There is a large number of two‐dimensional static in vitro studies about the uptake of colloidal nano‐ and microparticles, which has been published in the last decade. In this Minireview, different methods used for such studies are summarized and critically discussed. Supplementary experimental data allow for a direct comparison of the different techniques. Emphasis is given on how quantitative parameters can be extracted from studies in which different experimental techniques have been used, with the goal of allowing better comparison.

Ion channels of excitable membranes are known to be sensitive to various kinds of stimuli, but the case of simultaneous occurrence of different stimuli is poorly understood. Here, we theoretically analyze the influence of membrane tension on the dynamics of voltage-gated ion channels of excitable membranes. To do so, we develop a modification of the well-known Hodgkin-Huxley model to study numerically the spike generation and propagation in a single and two coupled excitable cells. We find that these cells can use membrane tension to trigger sub-threshold spike propagation, to suppress spike propagation and to alter the intensity of the signal transmission. These effects indicate that cells could use membrane tension to regulate cell-to-cell communication.

Intracellular cargos that are transported by groups of molecular motors often display bidirectional movement. This can be seen experimentally by tracking the trajectories of individual cargos in vivo. Typically, the cargo trajectories display many turning events that result from the stochastic nature of the involved motor processes. In this paper, we simulate cargo trajectories for different binding mechanisms. We introduce a series of statistical tools to analyze and quantitatively characterize these trajectories. As we demonstrate for specified single-motor properties, the novel statistical methods allow us to quantitatively distinguish between different models for bidirectional transport. In this way, the tools provide a quantitative connection between the statistical properties of the cargo trajectories and the molecular properties of the motor proteins. Such methods are also applicable to experimentally measured cargo trajectories and should be helpful in elucidating the mechanisms that lead to bidirectional transport.

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