Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Fluorescence Manipulation by Gold Nanoparticles: From Complete Quenching to Extensive Enhancement | Kang et al. Journal of Nanobiotechnology 2011 9 16 http content 9 1 16 RESEARCH JOURNAL OF NANOBIOTECHNOLOGY Open Access Fluorescence Manipulation by Gold Nanoparticles From Complete Quenching to Extensive Enhancement Kyung A Kang 1 Jianting Wang1 Jacek B Jasinski2 and Samuel Achilefu3 Abstract Background When a fluorophore is placed in the vicinity of a metal nanoparticle possessing a strong plasmon field its fluorescence emission may change extensively. Our study is to better understand this phenomenon and predict the extent of quenching and or enhancement of fluorescence to beneficially utilize it in molecular sensing imaging. Results Plasmon field intensities on around gold nanoparticles GNPs with various diameters were theoretically computed with respect to the distance from the GNP surface. The field intensity decreased rapidly with the distance from the surface and the rate of decrease was greater for the particle with a smaller diameter. Using the plasmon field strength obtained the level of fluorescence alternation by the field was theoretically estimated. For experimental studies 10 nm GNPs were coated with polymer layer s of known thicknesses. Cypate a near infrared fluorophore was placed on the outermost layer of the polymer coated GNPs artificially separated from the GNP at known distances and its fluorescence levels were observed. The fluorescence of Cypate on the particle surface was quenched almost completely and at approximately 5 nm from the surface it was enhanced 17 times. The level decreased thereafter. Theoretically computed fluorescence levels of the Cypate placed at various distances from a 10 nm GNP were compared with the experimental data. The trend of the resulting fluorescence was similar. The experimental results however showed greater enhancement than the theoretical estimates in general. The distance from the GNP surface that showed the maximum enhancement in the experiment was greater than the one .
