Poster Presentation Royal Australian Chemical Institute National Congress 2026

Substrate dependent peroxidase mimicking activity of noble metal decorated hybrid superparamagnetic iron oxide nanozymes (#206)

Faizan Z Simnani 1 2 , Paul K.M Sarpong 1 , Lhoussain Khrouz 3 , Ana Maria Pablo-Sainz-Ezquerra 1 , Jérémy Paris 4 , Chloé Gervasoni 4 , Nicholas Blanchard 5 , Rajesh Ramanathan 2 , Vipul Bansal 2 , Yann Chevolot 1 , Virginie Monnier 1
  1. Univ Lyon, Ecole Centrale de Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, INL, UMR5270, 69130 Ecully, France
  2. Sir Ian Potter NanoBioSensing Facility, NanoBiotechnology Research Laboratory, RMIT Universtiy, Melbourne, Victoria, 3000, Australia
  3. ENS de Lyon, CNRS, Laboratoire de Chimie, UMR 5182, 46 allée d’Italie, Lyon, F-69342, France
  4. "Synthesis of Nanohybrids” SON – SAS, 9, Avenue Alain Savary, Dijon, 21000, France
  5. Universite Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, UMR5306, Villeurbanne, F-69100, France

Nanozymes are emerging as promising alternatives to natural enzymes for applications in biosensing, therapeutics, and environmental remediation. In this study, superparamagnetic iron oxide nanoparticles (SPION) decorated with noble metal (SPION/Metal [Metal = Pt, Pd]) were systematically investigated for their peroxidase-mimicking (POD) activity in the presence of hydrogen peroxide (H2O2). The hybrids catalyzed the oxidation of three commonly used peroxidase substrates, TMB, ABTS, and OPD, allowing for a comprehensive, substrate-dependent kinetic evaluation. Kinetic parameters (Km, Vmax, Kcat, Keff) were determined using the classical Michaelis–Menten model, and catalytic efficiency was further benchmarked using turnover frequency (TOF), which is not commonly reported for nanozymes. Notably, the nanozymes exhibited substrate-specific activity, highlighting the importance of surface chemistry in modulating catalytic behavior. Among the hybrids, SPION/Pt showed ~11.36-fold higher TOF for OPD, while SPION/Pd excelled in all the substrates from ~2-5-fold higher as compared to SPION. This enhancement is due to the higher of the hybrids for H2O2, as illustrated by Km, which is facilitated by the metal decoration on SPIONs. Electron Spin Resonance (ESR) spectroscopy confirmed the generation of free radicals (OH) for SPION, providing insights into the underlying classical Fenton-like mechanism. Interestingly, free radicals were only detectable in the presence of OPD substrates for SPION/Metal. These findings advance the fundamental understanding of hybrid nanozymes and support their application in tailored, substrate-specific biosensing platforms and antibacterial applications.

Keywords: Nanozyme, Iron oxide, Hybrid nanomaterial, Reactive oxygen species, Peroxidase activity

Acknowledgment: Co-funded by the European Union under the Marie Skłodowska-Curie Grant Agreement No 101081465 (AUFRANDE). Views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union or the Research Executive Agency. Neither the European Union nor the Research Executive Agency can be held responsible for them. Nanolyon technological platform is acknowledged for its technical support.