Biocompatible chitosan/polyethylene glycol/multi-walled carbon nanotube composite scaffolds for neural tissue engineering / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Carbon nanotube (CNT) composite materials are very attractive for use in neural tissue engineering and biosensor coatings. CNT scaffolds are excellent mimics of extracellular matrix due to their hydrophilicity, viscosity, and biocompatibility. CNTs can also impart conductivity to other insulating materials, improve mechanical stability, guide neuronal cell behavior, and trigger axon regeneration. The performance of chitosan (CS)/polyethylene glycol (PEG) composite scaffolds could be optimized by introducing multi-walled CNTs (MWCNTs). CS/PEG/CNT composite scaffolds with CNT content of 1%, 3%, and 5% (1%=0.01 g/mL) were prepared by freeze-drying. Their physical and chemical properties and biocompatibility were evaluated. Scanning electron microscopy (SEM) showed that the composite scaffolds had a highly connected porous structure. Transmission electron microscope (TEM) and Raman spectroscopy proved that the CNTs were well dispersed in the CS/PEG matrix and combined with the CS/PEG nanofiber bundles. MWCNTs enhanced the elastic modulus of the scaffold. The porosity of the scaffolds ranged from 83% to 96%. They reached a stable water swelling state within 24 h, and swelling decreased with increasing MWCNT concentration. The electrical conductivity and cell adhesion rate of the scaffolds increased with increasing MWCNT content. Immunofluorescence showed that rat pheochromocytoma (PC12) cells grown in the scaffolds had characteristics similar to nerve cells. We measured changes in the expression of nerve cell markers by quantitative real-time polymerase chain reaction (qRT-PCR), and found that PC12 cells cultured in the scaffolds expressed growth-associated protein 43 (GAP43), nerve growth factor receptor (NGFR), and class III β‍-tubulin (TUBB3) proteins. Preliminary research showed that the prepared CS/PEG/CNT scaffold has good biocompatibility and can be further applied to neural tissue engineering research.

Preparation and Characterization of PTX-MWNTs-COOH and Its in Vitro Release / 中国药学杂志

OBJECTIVE: To prepare and characterize PTX-MWCNTs-COOH complex and study its in vitro release properties. METHODS: The PTX-MWCNTs-COOH complex was prepared by solvent blending method with paclitaxel as drug,phospholipid as surfactant. It was characterized by laser particle size analyzer,transmission electron microscope (TEM) and DSC analysis. The drug loading was determined by filtration membrane together HPLC method and the entrapment efficiency was determined by microcolumn separation together HPLC method. The in vitro release of the PTX-MWCNTs-COOH complex was studied in PBS buffer at pH 7.4(containing 1% Tween-80) with revers dialysis method. RESULTS: The Zeta potential of PTX-MWCNTs-COOH complex was (-24.5±1.01) mV,the drug loading was(50.09±0.02)%,and the entrapment efficiency was (76.80±0.02)%. The cumulative release in vitro was perfect. CONCLUSION: PTX-MWCNTs-COOH showed good physicochemical properties such as high drug loading and entrapment efficiency. The method of reverse dialysis can be used to study the release behavior of PTX-MWCNTs-COOH in vitro.

Preparation of Carboxylated Multi-Walled Carbon Nanotubes Loaded with Podophyllotoxin and Their Transdermal Penetration / 中国药学杂志

OBJECTIVE: To study the preparation of carboxylated multi-walled carbon nanotubes loaded with podophyllotoxin (PPT-CNTs-COOH) as well as the characteristics of the in vitro transdermal penetration. METHODS: PPT-CNTs-COOH was prepared by freezing milling method; IR, UV, XRD, and TGA were used to characterize the PPT-CNTs-COOH; HPLC method was used for determination of the content of podophyllotoxin loaded in the carboxylated multi-walled carbon nanotubes; franze diffusion cells method was used to determine the drug transdermal penetration rate. RESULTS: The IR spectrum of PPT-CNTs-COOH showed the main absorption peaks of PPT and CNTs-COOH and the peaks changed obviously. Compared with free PPT, the UV absorption peaks of PPT-CNTs-COOH changed obviously. The PPT content in the CNTs-COOH gel was 58.0 μg·mg-1; the transdermal penetration rate of PPT gel was 7.08 μg·cm-2·h-1 and that of the PPT-CNTs-COOH gel was 3.03 μg·cm-2·h-1; the skin retention of PPT-CNTs-COOH gel was 3.04 μg·cm-2, far less than the 1.52 μg·cm-2 of PPT gel. Mild irritation developed within 24 h following removal of the PPT-CNTs-COOH gel, and disappears after 72 h. CONCLUSION: Podophyllotoxin can successfully be loaded into the carboxylated multi-wall carbon nanotubes by using the frozen ball milling method. The product has remarkable sustained release effect in vitro and high retention in skin, which is beneficial to transdermal delivery.

Preparation of ethylenediamine functionally-modified multi-walled carbon nanotubes and biocompatibility on PC12 cells / 中国药学杂志

OBJECTIVE: To prepare multi-walled carbon nanotubes-ethylenediamine (MWCNTs-EDA) compound with low toxicity and belter dispersion using EDA functionally modified-multi-walled carbon nanotubes to lay a foundation for the further research of loading drugs with carbon nanotubes. METHODS: MWCNTs-EDA compound was synthesized by covalent crosslinking with carboxylated carbon nanotubes (MWCNTS-COOH) and ethylenediamine, and then scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy (KTIR), thermal gravimetric analysis (TG), Raman spectrum, and Zeta potential determination were used to characterize the compound, and the dispersion uniformity of MWCNTs before and after functionalization were examined. MIT assay and flow cytometry test were used to measure the toxicity of the compound against phcochromocytoma cells. RESULTS: The results of SEM, TEM, FTIR, TG, Raman, and Zeta potential analysis confirmed that MWCNTs had successfully received the EDA. The dispersibility test showed that MWCNTs-EDA had better dispersion stability in water. MTT assay and flow cytometry test showed that EDA functionally-modified MWCNTs greatly reduced the cytotoxicity of the MWCNTs. CONCLUSION: The EDA functionally-modified MWCNTs has significantly improved dispersibility, significantly reduced in vitro cytotoxicity, and better biocompatibility.

Multi-Walled Carbon Nanotube (MWCNT) Dispersion and Aerosolization with Hot Water Atomization without Addition of Any Surfactant

OBJECTIVES: Carbon nanotubes are an important new class of technological materials that have numerous novel and useful properties. Multi-walled carbon nanotubes (MWCNTs), which is a nanomaterial, is now in mass production because of its excellent mechanical and electrical properties. Although MWCNTs appear to have great industrial and medical potential, there is little information regarding their toxicological effects on researchers and workers who could be exposed to them by inhalation during the handling of MWCNTs. METHODS: The generation of an untangled MWCNT aerosol with a consistent concentration without using surfactants that was designed to be tested in in vivo inhalation toxicity testing was attempted. To do this, MWCNTs were dispersed in deionized water without the addition of any surfactant. To facilitate the dispersion of MWCNTs in deionized water, the water was heated to 40degrees C, 60degrees C, and 80degrees C depending on the sample with ultrasonic sonication. Then the dispersed MWCNTs were atomized to generate the MWCNT aerosol. After aerosolization of the MWCNTs, the shapes of the NTs were examined by transmission electron microscopy. RESULTS: The aerosolized MWCNTs exhibited an untangled shape and the MWCNT generation rate was about 50 mg/m3. CONCLUSION: Our method provided sufficient concentration and dispersion of MWNCTs to be used for inhalation toxicity testing.

Effects of Different Dose of Multi-Walled Carbon Nanotube on the Cellular Proliferation of HEK293 Cells / 医学研究杂志

Objective To study the effects of Multi-Walled Carbon Nanotube with different doses on the cellular proliferation of human embryo kidney 293 cells.Methods The cultured human embryo kidney cell line 293 was seeded into 96-well plates and various concentrations of Multi-Walled Carbon Nanotube were added into different groups of culture.Methyl thiazolyl tetrazolium(MTT)assay were applied to detect the cellular viabilities after being incubated with Multi-Walled Carbon Nanotube for 48 hours and the results were calculated with specific static software to protract the cell viability curve.Results The Multi-Walled Carbon Nanotube had different effects of inhibiting the multiplies of 293 cells depending on its concentrations.In addition,when the concentration of Multi-Walled Carbon Nanotube reached over 0.5ug/ml,the inhibition became significantly.Conclusions Multi-Walled Carbon Nanotube can penetrate the cell membrane of 293 cells to influence the activities of cells and the ability of proliferation will be decreased significantly when the concentration came to some degree.Therefore,the safety dosage of the Multi-Walled Carbon Nanotube on human normal embryo kidney 293 cells were estimated in this research.