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Radio frequency radiation-induced hyperthermia using Si nanoparticle-based sensitizers for mild cancer therapy

View Article: PubMed Central - PubMed

ABSTRACT

Offering mild, non-invasive and deep cancer therapy modality, radio frequency (RF) radiation-induced hyperthermia lacks for efficient biodegradable RF sensitizers to selectively target cancer cells and thus avoid side effects. Here, we assess crystalline silicon (Si) based nanomaterials as sensitizers for the RF-induced therapy. Using nanoparticles produced by mechanical grinding of porous silicon and ultraclean laser-ablative synthesis, we report efficient RF-induced heating of aqueous suspensions of the nanoparticles to temperatures above 45-50°C under relatively low nanoparticle concentrations (<1 mg/mL) and RF radiation intensities (1–5 W/cm2). For both types of nanoparticles the heating rate was linearly dependent on nanoparticle concentration, while laser-ablated nanoparticles demonstrated a remarkably higher heating rate than porous silicon-based ones for the whole range of the used concentrations from 0.01 to 0.4 mg/mL. The observed effect is explained by the Joule heating due to the generation of electrical currents at the nanoparticle/water interface. Profiting from the nanoparticle-based hyperthermia, we demonstrate an efficient treatment of Lewis lung carcinoma in vivo. Combined with the possibility of involvement of parallel imaging and treatment channels based on unique optical properties of Si-based nanomaterials, the proposed method promises a new landmark in the development of new modalities for mild cancer therapy.

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Assessment of heating rates in RF radiation-induced hyperthermia using nanosensitizers.(a) Heating rate of aqueous suspensions of PSi NPs with different concentrations (red circles), LA-Si NPs (green circles) and gold nanoparticles (black circles) under RF exposure at 5 W/cm2. Dashed lines represent linear fits of the experimental data. (b) Temperature increase of an aqueous suspension of PSi NPs with concentration of 1 mg/mL under its RF irradiation for 1 min. (squires), 2 min. (triangles), and 3 min (circles). Dashed line represents a linear fit of the experimental data.
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f3: Assessment of heating rates in RF radiation-induced hyperthermia using nanosensitizers.(a) Heating rate of aqueous suspensions of PSi NPs with different concentrations (red circles), LA-Si NPs (green circles) and gold nanoparticles (black circles) under RF exposure at 5 W/cm2. Dashed lines represent linear fits of the experimental data. (b) Temperature increase of an aqueous suspension of PSi NPs with concentration of 1 mg/mL under its RF irradiation for 1 min. (squires), 2 min. (triangles), and 3 min (circles). Dashed line represents a linear fit of the experimental data.

Mentions: Figure 2 c,d show typical time dependences of the temperature growth of PSi and LA-Si NPs suspensions, as well as of pure deionized water (for comparison), under the exposure in RF radiation with intensity of 5 W/cm2. As shown in the Figure, the heating rate of PSi NPs suspension having the concentration of ~1 mg/mL was about 10 K/min, which was much higher than the heating rate of deionized water (~0.7 K/min). LA-Si NPs were even more efficient RF-radiation sensitizers as they provided a significant heating rate of 5 K/min at 20-fold lower concentration (0.05 mg/mL), while a remarkable heating effect (1.3 K/min) was visible even for ultra-low LA-Si NPs concentrations (0.015 mg/mL) (Fig. 2d). Here, PSi NPs demonstrated a linear growth of solution temperature under the increase of irradiation time, while for LA-Si NPs the temperature growth rate slightly decreased after some irradiation time (~3 min), but still remained reasonably high. The reason of such decrease of the heating rate for LA-Si NPs is not clear and requires further investigation. As one of possibilities, we can imagine a certain modification of surface chemistry or/and size of LA-Si NPs during the RF-induced heating process. For both types of NPs the heating rate was almost linearly dependent on NPs concentration, while LA-Si NPs demonstrated a higher heating rate compared to PSi counterparts for the whole range of NPs concentrations. It should be noted that the reference experiments with aqueous suspension of LA-Au NPs at concentration of ~0.05 mg/mL (Figure S4 of SI) revealed the heating rate ~1.7 K/min, which is in agreement with the previously published results67. Thus, Si NPs suspensions exhibited similar heating rates (or higher in the case of LA-Si NPs) as Au NPs, which are widely used for hyperthermia applications. As shown in Figure 3b, the heating rate for 1 mg/mL PSi NPs solution was linearly proportional to RF intensity even if the irradiation time was different (1, 2, 3 minutes).


Radio frequency radiation-induced hyperthermia using Si nanoparticle-based sensitizers for mild cancer therapy
Assessment of heating rates in RF radiation-induced hyperthermia using nanosensitizers.(a) Heating rate of aqueous suspensions of PSi NPs with different concentrations (red circles), LA-Si NPs (green circles) and gold nanoparticles (black circles) under RF exposure at 5 W/cm2. Dashed lines represent linear fits of the experimental data. (b) Temperature increase of an aqueous suspension of PSi NPs with concentration of 1 mg/mL under its RF irradiation for 1 min. (squires), 2 min. (triangles), and 3 min (circles). Dashed line represents a linear fit of the experimental data.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382688&req=5

f3: Assessment of heating rates in RF radiation-induced hyperthermia using nanosensitizers.(a) Heating rate of aqueous suspensions of PSi NPs with different concentrations (red circles), LA-Si NPs (green circles) and gold nanoparticles (black circles) under RF exposure at 5 W/cm2. Dashed lines represent linear fits of the experimental data. (b) Temperature increase of an aqueous suspension of PSi NPs with concentration of 1 mg/mL under its RF irradiation for 1 min. (squires), 2 min. (triangles), and 3 min (circles). Dashed line represents a linear fit of the experimental data.
Mentions: Figure 2 c,d show typical time dependences of the temperature growth of PSi and LA-Si NPs suspensions, as well as of pure deionized water (for comparison), under the exposure in RF radiation with intensity of 5 W/cm2. As shown in the Figure, the heating rate of PSi NPs suspension having the concentration of ~1 mg/mL was about 10 K/min, which was much higher than the heating rate of deionized water (~0.7 K/min). LA-Si NPs were even more efficient RF-radiation sensitizers as they provided a significant heating rate of 5 K/min at 20-fold lower concentration (0.05 mg/mL), while a remarkable heating effect (1.3 K/min) was visible even for ultra-low LA-Si NPs concentrations (0.015 mg/mL) (Fig. 2d). Here, PSi NPs demonstrated a linear growth of solution temperature under the increase of irradiation time, while for LA-Si NPs the temperature growth rate slightly decreased after some irradiation time (~3 min), but still remained reasonably high. The reason of such decrease of the heating rate for LA-Si NPs is not clear and requires further investigation. As one of possibilities, we can imagine a certain modification of surface chemistry or/and size of LA-Si NPs during the RF-induced heating process. For both types of NPs the heating rate was almost linearly dependent on NPs concentration, while LA-Si NPs demonstrated a higher heating rate compared to PSi counterparts for the whole range of NPs concentrations. It should be noted that the reference experiments with aqueous suspension of LA-Au NPs at concentration of ~0.05 mg/mL (Figure S4 of SI) revealed the heating rate ~1.7 K/min, which is in agreement with the previously published results67. Thus, Si NPs suspensions exhibited similar heating rates (or higher in the case of LA-Si NPs) as Au NPs, which are widely used for hyperthermia applications. As shown in Figure 3b, the heating rate for 1 mg/mL PSi NPs solution was linearly proportional to RF intensity even if the irradiation time was different (1, 2, 3 minutes).

View Article: PubMed Central - PubMed

ABSTRACT

Offering mild, non-invasive and deep cancer therapy modality, radio frequency (RF) radiation-induced hyperthermia lacks for efficient biodegradable RF sensitizers to selectively target cancer cells and thus avoid side effects. Here, we assess crystalline silicon (Si) based nanomaterials as sensitizers for the RF-induced therapy. Using nanoparticles produced by mechanical grinding of porous silicon and ultraclean laser-ablative synthesis, we report efficient RF-induced heating of aqueous suspensions of the nanoparticles to temperatures above 45-50°C under relatively low nanoparticle concentrations (<1 mg/mL) and RF radiation intensities (1–5 W/cm2). For both types of nanoparticles the heating rate was linearly dependent on nanoparticle concentration, while laser-ablated nanoparticles demonstrated a remarkably higher heating rate than porous silicon-based ones for the whole range of the used concentrations from 0.01 to 0.4 mg/mL. The observed effect is explained by the Joule heating due to the generation of electrical currents at the nanoparticle/water interface. Profiting from the nanoparticle-based hyperthermia, we demonstrate an efficient treatment of Lewis lung carcinoma in vivo. Combined with the possibility of involvement of parallel imaging and treatment channels based on unique optical properties of Si-based nanomaterials, the proposed method promises a new landmark in the development of new modalities for mild cancer therapy.

No MeSH data available.


Related in: MedlinePlus