A list of key recent papers on action potentials and channels in pure lipid interfaces

The following is a list of my key papers on electromechanical waves in pure lipid monolayers, essentially a negative control for Hodgkin and Huxley based description of Action Potentials (AP) (without channel, pumps and chemical gradient). (posted previously as tweets)1/18

The observed electromechanical waves propagate as sound and not via ions and behave exactly like action potentials near a nonlinearity in the state diagram of the monolayer, e.g. due to a phase transition. 2/18

Also, some key control experiments from my colleagues related to channel and synapse activity are included that show how all these phenomena are related by the state (compressibility, heat capacity, etc.) of the system in a top down manner. 3/18

Fluorescent dyes in monolayer act as a thermodynamic observable of the system, intensity changes predictably as a function of pressure, temperature and surface potential, forming the basis for later papers on AP like sound waves (2013). http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0067524 4/18

First evidence of biphasic, solitary, all-or-none, electromechanical sound waves in a lipid monolayer (2014) http://rsif.royalsocietypublishing.org/content/11/97/20140098 5/18

My PhD thesis, presenting a concise story (2014), including many unpublished experiments, on the effect of pressure, temperature, lipid, cholesterol, headgroup charge, confined geometry, collision of subthreshold pulses.https://open.bu.edu/handle/2144/11049 6/18

Further characterisation of nonlinear waves, going deeper in to the thermodynamic origin of threshold and saturation and its relation to phase transitions and the equation of state (2015). https://journals.aps.org/pre/abstract/10.1103/PhysRevE.91.012715 7/18

Evidence that soundwaves in monolayer also couple to local pH, resulting pH waves that propagate at the speed of sound and not via diffusion (2016). https://www.nature.com/articles/srep22874 8/18

Numerical solution for the corresponding system of hydrodynamic equations derived from first principles. Explains observed pulses nonlinear fractional waves without fit parameters (2017). https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.2.114804 9/18

Evidence that observed AP like sound waves also annihilate upon head-on collision (2018), a property generally assumed to be not accessible to sound waves that led to much criticism when the acoustic hypothesis was proposed initially. http://rsif.royalsocietypublishing.org/content/15/143/20170803 10/18

Colleagues on how current fluctuations in pure lipid bilayers appear exactly like ion channels near phase transitions, and how their activity is predicted by a top-down approach starting from heat capacity and compressibility (2009). https://www.cell.com/biophysj/abstract/S0006-3495(09)00663-8 11/18

From colleagues (2016), “Herein, the widespread assumption of inactivity of ACh’s hydrolysis products at synapses is falsified.” Shows how APs in Chara cells are excited by protons, https://www.ncbi.nlm.nih.gov/pubmed/25874591 the work parallels pH waves mentioned above and in the next tweet. 12/18

Evidence from colleagues that acoustically propagating pH waves in a lipid monolayer are coupled to the local enzymatic activity of acetylcholine esterase embedded in the lipid monolayer (2018). https://pubs.acs.org/doi/abs/10.1021/acs.langmuir.7b01613 13/18

My “extended” preprint on how detonation can explain channeling of local chemical reaction, including energy stored in transmembrane electrochemical gradient into interfacial sound waves, and how channel activity can excite sound waves. https://arxiv.org/abs/1802.00294 14/18

Another preprint with insight on how local acoustic perturbation of lipid membrane, can change the solvation and energy spectra of embedded fluorescent probes, a potential mechanism for how sound affects channel and enzyme activity in membranes. https://arxiv.org/abs/1612.06709 15/18

My approach to the phenomenon of nerve impulse is based on principles as espoused by Einstein instead of constructive elements, like in H&H https://medium.com/@Shamits/applying-einstein-s-scientific-philosophy-to-biological-physics-a-revolution-waiting-to-happen-45018cec02b2. Instead of reasoning inductively starting from molecular models, I reason deductively starting from the thermodynamic state. 16/18

For every existing observation in excitable membrane, including the effects of ions, toxins, anesthetics, drugs, light, sound, pressure, temperature, etc. we ask how these forces cause a change in the thermodynamic state. 17/18

Then starting from the new thermodynamic state one can derive changes in microscopic (channels and enzymes) and macroscopic (pulse characteristics) properties of the membrane. 18/18

Biophysics of sound in membranes and its applications. Post Doctoral Researcher, Engineering Sciences, University of Oxford, UK www.shamits.org

Biophysics of sound in membranes and its applications. Post Doctoral Researcher, Engineering Sciences, University of Oxford, UK www.shamits.org