Boosted Hyperthermia Therapy by Combined AC Magnetic and Photothermal Exposures in Ag/Fe₃O₄ Nanoflowers

Abstract

Over the past two decades, magnetic hyperthermia and photothermal therapy are becoming very promising supplementary techniques to well-established cancer treatments such as radiotherapy and chemotherapy. These techniques have dramatically improved their ability to perform controlled treatments, relying on the procedure of delivering nanoscale objects into targeted tumor tissues, which can release therapeutic killing doses of heat either upon AC magnetic field exposure or laser irradiation. Although an intense research effort has been made in recent years to study, separately, magnetic hyperthermia using iron oxide nanoparticles and photothermal therapy based on gold or silver plasmonic nanostructures, the full potential of combining both techniques has not yet been systematically explored. Here we present a proof-of-principle experiment showing that designing multifunctional silver/magnetite (Ag/Fe3O4) nanoflowers acting as dual hyperthermia agents is an efficient route for enhancing their heating ability or specific absorption rate (SAR). Interestingly, the SAR of the nanoflowers is increased by at least 1 order of magnitude under the application of both an external magnetic field of 200 Oe and simultaneous laser irradiation. Furthermore, our results show that the synergistic exploitation of the magnetic and photothermal properties of the nanoflowers reduces the magnetic field and laser intensities that would be required in the case that both external stimuli were applied separately. This constitutes a key step toward optimizing the hyperthermia therapy through a combined multifunctional magnetic and photothermal treatment and improving our understanding of the therapeutic process to specific applications that will entail coordinated efforts in physics, engineering, biology, and medicine.

Thermal-Induced Stress of Plasmonic Magnetic Nanocomposites

“…Consequently, the second band can be interpreted as geometric effects and the interfacial interaction plays minor role in the absorption spectrum. To have the best agreement between our theoretical calculations and previous experiment, 5) an adjustable parameter f is altered to achieve the second peak at 620 nm (close to 615 nm in Ref. 5) ) and the 620 nm absorbance higher than the 400 nm resonance by a factor of 1.5.…”

“…To have the best agreement between our theoretical calculations and previous experiment, 5) an adjustable parameter f is altered to achieve the second peak at 620 nm (close to 615 nm in Ref. 5) ) and the 620 nm absorbance higher than the 400 nm resonance by a factor of 1.5. Based on these criteria, magnetite is found to cover 40 % volume of the shell ( f ≈ 0.4).…”

“…[1][2][3][4][5][6][7] The development of nanoscience allows the synthesis of a variety of hybrid systems with desired sizes and structures enabling the designing and creation of multifunctional and complex systems. Magnetite nanoparticles possess novel characteristics such as strong sensitivity to magnetic fields, 5) high biocompatibility and relatively low toxicity in human body, along with capability of removing heavy metal ions. 8) While the localized surface plasmon resonances of silver nanoparticles greatly enhance electric field around the nanostructures and induce other fascinating features in visible range.…”

“…Silver nanoparticles are also known as effectively antibacterial agents but toxic metal. 9) Local heating of Ag@Fe 3 O 4 nanocomposites using both photothermal and magnetic hyperthermia effects have been demonstrated to remarkably increase a rapid temperature rise compared to the single method, 5) and can be used for cancer treatment. Moreover, the localized heat generates spatiotemporally heterogeneous temperature distribution and can improve ultrasonic imaging.…”

“…In this paper, we theoretically investigate optical and elastic properties of Ag@Fe 3 O 4 core-shell nanoflowers (Fig.1), which has been experimentally synthesized in Ref. 5) in visible range.…”