Experimental study of Cu9S5 nanocrystals’ cytotoxicity and photothermal stability

Abstract

Objective With the continuous development of nanomaterials, more and more materials have been used in the biomedical field. The biological stability and security of material is becoming increasingly important. In addition to the damage of tumor cells, the effect of nanomaterials on normal cells as well as the physical characteristics after long-term storage need to be confirmed by further research. In this experiment, the typical photothermal material Cu9S5 nanoparticles is selected as the study object of nanomaterials toxicity and potential long-term stability of biology. Methods (1) The release of heavy metal ions released by Cu9S5 nanocrystals after long-term storage in the medium is detected by inductively coupled plasma (ICP) method. (2) Compare how Cu9S5 nanoparticles extraction and medium direct concentration gradient of Cu9S5 nanoparticles culture afftct on cartilage primary cells’ proliferation. (3) 960 nm 0.72 W/cm2 laser irradiation is used to irradiate chondrocytes, which has been put in Cu9S5 nanoparticles culture. Use flow cytometry to analyzed apoptosis, and use the reverse transcriotion-polymerase chain reaction (RT-PCR) to test the expression of cysteinyl aspartate-specific protease (Caspase)-3 and interleukin (IL)-1 in the sample. (4) The storaged Cu9S5 nanoparticles is applied to treat nude tumor. Research how photothermal effect affect on tumor core temperature. Results (1) In the Cu9S5 nanoparticles extraction medium, copper ion concentration is 85 μg/ml, silicon ion concentration was 158.8 μg/ml. Completely extracts can obviously inhibit the growth of cells in 12 hours (P=0.000), after 48 hours culture of completely extracts, Chondrocytes inhibition rate is higher than 30%). (2)The apoptotic rate was (6.30±0.50)% and (7.36±1.20)% before or after the addition of the material, and there was no significant difference (P=0.185). The apoptotic rate of the cells containing the material but without the laser irradiation was (7.83±0.94)%, which was not statistically different from that of the cells without laser irradiation (P=0.065). After the laser irradiation, cells not added material was not damaged obviously, while cells added material after 2 minutes illumination had high apoptosis rate and high inflammation factor expression and caspase-3 expression (P=0.000). (3) In the photothsermal damage model of nude mice, core temperature in experimental group was significantly higher than that in the control group (P=0.000). Conclusion The long-term storaged Cu9S5 nanoparticles release high concentrations copper ion, which can significantly inhibit normal cartilage cells in some concentrations. In this situation, laser obviously damage cells containing nanomaterials comparing to normal cells. In animal tumor therapeutic applications, Cu9S5 nanoparticles still can help kill tumor. Key words: Nano-materials; Stability; Security; Photothermal effect; Apoptosis