RESUMEN
vLUME is a virtual reality software package designed to render large three-dimensional single-molecule localization microscopy datasets. vLUME features include visualization, segmentation, bespoke analysis of complex local geometries and exporting features. vLUME can perform complex analysis on real three-dimensional biological samples that would otherwise be impossible by using regular flat-screen visualization programs.
Asunto(s)
Procesamiento de Imagen Asistido por Computador/métodos , Imagen Individual de Molécula/métodos , Realidad Virtual , Algoritmos , Animales , Células COS , Caulobacter crescentus/química , Línea Celular , Membrana Celular/química , Chlorocebus aethiops , Clatrina/química , Humanos , Células Jurkat , Microtúbulos/química , Poro Nuclear/química , Programas InformáticosRESUMEN
We quantified the electrical polarization properties of single bacterial cells using electrostatic force microscopy. We found that the effective dielectric constant, ε(r,eff), for the four bacterial types investigated (Salmonella typhimurium, Escherchia coli, Lactobacilus sakei, and Listeria innocua) is around 3-5 under dry air conditions. Under ambient humidity, it increases to ε(r,eff) ⼠6-7 for the Gram-negative bacterial types (S. typhimurium and E. coli) and to ε(r,eff) ⼠15-20 for the Gram-positive ones (L. sakei and L. innocua). We show that the measured effective dielectric constants can be consistently interpreted in terms of the electric polarization properties of the biochemical components of the bacterial cell compartments and of their hydration state. These results demonstrate the potential of electrical studies of single bacterial cells.
Asunto(s)
Fenómenos Fisiológicos Bacterianos , Microscopía/métodos , Electricidad EstáticaRESUMEN
Label-free detection of the material composition of nanoparticles could be enabled by the quantification of the nanoparticles' inherent dielectric response to an applied electric field. However, the sensitivity of dielectric nanoscale objects to geometric and non-local effects makes the dielectric response extremely weak. Here we show that electrostatic force microscopy with sub-piconewton resolution can resolve the dielectric constants of single dielectric nanoparticles without the need for any reference material, as well as distinguish nanoparticles that have an identical surface but different inner composition. We unambiguously identified unlabelled ~10 nm nanoparticles of similar morphology but different low-polarizable materials, and discriminated empty from DNA-containing virus capsids. Our approach should make the in situ characterization of nanoscale dielectrics and biological macromolecules possible.
