Ultrafine Pd Nanoparticles Encapsulated in Microporous Co₃O₄ Hollow Nanospheres for In Situ Molecular Detection of Living Cells

Recent progress in the in situ molecular detection of living cells has attracted tremendous research interests due to its great significance in biochemical, physiological, and pathological investigation. Especially for the electrochemical detection of hydrogen peroxide (H₂O₂) released by living cells, the highly efficient and cost-effective electrocatalysts are highly desirable. In this work, we develop a novel type of microporous Co₃O₄ hollow nanospheres containing encapsulated Pd nanoparticles (Pd@Co₃O₄). Owing to the synergy effect between the permeable microporous Co₃O₄ shell and the ultrafine Pd nanoparticles that encapsulated in it, the resultant Pd@Co₃O₄ based electrode exhibits excellent electrochemical sensor performance toward H₂O₂, even when the content of Pd in Pd@Co₃O₄ hollow nanospheres is as low as 1.14 wt %, which enable it be used for real-time tracking of the secretion of H₂O₂ in different types of living human cells.