Cicada wing-like nanopatterned surfaces can kill bacteria on contact based on their physical surface structure.

We present a quantitative thermodynamic model to elucidate the effects of a nanopatterned surface on bacterial adhesion. Based on the established model, we studied the equilibrium state of rodlike bacterial cells adhered to a nanopillar-patterned surface. Theoretical analyses showed the physical origin of bacterial adhesion on a nanopatterned surface is actually determined by the balance between adhesion energy and deformation energy of the cell membrane. We found that there are enhancement effects on bacterial adhesion to the patterned surface with large radius and small spacing of nanopillars, but suppression effects for nanopillars with a radius smaller than a critical value. In addition, according to our model, a phase diagram has been constructed which can clarify the interrelated effects of the radius and the spacing of nanopillars. The broad agreement with experimental observations implies that these studies would provide useful guidance to the design of nanopatterned surfaces for biomedical applications.

The effects of geometry and surface density distribution of nanopillars on cell adhesion studied by a quantitative thermodynamic model showed that high (low) surface distribution density and large (small) radius result in the “Top” (“Bottom”) mode.

Creating and manipulating materials at the nanoscale with controllable size, shape and nucleation site is an important task to meet the urgent demands for quantum structures with designed properties. In the last ten years, droplet epitaxy has been emerging as a versatile fabrication method for various complex nanostructures, such as quantum dots, quantum rings, double-rings, and so on. However, there is a lack of understanding of the deep nanohole formation based on droplet epitaxy at a high substrate temperature. Here we fabricate self-organized GaAs nanoholes by Ga droplet etching at high temperature based on droplet epitaxy, and they present good optoelectronic properties and have promising applications in fabrication of nanodevices due to their unique topology. A theoretical model is correspondingly proposed to explain the basic mechanism and simulate the time evolution of the nanohole structures. Our analysis shows that the morphology of the nanohole nanostructures can be well controlled through regulating experimental conditions.

We present a thermodynamic approach to elucidate the effects of the size and shape of nanoparticles (NPs) on endocytosis. It is found that endocytosis needs to surmount a thermodynamic energy barrier and has a minimum radius of NPs for endocytosis. Through referring to the concept of “diffusion length of receptors,” we obtain a simple and analytical expression for the optimal size of NPs. Furthermore, a phase diagram has been constructed, which can clarify the interrelated effects of the radius and the aspect ratio of NPs. We can identify from the phase the relation between the geometry of NP and its endocytosis rate. The theoretical results are in good agreement with the experimental observations and reveal physical mechanisms involved in the effects of the size and shape of NPs on endocytosis, which implies that these studies may provide useful guidance to the conscious design of NPs for diagnostic agents and drug delivery applications.