Spatial Organization of Biological Fuctions | BPS Thematic Meeting

Spatial Organization of Biological Functions Meeting

Poster Abstracts

19-POS Board 19 CHARGE-REGULATED MEMBRANE TRANSPORT: COUPLED EFFECTS OF SURFACE CHEMISTRY AND MACROION FUNCTIONALIZATION IN MULTIVALENT IONIC ENVIRONMENTS Saurav Tyagi 1 ; Sunita Kumari 1 ; 1 Indian Institute of Technology Jodhpur, Physics, Jodhpur, India The objective of this study is to elucidate how spatially patterned charge regulation on synthetic membranes and macroions governs selective transport in multivalent electrolyte solutions. Using large-scale molecular dynamics simulations with explicit charge regulation Monte Carlo moves, we constructed a model system comprising a three-layered neutral membrane with cylindrical pores, each pore lined with acid (pKₐ = 3) and base (pK_b = 3) functional groups on the lower and upper halves, respectively. A rigid macroion, functionalized with equal numbers of acidic (pKₐ = 3) and basic (pK_b = 6.5) sites, was positioned above a central pore. The system was solvated with explicit multivalent cations (Mg²⁺) and anions (SO₄²⁻).Simulations employed the LAMMPS molecular dynamics engine with the charge regulation fix, ensuring dynamic protonation/deprotonation of titratable groups in response to local pH and ionic environment. All surface and macroion sites were treated as rigid bodies to preserve structural integrity, and pairwise interactions between closely attached surface sites were excluded to prevent artificial aggregation. Results indicate that the interplay between membrane pore chemistry and macroion surface patterning leads to highly selective ion transport and macroion translocation behaviors. Acidic and basic regions of the pore dynamically modulate local ion concentrations and electric fields, promoting or inhibiting macroion passage depending on the macroion’s charge state and the local pH. The presence of both acidic and basic sites on the macroion enables tunable interactions with the membrane, leading to controllable gating and selectivity. These findings demonstrate that rational design of charge-regulated surfaces and macroion functionalization can be leveraged to control transport and selectivity in synthetic and biomimetic membranes, with implications for filtration, sensing, and nanofluidic applications.

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