Cytomimetic Organic Chemistry: Early Developments

This article describes how chemical and physical stimuli cause a simple system, the giant vesicle, to undergo a variety of “cytomimetic” transformations such as fusion, fission, endocytosis, budding, aggregation, birthing, and foraging. For example, when a giant vesicle, which happens to have a smaller vesicle inside it, is exposed to octyl glucoside, the smaller vesicle can pass through the outer membrane into the external medium (“birthing”). The resulting injury to the membrane of the host vesicle heals immediately. Addition of cholic acid, on the other hand, induces a feeding frenzy in which a vesicle grows rapidly as it consumes its smaller neighbors. After the food is gone, the giant vesicle then self‐destructs (a case of “birth, growth, and death”). Such lifelike morphological changes were obtained by using commercially available chemicals; thus these processes should be assigned to organic chemistry, and not to biology or even biochemistry, and not to biology or even biochemistry. Experimental details (e.g. the preparation and observation of the vesicles) are included in this review in hopes of helping others enter this undeveloped field. “How do you make those cells do that?” Little wonder that a visiting scientist to the authors' laboratory mistook the giant vesicles made from commercially available chemicals for cells, since these vesicles undergo the same biological processes (fusion, fission, etc.) as living cells in response to physical or chemical stimuli. The picture on the right shows a giant vesicle “foraging”, during which it “consumes” smaller vesicles in its proximity. Since the large vesicle disintegrates by sequential ejection of lipid molecules when no further small vesicles are available, birth, growth, and death are all observable.