Subpicomolar sensing of hydrogen peroxide with ovalbumin-embedded chitosan/polystyrene sulfonate multilayer membrane

The use of ovalbumin (OVA)-immobilized layer-by-layer-assembled chitosan/polystyrene sulfonate membranes for the detection of hydrogen peroxide (H2O2) at subpicomolar levels is reported. The detection of mercuric chloride (HgCl2) and potassium iodide (KI) was also investigated. While the detection limits of HgCl2 and KI remained in the micromolar concentration range, H2O2 could be sensed to a remarkably lower range (subpicomolar). Analysis of fluorescence quenching data of OVA by H2O2 using Stern–Volmer plots revealed a static quenching mechanism with high Stern–Volmer quenching constant (9.10 × 1012 L mol−1) and k (5.82 × 1021 L mol−1 s−1). The possibility of the conformational transition of OVA in the immobilized state is discussed using steady-state and time-resolved spectroscopic techniques. The resulting increased accessibility of tryptophan residues together with the reversibility of the bilayer for the sensing of H2O2 is also illustrated.