ABSTRACT Introduction: The global demographic panorama is changing. The population aged over 60 years is the fastest growing segment, as well as the one where bone tissue diseases are most common, increasing the demand of appropriate materials and technologies to restore those tissues. Objective: To analyze the information so far generated about the development of composite biomaterials for bone repair, with an emphasis on the identification of emerging technologies based on the use of the electromagnetic field, its applications and potential. Methods: An analysis was performed of scientific papers published in books, journals, patents and theses. Of the documentation selected, 80% was from the period 2010-2019. Data analysis and integration: The methods identified were classified into five groups: chemical electrodeposition, be it by in situ electrophoretic synthesis, electrolysis or electrophoresis; electroporation; electrospinning; distal magnetic control and electromagnetic biostimulation of cells and tissues, either directly or incorporating devices which convert electromagnetic energy into mechanical energy. Conclusions: These methods permit the conformation of composite cellular and acellular matrices as well as biostimulator devices controlling construction and action parameters in such a way that the processes obtained display greater reproducibility and are more in keeping with the specific requirements of each patient.

RESUMEN Introducción: El panorama demográfico en el mundo está cambiando. La población mayor de 60 años es el segmento que está creciendo más rápidamente y en el que las enfermedades del tejido óseo se presentan con más frecuencia, lo que aumenta la demanda de materiales y tecnologías apropiadas para restaurar estos tejidos. Objetivo: Analizar la información que se ha generado sobre el desarrollo de biomateriales compuestos para la reparación ósea, con énfasis en la identificación de las tecnologías emergentes basadas en el uso del campo electromagnético, sus aplicaciones y potencialidades. Métodos: Se consultaron trabajos científicos publicados en libros, revistas, patentes y tesis. El 80 % de la documentación seleccionada pertenece al periodo 2010-2019. Análisis e integración de la información: Los métodos identificados fueron clasificados en cinco grupos: electrodeposición química, ya sea por electrólisis, electroforesis o síntesis electroforética in situ; electroporación; electrohilado; control magnético distal y bioestimulación electromagnética de células y tejidos, directamente o por la introducción de dispositivos que convierten la energía electromagnética en energía mecánica. Conclusiones: Estos métodos permiten la conformación de matrices celulares y acelulares compuestas y, además, dispositivos bioestimuladores con control de los parámetros de construcción y acción, de tal manera, que se logran procesos con mayor grado de reproducibilidad y a la medida de los requerimientos específicos para cada paciente.

ABSTRACT The aim of this work was the synthesis and characterization of iron oxide magnetic nanoparticles coated with silica (Fe3O4@SiO2) intended for plasmid DNA isolation. Synthesis was carried out through co-precipitation method and coating was performed used the Stöber method. Materials were characterized by X-ray fluorescence, X-ray diffraction and Infrared spectroscopy. DNA purification was performed by comparing the ethanolic precipitation method, the QIAprep® commercial DNA purification kit and the synthesized Fe3O4@SiO2. Results showed that is possible to obtain Fe3O4@SiO2 (ranging size from 9 to 12 nm) through the proposed methodology. The amount of Si adsorbed onto the surface of magnetic particles and the crystal size of the Fe3O4@SiO2 were pH and washing-conditions dependent. The isolation assay showed that it is possible to recovery efficiently plasmid DNA using the Fe3O4@SiO2 obtain in normal conditions as solid support.

RESUMEN El trabajo propone la síntesis y caracterización de nanopartículas magnéticas de óxido de hierro recubiertas con silica (Fe3O4@SiO2) para el aislamiento de ADN plasmídico. La síntesis se realizó por co-precipitación y el recubrimiento por el método de Stöber. Los materiales fueron caracterizados por Fluorescencia de Rayos-X, Difracción de Rayos-X y Espectroscopía infrarroja. La purificación del ADN se realizó comparando los métodos de precipitación etanólica, el sistema comercial QIAprep® y las Fe3O4@SiO2 sintetizadas. Los resultados mostraron que es posible obtener Fe3O4@SiO2 con tamaños de cristalita en un rango de 9,9 a 11,7 nm por la metodología propuesta. La cantidad de Si adsorbida sobre la superficie de las nanopartículas y el tamaño de cristalita de las Fe3O4@SiO2, fueron dependientes del pH y de las condiciones de lavado. Se demostró que es posible recuperar eficientemente ADN plasmídico, utilizando como soporte sólido las Fe3O4@SiO2 obtenidas en condiciones normales.

Bioactivity, osteogenicity and mechanical properties of α-tricalcium phosphate (α-TCP) based phosphates cements can be improved by adding tricalcium silicate (C3S); however, the addition of C3S delays the precipitation and growth of calcium deficient hydroxyapatite (CDHA). Thus, the aim of this work was the study of in situ setting reaction of α-TCP/C3S composite bone cement under high energy X-ray generated by a synchrotron source within the first 72h. The results showed that the addition of C3S induces the precipitation of nanosized CDHA at early times depending on the added content. Calculated crystallite sizes showed that the higher the content of C3S, the smaller the crystal size at the beginning of the precipitation. These results are different from those obtained by conventional XRD method, suggesting that the proposed technique is a powerful tool in determining the composition and extent of reaction of CPCs surfaces in real time.

The addition of tricalcium silicate (C3S) to apatite cements results in an increase of bioactivity and improvement in the mechanical properties. However, adding large amounts raises the local pH at early stages, which retards the precipitation of hydroxyapatite and produces a loss of mechanical strength. The introduction of Pozzolanic materials in cement pastes could be an effective way to reduces basicity and enhance their mechanical resistance; thus, the effect of adding silica on the chemical, mechanical and biological properties of α-tricalcium phosphate/C3S cement was studied. Adding silica produces a reduction in the early pH and a decrease in setting times; nevertheless, the presence of more calcium silicate hydrate (C-S-H) delays the growth of hydroxyapatite crystals and consequently, reduces early compressive strength. The new formulations show a good bioactivity, but higher cytotoxicity than traditional cements and additions higher than 2.5% of SiO2 cause a lack of mechanical strength and an elevated degradability.

The effect of the method of sterilization on the physical, chemical and mechanical properties of a new bone repairing material was studied. The material was obtained by thermal hydrolysis of beta-tricalcium phosphate/orthophosphoric acid cement and was composed of calcium deficient hydroxyapatite, octacalcium phosphate (OCP), and beta-tricalcium phosphate. Partial decomposition of the OCP was observed after sterilization for the three methods. Decomposition increased to the following sequence of sterilization methods: ethylene oxide; autoclaving; dry oven. On the other hand, mechanical strength decreased with regard to non sterilized material in the sterilization sequence: ethylene oxide; dry oven; autoclaving. The compressive strength was 8.5 ± 1.0; 9.0 ± 1.2; 8.2 ± 0.8 and 6.5 ± 1.0 MPa, whereas diametral tensile strength was 2.1 ± 0.3; 2.5 ± 0.1; 1.9 ± 0.9 and 1.6 ± 0.3 for the material sterilized by ethylene oxide, dry oven, and autoclaving, respectively. Several compositional and microstuctural changes were detected after dry heat and autoclave sterilization. Ethylene oxide sterilization had lesser effect on the chemical composition and strength than dry heat and autoclaving.

A new hydrothermal route for preparing biphasic calcium phosphate monoliths is proposed. Firstly, a slurry of beta-tricalcium phosphate/ortho-phosphoric acid (<FONT FACE=Symbol>b</font>-TCP/H3PO4) is cast into the desired final shape and size to obtain a block composed of dicalcium phosphate dihydrate (DCPD) and <FONT FACE=Symbol>b</font>-TCP. This block is then treated in 1.0 M Na2HPO4 at 60 °C in order to hydrolyze the DCPD into Ca10-x(HPO4)x(PO4) 6-x(OH)2-x (CDHA) and Ca8H2(PO4)6 .5H2O (OCP). The result is a monolithic piece which preserves the initial shape and size, but which is composed instead of CDHA, OCP, and <FONT FACE=Symbol>b</font>-TCP. During the initial stage, when the pH is slightly alkaline, the product of DCPD hydrolysis is CDHA. However, when a neutral or slightly acidic pH is reached OCP is formed. Test samples processed by this method showed complete conversion of DCPD into CDHA and OCP after 112 h of hydrolysis, and with a compressive strength of 16.2 MPa, similar to cancellous bone.