A facile reactive-template strategy has been developed to fabricate porous SnO2 nanotubes using MnO2 nanorods as the sacrificial template. The formation of nanotubes is based on the redox reaction mechanism, which requires no post-treatment of the MnO2 templates. The morphological and structural characteristics of the samples have been systematically characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal-gravimetric (TG), and N2 adsorption–desorption techniques. A gas-sensor device was constructed using as-prepared SnO2 nanotubes and was tested for its ability to detect ethanol and some other compounds. Because of the porous structure and relative large specific surface area, the SnO2 nanotube sensor manifests remarkably improved sensing performance, including fast response recovery, high sensitivity, and excellent repeatability, suggesting the promising application of the SnO2 nanotube materials.
Objective To investigate the biodistribution of 125Ⅰ labeled dendrimer nanomaterialpolyamidoamine (PAMAM) in mice.Methods Tyrosine was conjugated to four generation PAMAM by NHydroxysuccinimide,then 125Ⅰ was labeled on PAMAM with chloramines-T method,and purified by dialysis.Labeling rate,radiochemical purity and stability of 125Ⅰ-PAMAM were detected by radioactive thin layer chromatography scanning.The gamma imaging and biodistribution were detected by in vivo imaging system and gamma counter at one,four,eight,twenty-four and forty-eight hours after intravenous injection.Results The IH nuclear magnetic resonance results showed that about two tyrosines were conjugated to PAMAM.The 125Ⅰ labeling rate was about 56％ and radiochemical purity was more than 98％.The radiochemical purity of labeled compound remained more than 90％ at 72 hours in vitro.In vivo imaging results showed that PAMAM was mainly accumulated in liver periphery.The gamma counter results showed that PAMAM mainly accumulated in liver,kidney and spleen,the excretion of PAMAM was slow and there has high dose of PAMAM in mice at 48 hours.Conclusion PAMAM with no chemical modification was mainly accumulated in liver,kidney and spleen,and the excretion of PAMAM was slow,so PAMAM is not fit as drug carrier.PAMAM need to chemical modification to accelerate excretion and prevent the emergence of toxicity caused by accumulation in body.
Key words:
Iodine radioisotopes; Polyamidoamine; Body distribution
Chemical investigation of the sponge Dysidea sp. afforded three new sesquiterpene phenols (1–3) and one new sesquiterpene aminoquinone (4), together with four known sesquiterpene derivatives (5–8). The structures of all compounds were unambiguously elucidated by extensive spectroscopic analysis, as well as by comparison with the literature. The absolute configurations of compounds 1–4 were determined by electron capture detector (ECD) calculations and circular dichroism (CD) spectrum analysis. Their antibacterial activity against Escherichia coli (25922), Bacillus subtilis (6633), and Staphylococcus aureus (25923) were evaluated. Compounds 1 and 3 showed weak antibacterial activity against the above three strains, whereas compounds 4–8 showed potent antibacterial activities with minimum inhibitory concentration (MIC) values in the range of 3.125 to 12.5 µg/mL.
Abstract Cell sheet technology is a very important strategy for scaffold‐free tissue engineering. In order to fabricate cell sheets by a simple method, peptide detergent A 6 K was grafted on mica surfaces by dropping its aqueous solution at different concentrations on the surface. As revealed by surface topographical observation and water contact angle measurement, the most hydrophobic surface was obtained using peptide solution at the concentration of 0.2 mg · mL −1 . The peptide‐grafted mica surface was used to culture mouse preosteoblast cell MC3T3‐E1. After the cells reached confluence and the peptide was biodegraded, an intact cell sheet was peeled from the mica. This simple method does not need any non‐biological reagents or complicated procedures, and may have great potential in tissue engineering based on cell sheet technology. magnified image
This work reports on the stimulated optical emission characteristics of ZnO nanobelts that were grown with a simple carbothermal evaporation method without using any catalyst or dopant. Such nanobelts grew along the a-axis enclosed by {0001} and {01−10} base planes through a vapor-solid mechanism. Room temperature and temperature-dependent photoluminescence results indicated that such nanobelts were of high optical qualityand were better than those nanobelts grown from dopant-assisted thermal evaporation or oxidation methods. Amplified spontaneous emission was observed from ZnO nanobelts with low-growth density while random laser was observed for high-density samples with increasing optical pumping density.
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