Morphological Modulation, Functionalization And Anticancer Activities Of Selenium Nanoparticles

Selenium nanopaticles (SeNPs), a Se species with low toxicity and excellent electrochemical performance, become the frontier and hot issue in the fields of materials, electronics, optical physics, biology, medicine and chemistry. In this thesis, Se nanomaterials with different morphology have been fabricated by two different systems and evaluated for their anticancer activities. The size distribution and stability of the products were examined by UV-vis spectrometry and dynamic laser light scattering (DLLS). The morphology, elemental composition and crystal form of the nanomaterials were characterized by Transmission electron microscopy (TEM), Scanning electron microscope (SEM), Energy dispersive X-ray spectroscopy (EDX), Raman spectra and XRD, respectively. The interaction pattern and modulation mechanism between SeNPs and the modifier were examined by Fourier transform infrared spectroscopy (FT-IR) and Nano-Zeta potential analysis. The in vitro anticancer activities of the SeNPs were screened by MTT assay against a number of human cancer and normal cell lines. The action mode of SeNPs in cancer cells was elucidated by flow cytometric analysis, Annexin-V-FLUOS and PI double staining, TUNEL-DAPI co-staining assay. Many interesting results have been obtained, including:1) Chitosan as the morphology modulation agent for the preparation of SeNPs and Se multiarmed nanorods. In this study, chitosan was used as a modulation agent for the large-scale preparation of SeNPs with uniform and ultralstable size. The molar ratio of Vitamin C and SeO2 in the mixture was 4:1. The average size of SeNPs was about 100 nm when the final concentration of Se and chitosan were 5 mM,0.8 mg/mL, respectively. When the above mixture was aged at 60℃for 72 h, the shell-core structure of Se multiarmed nanorods (SeMRs) formed. The edge of SeMRs was smooth and distinct with 0.4 mg/mL of chitosan. According to the results of SEM-EDX analysis and TEM exposure, we found that the shell of SeMRs was chitosan and Se existed in the inner side. 2) PEG as the dispersing and modulation agent for the preparation of SeNPs and Se nanorods/nanotubes. The hot solution of Se, as prepared by dissolving gray Se in PEG, was used as initial materials for fabrication of SeNPs, nanotubes and nanorods by physical methods. While the final concentration of Se was less than 1.6 mg/mL, the average size of PEG-modified SeNPs, prepared by cooling down the Se hot solution in the liquid nitrogen, was about 100 nm, which was stable at least for 120 days. While the final concentrations of Se, chitosan and PEG600 were 1 mM,0.4 mg/mL and 40 mg/mL, respectively, the average size of PEG-CS-SeNPs, as prepared by cooling down the hot solution of Se in the solution of chitosan, was about 100 nm and, which was stable for 240 h. Se nanorods and nanotubes were prepared by cooling down the hot solution of Se under the ultrasonic for 30 min. The molecular weight of PEG, cooling method, ultrasonic frequency, the ratio of Se and PEG, affect the morphology of Se nanomaterials.3) Asparagine as reductant for the preparation of SeNPs and nanorods in the PEG. PEG was used as dispersant agent for the redox reaction of asparagine and Se to prepare SeNPs and nanorods. When the molar ratio of asparagine and SeO2 was 4:1, the average size of the SeNPs prepared under 70 W of microwave heating for 10 min, was about 100 nm. After aging at 60℃for 72 h, the SeNPs transformed to t-Se nanorods. This method provides a strategy for the preparation of functional nanomaterials.4) The in vitro anticancer activities of SeNPs. Due to the uniform size and stable propertity, CS-SeNPs were selected for further investigation of in vitro anticancer activitise of Se nanomaterials. The result shows that CS-SeNPs exhibited a broad spectrum inhibition on A375, Hep G2 and MG-63 cancer cells with IC50 values ranging from 22.7 to 49.3μM. Despite this potency, CS-SeNPs showed lower cytotoxicity toward human normal cells (HK-2 kedney cells) with an IC50 value of 98.29μM, which was much higher than those of A375, Hep G2 and MG-63 cells. These results suggested that CS-SeNPs possesses great selectivity between cancer and normal cells and displays potential application in cancer chemoprevention and chemotherapy and the chitosan enhance cell-penetrating abilities of SeNPs. According to Flow Cytometry, PI labeling assay and TUNEL-DAPI co-staining assay, we found that CS-SeNPs inhibited A375 cancer cell growth through induction of apoptosis.