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 H(2)O(2) is very useful for gaining a full understanding of the role that H(2)O(2) plays in pathology and physiology, and the relationship between H(2)O(2) and environmental stresses and lipid peroxidation. This work developed and validated an electrochemical approach for the determination of extracellular H(2)O(2) released from RAW 264.7 murine macrophage cells. This approach is based on the electrocatalytic reduction of the released H(2)O(2) 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 μM), a wide linear range (5 μM 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 H(2)O(2) released from cells such as RAW 264.7 cells, which has potential utility to bioelectroanalytical chemistry, cellular biology, and pathophysiology. This journal is © The Royal Society of Chemistry 2011