Hydrothermal synthesis of a highly sensitive T2-weigthed MRI contrast agent: zinc-doped superparamagnetic iron oxide nanocrystals.

A highly efficient hydrothermal strategy for the synthesis of zinc-doped superparamagnetic iron oxide nanocrystals (SPION:Zn) with lower toxicity and improved sensitivity has been demonstrated. The saturation magnetizations of as-synthesized SPION:Zn were demonstrated to be Zn-dependent and could be tuned from 41.88 emu/g to 79.

A simple and effective sample preparation method for atomic force microscopy visualization of individual DNA molecules in situ.

A simple, controllable and effective sample preparation method was established for atomic force microscopy (AFM) imaging of individual DNA molecules in aqueous solution. Firstly, magnesium ion (Mg(2+)) at a concentration of 5.0-10.

Visible light-induced plasmid DNA damage catalyzed by a CdSe/ZnS-photosensitized nano-TiO2 film.

Visible light-induced photocatalytic degradation of environmental pollutants with improved TiO2 has attracted much attention in pollution control and management. The degradation of nucleic acids is of great significance for biological contaminants such as viruses. In the presentwork, visible light-induced plasmid DNA damage catalyzed by a CdSe/ZnS-photosensitized nano-TiO2 film (QDs-TiO2 film) was investigated by atomic force microscopy (AFM) and agarose gel electrophoresis.

Role of DNA in bacterial aggregation.

The role of DNA in bacterial aggregation was determined using various types of DNA and Escherichia coli, a good model for investigating the correlation between added polymer and bacterial aggregation and adsorption of polymer to bacterial surfaces. The results of the aggregation assay suggest that extracellular DNA indeed increased the aggregation percentage of E. coli, but this effect was dependent on DNA concentration and length.

Importance of size-to-charge ratio in construction of stable and uniform nanoscale RNA/dendrimer complexes.

Formation of RNA/dendrimer complexes between various RNA molecules and PAMAM dendrimers was studied using atomic force microscopy. Our results demonstrate that effective construction of stable nanoscale and uniform RNA/dendrimer complexes depends critically on the size of the RNA molecule, the dendrimer generation and the charge ratio between the dendrimer and the RNA. Larger RNA molecules, higher generations of dendrimers and larger dendrimer-to-RNA charge ratios lead to the formation of stable, uniform nanoscale RNA/dendrimer complexes.

pH effect on dynamic coating for capillary electrophoresis of DNA.

A buffer consisting of tris(hydroxymethyl)aminomethane, 2-(N-moropholino)ethanesulfonic acid (Mes) and EDTA with constant ion strength was used to investigate the effect of buffer pH on the dynamic coating behavior of poly(N-isopropylacrylamide) (PNIPAM) for DNA separation. The atomic force microscopy (AFM) image illustrated that PNIPAM in lower-pH buffer was much more efficient in covering a silica wafer than that in higher-pH buffer. The coating performance of PNIPAM was also quantitatively analyzed by Fourier transform IR attenuated total reflectance spectroscopy and by measuring the electroosmotic flow (EOF).

Preparation and third-order optical nonlinearity of self-assembled chitosan/CdSe-ZnS core-shell quantum dots multilayer films.

The self-assembled chitosan CdSe quantum dots (QDs) and chitosan CdSe-ZnS core-shell QDs films have been prepared by using layer-by-layer electrostatic technique. The well-ordered nanostructure and the layer-by-layer deposition of the QDs are revealed by AFM and exciton absorption spectra, respectively. The optical nonlinearity of the composite films were studied by using Z-scan technique with femtosecond pulses at the wavelength of 790 nm, the value of third-order susceptibility of core-shell QDs are measured to be about 1.

Direct electrochemistry and electrocatalysis of heme proteins entrapped in agarose hydrogel films in room-temperature ionic liquids.

The electrochemistry and electrocatalysis of a number of heme proteins entrapped in agarose hydrogel films in the room-temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]) have been investigated. UV-vis and FTIR spectroscopy show that the heme proteins retain their native structure in agarose film. The uniform distribution of hemoglobin in agarose-dimethylformamide film was demonstrated by atomic force microscopy.