Water-structuring molecules and nanomaterials enhance radiofrequency heating in biologically relevant solutions

Lara, Nadia C.; Haider, Asad A.; Ho, Jason; Wilson, Lon J.; Barron, Andrew R.; Curley, Steven A.; Corr, Stuart J.

doi:10.1039/c6cc06573b

Cited by 10 publications

(12 citation statements)

References 31 publications

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“…Due to the immense difficulty associated with measuring the strength of the electric field generated by the RF system, the second fit parameter, E app , is used. E app was previously estimated 3 to be 163 kV/m, which agrees well with the values presented here (Table II).…”

supporting

confidence: 82%

“…3 These studies however, are limited to aqueous systems and until now the theoretical models used to explain this behavior have not been validated for other materials. To fully characterize RF heating, materials representing a wider range of dielectric properties must be studied.…”

mentioning

confidence: 99%

“…S2, supplementary material). We have previously 3 performed the necessary corrections 10 on e 0 r of conductive aqueous systems. Generally, the corrected e 0 r of a conductive aqueous solution is essentially equal to that of pure water.…”

mentioning

confidence: 99%

“…The impedance analyzer and probe were calibrated and the measurements were performed as described previously. 3 Briefly, following calibration, 600 lL of sample was loaded onto the probe and 151 logarithmic data points were acquired for both real (e 0 r ) and imaginary (e 00 r ) permittivity across the frequency range 10 MHz-3 GHz. Probe calibration was performed periodically between samples, and a singlepoint calibration (air) was performed between every sample to eliminate the signal drift.…”

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confidence: 99%

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Unique heating curves generated by radiofrequency electric-field interactions with semi-aqueous solutions

Lara

Haider

Wilson

et al. 2017

Applied Physics Letters

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Aqueous and nanoparticle-based solutions have been reported to heat when exposed to an alternating radiofrequency (RF) electric-field. Although the theoretical models have been developed to accurately model such a behavior given the solution composition as well as the geometrical constraints of the sample holder, these models have not been investigated across a wide-range of solutions where the dielectric properties differ, especially with regard to the real permittivity. In this work, we investigate the RF heating properties of non-aqueous solutions composed of ethanol, propylene glycol, and glycine betaine with and without varying amounts of NaCl and LiCl. This allowed us to modulate the real permittivity across the range 25-132, as well as the imaginary permittivity across the range 37-177. Our results are in excellent agreement with the previously developed theoretical models. We have shown that different materials generate unique RF heating curves that differ from the standard aqueous heating curves. The theoretical model previously described is robust and accounts for the RF heating behavior of materials with a variety of dielectric properties, which may provide applications in non-invasive RF cancer hyperthermia. Published by AIP Publishing.[http://dx.doi.org/10.1063/1.4973218] It has been shown that saline solutions under exposure to radiofrequency (RF) electric fields display peak heating behavior at a certain concentration, 1,2 and this behavior has been generalized to include any aqueous system, regardless of the content or identity, including buffer solutions, blood, and nanoparticle suspensions.3 These studies however, are limited to aqueous systems and until now the theoretical models used to explain this behavior have not been validated for other materials. To fully characterize RF heating, materials representing a wider range of dielectric properties must be studied. Such an understanding may have direct applications in non-invasive RF cancer hyperthermia therapy. [4][5][6][7][8][9] Although most tissues in the human body are made up primarily of water and other tissues, such as fat and bone, have drastically different dielectric properties and are expected to behave differently. Overheating of the subcutaneous fat layer, for example, is a major limiting factor in hyperthermia cancer therapy (especially at 13.56 MHz) and must be overcome if this technology is to be safely implemented in the clinic. 10In this study we probe the dielectric and heating properties of materials with reduced water content and variable conductivity. Experimental RF heating curves similar to those of aqueous solutions are generated for each material, and these are used to confirm the generalization of the theoretical heating model to a wider range of systems. The dielectric properties, such as permittivity, of a material describe its response to electromagnetic (EM) fields. For time-varying alternating electric fields, the permittivity becomes a complex parameter given by the equationwhere e r , e 0 r , e 00 r are the co...

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confidence: 82%

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confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Unique heating curves generated by radiofrequency electric-field interactions with semi-aqueous solutions

Lara

Haider

Wilson

et al. 2017

Applied Physics Letters

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“…The higher heat conductivity to the tissue may be due to the higher number of ions in the saline solution. Specifically, RF waves are known to be partially reflected and absorbed by ion-rich fluids [23][24][25]. Consequently, RF waves are spread throughout the bladder more evenly, possibly leading to more homogeneous heating compared to sterile water.…”

Section: Discussionmentioning

confidence: 99%

Inducing intravesical hyperthermia of the ex-vivo porcine bladder wall: radiofrequency-induction versus recirculation using a custom-made device

Valenberg

Witjes

Aklan

et al. 2018

International Journal of Hyperthermia

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Introduction: Several techniques can be used to treat intravesical chemohyperthermia (ChHT). We compared radiofrequency-induced hyperthermia (RF-HT) with conductive hyperthermia (C-HT) for their ability to induce bladder wall temperatures of >40.5 C, the target temperature for ChHT. Materials and Methods: Fresh porcine bladders (n ¼ 12) were placed in a temperature-controlled saline bath to simulate body temperature and circulation. HT was induced with RF-HT (43 C) or C-HT (inflow temperature 44 and 46 C) using a custom-made device. In two additional bladders, we varied intravesical solution and volume. Temperatures were recorded with a three-way catheter containing three mucosal and two urethral thermocouples (TCs) and a 915 MHz RF antenna, and with external TCs in the bladder wall at three different levels and three different locations. Results: Target temperature (40.5 C) was reached in the submucosa at all locations by both techniques. In the detrusor, target temperature was reached by RF-HT at the bladder neck and side wall. C-HT 46 reached significantly higher submucosal temperatures at the side wall. The bladder dome seemed best heated by C-HT, although a high inflow temperature (46 vs. 44 C) was required (ns). Intravesical saline resulted in higher temperatures than sterile water for RF-HT. A volume of 100 mL resulted in higher bladder dome temperatures for RF-HT, and higher bladder neck with lower dome temperatures for C-HT. Conclusion: Our results indicate a slightly superior heating capacity for RF-HT compared to C-HT, whereas for the bladder dome, the reverse seems true. Comparative studies are warranted to evaluate whether HT efficacy differs between both techniques, with emphasis on tumor location.

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Multifunctional fluorescent iron quantum clusters for non-invasive radiofrequency ablationof cancer cells

Jose

Surendran

Fazal

et al. 2018

Colloids and Surfaces B: Biointerfaces

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Water-structuring molecules and nanomaterials enhance radiofrequency heating in biologically relevant solutions

Cited by 10 publications

References 31 publications

Unique heating curves generated by radiofrequency electric-field interactions with semi-aqueous solutions

Unique heating curves generated by radiofrequency electric-field interactions with semi-aqueous solutions

Inducing intravesical hyperthermia of the ex-vivo porcine bladder wall: radiofrequency-induction versus recirculation using a custom-made device

Multifunctional fluorescent iron quantum clusters for non-invasive radiofrequency ablationof cancer cells

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