An electrochemical enzymatic nanoreactor based on dendritic mesoporous silica nanoparticles for living cell H₂O₂ detection

The selective and quantitative detection of cellular H₂O₂ is essential for understanding its roles in physiology and pathology. A new electrochemical H₂O₂ biosensor, fabricated by immobilizing horseradish peroxidase onto dendritic mesoporous silica nanoparticles (HRP/DMSNs), is employed for living cell H₂O₂ detection. Taking advantage of the large pore volume and highly accessible internal surface areas of DMSNs, HRP/DMSNs display higher enzymatic loading, better stability and bioactivity in comparison with HRP on nonporous silica nanoparticles (NSNs). Therefore, a HRP/DMSN modified GCE (HRP/DMSNs/GCE) shows attractive electrochemical performance for sensitive and selective detection of H₂O₂ in 0.1 M pH 7.0 PBS, with a low Kappm value of 11.48 μM and a low detection limit of 0.11 μM. In addition, HRP/DMSNs/GCE is successfully applied to detect H₂O₂ released from a PC12 cell triggered by ascorbic acid (AA). The detected H₂O₂ amount is close to the reported values. The developed biosensor has potential in the dynamic detection of the flux of H₂O₂ from living cells for further evaluation of oxidative stress in cells.