<xavier.kesse@sigma-clermont.fr>

Xavier Kesse received his BS degree in general chemistry from Felix Houphouët Boigny University in Ivory Coast (west of Africa). Between 2013 and 2016, he obtained a MS degree in inorganic chemistry from Claude Bernard University (Lyon, France). He is currently pursuing his PhD position at Clermont Auvergne University. His research addresses the design, the synthesis and the evaluation of multifunctional nanoparticles of bioactive glass for bone metastases destruction and bone tissue regeneration


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Elaboration of magnetic and bioactive core/shell nanoparticles for hyperthermia treatment and bone tissue regeneration
Xavier Kesse*, Charlotte Vichery, Jean-Marie Nedelec
Université Clermont Auvergne, CNRS, SIGMA Clermont, ICCF, Aubiere, F-63000 France

Most of patients suffering of cancer develop bone metastases because of the migration of primary tumors cells. A surgical extraction of the tumors cells is thus needed and if the bone loss is important, a reconstruction through autograft is made. This procedure involves a second chirurgical intervention which causes a longer recovery process and pain.

In order to remedy these shortcomings, researchers developed bioactive synthetic materials (synthetic hydroxyapatite, calcium phosphate ceramics, bioactive glasses …) which are known for their ability to bind to living bones. Among them, binary bioactive glass (SiO2-CaO) obtained through sol-gel method is a promising material for bone regeneration (1). In fact, when immerged in biological fluid, the glass dissolves and induces precipitation of hydroxyapatite (HA), a crystalline phase with a composition close to the one of mineral part of bone. At nanometer scale, inherent physico-chemical properties like high surface to volume ratio and large specific surface area make them very reactive and accelerate the bone mineralization process (2).

Super-paramagnetic iron oxide particles especially magnetite and maghemite gained great popularity due to their biocompatibility, high saturation magnetization and low toxicity. They are already used as contrast agent for imaging diagnostic and are very promising for other biomedical application as magnetic drug delivery and magnetic hyperthermia cancer treatment. More recently, it has been shown that they improve in vitro bioactivity of bioactive materials (3). Considering this special feature, we propose to design a new kind of heterostructured biomaterial, composed of bioactive glass and super-paramagnetic iron oxide nanoparticles to combine the benefits of bone regeneration and of destruction of cancerous cells through hyperthermia. Indeed, these particles could be implanted into the cavity originating from the tumor removal, and after the hyperthermia treatment (under alternative magnetic field) would destroy the last cancerous cells with no injury to the healthy tissues, the bioactive glass would then permit the regeneration of the bone in the cavity.

In this work, core/shell nanoparticles composed of maghemite (γ-Fe2O3) and bioactive glass (SiO2-CaO) were synthesized using a two stage procedure. The first stage includes the synthesis of the super-paramagnetic maghemite core by co-precipitation. And in the second stage, the core/shell structure is obtained by growing the bioactive glass shell using sol-gel process. The structure, morphology, composition and magnetic properties of γ-Fe2O3@SiO2-CaO were characterized. The first results shows that spherical multi-core/shell nanoparticles are obtained with a narrow size distribution (see figure 1 and 2). To study the impact of the magnetic core upon the bioactivity of the bioactive glass, the samples were immerged in Simulated Body Fluid for 28 days and characterized at pre-determined time points.

Figure1: TEM images of the core/shell nanoparticles at low magnification and higher magnification

Figure2: Histogram of size distribution of the core/shell nanoparticles

References:
1. Martínez, I. Izquierdo-Barba, M. Vallet-Regí, Chemistry of Materials 12 (2000), 3080-3088
2. Lei, C. Xiaofeng, H. Xue, Z. Jiaan, Journal of Materials Chemistry 22 (2012), 16906
3. Rajendra Kumar, A. Srinivasan, Ceramics International 36 (2010), 283-290