Direct electrochemistry of myoglobin at silver nanoparticles/myoglobin biocomposite: Application for hydrogen peroxide sensing

•Direct electrochemistry of myoglobin has been achieved at Ag-NPs/MB biocomposite.•The Ag-NPs/myoglobin biocomposite has been obtained using a simple solution based approach.•Novel hydrogen peroxide biosensor has been constructed.

Herein we report a novel hydrogen peroxide (H2O2) sensor based on direct electrochemistry of myoglobin at a silver nanoparticles/myoglobin (Ag-NPs/MB) biocomposite modified electrode. The green synthesized Ag-NPs and MB were used for the fabrication of Ag-NPs/MB biocomposite. The fabricated Ag-NPs and Ag-NPs/MB biocomposite were characterized by using TEM and SEM respectively. A good direct electron transfer of MB is realized at Ag-NPs/MB biocomposite electrode rather than direct drop casting of MB onto Ag-NPs modified electrode, which indicates that the native structure of MB is retained in the biocomposite modified electrode. The apparent heterogenous electron transfer rate constant (ks) is calculated as 3.02 s−1, which confirms a fast direct electron transfer of MB at the biocomposite electrode. A fast amperometric response for H2O2 (<5 s) at Ag-NPs/MB biocomposite modified electrode indicates a good catalytic activity of the modified electrode. The H2O2 detection is found in the linear response range from 1 μM to 3 mM with the detection limit of 0.088 μM. The sensitivity is calculated as 0.357 μA μM−1 cm−2. In addition, the fabricated biosensor shows a good consistency along with excellent precision.

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