Superparamagnetic and Bioactive Nanoparticles for Bone Cancer Treatment

Abstract

Most patients who develop primary bone tumors require surgical intervention. In this respect, the design of a multifunctional material, used as bone substitute, is of high clinical interest to simultaneously treat cancer and promote bone regeneration.Bioactive glass (BG) nanoparticles are a promising material for bone tissue regeneration because when implanted, a hydroxyapatite layer is quickly formed onto their surface, bonding them to natural bone tissue [1,2]. By coupling the high bioactivity of large specific surface area bioactive glass particles with the heating ability of superparamagnetic iron oxide nanoparticles (SPIONs) under an alternating magnetic field [3], a multifunctional material could be designed and used to selectively destroy remaining or resurging cancer cells through hyperthermia treatment before promoting bone regeneration.In this scope, heterostructures consisting of SPIONs encapsulated in BG have been synthesized by sol-gel synthesis and characterized. The γ-Fe2O3@SiO2-CaO core-shell nanoparticles show promising hyperthermia and bioactivity properties, with a specific loss power (SLP) of 159 W/gFe and hydroxyapatite growth within 3 days [4].At a concentration of 1 mgFe/mL, a temperature rise of 4 °C was achieved within 3 minutes, which could be suitable for cancer treatment. However, the heating power of these core-shell nanoparticles can still be improved, for example by increasing the SPIONs size. Indeed, the presence of a non-negligible amount of SPIONs with a diameter under 10 nm due to size dispersion is not optimal for hyperthermia [3]. Moreover, as evidenced in Figure 2, this sample present magnetic cores clustering, that is known to induce a decrease of the SLP value due to magnetic dipolar interactions [5]. Single-core NPs with a larger core size would thus be a better candidate for more efficient heating.In that respect, the core-shell particle structure has been modified in order to study the impact of core size and clustering on the hyperthermia properties. Using larger SPIONs led to an increase in SLP and an increasing percentage of single-core heterostructures. Magnetic core aggregation was also controlled by varying SPIONs concentration. The BG shell thickness was also modified, by varying the ratio between the magnetic cores and the silica precursor, because it could affect the heat dissipation of the magnetic particles in fluids [6]. **