Controlled radical release from iron oxide nanoparticles grafted with thermosensitive alkoxyamine triggered by external stimuli

Abstract

We report an investigation of a controlled radical release produced by iron oxide nanoparticles (IONPs) of ca. 25 nm covalently grafted through phosphonic groups with a thermosensitive alkoxyamine, (6-(4-(1-((di-tert-butylamino)oxy)ethyl)benzamido)hexyl)phosphonate, having a relatively low homolysis temperature (kd = 6.4 × 10−4 s−1 at 77 °C, Ea = 117.8 kJ mol−1). Action of an alternating current magnetic field (AMF) or light irradiation at 808 nm produces a rapid heating of the nanoparticles’ surface, which induces the homolysis of the C–ON bond of alkoxyamines facilitating the efficient formation of free radicals. We demonstrated based on homolysis kinetics investigated by electron paramagnetic resonance (EPR) spectroscopy that light irradiation at 808 nm (2.6 W cm−2) enables efficient radical release from grafted nanoparticles at 44 °C (t1/2 = 23.6 min), whereas the free molecules required 20 h to show the same release at this temperature. AMF exposure accelerates the homolysis of alkoxyamine-grafted nanoparticles (16 kA m−1, 2.9 mg mL−1) twofold compared to the free alkoxyamine at 77 °C (t1/2 = 7.9 min vs. 18 min). These findings underscore the critical importance of localized nanoscale effects, demonstrating that the homolysis rate on the nanoparticle surface under external stimuli is significantly higher compared to that under external solution heating, with this enhancement being even more pronounced under light irradiation.

Graphical abstract: Controlled radical release from iron oxide nanoparticles grafted with thermosensitive alkoxyamine triggered by external stimuli

Supplementary files

Article information

Article type
Research Article
Submitted
22 Nov 2024
Accepted
25 May 2025
First published
28 May 2025
This article is Open Access
Creative Commons BY-NC license

Mater. Chem. Front., 2025, Advance Article

Controlled radical release from iron oxide nanoparticles grafted with thermosensitive alkoxyamine triggered by external stimuli

F. Abdel Sater, B. Bouvet, S. Sene, G. Félix, E. Adriaenssens, J. Joly, G. Audran, S. R. A. Marque, J. Larionova and Y. Guari, Mater. Chem. Front., 2025, Advance Article , DOI: 10.1039/D4QM01022A

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. You can use material from this article in other publications, without requesting further permission from the RSC, provided that the correct acknowledgement is given and it is not used for commercial purposes.

To request permission to reproduce material from this article in a commercial publication, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party commercial publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements