A sensitive electrochemical nonenzymatic biosensor for the detection of H₂O₂ released from living cells based on ultrathin concave Ag nanosheets

Facile synthesis of ultrathin two-dimensional metallic nanosheets with special physical and chemical properties is still challenging. In this work, ultrathin silver nanosheets were synthesized through the galvanic replacement reaction between silver nitrate and Cu microcages without using any surfactant at room temperature. The as-prepared Ag nanosheets (NSs) were concave and had a thickness of sub-10 nm. And the nanosheets exhibited excellent H₂O₂ detection property with a high sensitivity of about 320.3 uA mM⁻¹ cm⁻² and a low detection limit of 0.17 µM in a wide linear range of 5–6000 μM, and a fast response time (less than 2 s). Besides, the real-time detection of H₂O₂ induced from living HeLa and SH-SY5Y cells were also achieved, indicating the potential application of as-prepared Ag NSs in monitoring physiological and dynamic in-clinic pathological processes.