A novel modification method via in-situ reduction of AuAg bimetallic nanoparticles by polydopamine on carbon fiber microelectrode for H2O2 detection

Abstract

In this work, a facile in-situ reduction method was developed for the modification of carbon fiber microelectrode (CFME) to build novel electrochemical sensors for the detection of H2O2. The polydopamine (PDA) was employed as the surface modification material for one-step decoration of AuAg bimetallic nanoparticles through in-situ reduction on the surface of PDA/CFME. Compared to Au-PDA/CFME and Ag-PDA/CFME, 2Au1Ag-PDA/CFME (immersed PDA/CFME in AgNO3 for 1 h, HAuCl4•4H2O for 2 h in order) exhibited higher electrocatalytic activity toward H2O2 sensing due to bimetal synergism. Under the optimal condition, the 2Au1Ag-PDA/CFME appeared a wide linear range of 0 μM - 55 μM (R2 = 0.990), 55 μM – 2775 μM (R2 = 0.991) with high sensitivity (12966 μA mM−1cm−2, 0–55 μM; 2534 μA mM−1 cm−2, 55–2775 μM), and low detection limit (0.12 μM). Furthermore, good selectivity and repeatability of 2Au1Ag-PDA/CFME favored its applications in biological samples, especially in cellular level. The detection of H2O2 released from HepG2 living cells was realized by applying 2Au1Ag-PDA/CFME, indicating a potential usage of the fabricated electrode for H2O2 detection in cancer cells. In addition, the above simple in-situ reduction method based on PDA's adhesion and reducibility offered a universal strategy to decorate noble metals onto microelectrode for different application in the future.