Condensed Clustered Iron Oxides for Ultrahigh Photothermal Conversion and In Vivo Multimodal Imaging

• Published in: ACS applied materials & interfaces Vol. 13; no. 25; pp. 29247 - 29256
• Main Authors: Kolokithas-Ntoukas, Argiris, Bakandritsos, Aristides, Belza, Jan, Kesa, Peter, Herynek, Vit, Pankrac, Jan, Angelopoulou, Athina, Malina, Ondrej, Avgoustakis, Konstantinos, Georgakilas, Vasilios, Polakova, Katerina, Zboril, Radek
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 30.06.2021
• Subjects: Biological and Medical Applications of Materials and Interfaces; condensed clusters; photothermal agents; multimodal imaging; iron oxides; noncovalent functionalization
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.1c00908

Magnetic iron oxide nanocrystals (MIONs) are established as potent theranostic nanoplatforms due to their biocompatibility and the multifunctionality of their spin-active atomic framework. Recent insights have also unveiled their attractive near-infrared photothermal properties, which are, however, limited by their low near-infrared absorbance, resulting in noncompetitive photothermal conversion efficiencies (PCEs). Herein, we report on the dramatically improved photothermal conversion of condensed clustered MIONs, reaching an ultrahigh PCE of 71% at 808 nm, surpassing the so‑far MION‑based photothermal agents and even benchmark near‑infrared photothermal nanomaterials. Moreover, their surface passivation is achieved through a simple self-assembly process, securing high colloidal stability and structural integrity in complex biological media. The bifunctional polymeric canopy simultaneously provided binding sites for anchoring additional cargo, such as a strong near-infrared-absorbing and fluorescent dye, enabling in vivo optical and photoacoustic imaging in deep tissues, while the iron oxide core ensures detection by magnetic resonance imaging. In vitro studies also highlighted a synergy-amplified photothermal effect that significantly reduces the viability of A549 cancer cells upon 808 nm laser irradiation. Integration of suchpreviously elusivephotophysical properties with simple and cost-effective nanoengineering through self-assembly represents a significant step toward sophisticated nanotheranostics, with great potential in the field of nanomedicine.