Performance of single nanopore and multi-pore membranes for blue energy.

The salinity gradient power extracted from the mixing of electrolyte solutions at dierent concentrations through selective nanoporous membranes is a promising route to renewable energy. However, several challenges need to be addressed to make this technology protable, one of the most relevant being the increase of the extractable power per membrane area. Here, the performance of asymmetric conical and bullet-shaped nanopores in a 50 nm thick membrane are studied via electrohydrodynamic simulations, varying the pore radius, curvature, and surface charge. The output power reaches ∼ 60 pW per pore for positively charged membranes (surface charge σw =160 mC/m2 ) and ∼ 30 pW for negatively charges ones, σw =-160 mC/m2 and it is robust to minor variations of nanopore shape and radius. A theoretical argument that takes into account the interaction among neighbour pores allows to extrapolate the single-pore performance to multi-pore membranes showing that power densities from tens to hundreds of W/m2 can be reached by proper tuning of the nanopore number density and the boundary layer thickness. Our model for scaling single-pore performance to multi-pore membrane can be applied also to experimental data providing a simple tool to effectively compare different nanopore membranes in blue energy applications.

Controlling Electroosmosis in Nanopores Without Altering the Nanopore Sensing Region.

Nanopores are powerful tools for single-molecule sensing of biomolecules and nanoparticles. The signal coming from the molecule to be analyzed strongly depends on its interaction with the narrower section of the nanopore (constriction) that may be tailored to increase sensing accuracy. Modifications of nanopore constriction have also been commonly used to induce electroosmosis, that favors the capture of molecules in the nanopore under a voltage bias and independently of their charge. However, engineering nanopores for increasing both electroosmosis and sensing accuracy is challenging. Here it is shown that large electroosmotic flows can be achieved without altering the nanopore constriction. Using continuum electrohydrodynamic simulations, it is found that an external charged ring generates strong electroosmosis in cylindrical nanopores. Similarly, for conical nanopores it is shown that moving charges away from the cone tip still results in an electroosmotic flow (EOF), whose intensity reduces increasing the diameter of the nanopore section where charges are placed. This paradigm is applied to engineered biological nanopores showing, via atomistic simulations and experiments, that mutations outside the constriction induce a relatively intense electroosmosis. This strategy provides much more flexibility in nanopore design since electroosmosis can be controlled independently from the constriction, which can be optimized to improve sensing accuracy.

Conical nanopores highlight the pro-aggregating effects of pyrimethanil fungicide on Aß(1-42) peptides and dimeric splitting phenomena.

The Aß(1-42) aggregation is a key event in the physiopathology of Alzheimer's disease (AD). Exogenous factors such as environmental pollutants, and more particularly pesticides, can corrupt Aß(1-42) assembly and could influence the occurrence and pathophysiology of AD. However, pesticide involvement in the early stages of Aß(1-42) aggregation is still unknown. Here, we employed conical track-etched nanopore in order to analyse the Aß(1-42) fibril formation in the presence of pyrimethanil, a widely used fungicide belonging to the anilinopyrimidine class. Our results evidenced a pro-aggregating effect of pyrimethanil on Aß(1-42). Aß(1-42) assemblies were successfully detected using conical nanopore coated with PEG. Using an analytical model, the large current blockades observed (>0.7) were assigned to species with size close to the sensing pore. The long dwell times (hundreds ms scale) were interpreted by the possible interactions amyloid/PEG using molecular dynamic simulation. Such interaction could leave until splitting phenomena of the dimer structure. Our work also evidences that the pyrimethanil induce an aggregation of Aß(1-42) mechanism in two steps including the reorganization prior the elongation phase.