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We present the first demonstration of fluorescence correlation spectroscopy (FCS) using superconducting nanowire single-photon detectors (SSPDs) which are free of afterpulses unlike the avalanche photodiode (APD). Multimode-fiber-coupled SSPDs with high system detection efficiency for visible wavelengths were developed and implemented in the FCS system. We(More)
Conventional polarization-dependent fluorescence correlation spectroscopy (pol-FCS) requires two sets of photon detectors to eliminate after-pulse noises (dual-channel pol-FCS; DC-pol-FCS) in the sub-microsecond range. In this study, we successfully realized pol-FCS using a visible-wavelength superconductive nanowire single-photon detector (single-channel(More)
Fluorescent proteins have been widely used in biology because of their compatibility and varied applications in living specimens. Fluorescent proteins are often undesirably sensitive to intracellular conditions such as pH and ion concentration, generating considerable issues at times. However, harnessing these intrinsic sensitivities can help develop(More)
Glucocorticoid receptor α (GR) binds to the promoter regions of target genes as a homodimer and activates its transcriptional process. Though the homodimerization is thought to be the initial and essential process, the dissociation constant for homodimerization of GR remains controversial. To quantify homodimerization of (enhanced green fluorescence(More)
Rotational diffusion measurement is predicted as an important method in cell biology because the rotational properties directly reflect molecular interactions and environment in the cell. To prove this concept, polarization-dependent fluorescence correlation spectroscopy (pol-FCS) measurements of purified fluorescent proteins were conducted in viscous(More)
Glucocorticoid receptor (GRα) is a well-known ligand-dependent transcription-regulatory protein. The classic view is that unliganded GRα resides in the cytoplasm, relocates to the nucleus after ligand binding, and then associates with a specific DNA sequence, namely a glucocorticoid response element (GRE), to activate a specific gene as a homodimer. It is(More)
Quantum dot (QD) and quantum rod (QR) nanocrystals are widely used non-organic nanocrystals. Their strong fluorescence and photostability make them suitable for biomedical imaging applications. However, their pH-dependence and antibunching properties have not been studied much, especially in aqueous conditions. In this report, we used fluorescence(More)
Reducing intracellular DNA degradation is critical to enhance the efficiency of gene therapy. Exogenous DNA incorporation into cells is strictly blocked by the defense machinery of intracellular nuclease activity. Raster image correlation spectroscopy (RICS) and raster image cross-correlation spectroscopy (cross-correlation RICS; ccRICS) are image-based(More)
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