title: Oscillations of Bubble Shape Cause Anomalous Surfactant Diffusion: Experiments, Theory, and Simulations.
abstract: We investigate, both theoretically and experimentally, the role played by the oscillations of the cell membrane on the capture rate of substances freely diffusing around the cell. To obtain quantitative results, we propose and build up a reproducible and tunable biomimetic experimental model system to simulate the phenomenon of an oscillation-enhanced (or depressed) capture rate (chemoreception) of a diffusant. The main advantage compared to real biological systems is that the different oscillation parameters (type of deformation, frequencies, and amplitudes) can be finely tuned. The model system that we use is an anchored gas drop submitted to a diffusive flow of charged surfactants. When the surfactant meets the surface of the bubble, it is reversibly adsorbed. Bubble oscillations of the order of a few nanometers are selectively excited, and surfactant transport is accurately measured. The surfactant concentration past the oscillating bubbles was detected by conductivity measurements. The results highlight the role of surface oscillations on the diffusant capture rate. Particularly unexpected is the onset of intense overshoots during the adsorption process. The phenomenon is particularly relevant when the bubbles are exposed to intense forced oscillations near resonance.
authors: Antonio
authors: A
authors: Raudino
authors: Domenica
authors: D
authors: Raciti
authors: Antonio
authors: A
authors: Grassi
authors: Department of Physics, Carnegie Mellon University , 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213, United States.
authors: Martina
authors: M
authors: Pannuzzo
authors: Institute for Chemical and Physical Processes (IPCF), National Research Council (CNR) , Viale Ferdinando Stagno d'Alcontres 37, 98158 Messina, Italy.|Advanced Technology Interdisciplinary Laboratory (LITA), University of Milan , Via Fratelli Cervi 93, 20090 Segrate, Milano, Italy.
authors: Mario
authors: M
authors: Corti