Damien Mertz

Thermoresponsive magnetic core/shell nanoparticles were developed for controlled drug delivery in cancer therapy. Polyhedral Zn₀.₄Fe₂.₆O₄@MnFe₂O₄ nanoparticles with two core sizes (22 and 50 nm) were synthesized and coated with a thermosensitive copolymer shell composed of 2-(2-methoxy)ethyl methacrylate and oligo(ethylene glycol) methacrylate units, P(MEO₂MA₆₀–OEGMA₄₀). The copolymer was grafted directly from the nanoparticle surface using aqueous ARGET-ATRP, providing a controlled and environmentally friendly functionalization strategy. Doxorubicin (DOX) was successfully encapsulated within the polymer shell and released upon heating above the lower critical solution temperature (LCST). Structural and compositional characterizations confirmed successful polymer grafting while preserving the crystalline integrity of the magnetic cores. Dynamic light scattering revealed a sharp thermoresponsive transition around 40–42 °C. Size-dependent magnetic and hyperthermia performances were observed, with larger nanoparticles exhibiting enhanced heating efficiency. Drug release studies in water and physiological medium (DMEM) demonstrated efficient temperature-dependent DOX release with distinct release profiles depending on nanoparticle size, attributed to differences in polymer grafting density and drug loading capacity. In vitro cytotoxicity assays on human ovarian cancer cells (SKOV-3) showed enhanced antitumoral activity of DOX-loaded nanoparticles compared with free DOX, while unloaded nanoparticles displayed low intrinsic toxicity. These results highlight thermoresponsive magnetic nanoparticles as a promising platform for temperature-responsive drug delivery and hyperthermia-assisted cancer therapy.

Superparamagnetic iron oxide nanoparticles (SPIONs) offer promising applications in nanomedicine due to their appealing properties. Their magnetic and magnetic hyperthermia properties are considered as relevant tools for low invasive cancer therapeutic applications. In this work, we report on the synthesis of polyhedral core–shell SPIONs. Their size was tuned to improve their magnetic properties. Furthermore, by hybridizing into a core–shell inorganic/inorganic structure, the nanoparticles can achieve significantly improved magnetic-to-thermal energy conversion efficiency (at least tenfold). The designed core NPs are composed of a Zn _0.4 Fe _2.6 O ₄ core and a MnFe ₂ O ₄ shell. Their size and morphology were determined by transmission electron microscopy, Fourier-transform infrared spectroscopy was used to investigate their chemical composition. The iron oxide phase was confirmed by Mössbauer analysis, and the magnetic properties were studied to select the ideal size for magnetic hyperthermia application.

Mesoporous silica-based nanoparticles (NPs) are promising tools for developing targeted therapeutic interventions in cancer.

Mesoporous silica-based nanoparticles (NPs) are promising tools for developing targeted therapeutic interventions in cancer. Endowed with a large pore silica shell suitable for drug encapsulation and with a responsive magnetic core, iron oxide stellate mesoporous silica (IO STMS) NPs stand out. Yet, their impact and potential toxicity on relevant in vivo models has not been carefully tested yet. Herein, we assessed the impact of these IO STMS nanocomposites in a syngeneic metastasis assay in zebrafish. NPs were surface-modified with human serum albumin (HSA) and loaded or not with the chemotherapeutic doxorubicin (DOX). In vitro, DOX-loaded NPs were expectedly more toxic to zebrafish melanoma (Zmel) cells than no-DOX NPs. In zebrafish embryos, the NPs were rapidly distributed through blood circulation and were found to colocalize over time with the vascular endothelium and local macrophages. Suprisingly, the NPs efficiently reduced the outgrowth of Zmel tumoral masses in an experimental metastasis assay in zebrafish embryos regardless of their loading with DOX. The anti-metastatic effect of these NPs was further improved by increasing the amount of HSA coating, also resulting in higher embryo survival. Altogether, IO STMS NPs showed promising cytotoxic effects on a relevant zebrafish metastasis model, inhibiting metastatic outgrowth in vivo independently of the drug loading. This opens the door to further testing for better exploiting their targeting and drug delivery potentialities.

Superparamagnetic iron oxide nanoparticles (SPIONPs) offer promising applications in nanomedicine due to their appealing properties. Their magnetic and magnetic hyperthermia properties are considered as relevant tools for low invasive cancer therapeutic applications. In this work, we report on the synthesis of polyhedral core/shell SPIONPs. Their size was tuned to improve their magnetic properties. Furthermore, by hybridizing into a core/shell inorganic/inorganic structure, the nanoparticles can achieve significantly improved magnetic-to-thermal energy conversion efficiency (at least of 10 fold). The designed core NPs will then be composed of a core composed of Zn _0.4 Fe _2.6 O ₄ and a shell of MnFe ₂ O ₄ . Their size and morphology were determined by transmission electron microscopy (TEM), Fourier transform infra- red (FTIR) was used to investigate their chemical composition. The iron oxide phase was confirmed by Mössbauer analysis, and their magnetic properties were studied to select the ideal size for magnetic hyperthermia application.

Tuning the synthesis of iron oxide nanoparticles (IONPs) to modulate structural and vacancy defects has shown that IONPs with fewer defects are more suitable for combining MH and PTT with high efficiency.

The controlled growth of stellate silica shells around iron oxide nanoparticles allows the design of novel efficient theranostics for MRI, magnetic hyperthermia and photothermia.

In the biomaterials field, one major issue with hydrogels (HGs) loaded with active therapeutics is the spontaneous leaking of the cargo occurring rapidly, usually over several hours. However, biological processes involved in regenerative medicine would require to have a sustained drug delivery lasting over weeks/months or be triggered only when a specific biochemical stimulus (enzymatic, cellular, or antimicrobial) is applied. In this work, this challenge is addressed by demonstrating that the spontaneous protein release from an agarose HG (used as model HG) can be partially or totally blocked by the incorporation of stellate mesoporous silica (STMS) nanoparticles (NPs, ≈150 ± 28 nm size, 15 nm pore) within the HG. It is shown here that the porous silica NPs act as sub‐micrometer size reservoirs ensuring precise level retention simply by playing on the amount of STMS embedded in the HG. Further, this effect is shown for various proteins demonstrating the versatility of this concept.

Regulation of the sodium cations level in the case of renal failure diseases is a very challenging task for clinicians, and new pollutant extractors based on nanomaterials are emerging as potential treatments. In this work, we report different strategies for the chemical functionalization of biocompatible large pore mesoporous silica, denoted stellate mesoporous silica (STMS), with chelating ligands able to selectively capture sodium. We address efficient methods to covalently graft highly chelating macrocycles onto STMS NPs such as crown ethers (CE) and cryptands (C221) through complementary carbodiimidation reactions. Regarding sodium capture in water, C221 cryptand-grafted STMS showed better capture efficiency than CE-STMS due to higher sodium atom chelation in the cryptand cage (Na⁺ coverage of 15.5% vs. 3.7%). The sodium selectivity was hence tested with C221 cryptand-grafted STMS in a multi-element aqueous solution (metallic cations with the same concentration) and in a solution mimicking peritoneal dialysis solution. Results obtained indicate that C221 cryptand-grafted STMS are relevant nanomaterials to extract sodium cations in such media and allow us to regulate their levels.