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Silica nanoparticle-based zinc sensor for in vitro study of intracellular zinc.

Optimization of surface modified silica nanoparticles has been done for enhanced Zn(II) determination. The molecule (carboxymethyl-{4-{10 -(4-dicarboxymethylaminobenzyl)anthracen-9-ylmethyl}phenyl}amino) acetic acid dipotassium salt (CDAPAP) has shown a strong preference for Zn(II) with the interference of other metal ions. The reaction conditions, including buffer selection and pH, have been carefully studied. The reaction time has been compared for the detection of Zn(II) by the free CDAPAP molecule vs. the CDAPAP surface modified nanoparticles, this was measured by detecting the fluorescence intensity using a spectrofluorometer. When Zn(II) is introduced to the sensor it gives an increase in the emission peak at a wavelength of 430 nm, when excited at 377 nm. Although there is a high preference for Zn(II), the binding of the metal to the sensor is easily reversible for repeated use.

Zn(II) sensors are very popular because of its diverse role within biological systems. For instance, it is a necessary component in DNA synthesis and apoptosis. It also plays an important role in protein function. Zinc is also related to some diseases it has been found that the zinc concentration is very high for Alzheimer's patients.

Nanotechnology presents exciting and truly revolutionary approaches to address global challenges in the scientific world. A unique property of the nanoparticles is their size, resulting in two useful features, high mobility and high surface area to volume ratio. These features provide nanoparticles with very high sensitivity as a signaling reagent when combined with target-induced fluorescent compounds. By binding about 15,000 CDAPAP molecules to a single nanoparticle, the fluorescence signal can be localized for enhancement of the signal of low levels of Zn(II) present. This is particularly useful when using the fluorescence microscope to image cellular samples, and to monitor change over time.

Carrie L. Amiot, Yuhui Jin, David T. Pierce, Julia Xiaojun Zhao

University of North Dakota
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Author:Amiot, Carrie L.; Jin, Yuhui; Pierce, David T.; Zhao, Julia Xiaojun
Publication:Proceedings of the North Dakota Academy of Science
Article Type:Report
Geographic Code:1USA
Date:Apr 1, 2008
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