Multiscale Modelling of Biomembrane Interactions with Nano-Objects

Recent advances in the available experimental techniques to synthesize nanoscale objects (nanoparticles, nanotubes, fullerens, dendrimers) from a variety of starting materials and with a well controlled geometry, size distribution and surface chemistry have opened up new and unprecedented opportunities for using these nanoscale objects for drug delivery, imaging and as antimicrobial agents. The current principal goal is to develop an ability to design nano-objects with programmable functionalities. This requires a fundamental understanding of how nano-objects interact with cell membranes. Gaining this understanding is also important in the context of the potential toxicity of nano-objects and the mechanisms with which they can disrupt the integrity of the cell membrane. Despite a number of recent experimental studies reporting a variety of interaction mechanisms, which depend on the morphology of nano-objects (size, shape), as well as on the characteristics of the environment, the overall picture is incomplete and lacks consistency to offer any concrete design principles. A more systematic description of how nano-objects interact with biological membranes can be constructed with the aid of theoretical modelling and computer simulations. The principle challenge for the conventional atomistic simulations, however, is the characteristic time and length scales of biomolecular processes. For example, engulfing of a nanoparticle by a cell membrane may take microseconds to complete, with profound structural reorganization of the membrane taking place on a length scale of tens and hundreds of nanometers. These time and length scales are not routinely attainable within a typical atomistic-level computer simulation. Furthermore, translocation of a nanoparticle through a cell membrane is a complex process, involving a number of individual steps. These steps occur on very different time and length scales. Thus, to describe this translocation process in its full complexity requires an appropriate multiscale approach that systematically links different scales and levels of the system representation to each other. This special issue of Current Nanoscience is dedicated to the application of multiscale modelling approaches to biomembrane interactions with different types of nano-objects. Nine groups of experts in this field have been invited to present their recent work and share their views on further development and potential applications of the multiscale models. The contributed articles span a wide range of structures with which membranes interact (from structured supports to fullerenes to nanoparticles and nanotubes to proteins), methodologies (coarse-grained models, dissipative particle dynamics, mean field theories) and scales at which the systems are explored. It was a truly rewarding experience to prepare this issue, and I hope the readers of the Current Nanoscience will also find it very useful. I would like to thank Prof. Randy Snurr for suggesting that I put this issue together, and, of course, all the contributors and the reviewers for their diligent effort and timely responses.