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Porous silicon nanoparticles for cancer photothermotherapy.

Hong C, Lee J, Zheng H, Hong SS, Lee C - Nanoscale Res Lett (2011)

Bottom Line: Also, the cell deaths were mostly due to necrosis but partly due to late apoptosis.Tumors have not recurred at all in the PSi/NIR treatment groups thereafter.Both the in vitro cell test and in vivo animal test results suggest that thermotherapy based on PSi in combination with NIR laser irradiation is an efficient technique to selectively destroy cancer cells without damaging the surrounding healthy cells.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Materials Science and Engineering, Inha University, 253 Yonghyeon-dong, Incheon, 402-751, Republic of Korea. cmlee@inha.ac.kr.

ABSTRACT
The in vitro cell tests and in vivo animal tests were performed to investigate the feasibility of the photothermal therapy based on porous silicon (PSi) in combination with near-infrared (NIR) laser. According to the Annexin V- fluorescein isothiocyanate Apoptosis assay test results, the untreated cells and the cells exposed to NIR laser without PSi treatment had a cell viability of 95.6 and 91.3%, respectively. Likewise, the cells treated with PSi but not with NIR irradiation also had a cell viability of 74.4%. Combination of these two techniques, however, showed a cell viability of 6.7%. Also, the cell deaths were mostly due to necrosis but partly due to late apoptosis. The in vivo animal test results showed that the Murine colon carcinoma (CT-26) tumors were completely resorbed without nearly giving damage to surrounding healthy tissue within 5 days of PSi and NIR laser treatment. Tumors have not recurred at all in the PSi/NIR treatment groups thereafter. Both the in vitro cell test and in vivo animal test results suggest that thermotherapy based on PSi in combination with NIR laser irradiation is an efficient technique to selectively destroy cancer cells without damaging the surrounding healthy cells.

No MeSH data available.


Related in: MedlinePlus

Comparison of photothermal property between solid PSi, PSi/EtOH:PEG solution (0.7 g/L), and EtOH:PEG solution. ΔT1 and ΔT2, respectively, in this graph represent the temperature rises in solid PSi (a free-standing PSi layer) and PSi/EtOH:PEG solution upon NIR laser irradiation at 1.5 W/cm2.
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Figure 2: Comparison of photothermal property between solid PSi, PSi/EtOH:PEG solution (0.7 g/L), and EtOH:PEG solution. ΔT1 and ΔT2, respectively, in this graph represent the temperature rises in solid PSi (a free-standing PSi layer) and PSi/EtOH:PEG solution upon NIR laser irradiation at 1.5 W/cm2.

Mentions: The PSi nanoparticles functionalized with PEG were well solublized, so that they were uniformly distributed in the PSi/EtOH:PEG solution without forming any floating particles, precipitates, or agglomerates for a long period of time as shown Figure 1a. Functionalization of PSi with PEG is necessary to enhance the internalization of PSi particles into cells as well as the attachment of antibodies to PSi particles for the systematic administration of cancer. Ethyl alcohol was also used to enhance the dispersion of PSi nanoparticles in the solution. Figure 1b displays the size distribution of the PSi nanoparticles after being filtered by using a 220 nm membrane, which was in a range from 80-220 nm in diameter with a mean diameter of approximately 140 nm. The photothermal property was compared between solid PSi, PSi/EtOH:PEG solution (0.7 g/L), and EtOH:PEG solution in Figure 2. The surface temperature of each sample during exposure to 808 nm NIR laser at 1.5 W/cm2 was measured by using an IR thermometer. The PSi nanoparticles exhibited a very rapid increase in temperature for the first 1 min and a slow increase for the next 5-6 min. The temperature reached at approximately 70°C in about 6 min upon NIR laser irradiation and did not nearly changed thereafter. The net temperature rises shall have been 47°C, taking the temperatures of the PSi film at the exposure time of 0 min (~23°C) into consideration. This high photothermal effects in PSi is mainly attributed to the high absorbance and the high surface-to-volume ratio due to the numerous micropores in PSi [33]. The temperature of the PSi/EtOH:PEG solution changed with the NIR exposure time in a pattern similar to the solid PSi, but the temperature was much lower than that of the PSi nanoparticles presumably due to the absorption of heat by the liquid phases such as EtOH and PEG in the solution. The temperature difference between PSi/EtOH:PEG and EtOH:PEG is about 10°C for the NIR irradiation time larger than 15 min, which may seem to be somewhat small for thermotherapy. In the in vivo animal tests, the EtOH:PEG solution injected directly into tumors would move easily to the whole body of the mouse. Consequently, a very little amount of remnant solution would stay in the tumors. In contrast, the PSi/EtOH:PEG solution injected directly into tumors would stay in the tumors for a longer time because it has a higher viscosity than the simple EtOH:PEG solution. Therefore, there would be a big difference between the two solutions in the actual effect of destroying cancer cells.


Porous silicon nanoparticles for cancer photothermotherapy.

Hong C, Lee J, Zheng H, Hong SS, Lee C - Nanoscale Res Lett (2011)

Comparison of photothermal property between solid PSi, PSi/EtOH:PEG solution (0.7 g/L), and EtOH:PEG solution. ΔT1 and ΔT2, respectively, in this graph represent the temperature rises in solid PSi (a free-standing PSi layer) and PSi/EtOH:PEG solution upon NIR laser irradiation at 1.5 W/cm2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211409&req=5

Figure 2: Comparison of photothermal property between solid PSi, PSi/EtOH:PEG solution (0.7 g/L), and EtOH:PEG solution. ΔT1 and ΔT2, respectively, in this graph represent the temperature rises in solid PSi (a free-standing PSi layer) and PSi/EtOH:PEG solution upon NIR laser irradiation at 1.5 W/cm2.
Mentions: The PSi nanoparticles functionalized with PEG were well solublized, so that they were uniformly distributed in the PSi/EtOH:PEG solution without forming any floating particles, precipitates, or agglomerates for a long period of time as shown Figure 1a. Functionalization of PSi with PEG is necessary to enhance the internalization of PSi particles into cells as well as the attachment of antibodies to PSi particles for the systematic administration of cancer. Ethyl alcohol was also used to enhance the dispersion of PSi nanoparticles in the solution. Figure 1b displays the size distribution of the PSi nanoparticles after being filtered by using a 220 nm membrane, which was in a range from 80-220 nm in diameter with a mean diameter of approximately 140 nm. The photothermal property was compared between solid PSi, PSi/EtOH:PEG solution (0.7 g/L), and EtOH:PEG solution in Figure 2. The surface temperature of each sample during exposure to 808 nm NIR laser at 1.5 W/cm2 was measured by using an IR thermometer. The PSi nanoparticles exhibited a very rapid increase in temperature for the first 1 min and a slow increase for the next 5-6 min. The temperature reached at approximately 70°C in about 6 min upon NIR laser irradiation and did not nearly changed thereafter. The net temperature rises shall have been 47°C, taking the temperatures of the PSi film at the exposure time of 0 min (~23°C) into consideration. This high photothermal effects in PSi is mainly attributed to the high absorbance and the high surface-to-volume ratio due to the numerous micropores in PSi [33]. The temperature of the PSi/EtOH:PEG solution changed with the NIR exposure time in a pattern similar to the solid PSi, but the temperature was much lower than that of the PSi nanoparticles presumably due to the absorption of heat by the liquid phases such as EtOH and PEG in the solution. The temperature difference between PSi/EtOH:PEG and EtOH:PEG is about 10°C for the NIR irradiation time larger than 15 min, which may seem to be somewhat small for thermotherapy. In the in vivo animal tests, the EtOH:PEG solution injected directly into tumors would move easily to the whole body of the mouse. Consequently, a very little amount of remnant solution would stay in the tumors. In contrast, the PSi/EtOH:PEG solution injected directly into tumors would stay in the tumors for a longer time because it has a higher viscosity than the simple EtOH:PEG solution. Therefore, there would be a big difference between the two solutions in the actual effect of destroying cancer cells.

Bottom Line: Also, the cell deaths were mostly due to necrosis but partly due to late apoptosis.Tumors have not recurred at all in the PSi/NIR treatment groups thereafter.Both the in vitro cell test and in vivo animal test results suggest that thermotherapy based on PSi in combination with NIR laser irradiation is an efficient technique to selectively destroy cancer cells without damaging the surrounding healthy cells.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Materials Science and Engineering, Inha University, 253 Yonghyeon-dong, Incheon, 402-751, Republic of Korea. cmlee@inha.ac.kr.

ABSTRACT
The in vitro cell tests and in vivo animal tests were performed to investigate the feasibility of the photothermal therapy based on porous silicon (PSi) in combination with near-infrared (NIR) laser. According to the Annexin V- fluorescein isothiocyanate Apoptosis assay test results, the untreated cells and the cells exposed to NIR laser without PSi treatment had a cell viability of 95.6 and 91.3%, respectively. Likewise, the cells treated with PSi but not with NIR irradiation also had a cell viability of 74.4%. Combination of these two techniques, however, showed a cell viability of 6.7%. Also, the cell deaths were mostly due to necrosis but partly due to late apoptosis. The in vivo animal test results showed that the Murine colon carcinoma (CT-26) tumors were completely resorbed without nearly giving damage to surrounding healthy tissue within 5 days of PSi and NIR laser treatment. Tumors have not recurred at all in the PSi/NIR treatment groups thereafter. Both the in vitro cell test and in vivo animal test results suggest that thermotherapy based on PSi in combination with NIR laser irradiation is an efficient technique to selectively destroy cancer cells without damaging the surrounding healthy cells.

No MeSH data available.


Related in: MedlinePlus