title: Fluorescence life-time imaging and steady state polarization for examining binding of fluorophores to gold nanoparticles.
abstract: Nanocomposites as multifunctional agents are capable of combing imaging and cell biology technologies. The conventional methods used for validation of the conjugation process of nanoparticles (NPs) to fluorescent molecules such as spectroscopy analysis and surface potential measurements, are not sufficient. In this paper we present a new and highly sensitive procedure that uses the combination of (1) fluorescence spectrum, (2) fluorescence lifetime, and (3) steady state fluorescence polarization measurements. We characterize and analyze gold NPs with Lucifer yellow (LY) surface coating as a model. We demonstrate the ability to differentiate between LY-GNP (the conjugated complex) and a mixture of coated NP and free dyes. We suggest the approach for neuroscience applications where LY is used for detecting and labeling cells, studying morphology and intracellular communications. Histograms of Fluorescence lifetime imaging (FLIM) of free LY dye (Left) in comparison to the conjugated dye to gold nanoparticles, LY-GNP (Middle) enable the differentiation between LY-GNP (the conjugated complex) and a mixture of coated NP and free dyes (Right).
authors.affiliation: Gonda Multidisciplinary Brain Research Center, Bar Ilan University, 5290002, Ramat Gan, Israel.|Faculty of Engineering, Bar Ilan University, 5290002, Ramat Gan, Israel.|Institute of Nanotechnology and Advanced Materials, Bar Ilan University, 5290002, Ramat Gan, Israel.
authors.forename: Shmulik
authors.initials: S
authors.lastname: Schwartz
authors.affiliation: Faculty of Engineering, Bar Ilan University, 5290002, Ramat Gan, Israel.|Institute of Nanotechnology and Advanced Materials, Bar Ilan University, 5290002, Ramat Gan, Israel.
authors.forename: Dror
authors.initials: D
authors.lastname: Fixler
authors.affiliation: Faculty of Engineering, Bar Ilan University, 5290002, Ramat Gan, Israel.|Institute of Nanotechnology and Advanced Materials, Bar Ilan University, 5290002, Ramat Gan, Israel.
authors.forename: Rachela
authors.initials: R
authors.lastname: Popovtzer
authors.affiliation: Faculty of Engineering, Bar Ilan University, 5290002, Ramat Gan, Israel. orit.shefi@biu.ac.il.|Institute of Nanotechnology and Advanced Materials, Bar Ilan University, 5290002, Ramat Gan, Israel. orit.shefi@biu.ac.il.
authors.forename: Orit
authors.initials: O
authors.lastname: Shefi
mesh_terms: D005453:Fluorescence; D005456:Fluorescent Dyes; D006046:Gold; D053768:Metal Nanoparticles; D061848:Optical Imaging / Q000379:methods*; D010316:Particle Size; D011092:Polyethylene Glycols; D013057:Spectrum Analysis / Q000379:methods
chemical_list: D005456:Fluorescent Dyes; D011092:Polyethylene Glycols; D006046:Gold
keywords: fluorescence life time; fluorescence polarization; gold nanoparticles; nanoparticles