Abstract
In this article we suggest a new concept for cell destruction based upon manipulating magnetic nanoparticles (MNPs) by applying external, low frequency alternating magnetic field (AMF) that oscillates the particles, together with focused laser illumination. Assessment of temperature profiles in a head and neck squamous cell carcinoma sample showed that cells with MNPs, treated with AMF (3 Hz, 300 mW) and laser irradiation (30 mW), reached 42°C after 4.5 min, as opposed to cells treated with laser but without AMF. Moreover, a theoretical model was developed to assess the overall theoretical temperature rise, which was shown to be 50% lower than the experimental temperature. Furthermore, we found that the combination of laser irradiation and AMF decreased the number of live cells by ~50%. Thus, the concentrated assembly of laser heating with AMF-induced MNP oscillations leads to more rapid and efficient cell death. These results suggest that the manipulated MNP technique can serve as a superior agent for PTT, with improved cell death capabilities.
Highlights
To determine whether magnetic particles (MNPs) presence alone can cause cell death, we examined under microscope the viability of A431 cells with 10 mg/ml MNPs, with or without laser irradiation and alternating magnetic field (AMF) treatment (n = 3 plates per group, 106 cells/plate)
The temperature of 42°C did not cause cell death on its own, as seen in cells treated with laser only, or with AMF + laser but no MNPs, yet this goal was reached after only 5 min of combination treatment in the presence of particles, resulting in approximately half of the total cells dead, and after AMF alone, yielding approximately one quarter dead
The combination of MNPs with AMF and laser produced an effect over 5 min of treatment, which is more rapid than currently existing treatments that generally require 30 min of heating or more [32,33]
Summary
PTT was shown to be effective, various technical and physical limitations of currently available hyperthermia systems, including magnetic and laser-based systems, prevent adequate heating of some tissues. Common electromagnetic devices for magnetic hyperthermia are generators in the frequency range of 50kHz–1MHz, with magnetic field amplitudes up to a few tens of kAm−1 [6,7,8]. These parameters depend more on the technical availability of the generators used, rather than on theoretical predictions for optimized specific absorption rate [8].
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