Concluding remarks Back to the future: mechanics and thermodynamics of lipid biomembranes

Abstract

To some extent, Faraday Discussion 161 on Lipids andMembrane Biophysics is an off spring of the earlier Faraday Discussion 81 on Lipid Vesicles and Membranes in 1986, as brought to our attention by John Nagle in his Introductory Lecture. Yet, in my view, Discussion 161 has been far more polished in its content—revealing novel materials and challenging experiments, new instrumentation and computational methods—with very well organized presentations (plus posters). Personally, I was wowed by every 5 min abstract of a paper—all were succinct and each set the stage for a well balanced 25 min period of discussion. On the other hand, with the notable exception of an excellent Introductory Lecture and within the caveat of my failing memory, it seemed to me that there was less focus on the underlying physics of membranes than in Discussion 81. At the same time, there was more attention, in my opinion, than needed to the parochial issue of ‘‘raft–lipid membranes’’. Also, I was left with an uncertain feeling about whether coarse-graining in molecular-scale simulations will manage (in my lifetime) to completely fulfil its agonizing quest for ‘‘material reality’’. Beyond this hubris, I feel unqualified to pick and choose amongst the 24 excellent Discussion papers to praise or criticize. Instead, the objective of my Concluding remarks will be to expand on/add to the membrane biophysics emphasized in John Nagle’s Introductory Lecture which, although well appreciated by the ‘‘old guard’’, was perhaps too esoteric for many of the bright ‘‘new comers’’ to the subject. In particular, my aim is to provide some additional background, a kind of classroom ‘‘tutorial’’, regarding important mechanical and thermodynamic features of vesicle bilayers, lore established over the past two decades since Discussion 81. At the same time, I want to highlight some new directions in the biophysics of membranes suggested by these insights. My intent is not to give a balanced review of the literature. Rather, I have chosen references that have played seminal roles in the developments I will describe. I dedicate this paper to our dear friend Myer Bloom, soon to be 84 years of age (07/12/2012)—ever bright in mind, even though encumbered by Parkinson’s disease. Also, I want to express my sincere thanks to the Organizing Committee for the opportunity to participate in Faraday Discussion 161 and for the hospitality shown by their wonderful RSC associates. Evan Evans