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Development of optimal iron oxide nanoparticles with increased heating capabilities for application in magnetic fluid hyperthermia
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Abstract
Hipertermia de fluido magnético (MFH) a mostrado ser un método efectivo para la erradicación de células cancerosas. Esta técnica se basa en la absorción de nanopartÃculas magnéticas por parte de la célula seguido por la exposición a un campo de corriente alterna (AC), el cual, a través de interacciones magnéticas, causa que las partÃculas disipen energÃa calentando la célula a una temperatura lo suficientemente alta que resulta en muerte celular programada. Con el propósito de optimizar esta técnica para un futuro uso médico, es vital que las partÃculas respondan al campo magnético de manera que produzcan una gran energÃa para que sea un proceso efectivo y eficiente. La disipación óptima de calor en un medio fijo es lograda mediante la maximización del tiempo de relajación de Néel resultando en un incremento de energÃa del dipolo de rotación. Las nanopartÃtulas de óxido de hierro tienen el potencial de mejorar grandemente el proceso de MHF porque la magnetÃta es biocompatible a la vez que tiene la habilidad de ser modificada para responder al mecanismo de relajación de Néel. Los tiempos de relajación de Néel dependen de los diámetros magnéticos de las partÃculas y tienen un diámetro magnético ideal entre 14-19 nm, un tamaño caracterÃstico para alcanzar los diámetros más altos de transición de las regiones superparamagnéticas a ferromagnética. IONPs de este tamaño han sido sintetizados usando solventes de alto punto de ebullición en una reacción de descomposición termal monitoreada. SÃntesis exitosas han demostrado que IONPs con diámetro óptimo tienen el potencial de disipar diez veces la energÃa que IONPs con diámetro magnético menor que 10nm en campos comparable de AC. Con el propósito de proveer estabilidad coloidal a lo largo de una reducción en citotoxicidad, las partÃculas fueron funcionalizadas via el intercambio de ligando con aminopropyltriethoxysilane (APS) seguido por el enlace covalente de carboxymethyl dextran (CMDx). El diseño y funcionalización de estas partÃculas que puede disipar cantidades elevadas de energÃa ofrece mejoras a MFH mediante el incremento de la eficacia del calentamiento resultando en un número menor de partÃculas que necesitan ser eliminadas por el cuerpo.
Magnetic Fluid Hyperthermia has been proven to be an effective method for cancer cell eradication. This technique is based upon cellular uptake of magnetic nanoparticles followed by exposure to an AC field which, through magnetic interactions, causes the particles to dissipate energy heating the cell to a temperature high enough to result in programmed cell death. In order to optimize this technique for future medical use, it is vital that the particles respond to the magnetic field in a manner that produces the most energy so as to be an effective and efficient process. Optimal heat dissipation in a fixed medium is achieved by maximizing the Néel relaxation time, resulting in increased energy from dipole rotation. Iron oxide nanoparticles (IONPs) have the potential to improve the MFH process greatly because magnetite is biocompatible while having the ability to be modified to respond with Néel relaxation mechanism. Néel relaxation times are dependent upon magnetic diameters of the particles and there is an ideal magnetic diameter between 14-19nm, in the transition region from superparamagnetic to ferromagnetic. It was proposed that by adjusting reaction parameters, IONPs of larger diameter could be synthesized, and that these IONPs would dissipate more heat. IONPs of increased diameter have been synthesized using a high boiling point solvent in a monitored thermal decomposition reaction. Successful syntheses have demonstrated that optimal diameter IONPs have the potential to dissipate ten times the energy in comparable AC fields than IONPs with magnetic diameters less than 10nm. In order to provide colloidal stability along with decreasing cytotoxicity, the particles were functionalized via ligand exchange with aminopropyltriethoxysilane (APS) followed by the covalent attachment of carboxymethyl dextran (CMDx). Designing and functionalizing these targeted particles that can dissipate elevated amounts of energy offers improvements to MFH by increasing the heating efficiency resulting in less particles needed for disposal by the body.
Magnetic Fluid Hyperthermia has been proven to be an effective method for cancer cell eradication. This technique is based upon cellular uptake of magnetic nanoparticles followed by exposure to an AC field which, through magnetic interactions, causes the particles to dissipate energy heating the cell to a temperature high enough to result in programmed cell death. In order to optimize this technique for future medical use, it is vital that the particles respond to the magnetic field in a manner that produces the most energy so as to be an effective and efficient process. Optimal heat dissipation in a fixed medium is achieved by maximizing the Néel relaxation time, resulting in increased energy from dipole rotation. Iron oxide nanoparticles (IONPs) have the potential to improve the MFH process greatly because magnetite is biocompatible while having the ability to be modified to respond with Néel relaxation mechanism. Néel relaxation times are dependent upon magnetic diameters of the particles and there is an ideal magnetic diameter between 14-19nm, in the transition region from superparamagnetic to ferromagnetic. It was proposed that by adjusting reaction parameters, IONPs of larger diameter could be synthesized, and that these IONPs would dissipate more heat. IONPs of increased diameter have been synthesized using a high boiling point solvent in a monitored thermal decomposition reaction. Successful syntheses have demonstrated that optimal diameter IONPs have the potential to dissipate ten times the energy in comparable AC fields than IONPs with magnetic diameters less than 10nm. In order to provide colloidal stability along with decreasing cytotoxicity, the particles were functionalized via ligand exchange with aminopropyltriethoxysilane (APS) followed by the covalent attachment of carboxymethyl dextran (CMDx). Designing and functionalizing these targeted particles that can dissipate elevated amounts of energy offers improvements to MFH by increasing the heating efficiency resulting in less particles needed for disposal by the body.
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Date
2013
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Keywords
Magnetic fluid hyperthermia, Iron oxide nanoparticles