, such as uric acid (UA), ascorbic acid (AA), glucose, and 3,4-dihydroxyphenylacetic acid (DOPAC), etc., did not cause any interference due to the use of a low operating potential (-400 mV, versus SCE). Therefore, this work has demonstrated a simple and effective sensing platform for the detection of extracellular H2O2 released from cells such as RAW 264.7 cells, which has potential utility to bioelectroanalytical chemistry, cellular biology, and pathophysiology.