title: Imaging of cancer cells by multiphoton microscopy using gold nanoparticles and fluorescent dyes.
abstract: Due to their unique optical properties, optical probes, including metal nanoparticles (NPs) and fluorescent dyes, are increasingly used as labeling tools in biological imaging. Using multiphoton microscopy and fluorescence lifetime imaging (FLIM) at 750-nm excitation, we recorded intensity and FLIM images from gold NPs (30 nm) and the fluorescent dye Alexa 488 (A488) conjugated with monoclonal ACT-1 antibodies as well as Hoechst 33258 (H258) after incubation with the lymphoma cell line (Karpas-299). From the FLIM images, we can easily discriminate the imaging difference between cells and optical probes according to their distinct fluorescence lifetimes (cellular autofluorescence: 1 to 2 ns; gold NPs: <0.02 ns; A488: 3.5 ns; H258: 2.5 ns). The NP-ACT-1 and A488-ACT-1 conjugates were bound homogeneously on the surface of cells, whereas H258 stained the cell nucleus. We demonstrate that the emission intensity of gold NPs is about ten times stronger than that of the autofluorescence of Karpas-299 cells at the same excitation power. Compared with fluorescent dyes, stronger emission is also observed from gold NPs. Together with their high photostability, these observations suggest that gold NPs are a viable alternative to fluorescent dyes for cellular imaging and cancer diagnosis.
authors.affiliation: Xi'an Jiaotong University, The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, Institute of Biomedical Analytical Technology and Instrumentation, School of Life Science and Technology, Xi'an 710049, China.
authors.forename: Xiaochao
authors.initials: X
authors.lastname: Qu
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Zhenxi
authors.initials: Z
authors.lastname: Zhang
authors.forename: Norbert
authors.initials: N
authors.lastname: Koop
authors.forename: Ramtin
authors.initials: R
authors.lastname: Rahmanzadeh
authors.forename: Gereon
authors.initials: G
authors.lastname: Hüttmann
mesh_terms: D045744:Cell Line, Tumor; D003287:Contrast Media; D005456:Fluorescent Dyes; D006046:Gold; D006801:Humans; D006834:Hydrazines; D007089:Image Enhancement / Q000379:methods*; D008223:Lymphoma / Q000473:pathology*; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D053758:Nanoparticles / Q000648:ultrastructure
chemical_list: C417561:Alexa 488 hydrazide; D003287:Contrast Media; D005456:Fluorescent Dyes; D006834:Hydrazines; D006046:Gold