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.