In vitro cell tests of pancreatic malignant tumor cells by photothermotherapy based on DMSO porous silicon colloids.

Dimethyl sulfoxide porous silicon (DMSO-PSi) colloid in which DMSO was used as a surfactant suitable for inhibiting the agglomeration of PSi nanoparticles was prepared for use in cancer photothermotherapy. The photothermal effect of the DMSO-PSi colloid was found to be high enough to destroy cancer cells (T = ∼52 °C). The mean particle size of the PSi nanoparticles in the DMSO-PSi colloid was 67 nm, which is low enough to flow through blood vessels without causing a blockage. The DMSO-PSi colloid in combination with an NIR laser resulted in a cell viability of 5.70%, which is a sufficiently high cytotoxic effect.

Photothermal properties of inorganic nanomaterials as therapeutic agents for cancer thermotherapy.

In recent years, gold (Au) nanoparticles (NPs) and single-walled carbon nanotubes (SWCNTs) have attracted significant attention as potent therapeutic agents for cancer thermotherapy. In this paper the photothermal properties of inorganic nanomaterials including porous silicon (PSi), titania (TiO2) nanotubes (NTs), TiO2 NPs, and multiwalled carbon nanotubes (MWCNTs), Au NPs and SWCNTs have been systematically investigated. PSi shows by far the largest temperature rise (deltaT), TiO2 NTs the second largest deltaT, and MWCNTs the smallest deltaT upon exposure to near-infrared (NIR) laser. The high photothermal effect of PSi has been found to be attributed to the high absorbance and the high surface-to-volume ratio due to the numerous micropores in PSi In addition, the factors affecting the photothermal effects of nanomaterials have been discussed. Our results suggest that PSi and TiO2 NTs are also potential therapeutic agents for cancer thermotherapy with excellent photothermal properties as well as high biocompatibility.

In-vitro cell tests using doxorubicin-loaded polymeric TiO2 nanotubes used for cancer photothermotherapy.

To determine the appropriate surfactant to be added to TiO(2) nanotubes (TNTs) for use in cancer photothermotherapy, this study measured the increase in temperature and examined the size distribution of TNT particles loaded with different surfactants during near-infrared irradiation. In addition, in-vitro cell (fluorescein isothiocyanate and MTT assay) tests were carried out to examine the cytotoxic effect of doxorubicin-loaded and polyvinyl alcohol-added TNTs (pTNTs). The mean particle size of the pTNTs was 151.8 nm with a particle size variation of less than 3 nm, which is low enough to flow through blood vessels without causing a blockage. The temperature of the pTNTs was ∼47°C, which is high enough to destroy cancer cells. Doxorubicin-loaded TNTs and pTNTs in combination with a near-infrared laser showed a cell viability of 4.5% - a sufficiently high cytotoxic effect.

Comparison of oxidized porous silicon with bare porous silicon as a photothermal agent for cancer cell destruction based on in vitro cell test results.

In the systematic administration of cancer, cancer markers are normally used to help the therapeutic agents access the cancer cells spontaneously. Therefore, it is essential to functionalize the surface of porous silicon (pSi) for cancer markers to attach well to pSi in systematic administration because most cancer markers does not attach easily to pSi. The thermal oxidation of pSi is adopted most widely as a surface functionalization technique for pSi. This study examined the photothermal properties and cancer cell-killing ability of oxidized pSi (pSiO). The temperature measurement and in vitro cell tests including the annexin V-fluorescein isothiocyanate (FITC) apoptosis assay tests, MTT assay tests, and Trypan blue cell death assay tests were performed to compare the photothermal properties and the cytotoxic effect of pSiO with those of pSi in combination with an 808-nm NIR laser. pSiO showed lower photothermal properties and a lower cell-death rate than bare pSi. On the other hand, the pSiO treatment used in combination with an NIR laser treatment showed a cytotoxic effect high enough to kill a considerable portion of the cancer cells.

In-vivo cancer cell destruction using porous silicon nanoparticles.

In-vivo animal tests were performed to investigate the feasibility of photothermal therapy based on porous silicon nanoparticles (PSiNPs) in combination with a near-infrared (NIR) laser. The in-vivo animal test results showed that the murine colon carcinoma (CT-26) tumors were completely resorbed with minimal damage to surrounding healthy tissue within 5 days after PSiNPs and NIR laser treatments. In contrast, tumors in the groups treated only with PSiNPs or NIR and a control group continued to grow until the mice died. All of the mice treated with both PSiNPs and NIR remained healthy and free of tumors even 90 days after the treatment. In-vivo fluorescence imaging and the urine and feces tests revealed that PSiNPs injected intratumorally into mice were cleared mainly through the urine. The in-vivo animal test results suggest that thermotherapy based on porous silicon in combination with NIR laser irradiation can efficiently destroy cancer cells selectively without damaging the surrounding healthy cells.

Porous silicon nanoparticles for cancer photothermotherapy.

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.

TiO2 nanotubes as a therapeutic agent for cancer thermotherapy.

We report the photothermal properties as well as the in vitro cell test results of titanium oxide nanotubes (TiO(2) NTs) as a potential therapeutic agent for cancer thermotherapy in combination with near-infrared (NIR) light. TiO(2) NTs are found to have a higher photothermal effect upon exposure to NIR laser than Au nanoparticles and single-wall carbon nanotubes, which have also attracted considerable interest as therapeutic agents for cancer thermotherapy. The temperature increase of a TiO(2) NT/NaCl suspension during NIR laser exposure is larger than that of a TiO(2) NT/D.I. water suspension due to the heat generated by the formation of Na(2)TiF(6). According to the in vitro cell test results the cells exposed to NIR laser without TiO(2) NT treatment have a cell viability of 96.4%. Likewise, the cells treated with TiO(2) NTs but not with NIR irradiation also have a cell viability of 98.2%. Combination of these two techniques, however, shows a cell viability of 1.35%. Also, the cell deaths are mostly due to necrosis but partly due to late apoptosis. These results suggest that TiO(2) NTs can be used effectively as therapeutic agents for cancer thermotherapy due to their excellent photothermal properties and high biocompatibility.