Understanding the mechanism of cell migration and interaction with the microenvironment is not only of critical significance to the function and biology of cells, but also has extreme relevance and impact on physiological processes and diseases such as morphogenesis, wound healing, neuron guidance, and cancer metastasis. External guidance factors such as topography and physical cues of the microenvironment promote directional migration and can target specific changes in cell motility and signalling mechanisms. Recent studies have shown that cells can directionally respond to applied electric fields (EFs), in both in vitro and in vivo settings, a phenomenon called electrotaxis. However, the exact cellular mechanisms for sensing electrical signals are still not fully well understood, and it is thus far unknown how cells recognize and respond to electric fields, although some studies have suggested that electro-migration of some cell surface receptors and ion channels in cells could be involved. Applied electric fields may have a potential clinical role in guiding cell migration and present a more precise manageability to change the magnitude and direction of the electric field than most other guidance cues such as chemical cues. Here we present a review of recent studies used for studying electrotaxis to point out similarities, identify points of disagreement, and stimulate new directions for investigation. Insights into the mechanisms by which applied EFs direct cell migration, morphological change and development will enable current and future therapeutic applications to be optimized.

In our search for thiophene fluorophores that can overcome the limits of currently available organic dyes in live-cell staining, we synthesized biocompatible dithienothiophene-S,S-dioxide derivatives (DTTOs) that were spontaneously taken up by live mouse embryonic fibroblasts and HeLa cells. Upon treatment with DTTOs, the cells secreted nanostructured fluorescent fibrils, while cell viability remained unaltered. Comparison with the behavior of other cell-permeant, newly synthesized thiophene fluorophores showed that the formation of fluorescent fibrils was peculiar to DTTO dyes. Laser scanning confocal microscopy of the fluorescent fibrils showed that most of them were characterized by helical supramolecular organization. Electrophoretic analysis and theoretical calculations suggested that the DTTOs were selectively recognized by the HyPro component of procollagen polypeptide chains and incorporated through the formation of multiple H-bondings.

Physiological secretion of fluorescent nanostructured microfibers upon spontaneous uptake of the appropriate organic fluorophore by live cells and the effects of cell seeding on the isolated microfibers.