Tracking single particle

Kasumi A, Sako Y, Yamamoto M (1993) Confined lateral diffusion of membrane receptors as studied by single particle tracking (nanovid microscopy. Effects of calcium-induced differentiation in cultured epithelial cells. Biophys J 65 2021-2040... 

Single-particle tracking of endocytosis and exocytosis of single-walled carbon nanotubes in NIH-3T3 cells. Nano Letters, 8 (6), 1577-1585. 

Daumas, F., Destainville, N., Millot, C., Lopez, A., Dean, D. and Salome, L. Confined diffusion without fences of a G-protein-coupled receptor as revealed by single particle tracking. Biophys. J. 84 356-366, 2003. 

Members of the Caliciviridae family can hardly be examined in cell culture or animal models. Therefore, so-called virus-Hke particles (VLP) are employed in current experiments. These particles are expressed recombinantly in insect cells using a baculovirus system and do not carry infectious viral RNA [70-72]. It has been shown by single particle tracking studies that VLPs are internalized into the cells in a similar fashion to native viruses [73]. VLPs are believed to present identical molecular recognition elements to the outside world as do native viruses. 

Another technique, single particle tracking, allows one to follow the movement of a single lipid molecule in the plasma membrane on a much shorter time scale. Results from these studies confirm the rapid lateral diffusion within small, discrete regions of the cell sur-... 

Visualizing Uptake and Intracellular Trafficking of Gene Carriers by Single-Particle Tracking... 

Keywords DNA/RNA transfection, Fluorescence wide-field microscopy, Gene carriers, Gene therapy, Single-particle tracking, Trajectory analysis... 

Single-Particle Tracking of Gene Carrier Internalization. 290... 

Fig. 1 Schematic drawing of a wide-field single-particle tracking fluorescence microscope equipped. Several lasers are used as excitation source for different fluorophores with fast selection hy an acousto-optical tunable filter (AOTF). The collimated laser light is coupled into the objective such that only the observed area is illuminated. The emission light is separated from the excitation light by a dichroic mirror. In the case of multi-color imaging, the emission light is separated by...

This is in contrast to viruses, where the virus particles also show active transport when present in the cytosol after fusion with the plasma membrane or endosomal membrane [60-62], This is due to the ability of specific proteins of the virus particle to bind motor proteins. Single-particle tracking reveals that the quantitative intracellular transport properties of internalized non-viral gene vectors (e.g., polyplexes) are similar to that of viral vectors (e.g., adenovirus) [63]. Suk et al. showed that over 80% of polyplexes and adenoviruses in neurons are subdiffusive and 11-13% are actively transported. However, their trafficking pathways are substantially different. Polyplexes colocalized with endosomal compartments whereas adenovirus particles quickly escaped endosomes after endocytosis. Nevertheless, both exploit the intracellular transport machinery to be actively transported. 

Single-particle tracking in real rime is a powerful technique to follow the entry pathway of gene carriers as well as their intracellular fate in great detail. The development of nanoparticles as gene carriers will continue and further functionalities such as specihc targeting, redox- or pH-sensitivity, etc., will be added. This will lead to even smarter carrier systems [76]. Such systems are constructed to... 

Saxton MJ, Jacobson K (1997) Single-particle tracking applications to membrane dynamics. Annu Rev Biophys Biomol Struct 26 373-399... 

Qian H, Sheetz MP, Elson EL (1991) Single particle tracking. Analysis of diffusion and flow in two-dimensional systems. Biophys J 60 910-921... 

Sauer AM, de Bruin KG, Ruthardt N, Mykhaylyk O, Plank C, Brauchle C (2009) Dynamics of magnetic lipoplexes studied by single-particle tracking in living cells. J Control Release 137 136-145... 

Katayama Y, Burkacky O, Meyer M, Brauchle C, Gratton E, Lamb DC (2009) Real-time nanomicroscopy via three-dimensional single-particle tracking. Chemphyschem 10 2458-2464... 

Finally, Ruthardt andBraeuchle summarize recent findings, describing transfection pathways of non-viral gene carriers by single particle tracking approaches. This approach allows the detailed identification of potential hurdles for efficient nucleic acid delivery from a single cell viewpoint. 

Although not using a 3-D tracking, we have to mention the works related to single-particle tracking devices for such special purposes as motion in a flow or in an electric field. 

For the motion of particles submitted to an electric field we have described in the last section a single particle tracking method that allows one to determine the zeta potential. Nevertheless, if we want to have some statistics on this measurement, the selection and data recording for one particle can take typically between one and two minutes, which makes a determination on one... 

Single-particle tracking of colloidal particles is a direct way to obtain the size and the surface properties (roughness, zeta potential) of particles. 

Interestingly, the diffusional behavior of membrane proteins measured experimentally by FRAP, FCS, or single particle tracking in cells is more complex than predicted by this model. This technique is described best for the case of cell surface proteins, as assessed by FRAP. Such measurements indicate that diffusion is typically much slower than one would expect based on membrane viscosity. In cell membranes, typical values of D for transmembrane proteins are approximately 0.05 pm /s or less, which is much slower than observed in artificial membranes composed of purified lipids. In addition, a significant fraction of proteins is often immobile over the timescale of diffusion experiments (4, 5). Furthermore, diffusional mobilities vary among proteins, and sometimes they differ for the same protein expressed in different cell lines (4, 5). Deviations from pure diffusion are more readily apparent when the trajectories... 

Figure 1 Modes of diffusion of individual membrane proteins as revealed by single-molecule tracking techniques. The hypothetical trajectory of an individual plasma membrane protein as traced by single-particle tracking techniques is shown. An individual protein can switch between several different modes of over time, which include confined diffusion (region 1), free diffusion (region 2), and immobilization (region 3).

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