The Research Center for Advanced Science and Technology and The Institute of Industrial Science at The University of Tokyo scientists have used a new computer simulation to model the electrostatic self-organization of zwitterionic nanoparticles. These are useful for drug delivery. They found that including transient charge fluctuations greatly increased the accuracy. It will help lead to the development of new self-assembling smart nanomaterials.
Janus was the god of both beginnings and endings, in ancient Roman mythology. His dual nature was often reflected in his depiction with two faces. He also lends his name to so-called Janus particles. These are nanoparticles that contain two or more distinct physical or chemical properties on their surface. One promising “two-faced” solution uses zwitterionic particles. These are spheres with a positively charged side and a negatively charged side. Researchers hope to create self-organizing structures. These can be activated by changes in a solution’s salt concentration or pH. This kind of “bottom-up” engineering requires more accurate computer simulations to implement.
Scientists have created a new computer model that incorporates transient fluctuations in the change distributions on the surface of the particles that can give rise to a wider variety of structures.
Scientists showed that the previous method of assuming each of the particles carries a constant charge can give inaccurate results. The computer needed to include short-lived fluctuations in surface charge, to simulate the possible transition to compact clusters. These differences are particularly noticeable at low salt concentration and high electrostatic coupling strength.
Proteins fold into very specific shapes based in large part on the attraction between the positively and negatively charged regions. Artificially designed particles may be able to self-assemble when triggered by a change in conditions.