The formation of interfacial charge transfer (ICT) complexes between phenolic ligands and metal oxide surfaces enables surface functionalization strategies with potential applications in catalysis and bioconjugation. In this study, magnetite (Fe3O4) nanoparticles were modified with two phenolic ligands, 5-aminosalicylic acid (5ASA) and caffeic acid (CA), to generate ICT complexes capable of covalent or non-covalent enzyme immobilization, respectively. The modified nanomaterials were structurally characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR). Horseradish peroxidase (HRP) was immobilized on these functionalized supports using varying nanoparticle amounts (10-30 mg) and initial enzyme concentrations (25-250 µg mL-1). Catalytic activity was evaluated using pyrogallol oxidation assays. The Fe3O4/5ASA-HRP system exhibited a maximum activity of 2.5 U per 20 mg of support (approximately 125 U g-1), wherea...s Fe3O4/CA showed minimal activity under the same conditions. Enzyme loading studies confirmed that 5ASA-enabled covalent attachment resulted in significantly higher immobilization efficiency (up to 1068 mg g-1) compared to the CA system. Reusability tests demonstrated that the Fe3O4/5ASA system retained high absolute catalytic activity during the initial reaction cycles and consistently outperformed the non-covalently immobilized Fe3O4/CA system upon repeated reuse. The magnetic properties of Fe3O4 allowed rapid recovery of the biocatalysts using an external magnetic field. These results highlight the effectiveness of ICT-based functionalization for enzyme immobilization, positioning Fe3O4/5ASA as a promising platform for robust and reusable biocatalysts in environmental and industrial applications.
TY - JOUR
AU - Isaković, Katarina
AU - Jonović, Marko
AU - Sredojević, Dušan
AU - Bošković, Marko
AU - Periša, Jovana
AU - Knežević-Jugović, Zorica
AU - Lazić, Vesna M.
PY - 2026
UR - https://vinar.vin.bg.ac.rs/handle/123456789/16084
AB - The formation of interfacial charge transfer (ICT) complexes between phenolic ligands and metal oxide surfaces enables surface functionalization strategies with potential applications in catalysis and bioconjugation. In this study, magnetite (Fe3O4) nanoparticles were modified with two phenolic ligands, 5-aminosalicylic acid (5ASA) and caffeic acid (CA), to generate ICT complexes capable of covalent or non-covalent enzyme immobilization, respectively. The modified nanomaterials were structurally characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR). Horseradish peroxidase (HRP) was immobilized on these functionalized supports using varying nanoparticle amounts (10-30 mg) and initial enzyme concentrations (25-250 µg mL-1). Catalytic activity was evaluated using pyrogallol oxidation assays. The Fe3O4/5ASA-HRP system exhibited a maximum activity of 2.5 U per 20 mg of support (approximately 125 U g-1), whereas Fe3O4/CA showed minimal activity under the same conditions. Enzyme loading studies confirmed that 5ASA-enabled covalent attachment resulted in significantly higher immobilization efficiency (up to 1068 mg g-1) compared to the CA system. Reusability tests demonstrated that the Fe3O4/5ASA system retained high absolute catalytic activity during the initial reaction cycles and consistently outperformed the non-covalently immobilized Fe3O4/CA system upon repeated reuse. The magnetic properties of Fe3O4 allowed rapid recovery of the biocatalysts using an external magnetic field. These results highlight the effectiveness of ICT-based functionalization for enzyme immobilization, positioning Fe3O4/5ASA as a promising platform for robust and reusable biocatalysts in environmental and industrial applications.
T2 - Molecules
T1 - Magnetically Recoverable ICT-Functionalized Fe3O4 Nanoparticles for Efficient Horseradish Peroxidase Immobilization
VL - 31
IS - 1
SP - 178
DO - 10.3390/molecules31010178
ER -
@article{
author = "Isaković, Katarina and Jonović, Marko and Sredojević, Dušan and Bošković, Marko and Periša, Jovana and Knežević-Jugović, Zorica and Lazić, Vesna M.",
year = "2026",
abstract = "The formation of interfacial charge transfer (ICT) complexes between phenolic ligands and metal oxide surfaces enables surface functionalization strategies with potential applications in catalysis and bioconjugation. In this study, magnetite (Fe3O4) nanoparticles were modified with two phenolic ligands, 5-aminosalicylic acid (5ASA) and caffeic acid (CA), to generate ICT complexes capable of covalent or non-covalent enzyme immobilization, respectively. The modified nanomaterials were structurally characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR). Horseradish peroxidase (HRP) was immobilized on these functionalized supports using varying nanoparticle amounts (10-30 mg) and initial enzyme concentrations (25-250 µg mL-1). Catalytic activity was evaluated using pyrogallol oxidation assays. The Fe3O4/5ASA-HRP system exhibited a maximum activity of 2.5 U per 20 mg of support (approximately 125 U g-1), whereas Fe3O4/CA showed minimal activity under the same conditions. Enzyme loading studies confirmed that 5ASA-enabled covalent attachment resulted in significantly higher immobilization efficiency (up to 1068 mg g-1) compared to the CA system. Reusability tests demonstrated that the Fe3O4/5ASA system retained high absolute catalytic activity during the initial reaction cycles and consistently outperformed the non-covalently immobilized Fe3O4/CA system upon repeated reuse. The magnetic properties of Fe3O4 allowed rapid recovery of the biocatalysts using an external magnetic field. These results highlight the effectiveness of ICT-based functionalization for enzyme immobilization, positioning Fe3O4/5ASA as a promising platform for robust and reusable biocatalysts in environmental and industrial applications.",
journal = "Molecules",
title = "Magnetically Recoverable ICT-Functionalized Fe3O4 Nanoparticles for Efficient Horseradish Peroxidase Immobilization",
volume = "31",
number = "1",
pages = "178",
doi = "10.3390/molecules31010178"
}
Isaković, K., Jonović, M., Sredojević, D., Bošković, M., Periša, J., Knežević-Jugović, Z.,& Lazić, V. M.. (2026). Magnetically Recoverable ICT-Functionalized Fe3O4 Nanoparticles for Efficient Horseradish Peroxidase Immobilization. in Molecules, 31(1), 178.
https://doi.org/10.3390/molecules31010178
Isaković K, Jonović M, Sredojević D, Bošković M, Periša J, Knežević-Jugović Z, Lazić VM. Magnetically Recoverable ICT-Functionalized Fe3O4 Nanoparticles for Efficient Horseradish Peroxidase Immobilization. in Molecules. 2026;31(1):178.
doi:10.3390/molecules31010178 .
