Microbes used to transport microscopic cargoes move more quickly when they have cargo attached than they do on their own.
The unexpected result of a study on the carrying capacity of single-cell amoebas is that. The bacteria function as models for small “trucks” that can transport materials for tiny construction projects or carry medications to precisely target disease inside the human body (SN: 9/30/20).
Researchers used styrene balls varying in size from 10 microns, or about the size of a red blood cell, to 90 microns to examine the cargo capacity of the amoeba Dictyostelium discoideum. The balls, which are only about 10 microns across, spontaneously adhered to the microorganisms’ backs.
The amoebas wander about on their own. In a study that will be published in Physical Review Applied, the researchers find that when a little styrene ball is attached to them, they move more quickly. The research is unsure of the amoebas’ optimal carrying capacity, but they were able to move their cargo at astonishing rates with a load between 30 and 60 microns in diameter.
Biophysicist Carsten Beta of the University of Potsdam in Germany says, “To us, this was surprising.” According to him, the researchers reasoned that the bacteria would spread less effectively as the cargo size increased and would move more slowly with it than without it.
Additionally, Beta and his team discovered that the microorganisms propelled the balls with longer bursts as the balls got bigger. However, the amoebas moved the ball less frequently the bigger it was. The optimal location for cellular trucks, as Beta refers to them, is where relatively significant steps occur regularly enough to hasten the trucks’ journey to delivering supplies like medicine or minuscule construction materials.
According to Beta, “in the end, this will not be done with Dictyostelium cells, but with amoeboid cells that are intrinsically present in the human body,” such white blood cells. The amoebas serve as useful laboratory analogues in the meanwhile.
Bahareh Behkam, a mechanical engineer at Virginia Tech who specialises in cell-based microrobots but was not involved in the work, calls the findings “insightful.” If the particle properties change, it will be intriguing to watch how they might alter.
By examining how the bacteria fare when bearing shapes other than spheres, Beta wants to accomplish that next. Additionally, he wants to control the amoebas’ movements rather than letting them wander aimlessly, potentially by tempting them with chemical trails. Making sure that useful cargo arrives at the appropriate locations will depend on both of these challenges.