quantities of turnip tissue were added to a fixed volume of PBS buffer forming varying tissue com-positions (1–10% (w/v) disc−1) which were then immobilized on paper discs with 50 mM hexacyanoferrate (II) solution to deter-mine the optimum response for the paper-based H2O2 biosensor at an applied potential of −0.10 V (vs. Ag/AgCl). Fig. 5