ABSTRACT
We describe a novel two-photon fluorescence microscopy system capable of producing high-quality second harmonic generation (SHG) images in thick turbid media by using an innovative detection system. This novel detection system is capable of detecting photons from a very large surface area. This system has proven effective in providing images of thick turbid samples, both biological and artificial. Due to its transmission detection geometry, the system is particularly suitable for detecting SHG signals, which are generally forward directed. In this article, we present comparative data acquired simultaneously on the same sample with the forward and epidetection schemes.
Subject(s)
Microscopy, Fluorescence, Multiphoton/methods , Optical Imaging/methods , Animals , Collagen Type I , Mice, Inbred C57BL , Muscle Fibers, Skeletal/ultrastructure , Optical Phenomena , Photons , SiliconesABSTRACT
The depth of two-photon fluorescence imaging in turbid media can be significantly enhanced by the use of the here described fluorescence detection method that allows to efficiently collect scattered fluorescence photons from a wide area of the turbid sample. By using this detector we were able to perform imaging of turbid samples, simulating brain tissue, at depths up to 3 mm, where the two-photon induced fluorescence signal is too weak to be detected by means used in conventional two-photon microscopy.
Subject(s)
Diagnostic Imaging/methods , Microscopy, Fluorescence, Multiphoton/methods , Nephelometry and Turbidimetry/methods , Agar/chemistry , Brain/pathology , Brain/ultrastructure , Breast Neoplasms/pathology , Breast Neoplasms/ultrastructure , Cell Line, Tumor , Computer Simulation , Diagnostic Imaging/instrumentation , Female , Gelatin/chemistry , Humans , Microscopy, Fluorescence, Multiphoton/instrumentation , Microspheres , Models, Biological , Nephelometry and Turbidimetry/instrumentation , Scattering, Radiation , Silicon/chemistryABSTRACT
The photochemical redox reaction kinetics of [M(III)(C(2)O(4))(3)](3-) [M = Co, Fe] complexes have been reexamined and studied by time-resolved spectroscopy. The redox mechanisms of the two systems, Co and Fe, were found to be similar to each other, and solvated electrons were observed immediately after 266/267 nm photoexcitation. A reaction mechanism is proposed that involves photoelectron detachment as a primary process. The charge-transfer bands for both complexes, which had been attributed to ligand to metal charge-transfer (LMCT) transitions previously, are reassigned to charge transfer to solvent (CTTS) transitions.
Subject(s)
Cobalt/chemistry , Ferric Compounds/chemistry , Solvents/chemistry , Electrons , Kinetics , Oxidation-Reduction , Photochemistry , Spectrum AnalysisABSTRACT
An 800-nm 200-fs laser is used to produce DNA damage in rat kangaroo (PtK1) and human cystic fibrosis pancreatic adenoma carcinoma (CFPAC-1) cells. Immunofluorescence staining for DNA repair factors in irradiated cells displays localization of gammaH2AX, Nbs1, and Rad50 to the site of irradiation 3 to 30 min following laser exposure. It is concluded that the 200-fs near-infrared laser is an excellent source for the production and study of spatially defined regions of DNA damage.
