A non-enzymatic electrochemical biosensor based on Au@PBA(Ni–Fe):MoS2 nanocubes for stable and sensitive detection of hydrogen peroxide released from living cells

Abstract

Hydrogen peroxide (H₂O₂) is the main product of enzymatic reactions and plays an important role in biological processes. The detection of H₂O₂ inside organisms or cells is critical. Here, we report a nickel–iron Prussian blue analogue nanocube doped with molybdenum disulfide and Au nanoparticles (Au@PBA(Ni–Fe):MoS₂) as an electrochemical sensing material for the stable detection of H₂O₂ in neutral solutions for a long time. First, the Prussian blue analogue (PBA(Ni–Fe)) is synthesized by a simple charge-assembly technology, and then etched into PBA(Ni–Fe):MoS₂ hollow nanocubes by a high-temperature hydrothermal reaction. Finally, Au nanoparticles are reduced inside the PBA(Ni–Fe):MoS₂in situ to generate Au@PBA(Ni–Fe):MoS₂ nanocubes. Ni-doping enhances the nanocube's stability in neutral solutions; as a result, the sensor can maintain a stable current response towards H₂O₂ reduction for more than 1 h. The sensing material can meet the needs of a long-time test. The introduction of Au enhances the electron transfer efficiency, which endows the sensor with good reduction ability for H₂O₂ at 0 V over a wide linear range (0.5–200 μM and 210–3000 μM) and with a low detection limit (0.23 μM (S/N = 3)), which fulfills the requirements for the detection of H₂O₂ in a biological system. The sensor can sense H₂O₂ released from cells stimulated by ascorbic acid. Au@PBA(Ni–Fe):MoS₂ provides good guidance for the future development of efficient biosensors to be applied in cell biology.