Shaofeng Zhang

Desorption electrospray ionization (DESI) mass spectrometry (MS) was used to differentiate seven bacteria species on the basis of their measured DESI-mass spectral profile. Both gram-positive and gram-negative bacteria were tested and included Escherichia coli, Staphyloccocus aureus, Enterococcus sp., Bordetella bronchiseptica, Bacillus thuringiensis, Bacillus subtilis and Salmonella typhimurium. Distinct DESI-mass spectra, in the mass range of 50-500 u, were obtained from whole bacteria in either positive or negative ion modes in less than 2 mins analysis time. Positive ion DESI-mass spectral fingerprints were compared using principal components analysis (PCA) to investigate reproducibility for the intraday and the day-to-day measurements and the method selectivity to differentiate the bacteria studied. Detailed study of variances in the assay revealed that a large contribution to the DESI-mass spectral fingerprint variation was the growth media preparation procedure. Specifically, experiments conducted with the growth media prepared using the same batch yielded highly reproducible DESI-mass spectra, both in intraday and in day-to-day analyses (i.e. one batch of growth media used over a 3-day period versus a new batch every day over the same 3-day period). Conclusions are drawn from our findings in terms of strategies for rapid biodetection with DESI-MS.

High-purity solanesol can be used for pharmaceutical applications, but the current method for purifying solanesol has high cost and difficult continuous operation, and the use of molecular imprinting to purify natural products is a hot research topic of current research. Solanesol molecularly imprinted polymers were synthesized via emulsion polymerization for the first time. The morphology of the SSO-MIPs was observed with a scanning electron microscope, and the effects of the synthesis time, initiator dosage, functional monomer dosage, and cross-linking agent dosage on the adsorption effects under high-temperature and rapid synthesis conditions were discussed. The results demonstrate that the optimum synthesis conditions were a ratio of the template molecules to the functional monomers to the cross-linking agents of 1:8:30 (mol:mol:mol), 10 mg of the initiator, and a synthesis temperature of 70 °C. The imprinting factor of SSO-MIPs synthesized under the optimized process was found to reach 2.51, and the SSO-MIPs synthesized by this method exhibited a good adsorption effect, emitted less pollution during the synthesis process, and are convenient for demulsification. This research reports a reliable method for the synthesis of solanesol molecularly imprinted polymers.

Controlled synthesis of low-dimensional materials, such as nanoparticles, nanorods, and hollow nanospheres, is vitally important for achieving desired properties and fabricating functional devices. We report a systematic investigation of the growth of low-dimensional sub-100 nm SnO(2) hollow nanostructures by a mild template- and surfactant-free hydrothermal route, aiming to achieve precise control of morphology and size. The starting materials are potassium stannate and urea in an ethylene glycol (EG)/H(2)O system. We found the size of the SnO(2) hollow nanospheres can be controlled by simply adjusting the urea concentration. Investigation of the mechanism of formation of the SnO(2) hollow nanospheres revealed that reaction time, urea concentration, and reaction temperature make significant contributions to the growth of hollow nanospheres. On switching the solvent from EG/H(2)O to H(2)O or ethanol, the SnO(2) nanostructures changed from nanospheres to ultrafine nanorods and nanoparticles. On the basis of reaction parameter dependent experiments, oriented self-assembly and subsequent evacuation through Ostwald ripening are proposed to explain the formation of hollow nanostructures. Their size-dependent optical properties, including UV/Vis absorption spectra and room-temperature fluorescence spectra, were also studied. Moreover, the studies on the photocatalytic property demonstrate that the fabricated hollow structures have slightly enhanced photocatalytic degradation activity for rhodamine B when exposed to mercury light irradiation compared to solid SnO(2) nanospheres under the same conditions. The synthesized tin oxide nanoparticles display high photocatalytic efficiency and have potential applications for cleaning polluted water in the textile industry.