Morphological and topological transformation of membrane vesicles

Controlled Construction of Stable Network Structure Composed of Honeycomb-Shaped Microhydrogels

Recently, the construction of models for multicellular systems such as tissues has been attracting great interest. These model systems are expected to reproduce a cell communication network and provide insight into complicated functions in living systems./Such network structures have mainly been modelled using a droplet and a vesicle. However, in the droplet and vesicle network, there are difficulties attributed to structural instabilities due to external stimuli and perturbations. Thus, the fabrication of a network composed of a stable component such as hydrogel is desired. In this article, the construction of a stable network composed of honeycomb-shaped microhydrogels is described. We produced the microhydrogel network using a centrifugal microfluidic technique and a photosensitive polymer. In the network, densely packed honeycomb-shaped microhydrogels were observed. Additionally, we successfully controlled the degree of packing of microhydrogels in the network by changing the centrifugal force. We believe that our stable network will contribute to the study of cell communication in multicellular systems.

A physical model of axonal damage due to oxidative stress

Oxidative damage is implicated in the pathogenesis of neurodegenerative disorders, including Alzheimer's, Parkinson's, and Huntington's diseases, and in normal aging. Here, we model oxidative stress in neurons using photogenerated radicals in a simplified membrane-encapsulated microtubule system. Using fluorescence and differential interference contrast microscopies, we monitor photochemically induced microtubule breakdown on the supported region of membrane in encapsulating synthetic liposomes as a function of lipid composition and environment. Degradation of vesicle-encapsulated microtubules is caused by attack from free radicals formed upon UV excitation of the lipid-soluble fluorescent probe, 6-(9-anthroyloxy)stearic acid. Probe concentration was typically limited to a regime in which microtubule degradation was slow, and microtubule degradation was monitored by changes in the observed protrusion of the membrane surface. The kinetics of microtubule degradation are influenced by lipid saturation level, fluorescent probe concentration, and the presence of free-radical scavengers. This system is sufficient to reproduce some degenerative morphologies found in vivo.