title: Fluorescence lifetime correlation spectroscopic study of fluorophore-labeled silver nanoparticles.
abstract: In this paper, we introduce the use of fluorescence lifetime correlation spectroscopy to study the metal-fluorophore interactions in solution at the single-fluorophore level. A single-stranded oligonucleotide was chemically bound to a 50-nm-diameter single silver particle, and a Cy5-labeled complementary single-stranded oligonucleotide was hybridized with the silver particle-bound oligonucleotide. The distance between the fluorophore and silver particle was maintained by a rigid hybridized DNA duplex of 8 nm in length. The single Cy5-DNA-Ag particles showed more than 10-fold increase in fluorescence intensity and a 5-fold decrease in emission lifetimes as compared with Cy5-DNA free molecules in the absence of metal. The decrease of lifetime for the Cy5-DNA-Ag particle allowed us to resolve the correlation functions of the two species based on the intensity decays. The increased brightness of the Cy5-DNA-Ag particle as compared to free Cy5-DNA resulted in an increased contribution of Cy5-DNA-Ag to the correlation function of the mixture. These results show that the effects of metal particles on fluorophores can be used to detect the small fractional populations of the metal-bound species in the presence of a larger number of less bright species. Our results also suggest that these bright fluorophores conjugated to silver particles could be used as the fluorescent probes for clinical detection in the biological samples with the high background.
authors.affiliation: Center for Fluorescence Spectroscopy, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, Maryland 21201, USA. krishanu@cfs.umbi.umd.edu
authors.forename: Krishanu
authors.initials: K
authors.lastname: Ray
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Lakowicz
mesh_terms: D002232:Carbocyanines / Q000737:chemistry*; D004247:DNA / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D009693:Nucleic Acid Hybridization; D009841:Oligonucleotides / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D002232:Carbocyanines; D005456:Fluorescent Dyes; D009841:Oligonucleotides; C085321:cyanine dye 5; D012834:Silver; D004247:DNA
references.citation: J Phys Chem C Nanomater Interfaces. 2007;111(19):7091-7097
references.pmid: 18802494
references.citation: Biophys J. 2007 Mar 15;92(6):2184-98
references.pmid: 17189306
references.citation: J Am Chem Soc. 2006 Jul 19;128(28):8998-9
references.pmid: 16834349
references.citation: J Fluoresc. 2007 Jan;17(1):43-8
references.pmid: 17171439
references.citation: Acc Chem Res. 2005 Jul;38(7):549-56
references.pmid: 16028889
references.citation: Nano Lett. 2007 Feb;7(2):496-501
references.pmid: 17256995
references.citation: Anal Chem. 1998 Sep 15;70(18):3898-905
references.pmid: 9751028
references.citation: Phys Rev Lett. 2006 Mar 24;96(11):113002
references.pmid: 16605818
references.citation: Nano Lett. 2005 Aug;5(8):1557-61
references.pmid: 16089488
references.citation: Anal Biochem. 2005 Feb 15;337(2):171-94
references.pmid: 15691498
references.citation: J Phys Chem C Nanomater Interfaces. 2007 Dec 11;112(1):18
references.pmid: 20151044
references.citation: J Am Chem Soc. 2004 Oct 6;126(39):12669-76
references.pmid: 15453801
references.citation: Nano Lett. 2007 Jul;7(7):2101-7
references.pmid: 17580926
references.citation: J Phys Chem C Nanomater Interfaces. 2007 Aug 16;111(32):11784-11792
references.pmid: 19890406
references.citation: Photochem Photobiol Sci. 2007 Jan;6(1):13-8
references.pmid: 17200732
references.citation: Acc Chem Res. 2000 Jan;33(1):27-36
references.pmid: 10639073
references.citation: Proc Natl Acad Sci U S A. 1997 Oct 28;94(22):11753-7
references.pmid: 9342306
references.citation: J Phys Chem B. 2004 Aug 1;108(32):12210-12214
references.pmid: 31896953
references.citation: Plasmonics. 2006 Mar 1;1(1):5-33
references.pmid: 19890454
references.citation: Phys Rev Lett. 2006 Jul 7;97(1):017402
references.pmid: 16907406
references.citation: Chem Rev. 1999 Oct 13;99(10):2929-56
references.pmid: 11749506
references.citation: Langmuir. 2006 Nov 7;22(23):9580-5
references.pmid: 17073482
references.citation: J Chem Phys. 2004 Feb 15;120(7):3439-45
references.pmid: 15268501