Transport of soft materials in crowded environment

Abstract

Fluorescent microscopy was used to study the transport of soft material objects in crowded environment. Delaunay triangulation and wavelet transform were adapted to extract more information from images of macromolecules with irregular shapes and heterogeneous transportation dynamics. Systems studied are actively transported endosomes in living cells, and diffusing semi-flexible polymer chains in rigid networks. By going beyond traditional particle tracking and trajectory analysis, it was discovered that for protein transportation rather than directing the protein-containing endosomes steadily towards intended destination with regulatory mechanisms as commonly believed, efficient random search is an alternative mechanism that can offer both high energy efficiency and delivery accuracy. The imaging study of double-stranded DNA molecules in actin and agarose gel showed that the popular mental image of a snake sliding back and forth may not be how polymers actually reptate. The application of advanced analytical tools to high resolution microscopy images of dynamic systems is expected to lead to the discoveries of many more new mechanisms and concepts