Quantitative Comparison of the Light-to-Heat Conversion Efficiency in Nanomaterials Suitable for Photothermal Therapy

Abstract

Functional colloidal nanoparticles capable of converting between various energy types are finding an increasing number of applications. One of the relevant examples concerns light-to-heat-converting colloidal nanoparticles that may be useful for localized photothermal therapy of cancers. Unfortunately, quantitative comparison and ranking of nanoheaters are not straightforward as materials of different compositions and structures have different photophysical and chemical properties and may interact differently with the biological environment. In terms of photophysical properties, the most relevant information to rank these nanoheaters is the light-to-heat conversion efficiency, which, along with information on the absorption capacity of the material, can be used to directly compare materials. In this work, we evaluate the light-to-heat conversion properties of 17 different nanoheaters belonging to different groups (plasmonic, semiconductor, lanthanide-doped nanocrystals, carbon nanocrystals, and metal oxides). We conclude that the light-to-heat conversion efficiency alone is not meaningful enough as many materials have similar conversion efficienciesin the range of 80–99%while they significantly differ in their extinction coefficient. We therefore constructed their qualitative ranking based on the external conversion efficiency, which takes into account the conventionally defined light-to-heat conversion efficiency and its absorption capacity. This ranking demonstrated the differences between the samples more meaningfully. Among the studied systems, the top-ranking materials were black porous silicon and CuS nanocrystals. These results allow us to select the most favorable materials for photo-based theranostics and set a new standard in the characterization of nanoheaters.

Influence of Magnetic Nanoparticle Degradation in the Frame of Magnetic Hyperthermia and Photothermal Treatments

“…In the frame of magnetic hyperthermia, it was previously described that small fluctuations on the particle size or particle size distribution have a strong impact on the heating properties of iron oxides, and our results agree with such observations. In contrast, in the frame of photothermal experiments, not so many studies have evaluated the role that particle size has on the heating properties of iron oxides, and in some cases, the obtained results are contradictory and remain under study . If the photothermal heating is related to the band structures of magnetite/maghemite, size should not have a strong impact on the heating, and the changes observed in this work would be attributed to a decrease in the total amount of magnetite/maghemite mass in the sample due to the formation of other iron-containing species, related to the paramagnetic contributions observed in the magnetic characterization data (Figure ).…”

“…In contrast, in the frame of photothermal experiments, not so many studies have evaluated the role that particle size has on the heating properties of iron oxides, and in some cases, the obtained results are contradictory and remain under study. 34 If the photothermal heating is related to the band structures of magnetite/maghemite, 35 size should not have a strong impact on the heating, and the changes observed in this work would be attributed to a decrease in the total amount of magnetite/ maghemite mass in the sample due to the formation of other iron-containing species, related to the paramagnetic contributions observed in the magnetic characterization data (Figure 4). Our observations indicated a smaller influence of the particle size on the heating properties of particles when exposed to an NIR light than to an AMF, pointing to the fact that the particle degradation along time could have a smaller impact on photothermal therapies in magnetic hyperthermia treatments when performed along long periods of time after particle administration.…”

Gold nanocluster decorated fibrous substrate for photo-modulated cellular growth

“…The photothermal heating-cooling curves of water were obtained, which were used to calculate the photothermal conversion efficiency according to the published procedure. 47,48…”

“…The photothermal heating-cooling curves of water were obtained, which were used to calculate the photothermal conversion efficiency according to the published procedure. 47,48 2.4 Protein release in the fibrous substrate FITC-whey protein was used as a model protein to prepare fibrous-Au/protein-GG. One set of fibrous-Au/protein-GG was immersed into 2 mL of PBS for 30 min.…”

A Local Water Molecular-heating Strategy for NIR Long-lifetime Imaging-guided Photothermal Therapy of Deep-tissue-bearing Tumor

“…This cascade energy transfer in Nd 3+ ions can generate heat by an interionic interaction between the states of ( 4 F 3/2 , 4 I 15/2 ) ↔ ( 4 I 15/2 , 4 I 9/2 ), and its photothermal performance is determined by the doping concentrations of Nd 3+ since CR mainly depends on the distance between Nd 3+ ions 8, 9 . However, the photothermal performance of Nd-doped nanomaterials is not su cient to achieve the threshold temperature for thermal ablation of tumors even with highly Nd-doped photothermal agents (PTAs) because their absorption coe cient is small and narrow around 800 nm (their photothermal conversion e ciency was less than 10%) 8,10 . To overcome this limitation, NaNdF 4 NPs have been additionally decorated with heterogeneous materials such as Prussian blue, CuS, MnO 2 , and carbon 8,11 .…”