Mikael Käll

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Quantification of protein abundance and subcellular localization dynamics from fluorescence microscopy images is of high contemporary interest in cell and molecular biology. For large-scale studies of cell populations and for time-lapse studies, such quantitative analysis can not be performed effectively without some kind of automated image analysis tool.(More)
We utilized the nuclear localization of a stress-sensitive transcription factor, Msn2p, to study light-induced stress caused by time-lapse fluorescence imaging of green fluorescent protein (GFP) in budding yeast Saccharomyces cerevisiae. A range of exposure times, light intensities and intervals between exposures were tested in order to provide guidelines(More)
The optical responses of 75-150 nm diameter gold nanorings to changes in local refractive index have been quantified by near-infrared extinction spectroscopy and compared to DDA calculations and an analytical approach. The "bulk" refractive index sensitivities of gold nanorings are substantially (>5 times) larger than those of nanodisks with similar(More)
We studied scattering and extinction of individual silver nanorods coupled to the J-aggregate form of the cyanine dye TDBC as a function of plasmon--exciton detuning. The measured single particle spectra exhibited a strongly suppressed scattering and extinction rate at wavelengths corresponding to the J-aggregate absorption band, signaling strong(More)
The optical response of ring-shaped gold nanoparticles prepared by colloidal lithography is investigated. Compared to solid gold particles of similar size, nanorings exhibit a redshifted localized surface plasmon that can be tuned over an extended wavelength range by varying the ratio of the ring thickness to its radius. The measured wavelength variation is(More)
The vacuolar/endosomal network has an important but as yet undefined role in the cellular tolerance to salt stress. We hypothesized that the mechanistic basis for the importance of vacuolar protein sorting (vps) components in salt tolerance is the targeting of the crucial sodium exporter Ena1p to the plasma membrane. The link between Ena1p and the vps(More)
The effect of diffractive coupling on the collective plasmon line shape of linear arrays of Ag nanoparticles fabricated by electron beam lithography has been investigated using Rayleigh scattering spectroscopy. The array spectra exhibit an intricate multi-peak structure, including a narrow mode that gains strength for interparticle distances that are close(More)
Light in the visible range can be stressful to non-photosynthetic organisms. The yeast Saccharomyces cerevisiae has earlier been reported to respond to blue light via activation of the stress-regulated transcription factor Msn2p. Environmental changes also induce activation of calcineurin, a Ca/calmodulin dependent phosphatase, which in turn controls gene(More)
We show that the plasmon resonances of a metallic nanoparticle interacting with the surface plasmons of a metallic film is an electromagnetic analogue of the spinless Anderson-Fano model. This is the same model used to describe the interaction of a localized electronic state with a continuous band of electronic states. The three characteristic regimes of(More)
We present a simple and robust scheme for biosensing with an ultralow limit-of-detection down to several pg cm(-2) (or several tens of attomoles cm(-2)) based on optical label-free biodetection with localized surface plasmon resonances. The scheme utilizes cost-effective optical components and comprises a white light source, a properly functionalized sensor(More)