Castro Torres, Jorge L.

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    Development of handheld induction heaters for magnetic fluid hyperthermia applications and in-vitro evaluation on ovarian and prostate cancer cell lines
    (2022-12-15) Castro Torres, Jorge L.; Juan García, Eduardo J.; College of Engineering; Torres Lugo, Madeline; Domenech García, Maribella; León Colón, Leyda; Other; Tirado Corbalá, Rebecca
    Magnetic fluid hyperthermia (MFH) is a still experimental technique that has been found to have a potential application in the treatment of cancer. The goal of this method is to reach around 41-47°C in the tumor by exciting magnetic nanoparticles with an externally applied alternating magnetic field (AMF). As a result, various mechanisms of cell death are induced depending on therapeutic conditions. Applying these AMFs with high spatial resolution is still a challenge. Since the area of the body that is treated with current magnetic field generators is relatively large, their use is not suitable for patients having metallic implants anywhere near the treatment area. Thus, there will be a clinical need for smaller, more focused magnetic field applicators that can be used in patients having metallic implants that would otherwise be ineligible to receive MFH therapy. Therefore, a novel laparoscopic induction heater (LIH) and a transrectal induction heater (TRIH), both capable of applying high-frequency, high-intensity AMFs in hard-to-reach places within the human body were developed. Miniature multilayer “pancake” coils were wound using Litz wire and inserted into 3D printed enclosures, aimed at laparoscopic and transrectal applications for cancer. Ovarian cancer cell lines (SKOV-3, A2780) and prostate cancer cell lines (PC-3, LNCaP) were used to evaluate the instruments’ capabilities in killing cancer cells in vitro, using Synomagr-D nanoparticles as the heat mediator. Maximum magnetic field intensities reached by the LIH and TRIH were 42.6 kA/m at 326 kHz and 26.3 kA/m at 303 kHz, respectively. Temperatures reached in the samples were 41°C by the LIH and 43°C by the TRIH. Both instruments successfully accomplished killing cancer cells, with minimal effects on normal cells. This work presents what is believed to be the first line of portable medical devices having induction heaters for cancer treatment. These innovative instruments could potentially enable the development of new MFH modalities that will certainly facilitate the clinical translation of this thermal treatment.
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    Miniature magnetic field generators for magnetic fluid hyperthermia applications
    (2017-05) Castro Torres, Jorge L.; Juan García, Eduardo J.; College of Engineering; León Colón, Leyda; Torres Lugo, Madeline; Department of Electrical and Computer Engineering; Araya, Guillermo
    Magnetic fluid hyperthermia (MFH) is a non-invasive cancer treatment in which magnetic nanoparticles are administered to cancerous tissues. This raises the temperature of the affected region above a certain threshold (43-47°C), when exposed to an alternating magnetic field, inducing programmed cell death. Heating induction systems have been used in the medical field to induce hyperthermia by means of a ferrofluid but to this day, there is no evidence of a laparoscopic instrument capable of carrying out such task. Therefore, this work proposes the design and implementation of a laparoscopic instrument capable of generating a high-frequency magnetic field to use in laparoscopic procedures and a larger design to compare results. The device was constructed by winding a 21-turn Litz wire miniature magnetic field generator. This special wire minimizes skin and proximity phenomena present in conductors, at high frequencies. The coil was water cooled, inside a polycarbonate tube, removing the heat dissipated by resistive losses. Magnetic field profile of both coils was obtained experimentally and through simulations. Performance of the completed devices was assessed by conducting in vitro experiments involving SKOV-3 SC2 ovarian cancer cell lines and Polyethylene glycol coated nanoparticles at a concentration of 1.2 mg/mL. Cooling chamber experiments showed no significant reduction in cell viability in cells treated with nanoparticles and maximum magnetic field intensity of 21 kA/m at 291 kHz during 30 minutes of exposure. The laparoscopic instrument reduced cell viability down to 75% in cells treated with nanoparticles exposed to a maximum magnetic field of 13 kA/m at 286 kHz. Uncoated magnetic nanoparticles were exposed to the magnetic field of the laparoscopic instrument to investigate their heating performance. A laparoscopic instrument capable of generating a high-frequency magnetic field, high enough to actuate on cancer cells, but small enough to spare nearby healthy cells, was successfully designed. Results demonstrate that nanoparticles heat solely by magnetic induction, but further design improvements and experimentation are needed to determine its efficiency in the medical field. Notwithstanding, this design is suitable to treat deep-seated tumors during laparoscopic procedures, which are unreachable by other designs, and eliminating tumor remnants which conventional surgery cannot remove.