Boosting electrochemical immunosensing performance by employing acetaminophen as a peroxidase substrate

Trypsin Detection Using Electrochemical Reduction‐based Redox Cycling

“…To obtain a high signal‐to‐background ratio for trypsin detection, the electrochemical signal obtained in a solution containing GPR‐AP and H 2 O 2 in the presence of Cyt c (or HRP) should be similar to that obtained in the absence of Cyt c (or HRP), and much lower than that obtained in the presence of Cyt c (or HRP) and trypsin. p ‐Acetylaminophenol (acetaminophen) is oxidized to its quinone imine form without cleavage of its peptide bond in the presence of HRP and H 2 O 2 4 . Accordingly, EN redox cycling involving an electrode, p ‐acetylaminophenol, HRP, and H 2 O 2 can occur, thereby increasing the electrochemical signal.…”

“…In electrochemical biosensors, electrochemical oxidation is more commonly employed than electrochemical reduction, because it is more difficult to obtain high signal‐to‐background ratios in biosensors using electrochemical reduction 1–4 . Redox cycling involving a signaling species such as electrochemical‐chemical (EC) redox cycling and electrochemical‐enzymatic (EN) redox cycling 5–7 can be used to obtain significantly increased electrochemical reduction signals.…”

“…However, to obtain fast EC redox cycling, the formal potential of a signaling species should be much lower than that of O 2 , causing high background currents because of the direct electrochemical reduction of O 2 during the EC redox cycling. When H 2 O 2 is employed as an oxidizing agent, EN redox cycling involving an electrode, a signaling species, horseradish peroxidase (HRP), and H 2 O 2 is primarily used 1–4 . However, the direct electrochemical reduction of H 2 O 2 significantly increases the background levels, and the direct reduction of H 2 O 2 is higher than that of O 2 .…”

“…In electrochemical biosensors, electrochemical oxidation is more commonly employed than electrochemical reduction, because it is more difficult to obtain high signal-tobackground ratios in biosensors using electrochemical reduction. [1][2][3][4] Redox cycling involving a signaling species such as electrochemical-chemical (EC) redox cycling and electrochemical-enzymatic (EN) redox cycling [5][6][7] can be used to obtain significantly increased electrochemical reduction signals. In electrochemical reduction-based EC and EN redox cycling, a signaling species is reduced at the electrode and is then regenerated by an oxidizing agent dissolved in an aqueous electrolyte solution.…”

“…In electrochemical reduction-based EC and EN redox cycling, a signaling species is reduced at the electrode and is then regenerated by an oxidizing agent dissolved in an aqueous electrolyte solution. 4,8 The regenerated signaling species is electrochemically reduced again, and this redox cycling leads to increased electrochemical signal levels. To obtain reproducible signal levels and low background levels, oxidizing agents should be stable in aqueous electrolyte solutions, and electrochemically inactive in potential regions where electrochemical measurements are performed.…”