DEVELOPMENT OF MAGNETIC BONE CEMENT BASED ON CALCIUM PHOSPHATE AND IRON OXIDE NANOPARTICLES.

CALDERON BEDOYA, P.A.; ALVAREZ, MARÍA V.; FANOVICH, MARÍA A.; BOTTA, PABLO M.

Mar del Plata

Congreso; XII Latin American Congress of Artificial Organs and Biomaterials; 2023

INTEMA

Introduction and objective: The purpose of this work was to contribute to the physical chemistry of innovative magnetic bone cements based on calcium phosphates (CPC) and magnetic iron oxide nanoparticles (IONPs). The focus of study was the synthesis of magnetic nanoparticles and their functionalization for protection and simultaneously for the retention of a model drug, facilitating its long-term effectiveness. Finally, it was intended to establish the changes that may occur in the physicochemical properties, and especially in the setting reaction of the CPC by the presence of IONPs with and without functionalization.Methodology: IONPs were synthesized by the method developed by Tsuzuki et al. [1] obtaining a product composed of magnetite/maghemite phases. This was achieved by mechanochemically processing of a mixture of FeCl3.6H2O, Fe° and NaOH during 12 h, and ulterior washing to remove saline by-products. The functionalization of synthesized IONPs with a silane (Glymo) and usnic acid (AU) was made at 300-400 bar and 40-60°C in a supercritical CO2 equipment. Mixtures of calcium phosphates (TTCP + DCPA) containing naked and functionalized IONPs with good setting properties were developed. The influence of IONPs content in mixtures of tetracalcium phosphate (TTCP) and anhydrous calcium acid phosphate (DCPA) was studied. Characterization was carried out by X-ray diffraction (XRD), FTIR spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and in vitro antibacterial assays. Results and discussion: The synthesis led to obtain particle agglomerates of ≈300 nm, formed by nanoparticles with a mean size of ≈9 nm and high saturation magnetization and low coercivity. The IONPs functionalized with Glymo/AU showed chemical and magnetic stability after the 30 days of incubation in simulated biological fluid (SBF) at 37°C. Functionalized IONPs exhibited a marked antibacterial activity against the strains L. innocua and P. aeruginosa. The setting reaction of the CPCs yielded hydroxyapatite (HA) crystals, process favoured by addition of 10 or 20 % IONPs (hardening times were not significantly retarded by IONPs). Promising compositions were formulated with 10% of IONPs and 94 mg AU/g sample. These magnetic CPCs showed high conversion to HA, improved mechanical properties, hyperthermia capacity and bactericidal activity against L. innocua.Conclusions: New cement formulations based on calcium phosphates and functionalized IONPs were developed. Functional properties showed the effectiveness of these multicomponent systems as theranostic materials.References1. T. Tsuzuki, «Mechanochemical synthesis of metal oxide nanoparticles», Communications Chemistry, vol. 4, p. 143, 2021.AcknowledgmentsThe authors gratefully acknowledge CONICET and Universidad Nacional de Mar del Plata for the financial support given to this work.