title: Dimethyl-pepep: a DNA probe in two-photon excitation cellular imaging.
abstract: Dimethyl-pepep (D-pepep), a newly developed and very efficient two-photon absorber, has been tested here for two-photon excitation (TPE) cellular imaging. The spectral characteristics of the dye following one-photon excitation (OPE) and TPE (excitation and emission spectra, fluorescence lifetime, molecular brightness, saturation intensity) are reported. In vitro interaction studies with biomolecules show that dimethyl-pepep has a large affinity for DNA. A comparison with a widely used DNA stainer, 4-6-diamidino-2-phenylindole (DAPI) bound to DNA shows that the D-pepep brightness is one order of magnitude higher than that of DAPI, making this dye suitable for microscopy and imaging applications. TPE images taken from double-stained yeast Saccharomyces cerevisiae cells have revealed that D-pepep localizes mainly in the nucleus, similarly to DAPI, and in mitochondria, although to a minor extent. Preliminary tests have shown that the dye cellular toxicity is negligible.
authors.affiliation: Dipartimento di Scienza dei Materiali and INSTM, Università di Milano Bicocca, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Abbotto
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Baldini
authors.forename: Luca
authors.initials: L
authors.lastname: Beverina
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Chirico
authors.forename: Maddalena
authors.initials: M
authors.lastname: Collini
authors.forename: Laura
authors.initials: L
authors.lastname: D'Alfonso
authors.forename: Alberto
authors.initials: A
authors.lastname: Diaspro
authors.forename: Raffaella
authors.initials: R
authors.lastname: Magrassi
authors.forename: Luca
authors.initials: L
authors.lastname: Nardo
authors.forename: Giorgio A
authors.initials: GA
authors.lastname: Pagani
mesh_terms: D004247:DNA / Q000737:chemistry*; D015342:DNA Probes; D005456:Fluorescent Dyes / Q000737:chemistry; D007211:Indoles / Q000737:chemistry; D017785:Photons; D011726:Pyridinium Compounds / Q000737:chemistry*; D011758:Pyrroles / Q000737:chemistry*; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000378:metabolism; D013050:Spectrometry, Fluorescence
chemical_list: C503166:1-methyl-2,5-bis(2-(1-methylpyridinium-4-yl)ethenyl)pyrrole; D015342:DNA Probes; D005456:Fluorescent Dyes; D007211:Indoles; D011726:Pyridinium Compounds; D011758:Pyrroles; C007293:DAPI; D004247:DNA