Catalase-like activity of perylene diimide based radical anion: Chromogenic substrate for achieving glucose sensing

In this work, perylene diimide based radical anion (PH2^-) is synthesized and characterized using optical, NOBF₄ methods; cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The PH2^- is stable for 120 min (2 h) in oxygenated environment and 273 min (4.5 h) in hypoxic conditions. The PH2^- showed catalase-like activity to reduce H₂O₂ to H₂O with turn-over number (TON) = 20 and turn-over frequency (TOF) = 40 h^-1. The catalase-like activity can be measured using optical and electrochemical methods by monitoring the changes at 726 nm (absorbance); 585 nm (emission) and at 0.27 V. We were able to quantitatively monitor the ultra low-level concentrations of the H₂O₂ as low as 320 fM (absorbance) and 200 fM (emission). Moreover, PH2^- could be used as a chromogenic and fluorogenic substrate for monitoring the low-level concentrations of the glucose using GOx based biochemical assay. We have demonstrated the development and validation of the glucose assay kit for the detection of glucose as low as 3.6/2.8 nM in aqueous medium and 6.2/5.6 nM in blood serum.