One-step screen-printed electrode modified in its bulk with HRP based on direct electron transfer for hydrogen peroxide detection in flow injection mode

The preparation and performances of screen-printed carbon electrodes modified in their bulk with HRP (HRP-SPCE) is reported. The resulting modified HRP-SPCE was prepared in a one-step procedure, and then was optimised as an amperometric biosensor operating at 0-100] mV versus Ag/AgCl in flow injection mode for hydrogen peroxide. The amperometric response was due to direct electron transfer (DET) between HRP and SPCE surface. Factors such as chemical modification of the enzyme or the nature and rate of the binder were investigated regards to their influence on the sensitivity, linear range and operational stability. The best performing HRP-SPCE in terms of sensitivity and operational stability was obtained when graphite powder was modified with HRP previously oxidised by periodate ion (IO(4)(-)).