Enhancing degradability, bioactivity, and osteocompatibility of poly (propylene fumarate) bone filler by incorporation of Mg-Ca-P nanoparticles.

As an alternative for polymethyl methacrylate, poly(propylene fumarate) (PPF) has been considered as injectable and biodegradable bone cement; however, its mechanical and biological properties need more attention. Hence, the current study aimed to develop the properties by compositing PPF with magnesium calcium phosphate (MCP) nano-powders. In this regard, the pure PPF was compared with PPF/MCP by evaluating their composition, mechanical properties, hydrophilicity, and biodegradability. Furthermore, their bioactivity in the simulated body fluid (SBF) and, via applying MG-63 cells, their cell interaction, including proliferation, adhesion, differentiation, and mineralization, were assessed. The addition of MCP improved compressive strength and elastic modulus of PPF, e.g., 10 wt% MCP increased them to 32.7 and 403 MPa, respectively. Also, hydrophilicity and biodegradation of PPF were enhanced in the presence of MCP; so that the highest hydrophilicity, 42% higher than PPF, was achieved at the presence of 20 wt% MCP. In this condition, after 21-day immersion in SBF, the surface of the sample was covered with a dense and continuous layer of hydroxyapatite. The composite proliferation, adhesion, differentiation, and mineralization of MG-63 cells improved in comparison to the pure PPF. Hence, controllable strength and biodegradation of the composite, along with its proved bioactivity and osteoconductivity, make PPF/MCP as a candidate for bone therapeutic application.

Poly(propylene fumarate)/magnesium calcium phosphate injectable bone composite: Effect of filler size and its weight fraction on mechanical properties.

This study aimed to produce a composite of poly(propylene fumarate)/magnesium calcium phosphate as a substitutional implant in the treatment of trabecular bone defects. So, the effect of magnesium calcium phosphate particle size, magnesium calcium phosphate:poly(propylene fumarate) weight ratio on compressive strength, Young's modulus, and toughness was assessed by considering effective fracture mechanisms. Micro-sized (∼30 µm) and nano-sized (∼50 nm) magnesium calcium phosphate particles were synthesized via emulsion precipitation and planetary milling methods, respectively, and added to poly(propylene fumarate) up to 20 wt.%. Compressive strength, Young's modulus, and toughness of the composites were measured by compressive test, and effective fracture mechanisms were evaluated by imaging fracture surface. In both micro- and nano-composites, the highest compressive strength was obtained by adding 10 wt.% magnesium calcium phosphate particles, and the enhancement in nano-composite was superior to micro-one. The micrographs of fracture surface revealed different mechanisms such as crack pinning, void plastic growth, and particle cleavage. According to the results, the produced composite can be considered as a candidate for substituting hard tissue.

Evaluation of setting time and compressive strength of a new bone cement precursor powder containing Mg-Na-Ca.

Taking the advantage of a novel magnesium phosphate precursor containing Na and Ca, the cementation rate of the cement, including only Mg/Mg-Na-Ca, was studied. Besides, two effective parameters, that is, calcination temperature, 650 °C and 800 °C, and powder-to-cement liquid ratio, 1 and 1.5 g/mL, were assessed. X-ray diffraction, scanning electron microscopy, ion chromatography, particle size analyser, Vicat needle and compression test were used to characterize the powders and obtained cements. The sample containing Mg-Na-Ca, calcined at 800 °C with powder-to-cement liquid ratio of 1.5, obtained the highest compressive strength, 20 MPa, but set fast. To control the kinetics of cementation, the powder containing Mg-Na-Ca calcined at 950 °C with powder-to-cement liquid ratio of 1.5 and 2 g/mL was assessed and the one with 2 g/mL set in 9 min possessing 22 MPa compressive strength was selected as optimal condition to be used as a candidate, injectable bone cement.