Cellular senescence may contribute to aging and age-related diseases and senolytic drugs that selectively kill senescent cells may delay aging and promote healthspan. More recently, several categories of senolytics have been established, namely HSP90 inhibitors, Bcl-2 family inhibitors and natural compounds such as quercetin and fisetin. However, senolytic and senostatic potential of nanoparticles and surface-modified nanoparticles has never been addressed. In the present study, quercetin surface functionalized Fe₃O₄ nanoparticles (MNPQ) were synthesized and their senolytic and senostatic activity was evaluated during oxidative stress-induced senescence in human fibroblasts in vitro. MNPQ promoted AMPK activity that was accompanied by non-apoptotic cell death and decreased number of stress-induced senescent cells (senolytic action) and the suppression of senescence-associated proinflammatory response (decreased levels of secreted IL-8 and IFN-β, senostatic action). In summary, we have shown for the first time that MNPQ may be considered as promising candidates for senolytic- and senostatic-based anti-aging therapies.

Magnetic nanoparticles Fe₃O₄ doped by different amounts of Y³⁺ (0, 0.1, 1, 10 %) ions were designed to obtain maximum heating efficiency in magnetic hyperthermia for cancer treatment. Single phase formation was evident by XRD measurements. Improved magnetization value was obtained for the Fe₃O₄ sample with 1% of Y³⁺ doping. The specific absorption rate (SAR) and intrinsic loss of power (ILP) values for prepared colloids was obtained in water. The best results was estimated for Fe₃O₄ with 0.1% of Y³⁺ ions (SAR=194 W/g and ILP=1.85 nHm²/kg for magnetic field of 16kA/m with the frequency 413 kHz). The excellent biocompatibility with low cell cytotoxicity of Fe₃O₄:Y nanoparticles was observed. Immediately after magnetic hyperthermia treatment with Fe₃O₄:0.1%Y, the 4T1 cells viability decrease was observed (77% for 35 μg/ml, 68 % for 100 μg/ml). These results suggest that Fe₃O₄ doped by Y³⁺ ions nanoparticles are suitable for biomedical applications, especially for the hyperthermia treatment.

The rapid hot-injection (HI) technique was employed to synthesize magnetic nanoparticles with well-defined morphology (octahedrons, cubes, and star-like). It was shown that the proposed synthetic approach could be an alternative for the heat-up and flow hot-injection routes. Instant injection of the precursor to the hot reaction mixture (solvent(s) and additives) at high temperatures promotes fast nucleation and particle directional growth towards specific morphologies. We state that the use of saturated hydrocarbon namely hexadecane (sHD) as a new co-solvent affects the activity coefficient of monomers, forces shape-controllable growth, and allows downsizing of particles. We have shown that the rapid hot-injection route can be extended for other ferrites as well (ZnFe₂O₄, CoFe₂O₄, NiFe₂O_4, and MnFe₂O₄) which has not been done previously through the HI process before.

Fe ₃ O ₄ @APTES–Ag is a potential multipurpose platform for biological applications such as photomagnetic therapies, analytic probes exploiting the SERS effect and antibacterial activity.