Non-enzymatic screen-printed sensor based on PtNPs@polyazure A for the real-time tracking of the H2O2 secreted from living plant cells

Abstract

Monitoring of hydrogen peroxide (H₂O₂) in living cells has high significance for understanding its functions. We herein report an enzymeless H₂O₂ sensor consisting of a previously activated screen-printed carbon electrode modified with Pt nanoparticles electrogenerated on a supporting conductive layer of polyazure A-dodecyl sulfate. This electrode was used to investigate the dynamic process of H₂O₂ release from living grapevine cells under different (a)biotic stresses. The modified surfaces were characterized by FESEM/EDX, EIS and cyclic voltammetry. Sensor analytical performance was studied in a cell culture medium under aerobic conditions, as required for cell survival. In relation to the synergistic effect between the metal nanoparticles and the conjugated polymer, this electrode showed good stability, excellent analytical performance combined with a rapid response (<2s) and limit of detection of 24.9 nM in the culture medium. The modified electrodes could fulfill the real-time measurement requirement of H₂O₂ release from living plant cells to the extracellular medium operating continuously, even in experiments lasting more than 12 h. Methyl jasmonate, L-methionine, clopyralid and the fungus Botrytis cinerea were the eliciting agents chosen to induce oxidative stress in the plant cells. This work demonstrates the huge potential of this sensor for the real-time tracking of the H₂O₂ released from living cells under different physiological conditions.

Keywords: Hydrogen peroxide; Living cells; Non-enzymatic sensor; Oxidative stress; Platinum nanoparticles; Polyazure A.