The Use of Silica Microparticles to Improve the Efficiency of Optical Hyperthermia (OH)

Although optical hyperthermia could be a promising anticancer therapy, the need for high concentrations of light-absorbing metal nanoparticles and high-intensity lasers, or large exposure times, could discourage its use due to the toxicity that they could imply. In this article, we explore a possible role of silica microparticles that have high biocompatibility and that scatter light, when used in combination with conventional nanoparticles, to reduce those high concentrations of particles and/or those intense laser beams, in order to improve the biocompatibility of the overall procedure. Our underlying hypothesis is that the scattering of light caused by the microparticles would increase the optical density of the irradiated volume due to the production of multiple reflections of the incident light: the nanoparticles present in the same volume would absorb more energy from the laser than without the presence of silica particles, resulting either in higher heat production or in the need for less laser power or absorbing particles for the same required temperature rise. Testing this new optical hyperthermia procedure, based on the use of a mixture of silica and metallic particles, we have measured cell mortality in vitro experiments with murine glioma (CT-2A) and mouse osteoblastic (MC3T3-E1) cell lines. We have used gold nanorods (GNRs) that absorb light with a wavelength of 808 nm, which are conventional in optical hyperthermia, and silica microparticles spheres (hereinafter referred to as SMSs) with a diameter size to scatter the light of this wavelength. The obtained results confirm our initial hypothesis, because a high mortality rate is achieved with reduced concentrations of GNR. We found a difference in mortality between CT2A cancer cells and cells considered non-cancer MC3T3, maintaining the same conditions, which gives indications that this technique possibly improves the efficiency in the cell survival. This might be related with differences in the proliferation rate. Since the experiments were carried out in the 2D dimensions of the Petri dishes, due to sedimentation of the silica particles at the bottom, whilst light scattering is a 3D phenomenon, a large amount of the energy provided by the laser escapes outside the medium. Therefore, better results might be expected when applying this methodology in tissues, which are 3D structures, where the multiple reflections of light we believe will produce higher optical density in comparison to the conventional case of no using scattering particles. Accordingly, further studies deserve to be carried out in this line of work in order to improve the optical hyperthermia technique.This study was partially supported by CIBER-BBN (Spain) and the NEUROCENTRO-CM (B2017/BMD-3760) Consortium. Characterization of the MNPs was performed by the ICTS ‘NANBIOSIS’, Unit 15, Functional Characterization of Magnetic Nanoparticles of the CIBER in Bioengineering, Biomaterials & Nanomedicine (CIBER-BBN) at the Center for Biomedical Technology (CTB) of the ‘Universidad Politécnica de Madrid’ (UPM). This work was carried out as a part of Project PGC2018-097531-B-I00, funded by the Ministry of Science of Spain

Influence of Medium Viscosity and Intracellular Environment on the Magnetization of Superparamagnetic Nanoparticles in Silk Fibroin Solutions and 3T3 Mouse Fibroblast Cell Cultures

IOP also requests that you include the following statement of provenance: "This is an author-created, un-copyedited versíon of an article published in Nanotechnology. IOP Publishing Ltd is not responsíble for any errors or omissíons in this versíon of the manuscript or any versíon derived from it. The Versíon of Record is available online at https://doi.org/10.1088/1361-6528/aacf4a.[EN] Biomedical applications based on the magnetic properties of superparamagnetic iron oxide nanoparticles (SPIONs) may be altered by the mechanical attachment or cellular uptake of these nanoparticles. When nanoparticles interact with living cells, they are captured and internalized into intracellular compartments. Consequently, the magnetic behavior of the nanoparticles is modified. In this paper, we investigated the change in the magnetic response of 14 nm magnetic nanoparticles (Fe3O4) in different solutions, both as a stable liquid suspension (one of them mimicking the cellular cytoplasm) and when associated with cells. The field-dependent magnetization curves from inert fluids and cell cultures were determined by using an alternating gradient magnetometer, MicroMagTM 2900. The equipment was adapted to measure liquid samples because it was originally designed only for solids. In order to achieve this goal, custom sample holders were manufactured. Likewise, the nuclear magnetic relaxation dispersion profiles for the inert fluid were also measured by fast field cycling nuclear magnetic relaxation relaxometry. The results show that SPION magnetization in inert fluids was affected by the carrier liquid viscosity and the concentration. In cell cultures, the mechanical attachment or confinement of the SPIONs inside the cells accounted for the change in the dynamic magnetic behavior of the nanoparticles. Nevertheless, the magnetization value in the cell cultures was slightly lower than that of the fluid simulating the viscosity of cytoplasm, suggesting that magnetization loss was not only due to medium viscosity but also to a reduction in the mechanical degrees of freedom of SPIONs rotation and translation inside cells. The findings presented here provide information on the loss of magnetic properties when nanoparticles are suspended in viscous fluids or internalized in cells. This information could be exploited to improve biomedical applications based on magnetic properties such as magnetic hyperthermia, contrast agents and drug delivery.The authors are thankful to their supporters: a grant from Universidad Politecnica de Madrid to Ana Lorena Urbano-Bojorge and a grant from Universidad Nacional Experimental del Tachira (UNET)- Venezuela to Oscar Casanova-Carvajal. This study was also financially supported in part by CIBER-BBN (Spain) and Madr.ib-CM (Spain).Urbano-Bojorge, AL.; Casanova-Carvajal, O.; González, N.; Fernández, L.; Madurga, R.; Sánchez-Cabezas, S.; Aznar, E.... (2018). Influence of Medium Viscosity and Intracellular Environment on the Magnetization of Superparamagnetic Nanoparticles in Silk Fibroin Solutions and 3T3 Mouse Fibroblast Cell Cultures. Nanotechnology. 29(38):1-13. https://doi.org/10.1088/1361-6528/aacf4aS113293

Influence of Medium Viscosity and Intracellular Environment on the Magnetization of Superparamagnetic Nanoparticles in Silk Fibroin Solutions and 3T3 Mouse Fibroblast Cell Cultures

IOP also requests that you include the following statement of provenance: "This is an author-created, un-copyedited versíon of an article published in Nanotechnology. IOP Publishing Ltd is not responsíble for any errors or omissíons in this versíon of the manuscript or any versíon derived from it. The Versíon of Record is available online at https://doi.org/10.1088/1361-6528/aacf4a.[EN] Biomedical applications based on the magnetic properties of superparamagnetic iron oxide nanoparticles (SPIONs) may be altered by the mechanical attachment or cellular uptake of these nanoparticles. When nanoparticles interact with living cells, they are captured and internalized into intracellular compartments. Consequently, the magnetic behavior of the nanoparticles is modified. In this paper, we investigated the change in the magnetic response of 14 nm magnetic nanoparticles (Fe3O4) in different solutions, both as a stable liquid suspension (one of them mimicking the cellular cytoplasm) and when associated with cells. The field-dependent magnetization curves from inert fluids and cell cultures were determined by using an alternating gradient magnetometer, MicroMagTM 2900. The equipment was adapted to measure liquid samples because it was originally designed only for solids. In order to achieve this goal, custom sample holders were manufactured. Likewise, the nuclear magnetic relaxation dispersion profiles for the inert fluid were also measured by fast field cycling nuclear magnetic relaxation relaxometry. The results show that SPION magnetization in inert fluids was affected by the carrier liquid viscosity and the concentration. In cell cultures, the mechanical attachment or confinement of the SPIONs inside the cells accounted for the change in the dynamic magnetic behavior of the nanoparticles. Nevertheless, the magnetization value in the cell cultures was slightly lower than that of the fluid simulating the viscosity of cytoplasm, suggesting that magnetization loss was not only due to medium viscosity but also to a reduction in the mechanical degrees of freedom of SPIONs rotation and translation inside cells. The findings presented here provide information on the loss of magnetic properties when nanoparticles are suspended in viscous fluids or internalized in cells. This information could be exploited to improve biomedical applications based on magnetic properties such as magnetic hyperthermia, contrast agents and drug delivery.The authors are thankful to their supporters: a grant from Universidad Politecnica de Madrid to Ana Lorena Urbano-Bojorge and a grant from Universidad Nacional Experimental del Tachira (UNET)- Venezuela to Oscar Casanova-Carvajal. This study was also financially supported in part by CIBER-BBN (Spain) and Madr.ib-CM (Spain).Urbano-Bojorge, AL.; Casanova-Carvajal, O.; González, N.; Fernández, L.; Madurga, R.; Sánchez-Cabezas, S.; Aznar, E.... (2018). Influence of Medium Viscosity and Intracellular Environment on the Magnetization of Superparamagnetic Nanoparticles in Silk Fibroin Solutions and 3T3 Mouse Fibroblast Cell Cultures. Nanotechnology. 29(38):1-13. https://doi.org/10.1088/1361-6528/aacf4aS113293

Contribución a las tecnologías hipertérmicas mediadas por nanopartículas para terapias anticancerígenas

Tras la fusión de la nanotecnología con la medicina y la bioingeniería, se crearon campos de investigación en nanomedicina y nanobioingeniería, lo que amplió la perspectiva de las investigaciones médicas y las nuevas fronteras emergentes. Estas investigaciones han permitido nuevos métodos de abordaje para encontrar soluciones a problemas biológicos humanos de larga data y el desarrollo y administración de diagnósticos terapéuticos o farmacológicos. Para lograrlo, se han desarrollado nanopartículas, que son agentes miniaturizados, los cuales han dado paso a la nanomedicina. Por un lado, las nanopartículas de oro utilizadas en este estudio son nanorods (GNR) recubiertas con proteína G, un receptor común para anclar anticuerpos mecánicamente. El tipo de nanorod utilizado permitió elegir estas nanopartículas de oro, bastante comunes en aplicaciones biomédicas. En la realización de la investigación desarrollada juega un papel de la mayor importancia la hipertermia, la cual se refiere a la aplicación de calor para destruir células malignas por inducción de apoptosis a través de la desnaturalización de proteínas y la ruptura de membranas celulares, con la aplicación de las nanoparticulas de oro se generó hipertermia óptica para mejorar la terapia in-vitro, así como también se realizaron avances considerables in-vivo en modelos animales. En la hipertermia magnética, la conversión de energía electromagnética en calor generado por SPIONs sometidas a campos magnéticos alternos (HAC) se puede utilizar para causar la muerte de células tumorales. Estudios recientes han demostrado que la respuesta magnética, y por lo tanto la eficiencia de calentamiento de SPIONs, se reduce significativamente cuando estas nanopartículas se colocan en líquidos portadores viscosos y dentro de células vivas o tejidos biológicos. La mayor viscosidad del entorno biológico y la distribución espacial o la aglomeración de nanopartículas dentro de los orgánulos intracelulares influyen fuertemente en la eficacia de SPIONs para aumentar la temperatura del medio circundante. Estos factores que surgen de la interacción nanobio hacen que la eficiencia del calentamiento en aplicaciones in-vivo sea menos eficiente y previsible que en los ferrofluídos ideales. Se realizaron avances considerables en ambas técnicas, en hipertermia óptica se investigó hasta obtener mejoras en la introducción de material dispersantes y biocompatible de luz como el silice. Los resultados sugieren una mejora considerable en todas las variables involucradas en el sistema como: potencia irradiada, tiempo de exposición al laser, concentración de nanoparticulas de oro (nanorods) y mantenimiento de la tasa de mortalidad en células cancerígenas (CT2A) frente a líneas celulares consideradas sanas (MC3T3). En el caso de la hipertermia magnética se diseñó y construyó un sistema electrónico que permite generar formas de onda excitadoras distintas a las convencionales (sinusoidales), se realizaron ensayos de tolerancia a las nanopartículas que son empleadas en dicho sistema, así como se demostró el fenómeno físico existente cuando las SPIONs son fagocitadas por las células, aplicando un emulador del interior intracelular y utilizando materiales biocompatibles como la fíbroina de seda de gusano. ----------ABSTRACT---------- After the fusion of nanotechnology with medicine and bioengineering, fields of research in nanomedicine and nanobioengineering were created, which broadened the perspective of medical research and emerging new frontiers. These investigations have allowed new methods of approach to find solutions to long-standing human biological problems and the development and administration of therapeutic or pharmacological diagnoses. To achieve this, nanoparticles have been developed, which are miniaturized agents, which have given way to nanomedicine. The gold nanoparticles used in this study are nanorods (GNR) coated with G protein, a common receptor for mechanically anchoring antibodies. In this research hyperthermia plays a role of greatest importance which refers to the application of heat to destroy malignant cells by induction of apoptosis through the denaturation of proteins and the rupture of cell membranes. The application of gold nanoparticles generated by optical hyperthermia improve in-vitro therapy, and considerable advances were made in-vivo for animal models. In magnetic hyperthermia, the conversion of electromagnetic energy into heat generated by SPIONs subjected to alternating magnetic fields (HAC) can be used to cause the death of tumor cells. Recent studies have shown that the magnetic response, and therefore the heating efficiency of SPIONs, are significantly reduced when these nanoparticles are placed in viscous carrier liquids and within living cells or biological tissues. The higher viscosity of the biological environment and the spatial distribution or agglomeration of nanoparticles within the intracellular organelles strongly influence the efficacy of SPIONs to increase the temperature of the surrounding medium. These factors that arise from the nanobio interaction make the heating efficiency in in-vivo applications less efficient and predictable than in ideal ferrofluids. Considerable advances were made in both techniques, in optical hyperthermia it was included until obtaining improvements in the introduction of dispersant material and biocompatible light such as Silice. The results suggested a considerable improvement in all the variables involved in the system such as irradiated power, time of exposure to the laser, concentration of gold nanoparticles (nanorods) and maintaining the mortality rate in cancer cells (CT2A) against cell lines considered healthy (MC3T3). In the case of magnetic hyperthermia, an electronic system was designed and built to generate excitatory waveforms different from conventional ones (sinusoidal), tolerance tests were carried out on the nanoparticles that will be used in the system. Also, it was demonstrated the existing physical phenomenon when the SPIONs are phagocytized by the cells, applying an intracellular interior emulator using biocompatible materials such as worm silk fibroine

Slowdown intracranial glioma progression by optical hyperthermia therapy: study on a CT-2A mouse astrocytoma model

Metallic nanorods are promising agents for a wide range of biomedical applications. We report an optical hyperthermia method capable of inducing slowdown tumor progression of an experimental in vivo CT-2A glioblastoma tumor. The tumor model used in this research is based on the transplantation of mouse astrocytoma CT-2A cells in the striatum of mice by intracranial stereotaxic surgery. Two weeks after cell implant, the resulting tumor is treated by irradiating intratumoral injected gold nanorods, biofunctionalized with CD133 antibody (B-GNRs), using a continuous wave laser. Nanoparticles convert the absorbed light into localized heat (reaching up to 44 °C) due to the effect of surface plasmon resonance. A significant slowdown in CT-2A tumor progression is evident, by histology and magnetic resonance imaging, at one (p = 0.03) and two weeks (p = 0.008) after irradiation treatment. A notable deceleration in tumor size (15%–75%) as compared to the control untreated groups, it is observed. Thus, laser irradiation of B-GNRs is found to be effective for the treatment of CT-2A tumor progression. Similarities between the pre-clinical CT-2A tumor model and the human astrocytoma disease, in terms of anatomy, metastatic behavior and histopathology, suggest that hyperthermic treatment by laser irradiation of B-GNRs administered into high-grade human astrocytoma might constitute a promising alternative treatment to limit the progression of this deadly disease