A novel dual-function sustainable method for H2O2 determination and dye biomineralization utilizing peroxidase-like MnFe2O4@CrFe2O4 nanocomposite

In this contribution, a novel dual-function sustainable green nanozyme-mediated method for highly sensitive and selective H₂O₂ quantification and reusable rhodamine B biomineralization utilizing highly active MnFe₂O₄@CrFe₂O₄ nanocomposite with synergistic peroxidase-like activity was designed and developed. This method also introduced a sustainable approach for probing the analyte instead of exploiting prevalent carcinogenic nanozyme-based analytical probes, making it absolutely more sustainable than the conventional methods. The hydrogen peroxide biosensor acquired a linear range of 1–100 μM and a very low detection limit of 0.6 μM, along with an inter-day %RSD of 2.74 % and a highly selective response against coexisting materials. Ultimately, the sensor was employed for H₂O₂ quantification in milk, revealing a recovery of 96.1–102.8 %, %RSD = 1.4–3.6 %. Besides, the effective factors on decolorization yield were optimized, providing a high biomineralization yield of 99.4 % at optimal experimental conditions within a short time of 35.0 min. The breakthrough volume, storage stability, and reusability of the nanozymes were assessed, revealing a breakthrough volume of 5.0–1000 mL, a shelf-life of 20 days, and 70 % yield saving after 10 cycles. The method was applied for dye degradation in real water media, including river water, pool water, and tap water, revealing a high yield of over 95.4–99.5 %, %RSD = 1.8–4.2 %.