Initial Exploration Of Biology Effects Of Gold Nanorods On Nasopharyngeal Carcinoma In Vitro

【Background and Objects】Nasopharyngeal carcinoma(NPC) is a common malignant tumor of head and neck in China,especially with high incidence in South of China.Radiotherapy is the first choice in its treatment,but with serious adverse effects.Gold nanorods(GNPs) is a new kind of nanomaterials,which can produce heat in local area after absorbing lights at near-infrared(NIR) frequencies.We applied GNPs to NPC cell line and primary nasal epithelial cells in vitro to observe its thermal ablative effect and cytotoxicity to these cells.We hope to explore a new kind therapy for NPC with less adverse effects than radiotherapy.【Material and Methods】Human nasal epithelium(HNE) cells were obtained by enzyme digestion 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay was used in the growth of HNE and Human pharyngeal carcinoma CNE-1 cell line.We applied gold nanorods in HNE cells and CNE-1 in vitro and evaluated intrinsic cytotoxicity and endocytosis in these cells.HNE cells and CNE-1 were respectively devided into two groups for the photothermal destruction by GNPs.Nanorod solution with safe concentration was substituted for the control treatment group.No nanorods were given for the sham treatment group.Each group was exposed to NIR illumination with the same periods and conditions.The viabilities of these cells were reported. 【RESULT】After inoculation,HNE cells adherence was observed under phase contrast inverted microscope in 8-12 hours,which presented a pavestone-like appearance and anti-keratin monoclonal antibody positive multangular cells.Vacuoles appeared in the passage cells around the 7^th day.CNE-1 cell line was characterized by immortalized cell.MTT assay was used to assess GNP-related cytotoxicity.The results showed HNE cells could survived with 2.5×10^-4mol/L GNPs dose within 48 hours.GNPs could be observed within CNE-1 cells under transmission election microscopy(TEM).Two inflection points existed in the absorption curves.The first came up in the several minutes after administrating of 2.0×10^-4mol / L GNPs into the cultures and formed a peak structure with different size and rising level according to different cell type.The second indicated the formation of platform phases,which were about 4 hours in HNE and 6 hours in CNE-1 after administration.The control treatment group of CNE-1 incubated with 2.0×10^-4mol/l nanorods in vitro was found to undergo photothermy-induced mortality on exposure to NIR light(780nm,12.7W/cm²).The longer time tumor cells exposed,the more died.Exposing to 25.4W/cm² NIR for 2 minutes only compromise viability of CNE-1 cell with nanorods.The nanorods rendered the tumor cells highly susceptible to photothermal damage.【Conclusion】We demonstrated that GNPs had no intrinsic cytotoxicity to HNE cells if the concentration was below 2.50×10^-4mol / L in vitro and CNE-1 cell line had more effective endocytosis.The malignant cells required less NIR energy to be killed than the benign after incubation with the same GNPs concentration.The results of our experiment will be helpful to increase the therapeutic validity to NPC without nearby organs damage by combining nanorods and NIR.