Effect of functionalized multi-walled carbon nanotubes on L02 cells / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate the cytotoxic effect of multi-walled carbon nanotubes (MWCNTs) on human liver L02 cells and its relevant mechanism.</p><p><b>METHODS</b>MWCNTs, carboxyl modification MWCNTs (MWCNTs-COOH), and hydroxyl modification MWCNTs (MWCNTs-OH) were characterized by transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. The carbon nanotubes at concentrations of 12.5, 25, 50, 100, and 200 μg/ml were incubated with human liver L02 cells for 24, 48 and 72 hours, respectively. The cell viability was evaluated by water soluble tetrazolium salts assay and the intercellular reactive oxygen species induced by the carbon nanotubes were detected by 2', 7'-dichlorodihydrofluorescein diacetate method.</p><p><b>RESULTS</b>Transmission electron microscope showed that the average outside diameters (10 to 20 nm) and the average length (10 to 30 μm) of the three MWCNTs were similar. Scanning electron microscope indicated that the three MWCNTs had a similar surface topography. X-ray photoelectron spectroscopy demonstrated that the MWCNTs-COOH and MWCNTs-OH had relatively high peak areas at 289 and 286ev, respectively,indicating that they have been modified by carboxyl and hydroxyl groups,respectively. Water soluble tetrazolium salts assay showed that the MWCNTs-COOH was less cytotoxic when compared to MWCNTs which demonstrated to be slightly more cytotoxic than MWCNTs-OH. The capability to induce increase in intracellular reactive oxygen species was in the following order: MWCNTs > MWCNTs-COOH > MWCNTs-OH.</p><p><b>CONCLUSIONS</b>Modification of MWCNTs with carboxyl group and hydroxyl group improves the biocompatibility of MWCNTs to some extents. MWCNTs-COOH has better compatibility than MWCNTs at the low concentration,and MWCNTs-OH showed better compatibility than MWCNTs after 48 hours. Different mechanisms may be involved in the interaction between cells and the MWCNTs with different chemical surfaces.</p>

Cellular uptake and cytotoxicity of modified chitosans as gene carriers / 中国医学科学院学报

<p><b>OBJECTIVE</b>To evaluate the effects of arginine modified chitosan or hexadecylated modified chitosan as gene carriers on the cellular uptake by vascular smooth muscle cells and its in vitro cytotoxicity. METHODS Plasmid DNA was labeled with alpha-32P-dATP and complexed with the modified chitosans or unmodified chitosan to form nanoparticle complexes by complex coacervation method. Uptake of all kinds of chitosan/ DNA nanoparticle complexes (CNC) by A10 cells was measured by beta-liquid scintillation counting. The in vitro cytotoxicity of the CNC was evaluated by the 3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT) assay.</p><p><b>RESULTS</b>The diameters of the CNC ranged from 55.9-174.9 nm and the zeta potentials were from 10. 8 mV for the arginine modified chitosan/DNA nanoparticle complexes (ACNC) to 1.8 mV for the hexadecylated chitosan/DNA nanoparticle complexes (HCNC). The cellular uptake of the modified chitosan/ DNA nanoparticle complexes (MCNC) by A10 cells increased significantly when compared with the unmodified chitosan/DNA nanoparticle complexes (UCNC) (P < 0.05), with the HCNC at N/P ratio of 1:1 and the ACNC at ratio of 8:1 showing the highest cellular uptake (1.3 fold higher than UCNC, P < 0.05). MCNC were much less cytotoxic when compared with Lipofectamine 2000-DNA nanoparticles.</p><p><b>CONCLUSION</b>DNA nanoparticle complexes prepared with either arginine or hexadecylated modified chitosan can improve the cellular uptake of the DNA, while the in vitro cytotoxicity of both of the modified chitosan is much less than that of Lipofectamine 2000.</p>