分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: Excessive uptake of NO2− is detrimental to human health, but the currently available methods used to sensitively detect this ion in the environment are cumbersome and expensive. In this study, we developed an improved NO2− detection system based on a redox etching strategy of CTAB-stabilized Ag–Au core– shell nanoparticles (Ag@AuNPs). The detection mechanism was verified by UV-Vis spectroscopy, TEM and XPS. The detection system produces a color change from purple to colorless in response to an increase of NO2− concentration. The selectivity of detection of NO2−, both with the unaided eye and by measure- ment of UV-Vis spectra, is excellent in relation to other ions, including Cu2+, Co2+, Ni2+, Cr3+, Al3+, Pb2+, Cd2+, Ca2+, Ba2+, Zn2+, Mn2+, Mg2+, Fe3+, Hg2+, Ag+, K+, F−, PO43−, C2O42−, SO32−, CO32−, SO42−, NO3− and CH3–COO− (Ac−). The limit of detection (LOD) for NO2− is 1.0 μM by eye and 0.1 μM by UV-Vis spec- troscopy. The LOD by eye is lower than the lowest previously reported value (4.0 μM). There is a good linear relationship between A/A0 and the concentration of NO2− from 1.0 to 20.0 μM NO2−, which permits a quantitative assay. The applicability of our detection system was also verified by analysis of NO2− in tap water and lake water. The results demonstrate that our Ag@AuNP-based detection system can be used for the rapid colorimetric detection of NO2− in complex environmental samples, with excellent selectivity and high sensitivity.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: Layered bismuth oxyhalide nanomaterials have received much more interest as promising photocatalysts because of their unique layered structures and high photocatalytic performance, which can be used as potential inorganic photosensitizers in tumor photodynamic therapy (PDT). In recent years, photocatalytic materials have been widely used in PDT and photothermal therapy (PTT) as inorganic photosensitizers. This investigation focuses on applying layered bismuth oxyhalide nanomaterials toward cancer PDT, an application that has never been reported so far. The results of our study indicate that the efficiency of UV- triggered PDT was highest when using BiOCl nanoplates followed by BiOCl nanosheets, and then TiO2. Of particular interest is the fact that layered BiOCl nanomaterials showed excellent PDT effects under low nanomaterial dose (20 μg mL−1) and low UV dose (2.2 mW cm−2 for 10 min) conditions, while TiO2 showed almost no therapeutic effect under the same parameters. BiOCl nanoplates and nanosheets have shown excellent performance and an extensive range of applications in PDT.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: Multifunctional nanoprobes used in magnetic resonance imaging (MRI) and photodynamic therapy (PDT) also have potential applications in diagnosis and visualized therapy of cancers, and hence it is important to investigate the active-targeting ability and in vivo reliability of these nanoprobes. In this work, folic acid (FA)-targeted, photosensitizer (PS)-loaded Fe3O4@NaYF4:Yb/Er (FA-NPs-PS) nanocomposites were syn- thesized for in vivo T2-weighted MRI and visualized PDT of cancers by modeling MCF-7 tumor-bearing nude mice. By measuring the upconversion luminescence (UCL) and fluorescence emission spectra, the as-prepared FA-NPs-PS nanocomposites showed near-infrared (NIR)-triggered PDT performance due to the production of a singlet oxygen species. Moreover, by tracing PS fluorescence in MCF-7, HeLa cells and in MCF-7 tumors, the FA-targeted nanocomposites demonstrated good targeting ability both in vitro and in vivo. Under the irradiation of a 980 nm laser, the viabilities of MCF-7 and HeLa cells incubated with FA-NPs-PS nanocomposites could decrease to about 18.4% and 30.7%, respectively, and the inhibition of MCF-7 tumors could reach about 94.9%. The transverse MR relaxivity of 63.79 mM−1 s−1 (r2 value) and in vivo MR imaging of MCF-7 tumors indicated an excellent T2-weighted MR performance. This work demonstrated that FA-targeted MRI/PDT nanoprobes are effective for in vivo diagnosis and visualized therapy of breast cancers.
提交时间: 2017-05-02
摘要: White TiO2 nanoparticles [NPs] have been widely used for cancer photodynamic therapy based on their ultraviolet light-triggered properties. To date, biomedical applications using white TiO2 NPs have been limited, since ultraviolet light is a well-known mu