Radio frequency absorption in gold nanoparticle suspensions: a phenomenological study

Parameter studies on optimal absorption and electrophoretic resonances in lossy media

“…and where k 0 is the wave number of vacuum, see [4,5]. It has recently been shown in [4] that (2), and hence also (1) are locally concave functions in the complex parameter ε 1 and which are maximized by the conjugate match…”

“…where σ 1 = N q 2 /β and τ 1 = m/β , where N is the number of particles per unit volume, q the particle charge, β the friction constant of the host medium and m the mass of the particle, cf., [5]. The Drude parameters can furthermore be tuned to the conjugate match by choosing…”

“…The ligands are assumed to have a mass density similar to water. The friction constant β is modelled as β = 6π µ f a, where µ f = 10 −3 Nsm −2 is the dynamic shear viscosity of the host medium (water at room temperature) as in [5]. The number of particles per unit volume is given by N = φ /(4πa 3 /3), where φ is the volume fraction of GNPs in the spherical suspension.…”

“…The number of particles per unit volume is given by N = φ /(4πa 3 /3), where φ is the volume fraction of GNPs in the spherical suspension. Here, we have chosen φ = 2 · 10 −3 as in [5]. The net charge of the GNP is modeled as q = (3a Au + 0.5a 2 Au )e 0 + n L e 0 , where the charge of the gold core is modeled as in [5], n L is the assumed net electron count in the ligand shell and e 0 denotes the electron charge e 0 = 1.6 · 10 −19 C.…”

“…In particular, gold nanoparticles (GNPs) can be coated with ligands that target specific cancer cells as well as providing a net electronic charge of the GNPs. One hypothesis is then that the charged GNPs will facilitate an electrophoretic current that can destroy the cancer under electromagnetic radiation [1,4,5]. However, it is also important to observe the complexity of the clinical application with many possible physical and biophysical phenomena to consider, as well as the fact that several authors have questioned whether metal nanoparticles can be heated in radio frequency at all, see e.g., [1,3].…”