Nanodiamond based sponges with entrapped enzyme: A novel electrochemical probe for hydrogen peroxide

A “modular approach” has been demonstrated for the preparation of nanodiamond (ND) based sponges (NS) with entrapped enzyme (horseradish peroxidase, HRP) (ND-NS(HRP)) and utilization as an electrochemical probe for detection of hydrogen peroxide (H2O2). ND-NS comprises ND, porous poly(aniline)–poly(2-acrylamido 2-methyl propane sulfonic acid) (PANI–PAMPSA) network and entrapped HRP. Field emission scanning electron microscope image of ND-NS(HRP) reveals sponge like suprastructure comprising interconnected nanospheres with numerous openings/pinholes/cavities. The entrapped HRP in ND-NS exhibits effective direct electron transfer with an electron transfer rate constant of 1.85 s−1. ND-NS(HRP) exhibited excellent bioelectrocatalytic reduction of hydrogen peroxide (H2O2) with a wide linear concentration range (1–45 mM), quick response (5 s), high sensitivity (129.6 μAM−1) and low detection limit 59 μM (S/N=3).

► New strategy for the preparation of nanodiamond based sponges has been developed.
► Horseradish peroxidase molecules have been effectively entrapped into the sponges.
► The enzyme entrapped sponge has been fabricated as an electrochemical probe.
► The bioactivity of entrapped enzyme is well documented through direct electron transfer.
► Bioelectrocatalytic properties toward hydrogen peroxide have been reported.