Hydrogen peroxide sensor using the biomimetic structure of peroxidase including a metal organic framework

Highlights: • Catalyst consisting of hemin-encapsulated MOF and CNT (Hemin⊂MIL-88-NH₂/CNT) is introduced. • Hemin⊂MIL-88-NH₂/CNT shows higher catalytic activity than heme protein catalysts. • The sensitivity of Hemin⊂MIL-88-NH₂/CNT was 0.538 μA μM⁻¹ cm⁻². • Hemin⊂MIL-88-NH₂ based catalyst can be used for the H₂O₂ sensors. In this study, hemin that has excellent catalytic activity is adopted as a catalyst component and other materials, such as metal organic framework (MOF) and carbon nanotube (CNT), are further used to alleviate drawbacks of hemin, such as location issue and molecular aggregation. Based on that, a new catalyst consisting of hemin-encapsulated MOF and CNT is developed (Hemin⊂MIL-88-NH₂/CNT). To evaluate its catalytic activity, colorimetric and electrochemical evaluations are conducted. When colorimetric method is used, Hemin⊂MIL-88-NH₂/CNT shows good catalytic activity due to proper interaction between water media and amine bond of MOF. In electrochemical evaluations, Hemin⊂MIL-88-NH₂/CNT has high sensitivity (0.538 μAμM⁻¹cm⁻²) and low detection limit (0.06 μM) at 0.5–203 μM (R² = 0.999). Even in amperometric response tests, when 10 μM H₂O₂ is injected, Hemin⊂MIL-88-NH₂/CNT shows a better response than other heme protein- based catalysts ((Hb, Mb and HRP)/CNT) by 2.06–3.26 times. In terms of stability, its catalytic activity is well preserved even under harsh pH and temperature conditions for a long time (89.5% of the initial value after 15 days). With that, it is confirmed that the Hemin⊂MIL-88-NH₂/CNT as the catalyst for use in H₂O₂ sensors is attractive and better than other heme proteins.